{"id":1144,"date":"2017-10-19T13:20:25","date_gmt":"2017-10-19T13:20:25","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/?post_type=chapter&#038;p=1144"},"modified":"2018-10-05T17:38:00","modified_gmt":"2018-10-05T17:38:00","slug":"addition-of-carbenes-to-alkenes-cyclopropane-synthesis","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/chapter\/addition-of-carbenes-to-alkenes-cyclopropane-synthesis\/","title":{"raw":"Addition of Carbenes to Alkenes: Cyclopropane Synthesis","rendered":"Addition of Carbenes to Alkenes: Cyclopropane Synthesis"},"content":{"raw":"<div class=\"elm-header\">\r\n<div class=\"textbox learning-objectives\">\r\n<h3>Objectives<\/h3>\r\n<div id=\"elm-main-content\" class=\"elm-content-container\">\r\n<div>\r\n<div id=\"skills\">\r\n\r\nAfter completing this section, you should be able to\r\n<ol>\r\n \t<li>describe, and write the detailed mechanism for, the formation of a carbene, such as dichlorocarbene.<\/li>\r\n \t<li>describe the structure of a carbene in terms of the hybridization of the central carbon atom.<\/li>\r\n \t<li>write an equation for the formation of a substituted cyclopropane from an alkene and a carbene.<\/li>\r\n \t<li>identify the reagents, the alkene, or both, needed to prepare a given substituted cyclopropane by addition of a carbene to a double bond.<\/li>\r\n \t<li>identify the substituted cyclopropane formed from the reaction of a given alkene with the reagents necessary to form a carbene.<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div id=\"elm-main-content\" class=\"elm-content-container\">\r\n<div>\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Key TERMS<\/h3>\r\n<p class=\"boxtitle\">Key Terms<\/p>\r\nMake certain that you can define, and use in context, the key terms below.\r\n<ul>\r\n \t<li>carbene (R<sub>2<\/sub>C:)<\/li>\r\n \t<li>carbenoid<\/li>\r\n \t<li>Simmons-Smith reaction<\/li>\r\n \t<li>stereospecific<\/li>\r\n<\/ul>\r\n<\/div>\r\n<div class=\"textbox\">\r\n<h3>\u00a0Study Notes<\/h3>\r\n<div id=\"note\">\r\n\r\nA <em>carbenoid<\/em> is best considered to be a reagent which, while not actually a carbene, behaves as if it were an intermediate of this type.\r\n\r\nDichlorocarbenes can also form cyclopropane structures and are created in situ from reagents such as chloroform and KOH.<img class=\"aligncenter\" src=\"http:\/\/chem.libretexts.org\/@api\/deki\/files\/84950\/8-9a.png?origin=mt-web\" alt=\"dichlorocyclopropane structure from alkene and an in situ dichlorocarbene\" \/>\r\n\r\n&nbsp;\r\n\r\nThe detailed mechanism of the formation of dichlorocarbene is given below. Note that the deprotonation of chloroform generates the trichloromethanide anion, which spontaneously expels the chloride anion.<img class=\"aligncenter\" src=\"http:\/\/chem.libretexts.org\/@api\/deki\/files\/84948\/8-9b.png?origin=mt-web\" alt=\"mechanism of carbene generation from chloroform\" \/>\r\n\r\n&nbsp;\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\nThe highly strained nature of cyclopropane compounds makes them very reactive and interesting synthetic targets. Additionally cyclopropanes are present in numerous biological compounds. One common method of cyclopropane synthesis is the reaction of carbenes with the double bond in alkenes or cycloalkenes. Methylene, H<sub>2<\/sub>C, is simplest carbene, and in general carbenes have the formula R<sub>2<\/sub>C. Other species that will also react with alkenes to form cyclopropanes but do not follow the formula of carbenes are referred to as carbenoids.\r\n<div id=\"section_1\">\r\n<h3 class=\"editable\">Introduction<\/h3>\r\nCarbenes were once only thought of as short lived intermediates. The reactions of this section only deal with these short lived carbenes which are mostly prepared in situ, in conjunction with the main reaction. However, there do exist so called persistent carbenes. These persistent carbenes are stabilized by a variety of methods often including aromatic rings or transition metals. In general a carbene is neutral and has 6 valence electrons, 2 of which are non bonding. These electrons can either occupy the same sp<sup>2<\/sup> hybridized orbital to form a singlet carbene (with paired electrons), or two different sp<sup>2<\/sup> orbitals to from a triplet carbene (with unpaired electrons). The chemistry of triplet and singlet carbenes is quite different but can be oversimplified to the statement: singlet carbenes usually retain stereochemistry while triplet carbenes do not. The carbenes discussed in this section are singlet and thus retain stereochemistry.\r\n\r\nThe reactivity of a singlet carbene is concerted and similar to that of electrophilic or nucleophilic addition (although, triplet carbenes react like biradicals, explaining why sterochemistry is not retained). The highly reactive nature of carbenes leads to very fast reactions in which the rate determining step is generally carbene formation.\r\n\r\n<\/div>\r\n<div id=\"section_2\">\r\n<h3 class=\"editable\">Preparation of methylene<\/h3>\r\nThe preparation of methylene starts with the yellow gas diazomethane, CH<sub>2<\/sub>N<sub>2<\/sub>. Diazomethane can be exposed to light, heat or copper to facilitate the loss of nitrogen gas and the formation of the simplest carbene methylene. The process is driven by the formation of the nitrogen gas which is a very stable molecule.\r\n\r\n<img class=\"internal aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142852\/im1.jpg\" alt=\"im1.jpg\" width=\"437px\" height=\"97px\" \/>\r\n\r\n<\/div>\r\n<div id=\"section_3\">\r\n<h3 class=\"editable\">Carbene reaction with alkenes<\/h3>\r\nA carbene such as methlyene will react with an alkene which will break the double bond and result with a cyclopropane. The reaction will usually leave stereochemistry of the double bond unchanged. As stated before, carbenes are generally formed along with the main reaction; hence the starting material is diazomethane not methylene.\r\n\r\n<img class=\"internal aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142854\/im2.jpg\" alt=\"im2.jpg\" width=\"667px\" height=\"98px\" \/>\r\n\r\nIn the above case <em>cis-<\/em>2-butene is converted to <em>cis<\/em>-1,2-dimethylcyclopropane. Likewise, below the <em>trans<\/em> configuration is maintained.\r\n\r\n<img class=\"internal aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142856\/im3.jpg\" alt=\"im3.jpg\" width=\"679px\" height=\"99px\" \/>\r\n\r\n<\/div>\r\n<div id=\"section_4\">\r\n<h3 class=\"editable\">Additional Types of Carbenes and Carbenoids<\/h3>\r\nIn addition to the general carbene with formula R<sub>2<\/sub>C there exist a number of other compounds that behave in much the same way as carbenes in the synthesis of cyclopropane. <strong>Halogenated<\/strong> <strong>carbenes<\/strong> are formed from halomethanes. An example is dicholorcarbene, Cl<sub>2<\/sub>C. These halogenated carbenes will form cyclopropanes in the same manner as methylene but with the interesting presence of two halogen atoms in place of the hydrogen atoms.\r\n\r\n<strong>Carbenoids<\/strong> are substances that form cyclopropanes like carbenes but are not technically carbenes. One common example is the stereospecific Simmon-Smith reaction which utilizes the carbenoid ICH<sub>2<\/sub>ZnI. The carbenoid is formed in situ via the mixing of a Zn-Cu couple with CH<sub>2<\/sub>I<sub>2<\/sub>.Since this reacts thesame as a carbene, the same methods can be applied to determine the product. An example of this is given as problem 5.\r\n\r\n<\/div>\r\n<div id=\"section_5\">\r\n<h3 class=\"editable\">Outside links<\/h3>\r\n<ul>\r\n \t<li><a class=\"external\" title=\"http:\/\/en.wikipedia.org\/wiki\/Simmons-Smith_reaction\" href=\"http:\/\/en.wikipedia.org\/wiki\/Simmons-Smith_reaction\" rel=\"freeklink\">http:\/\/en.wikipedia.org\/wiki\/Simmons-Smith_reaction<\/a><\/li>\r\n \t<li><a class=\"external\" title=\"http:\/\/en.wikipedia.org\/wiki\/Carbene\" href=\"http:\/\/en.wikipedia.org\/wiki\/Carbene\" rel=\"freeklink\">http:\/\/en.wikipedia.org\/wiki\/Carbene<\/a><\/li>\r\n<\/ul>\r\n<\/div>\r\n<div id=\"section_6\">\r\n<div class=\"textbox examples\">\r\n<h3>Examples<\/h3>\r\n<div id=\"section_6\">\r\n<h3 class=\"editable\">Problems<\/h3>\r\n1. Knowing that cycloalkenes react much the same as regular alkenes what would be the expected structure of the product of cyclohexene and diazomethane facilitated by copper metal?\r\n\r\n2. What would be the result of a Simmons-Smith reaction that used <em>trans<\/em>-3-pentene as a reagent?\r\n\r\n3. What starting material could be used to form <em>cis<\/em>-1,2-diethylcyclopropane?\r\n\r\n4. What would the following reaction yield?\r\n\r\n<img class=\"internal aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142858\/qu4.jpg\" alt=\"qu4.jpg\" width=\"426px\" height=\"85px\" \/>\r\n\r\n5. Draw the product of this reaction. What type of reaction is this?\r\n\r\n<img class=\"internal aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142900\/qu5.jpg\" alt=\"qu5.jpg\" width=\"453px\" height=\"109px\" \/>\r\n\r\n<\/div>\r\n<div id=\"section_7\">\r\n<h3 class=\"editable\">Answers<\/h3>\r\n1.\r\n[reveal-answer q=\"3141\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"3141\"]The product will be a bicyclic ring, Bicyclo[4.1.0]heptane.\r\n\r\n<img class=\"internal aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142902\/ans1.jpg\" alt=\"ans1.jpg\" width=\"643px\" height=\"95px\" \/>[\/hidden-answer]\r\n\r\n2.\r\n\r\n[reveal-answer q=\"565478\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"565478\"]The stereochemistry will be retained making a cyclopropane with trans methyl and ethyl groups. Trans-1-ethyl-2-methylcyclopropane[\/hidden-answer]\r\n\r\n3.\r\n[reveal-answer q=\"126706\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"126706\"]The cis configuration will be maintained from reagent to product so we would want to start with cis-3-hexene. A Simmons Smith reagent, or methylene could be used as the carbene or carbenoid.[\/hidden-answer]\r\n\r\n4.\r\n[reveal-answer q=\"141423\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"141423\"]The halogenated carbene will react the same as methylene yielding, cis-1,1-dichloro-2,3dimethylcyclopropane.<img class=\"internal aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142904\/ans4_1.jpg\" alt=\"ans4 (1).jpg\" width=\"158px\" height=\"105px\" \/>[\/hidden-answer]\r\n\r\n5.\r\n[reveal-answer q=\"929940\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"929940\"] This is a Simmons-Smith reaction which uses the carbenoid formed by the CH2I2 and Zu-Cu. The reaction results in the same product as if methylene was used and retains stereospecificity. Iodine metal and the Zn-Cu are not part of the product. The product is trans-1,2-ethyl-methylcyclopropane.<a title=\"ans5.jpg\" href=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2013\/ans5.jpg?revision=1\" rel=\"internal\"><img class=\"internal aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142905\/ans5.jpg\" alt=\"ans5.jpg\" width=\"622px\" height=\"126px\" \/><\/a>[\/hidden-answer]\r\n\r\n&nbsp;\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div id=\"section_7\"><\/div>\r\n<div id=\"section_8\">\r\n<h3 class=\"editable\">References<\/h3>\r\n<ol>\r\n \t<li>Vollhardt, K. Peter C. and Schore, Neil E. <u>Organic Chemistry: Structure and Function<\/u>. New York: Bleyer, Brennan, 2007.<\/li>\r\n \t<li>Abdel-Wahab, Aboel-Magd A. Ahmed, Saleh A. and D\u00fcrr, Heinz. \"Carbene Formation by Extrusion of Nitrogen\" in <u>CRC Handbook of Organic Photochemistry and Photobiology.<\/u> CRC Press, 2004.<\/li>\r\n<\/ol>\r\n<\/div>\r\n<div id=\"section_9\">\r\n<div class=\"textbox exercises\">\r\n<h3 class=\"editable\">Exercise<\/h3>\r\n<div id=\"s61713\">\r\n<div id=\"section_30\">\r\n<h4 id=\"Questions-61713\">Question<\/h4>\r\n<b>1.<\/b>\r\n\r\nPredict the following products. Will they be the same product?\r\n\r\n<img class=\"internal default aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142913\/8-9qu.png\" alt=\"\" width=\"333\" height=\"228\" \/>\r\n\r\n<\/div>\r\n<div id=\"section_31\">\r\n<h3 id=\"Solutions-61713\">Solution<\/h3>\r\n<b>1.\u00a0<\/b>\r\n\r\n[reveal-answer q=\"643115\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"643115\"]\r\n\r\nNo they will not be the same product, they will be isomers of each other.\r\n\r\n<img class=\"internal default aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142916\/8-9sol.png\" alt=\"\" width=\"594\" height=\"236\" \/>[\/hidden-answer]\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div id=\"section_10\">\r\n<h3 class=\"editable\">Contributors<\/h3>\r\n<ul>\r\n \t<li><a class=\"external\" title=\"http:\/\/science.athabascau.ca\/staff-pages\/dietmark\" href=\"http:\/\/science.athabascau.ca\/staff-pages\/dietmark\" target=\"_blank\" rel=\"external nofollow noopener\">Dr. Dietmar Kennepohl<\/a> FCIC (Professor of Chemistry, <a class=\"external\" title=\"http:\/\/www.athabascau.ca\/\" href=\"http:\/\/www.athabascau.ca\/\" target=\"_blank\" rel=\"external nofollow noopener\">Athabasca University<\/a>)<\/li>\r\n \t<li>Prof. Steven Farmer (<a class=\"external\" title=\"http:\/\/www.sonoma.edu\" href=\"http:\/\/www.sonoma.edu\" target=\"_blank\" rel=\"external nofollow noopener\">Sonoma State University<\/a>)<\/li>\r\n \t<li>Paul Tisher<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>","rendered":"<div class=\"elm-header\">\n<div class=\"textbox learning-objectives\">\n<h3>Objectives<\/h3>\n<div id=\"elm-main-content\" class=\"elm-content-container\">\n<div>\n<div id=\"skills\">\n<p>After completing this section, you should be able to<\/p>\n<ol>\n<li>describe, and write the detailed mechanism for, the formation of a carbene, such as dichlorocarbene.<\/li>\n<li>describe the structure of a carbene in terms of the hybridization of the central carbon atom.<\/li>\n<li>write an equation for the formation of a substituted cyclopropane from an alkene and a carbene.<\/li>\n<li>identify the reagents, the alkene, or both, needed to prepare a given substituted cyclopropane by addition of a carbene to a double bond.<\/li>\n<li>identify the substituted cyclopropane formed from the reaction of a given alkene with the reagents necessary to form a carbene.<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"elm-main-content\" class=\"elm-content-container\">\n<div>\n<div class=\"textbox key-takeaways\">\n<h3>Key TERMS<\/h3>\n<p class=\"boxtitle\">Key Terms<\/p>\n<p>Make certain that you can define, and use in context, the key terms below.<\/p>\n<ul>\n<li>carbene (R<sub>2<\/sub>C:)<\/li>\n<li>carbenoid<\/li>\n<li>Simmons-Smith reaction<\/li>\n<li>stereospecific<\/li>\n<\/ul>\n<\/div>\n<div class=\"textbox\">\n<h3>\u00a0Study Notes<\/h3>\n<div id=\"note\">\n<p>A <em>carbenoid<\/em> is best considered to be a reagent which, while not actually a carbene, behaves as if it were an intermediate of this type.<\/p>\n<p>Dichlorocarbenes can also form cyclopropane structures and are created in situ from reagents such as chloroform and KOH.<img decoding=\"async\" class=\"aligncenter\" src=\"http:\/\/chem.libretexts.org\/@api\/deki\/files\/84950\/8-9a.png?origin=mt-web\" alt=\"dichlorocyclopropane structure from alkene and an in situ dichlorocarbene\" \/><\/p>\n<p>&nbsp;<\/p>\n<p>The detailed mechanism of the formation of dichlorocarbene is given below. Note that the deprotonation of chloroform generates the trichloromethanide anion, which spontaneously expels the chloride anion.<img decoding=\"async\" class=\"aligncenter\" src=\"http:\/\/chem.libretexts.org\/@api\/deki\/files\/84948\/8-9b.png?origin=mt-web\" alt=\"mechanism of carbene generation from chloroform\" \/><\/p>\n<p>&nbsp;<\/p>\n<\/div>\n<\/div>\n<\/div>\n<p>The highly strained nature of cyclopropane compounds makes them very reactive and interesting synthetic targets. Additionally cyclopropanes are present in numerous biological compounds. One common method of cyclopropane synthesis is the reaction of carbenes with the double bond in alkenes or cycloalkenes. Methylene, H<sub>2<\/sub>C, is simplest carbene, and in general carbenes have the formula R<sub>2<\/sub>C. Other species that will also react with alkenes to form cyclopropanes but do not follow the formula of carbenes are referred to as carbenoids.<\/p>\n<div id=\"section_1\">\n<h3 class=\"editable\">Introduction<\/h3>\n<p>Carbenes were once only thought of as short lived intermediates. The reactions of this section only deal with these short lived carbenes which are mostly prepared in situ, in conjunction with the main reaction. However, there do exist so called persistent carbenes. These persistent carbenes are stabilized by a variety of methods often including aromatic rings or transition metals. In general a carbene is neutral and has 6 valence electrons, 2 of which are non bonding. These electrons can either occupy the same sp<sup>2<\/sup> hybridized orbital to form a singlet carbene (with paired electrons), or two different sp<sup>2<\/sup> orbitals to from a triplet carbene (with unpaired electrons). The chemistry of triplet and singlet carbenes is quite different but can be oversimplified to the statement: singlet carbenes usually retain stereochemistry while triplet carbenes do not. The carbenes discussed in this section are singlet and thus retain stereochemistry.<\/p>\n<p>The reactivity of a singlet carbene is concerted and similar to that of electrophilic or nucleophilic addition (although, triplet carbenes react like biradicals, explaining why sterochemistry is not retained). The highly reactive nature of carbenes leads to very fast reactions in which the rate determining step is generally carbene formation.<\/p>\n<\/div>\n<div id=\"section_2\">\n<h3 class=\"editable\">Preparation of methylene<\/h3>\n<p>The preparation of methylene starts with the yellow gas diazomethane, CH<sub>2<\/sub>N<sub>2<\/sub>. Diazomethane can be exposed to light, heat or copper to facilitate the loss of nitrogen gas and the formation of the simplest carbene methylene. The process is driven by the formation of the nitrogen gas which is a very stable molecule.<\/p>\n<p><img decoding=\"async\" class=\"internal aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142852\/im1.jpg\" alt=\"im1.jpg\" width=\"437px\" height=\"97px\" \/><\/p>\n<\/div>\n<div id=\"section_3\">\n<h3 class=\"editable\">Carbene reaction with alkenes<\/h3>\n<p>A carbene such as methlyene will react with an alkene which will break the double bond and result with a cyclopropane. The reaction will usually leave stereochemistry of the double bond unchanged. As stated before, carbenes are generally formed along with the main reaction; hence the starting material is diazomethane not methylene.<\/p>\n<p><img decoding=\"async\" class=\"internal aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142854\/im2.jpg\" alt=\"im2.jpg\" width=\"667px\" height=\"98px\" \/><\/p>\n<p>In the above case <em>cis-<\/em>2-butene is converted to <em>cis<\/em>-1,2-dimethylcyclopropane. Likewise, below the <em>trans<\/em> configuration is maintained.<\/p>\n<p><img decoding=\"async\" class=\"internal aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142856\/im3.jpg\" alt=\"im3.jpg\" width=\"679px\" height=\"99px\" \/><\/p>\n<\/div>\n<div id=\"section_4\">\n<h3 class=\"editable\">Additional Types of Carbenes and Carbenoids<\/h3>\n<p>In addition to the general carbene with formula R<sub>2<\/sub>C there exist a number of other compounds that behave in much the same way as carbenes in the synthesis of cyclopropane. <strong>Halogenated<\/strong> <strong>carbenes<\/strong> are formed from halomethanes. An example is dicholorcarbene, Cl<sub>2<\/sub>C. These halogenated carbenes will form cyclopropanes in the same manner as methylene but with the interesting presence of two halogen atoms in place of the hydrogen atoms.<\/p>\n<p><strong>Carbenoids<\/strong> are substances that form cyclopropanes like carbenes but are not technically carbenes. One common example is the stereospecific Simmon-Smith reaction which utilizes the carbenoid ICH<sub>2<\/sub>ZnI. The carbenoid is formed in situ via the mixing of a Zn-Cu couple with CH<sub>2<\/sub>I<sub>2<\/sub>.Since this reacts thesame as a carbene, the same methods can be applied to determine the product. An example of this is given as problem 5.<\/p>\n<\/div>\n<div id=\"section_5\">\n<h3 class=\"editable\">Outside links<\/h3>\n<ul>\n<li><a class=\"external\" title=\"http:\/\/en.wikipedia.org\/wiki\/Simmons-Smith_reaction\" href=\"http:\/\/en.wikipedia.org\/wiki\/Simmons-Smith_reaction\" rel=\"freeklink\">http:\/\/en.wikipedia.org\/wiki\/Simmons-Smith_reaction<\/a><\/li>\n<li><a class=\"external\" title=\"http:\/\/en.wikipedia.org\/wiki\/Carbene\" href=\"http:\/\/en.wikipedia.org\/wiki\/Carbene\" rel=\"freeklink\">http:\/\/en.wikipedia.org\/wiki\/Carbene<\/a><\/li>\n<\/ul>\n<\/div>\n<div id=\"section_6\">\n<div class=\"textbox examples\">\n<h3>Examples<\/h3>\n<div id=\"section_6\">\n<h3 class=\"editable\">Problems<\/h3>\n<p>1. Knowing that cycloalkenes react much the same as regular alkenes what would be the expected structure of the product of cyclohexene and diazomethane facilitated by copper metal?<\/p>\n<p>2. What would be the result of a Simmons-Smith reaction that used <em>trans<\/em>-3-pentene as a reagent?<\/p>\n<p>3. What starting material could be used to form <em>cis<\/em>-1,2-diethylcyclopropane?<\/p>\n<p>4. What would the following reaction yield?<\/p>\n<p><img decoding=\"async\" class=\"internal aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142858\/qu4.jpg\" alt=\"qu4.jpg\" width=\"426px\" height=\"85px\" \/><\/p>\n<p>5. Draw the product of this reaction. What type of reaction is this?<\/p>\n<p><img decoding=\"async\" class=\"internal aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142900\/qu5.jpg\" alt=\"qu5.jpg\" width=\"453px\" height=\"109px\" \/><\/p>\n<\/div>\n<div id=\"section_7\">\n<h3 class=\"editable\">Answers<\/h3>\n<p>1.<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q3141\">Show Answer<\/span><\/p>\n<div id=\"q3141\" class=\"hidden-answer\" style=\"display: none\">The product will be a bicyclic ring, Bicyclo[4.1.0]heptane.<\/p>\n<p><img decoding=\"async\" class=\"internal aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142902\/ans1.jpg\" alt=\"ans1.jpg\" width=\"643px\" height=\"95px\" \/><\/div>\n<\/div>\n<p>2.<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q565478\">Show Answer<\/span><\/p>\n<div id=\"q565478\" class=\"hidden-answer\" style=\"display: none\">The stereochemistry will be retained making a cyclopropane with trans methyl and ethyl groups. Trans-1-ethyl-2-methylcyclopropane<\/div>\n<\/div>\n<p>3.<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q126706\">Show Answer<\/span><\/p>\n<div id=\"q126706\" class=\"hidden-answer\" style=\"display: none\">The cis configuration will be maintained from reagent to product so we would want to start with cis-3-hexene. A Simmons Smith reagent, or methylene could be used as the carbene or carbenoid.<\/div>\n<\/div>\n<p>4.<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q141423\">Show Answer<\/span><\/p>\n<div id=\"q141423\" class=\"hidden-answer\" style=\"display: none\">The halogenated carbene will react the same as methylene yielding, cis-1,1-dichloro-2,3dimethylcyclopropane.<img decoding=\"async\" class=\"internal aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142904\/ans4_1.jpg\" alt=\"ans4 (1).jpg\" width=\"158px\" height=\"105px\" \/><\/div>\n<\/div>\n<p>5.<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q929940\">Show Answer<\/span><\/p>\n<div id=\"q929940\" class=\"hidden-answer\" style=\"display: none\"> This is a Simmons-Smith reaction which uses the carbenoid formed by the CH2I2 and Zu-Cu. The reaction results in the same product as if methylene was used and retains stereospecificity. Iodine metal and the Zn-Cu are not part of the product. The product is trans-1,2-ethyl-methylcyclopropane.<a title=\"ans5.jpg\" href=\"https:\/\/chem.libretexts.org\/@api\/deki\/files\/2013\/ans5.jpg?revision=1\" rel=\"internal\"><img decoding=\"async\" class=\"internal aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142905\/ans5.jpg\" alt=\"ans5.jpg\" width=\"622px\" height=\"126px\" \/><\/a><\/div>\n<\/div>\n<p>&nbsp;<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"section_7\"><\/div>\n<div id=\"section_8\">\n<h3 class=\"editable\">References<\/h3>\n<ol>\n<li>Vollhardt, K. Peter C. and Schore, Neil E. <u>Organic Chemistry: Structure and Function<\/u>. New York: Bleyer, Brennan, 2007.<\/li>\n<li>Abdel-Wahab, Aboel-Magd A. Ahmed, Saleh A. and D\u00fcrr, Heinz. &#8220;Carbene Formation by Extrusion of Nitrogen&#8221; in <u>CRC Handbook of Organic Photochemistry and Photobiology.<\/u> CRC Press, 2004.<\/li>\n<\/ol>\n<\/div>\n<div id=\"section_9\">\n<div class=\"textbox exercises\">\n<h3 class=\"editable\">Exercise<\/h3>\n<div id=\"s61713\">\n<div id=\"section_30\">\n<h4 id=\"Questions-61713\">Question<\/h4>\n<p><b>1.<\/b><\/p>\n<p>Predict the following products. Will they be the same product?<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"internal default aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142913\/8-9qu.png\" alt=\"\" width=\"333\" height=\"228\" \/><\/p>\n<\/div>\n<div id=\"section_31\">\n<h3 id=\"Solutions-61713\">Solution<\/h3>\n<p><b>1.\u00a0<\/b><\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q643115\">Show Answer<\/span><\/p>\n<div id=\"q643115\" class=\"hidden-answer\" style=\"display: none\">\n<p>No they will not be the same product, they will be isomers of each other.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"internal default aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1518\/2017\/10\/05142916\/8-9sol.png\" alt=\"\" width=\"594\" height=\"236\" \/><\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"section_10\">\n<h3 class=\"editable\">Contributors<\/h3>\n<ul>\n<li><a class=\"external\" title=\"http:\/\/science.athabascau.ca\/staff-pages\/dietmark\" href=\"http:\/\/science.athabascau.ca\/staff-pages\/dietmark\" target=\"_blank\" rel=\"external nofollow noopener\">Dr. Dietmar Kennepohl<\/a> FCIC (Professor of Chemistry, <a class=\"external\" title=\"http:\/\/www.athabascau.ca\/\" href=\"http:\/\/www.athabascau.ca\/\" target=\"_blank\" rel=\"external nofollow noopener\">Athabasca University<\/a>)<\/li>\n<li>Prof. Steven Farmer (<a class=\"external\" title=\"http:\/\/www.sonoma.edu\" href=\"http:\/\/www.sonoma.edu\" target=\"_blank\" rel=\"external nofollow noopener\">Sonoma State University<\/a>)<\/li>\n<li>Paul Tisher<\/li>\n<\/ul>\n<\/div>\n<\/div>\n","protected":false},"author":44985,"menu_order":8,"template":"","meta":{"_candela_citation":"[]","CANDELA_OUTCOMES_GUID":"","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-1144","chapter","type-chapter","status-publish","hentry"],"part":24,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/pressbooks\/v2\/chapters\/1144","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/wp\/v2\/users\/44985"}],"version-history":[{"count":5,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/pressbooks\/v2\/chapters\/1144\/revisions"}],"predecessor-version":[{"id":2309,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/pressbooks\/v2\/chapters\/1144\/revisions\/2309"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/pressbooks\/v2\/parts\/24"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/pressbooks\/v2\/chapters\/1144\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/wp\/v2\/media?parent=1144"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/pressbooks\/v2\/chapter-type?post=1144"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/wp\/v2\/contributor?post=1144"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-organicchemistry\/wp-json\/wp\/v2\/license?post=1144"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}