Sn(OTf)2 as an Effective Lewis Acid in Reactions of Cyclopropyl Ketones with Acetic Anhydride: Application in the Synthesis of a 19-Nor-B-homo Steroid
Attempts to convert 3β‐acetoxy‐5,19‐cyclo‐pregna‐6,20‐dione (8) into a cyclocitrinol‐related steroid with a bicyclo[4.4.1]‐undecane AB‐ring substructure through a Lewis acid‐assisted fragmentation failed. Instead, treating 8 with an excess of Ac2O and BF3·Et2O afforded B‐homo steroid 9 in 90 % yield...
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| Veröffentlicht in: | European Journal of Organic Chemistry 2011-05, Vol.2011 (15), p.2860-2866 |
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| container_issue | 15 |
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| container_title | European Journal of Organic Chemistry |
| container_volume | 2011 |
| creator | Kranz, Darius Paul Meier zu Greffen, Aike El Sheikh, Sherif Neudörfl, Jörg Martin Schmalz, Hans-Günther |
| description | Attempts to convert 3β‐acetoxy‐5,19‐cyclo‐pregna‐6,20‐dione (8) into a cyclocitrinol‐related steroid with a bicyclo[4.4.1]‐undecane AB‐ring substructure through a Lewis acid‐assisted fragmentation failed. Instead, treating 8 with an excess of Ac2O and BF3·Et2O afforded B‐homo steroid 9 in 90 % yield. This unexpected rearrangement is assumed to proceed via an intermediate bicyclobutonium cation. Remarkably, tricyclo[4.4.1.0]undecane‐1‐one (rac‐13), prepared as a model substrate, did not react under the same conditions. However, by screening various Lewis acids, stannous triflate was identified as a particularly efficient reagent for this and related Lewis acid‐assisted ring‐opening reactions of cyclopropyl ketones in the presence of Ac2O, and even catalytic amounts of Sn(OTf)2 (5 mol‐%) proved to be effective.
The Lewis acid‐mediated ring‐opening rearrangement of bicyclo[4.4.1.0]‐undecane‐1‐one and related cyclopropyl ketones proceeds smoothly using a combination of stannous triflate [Sn(OTf)2] and Ac2O. |
| doi_str_mv | 10.1002/ejoc.201100020 |
| format | Article |
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The Lewis acid‐mediated ring‐opening rearrangement of bicyclo[4.4.1.0]‐undecane‐1‐one and related cyclopropyl ketones proceeds smoothly using a combination of stannous triflate [Sn(OTf)2] and Ac2O.</description><identifier>ISSN: 1434-193X</identifier><identifier>EISSN: 1099-0690</identifier><identifier>DOI: 10.1002/ejoc.201100020</identifier><language>eng</language><publisher>Weinheim: WILEY-VCH Verlag</publisher><subject>Alicyclic compounds ; Alicyclic compounds, terpenoids, prostaglandins, steroids ; Cations ; Chemistry ; Exact sciences and technology ; Fused-ring systems ; Lewis acids ; Organic chemistry ; Preparations and properties ; Rearrangement ; Steroids</subject><ispartof>European Journal of Organic Chemistry, 2011-05, Vol.2011 (15), p.2860-2866</ispartof><rights>Copyright © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim</rights><rights>2015 INIST-CNRS</rights><lds50>peer_reviewed</lds50><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-c2720-2b5693a6e49a87cfa51e5d75ff463dc675de4a87fe31bf6355f55c35746d94b43</citedby><cites>FETCH-LOGICAL-c2720-2b5693a6e49a87cfa51e5d75ff463dc675de4a87fe31bf6355f55c35746d94b43</cites></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><linktopdf>$$Uhttps://onlinelibrary.wiley.com/doi/pdf/10.1002%2Fejoc.201100020$$EPDF$$P50$$Gwiley$$H</linktopdf><linktohtml>$$Uhttps://onlinelibrary.wiley.com/doi/full/10.1002%2Fejoc.201100020$$EHTML$$P50$$Gwiley$$H</linktohtml><link.rule.ids>313,314,776,780,788,1411,27899,27901,27902,45550,45551</link.rule.ids><backlink>$$Uhttp://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=24190574$$DView record in Pascal Francis$$Hfree_for_read</backlink></links><search><creatorcontrib>Kranz, Darius Paul</creatorcontrib><creatorcontrib>Meier zu Greffen, Aike</creatorcontrib><creatorcontrib>El Sheikh, Sherif</creatorcontrib><creatorcontrib>Neudörfl, Jörg Martin</creatorcontrib><creatorcontrib>Schmalz, Hans-Günther</creatorcontrib><title>Sn(OTf)2 as an Effective Lewis Acid in Reactions of Cyclopropyl Ketones with Acetic Anhydride: Application in the Synthesis of a 19-Nor-B-homo Steroid</title><title>European Journal of Organic Chemistry</title><addtitle>Eur. J. Org. Chem</addtitle><description>Attempts to convert 3β‐acetoxy‐5,19‐cyclo‐pregna‐6,20‐dione (8) into a cyclocitrinol‐related steroid with a bicyclo[4.4.1]‐undecane AB‐ring substructure through a Lewis acid‐assisted fragmentation failed. Instead, treating 8 with an excess of Ac2O and BF3·Et2O afforded B‐homo steroid 9 in 90 % yield. This unexpected rearrangement is assumed to proceed via an intermediate bicyclobutonium cation. Remarkably, tricyclo[4.4.1.0]undecane‐1‐one (rac‐13), prepared as a model substrate, did not react under the same conditions. However, by screening various Lewis acids, stannous triflate was identified as a particularly efficient reagent for this and related Lewis acid‐assisted ring‐opening reactions of cyclopropyl ketones in the presence of Ac2O, and even catalytic amounts of Sn(OTf)2 (5 mol‐%) proved to be effective.
The Lewis acid‐mediated ring‐opening rearrangement of bicyclo[4.4.1.0]‐undecane‐1‐one and related cyclopropyl ketones proceeds smoothly using a combination of stannous triflate [Sn(OTf)2] and Ac2O.</description><subject>Alicyclic compounds</subject><subject>Alicyclic compounds, terpenoids, prostaglandins, steroids</subject><subject>Cations</subject><subject>Chemistry</subject><subject>Exact sciences and technology</subject><subject>Fused-ring systems</subject><subject>Lewis acids</subject><subject>Organic chemistry</subject><subject>Preparations and properties</subject><subject>Rearrangement</subject><subject>Steroids</subject><issn>1434-193X</issn><issn>1099-0690</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2011</creationdate><recordtype>article</recordtype><recordid>eNqFkEtvEzEURkcIpJbCtmtvkGDh4PdgdiEK5ZEmUtMKxMZyPNeKy3Q8skek80f4vXVIFbHr6vrxnXOlr6rOKZlQQth7uI1uwggtF8LIs-qUEq0xUZo8L2fBBaaa_zypXuZ8WyJaKXpa_V13b1fX_h1DNiPbobn34IbwB9ACdiGjqQsNCh26AlueY5dR9Gg2ujb2KfZji77DEDvIaBeGbUnDEByadtuxSaGBj2ja921wdo_uNcMW0Hrsysjhn8oiqvEyJvwJb-NdROsBUgzNq-qFt22G14_zrLr5PL-efcGL1cXX2XSBHasZwWwjleZWgdD2Q-28lRRkU0vvheKNU7VsQJQfD5xuvOJSeikdl7VQjRYbwc-qycHrUsw5gTd9Cnc2jYYSs2_V7Fs1x1YL8OYA9DY72_pkOxfykWKCalL0JacPuV1oYXzCaubfVrP_d-ADG_IA90fWpt9G1byW5sfywlxdLrVgC25-8Qeaipfo</recordid><startdate>201105</startdate><enddate>201105</enddate><creator>Kranz, Darius Paul</creator><creator>Meier zu Greffen, Aike</creator><creator>El Sheikh, Sherif</creator><creator>Neudörfl, Jörg Martin</creator><creator>Schmalz, Hans-Günther</creator><general>WILEY-VCH Verlag</general><general>WILEY‐VCH Verlag</general><general>Wiley-VCH</general><scope>BSCLL</scope><scope>IQODW</scope><scope>AAYXX</scope><scope>CITATION</scope></search><sort><creationdate>201105</creationdate><title>Sn(OTf)2 as an Effective Lewis Acid in Reactions of Cyclopropyl Ketones with Acetic Anhydride: Application in the Synthesis of a 19-Nor-B-homo Steroid</title><author>Kranz, Darius Paul ; Meier zu Greffen, Aike ; El Sheikh, Sherif ; Neudörfl, Jörg Martin ; Schmalz, Hans-Günther</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c2720-2b5693a6e49a87cfa51e5d75ff463dc675de4a87fe31bf6355f55c35746d94b43</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2011</creationdate><topic>Alicyclic compounds</topic><topic>Alicyclic compounds, terpenoids, prostaglandins, steroids</topic><topic>Cations</topic><topic>Chemistry</topic><topic>Exact sciences and technology</topic><topic>Fused-ring systems</topic><topic>Lewis acids</topic><topic>Organic chemistry</topic><topic>Preparations and properties</topic><topic>Rearrangement</topic><topic>Steroids</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Kranz, Darius Paul</creatorcontrib><creatorcontrib>Meier zu Greffen, Aike</creatorcontrib><creatorcontrib>El Sheikh, Sherif</creatorcontrib><creatorcontrib>Neudörfl, Jörg Martin</creatorcontrib><creatorcontrib>Schmalz, Hans-Günther</creatorcontrib><collection>Istex</collection><collection>Pascal-Francis</collection><collection>CrossRef</collection><jtitle>European Journal of Organic Chemistry</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Kranz, Darius Paul</au><au>Meier zu Greffen, Aike</au><au>El Sheikh, Sherif</au><au>Neudörfl, Jörg Martin</au><au>Schmalz, Hans-Günther</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Sn(OTf)2 as an Effective Lewis Acid in Reactions of Cyclopropyl Ketones with Acetic Anhydride: Application in the Synthesis of a 19-Nor-B-homo Steroid</atitle><jtitle>European Journal of Organic Chemistry</jtitle><addtitle>Eur. J. Org. Chem</addtitle><date>2011-05</date><risdate>2011</risdate><volume>2011</volume><issue>15</issue><spage>2860</spage><epage>2866</epage><pages>2860-2866</pages><issn>1434-193X</issn><eissn>1099-0690</eissn><abstract>Attempts to convert 3β‐acetoxy‐5,19‐cyclo‐pregna‐6,20‐dione (8) into a cyclocitrinol‐related steroid with a bicyclo[4.4.1]‐undecane AB‐ring substructure through a Lewis acid‐assisted fragmentation failed. Instead, treating 8 with an excess of Ac2O and BF3·Et2O afforded B‐homo steroid 9 in 90 % yield. This unexpected rearrangement is assumed to proceed via an intermediate bicyclobutonium cation. Remarkably, tricyclo[4.4.1.0]undecane‐1‐one (rac‐13), prepared as a model substrate, did not react under the same conditions. However, by screening various Lewis acids, stannous triflate was identified as a particularly efficient reagent for this and related Lewis acid‐assisted ring‐opening reactions of cyclopropyl ketones in the presence of Ac2O, and even catalytic amounts of Sn(OTf)2 (5 mol‐%) proved to be effective.
The Lewis acid‐mediated ring‐opening rearrangement of bicyclo[4.4.1.0]‐undecane‐1‐one and related cyclopropyl ketones proceeds smoothly using a combination of stannous triflate [Sn(OTf)2] and Ac2O.</abstract><cop>Weinheim</cop><pub>WILEY-VCH Verlag</pub><doi>10.1002/ejoc.201100020</doi><tpages>7</tpages></addata></record> |
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| source | Wiley Online Library Journals Frontfile Complete |
| subjects | Alicyclic compounds Alicyclic compounds, terpenoids, prostaglandins, steroids Cations Chemistry Exact sciences and technology Fused-ring systems Lewis acids Organic chemistry Preparations and properties Rearrangement Steroids |
| title | Sn(OTf)2 as an Effective Lewis Acid in Reactions of Cyclopropyl Ketones with Acetic Anhydride: Application in the Synthesis of a 19-Nor-B-homo Steroid |
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