Unusually Low Barrier to Carbamate C−N Rotation
The barrier for rotation about an N-alkylcarbamate C(carbonyl)−N bond is around 16 kcal/mol. In the case of an N-phenylcarbamate, the rotational barrier is lowered to 12.5 kcal/mol, but with N-(2-pyrimidyl)carbamates the barriers are so low (
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| Veröffentlicht in: | Journal of organic chemistry 2002-05, Vol.67 (11), p.3949-3952 |
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| container_end_page | 3952 |
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| container_issue | 11 |
| container_start_page | 3949 |
| container_title | Journal of organic chemistry |
| container_volume | 67 |
| creator | Deetz, Martin J Forbes, Christopher C Jonas, Marco Malerich, Jeremiah P Smith, Bradley D Wiest, Olaf |
| description | The barrier for rotation about an N-alkylcarbamate C(carbonyl)−N bond is around 16 kcal/mol. In the case of an N-phenylcarbamate, the rotational barrier is lowered to 12.5 kcal/mol, but with N-(2-pyrimidyl)carbamates the barriers are so low ( |
| doi_str_mv | 10.1021/jo025554u |
| format | Article |
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In the case of an N-phenylcarbamate, the rotational barrier is lowered to 12.5 kcal/mol, but with N-(2-pyrimidyl)carbamates the barriers are so low (<9 kcal/mol) that the syn and anti rotamers cannot be observed as separate signals by 500 MHz NMR spectroscopy at 183 K. X-ray and computational data show that the N-(2-pyrimidyl) carbamates have C(carbonyl)−N bonds that are on average 0.03 Å longer than for related N-phenylcarbamates. The computational results trace the origin of the effect to increased single bond character for the C(carbonyl)−N bond due to the increased electron-withdrawing ability of the pyrimidyl ring.</description><identifier>ISSN: 0022-3263</identifier><identifier>EISSN: 1520-6904</identifier><identifier>DOI: 10.1021/jo025554u</identifier><identifier>PMID: 12027723</identifier><identifier>CODEN: JOCEAH</identifier><language>eng</language><publisher>Washington, DC: American Chemical Society</publisher><subject>Chemistry ; Exact sciences and technology ; Heterocyclic compounds ; Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings ; Organic chemistry ; Preparations and properties</subject><ispartof>Journal of organic chemistry, 2002-05, Vol.67 (11), p.3949-3952</ispartof><rights>Copyright © 2002 American Chemical Society</rights><rights>2003 INIST-CNRS</rights><lds50>peer_reviewed</lds50><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-a445t-fa3f36ac79898fadbca3dffae3f719eea78618d9bb79ed65b6717eb89677d1f23</citedby><cites>FETCH-LOGICAL-a445t-fa3f36ac79898fadbca3dffae3f719eea78618d9bb79ed65b6717eb89677d1f23</cites></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><linktopdf>$$Uhttps://pubs.acs.org/doi/pdf/10.1021/jo025554u$$EPDF$$P50$$Gacs$$H</linktopdf><linktohtml>$$Uhttps://pubs.acs.org/doi/10.1021/jo025554u$$EHTML$$P50$$Gacs$$H</linktohtml><link.rule.ids>314,780,784,2765,27076,27924,27925,56738,56788</link.rule.ids><backlink>$$Uhttp://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=13698249$$DView record in Pascal Francis$$Hfree_for_read</backlink><backlink>$$Uhttps://www.ncbi.nlm.nih.gov/pubmed/12027723$$D View this record in MEDLINE/PubMed$$Hfree_for_read</backlink></links><search><creatorcontrib>Deetz, Martin J</creatorcontrib><creatorcontrib>Forbes, Christopher C</creatorcontrib><creatorcontrib>Jonas, Marco</creatorcontrib><creatorcontrib>Malerich, Jeremiah P</creatorcontrib><creatorcontrib>Smith, Bradley D</creatorcontrib><creatorcontrib>Wiest, Olaf</creatorcontrib><title>Unusually Low Barrier to Carbamate C−N Rotation</title><title>Journal of organic chemistry</title><addtitle>J. Org. Chem</addtitle><description>The barrier for rotation about an N-alkylcarbamate C(carbonyl)−N bond is around 16 kcal/mol. In the case of an N-phenylcarbamate, the rotational barrier is lowered to 12.5 kcal/mol, but with N-(2-pyrimidyl)carbamates the barriers are so low (<9 kcal/mol) that the syn and anti rotamers cannot be observed as separate signals by 500 MHz NMR spectroscopy at 183 K. X-ray and computational data show that the N-(2-pyrimidyl) carbamates have C(carbonyl)−N bonds that are on average 0.03 Å longer than for related N-phenylcarbamates. The computational results trace the origin of the effect to increased single bond character for the C(carbonyl)−N bond due to the increased electron-withdrawing ability of the pyrimidyl ring.</description><subject>Chemistry</subject><subject>Exact sciences and technology</subject><subject>Heterocyclic compounds</subject><subject>Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings</subject><subject>Organic chemistry</subject><subject>Preparations and properties</subject><issn>0022-3263</issn><issn>1520-6904</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2002</creationdate><recordtype>article</recordtype><recordid>eNpt0L1OwzAUBWALgWgpDLwAygISQ8A_iR2PUCggSkG0na2bxJZS0qTYiaBvwMwj8iQYtWoX7uLhfj66OggdE3xBMCWXsxrTOI6jdgd1SUxxyCWOdlEXY0pDRjnroAPnZtiPZ_uoQyimQlDWRWRata6FslwGw_ojuAZrC22Dpg76YFOYQ6OD_s_X9yh4rRtoiro6RHsGSqeP1m8PTQe3k_59OHy-e-hfDUOIorgJDTDDOGRCJjIxkKcZsNwY0MwIIrUGkXCS5DJNhdQ5j1MuiNBpIrkQOTGU9dDZKndh6_dWu0bNC5fpsoRK161TnpOIEe7h-QpmtnbOaqMWtpiDXSqC1V8_atOPtyfr0Dad63wr14V4cLoG4DIojYUqK9zWMS4TGknvwpUrXKM_N3uwb4oLJmI1eRmrm9H48WkgJv7bJhcy5-9pbeW7--fAX2EtiHo</recordid><startdate>20020531</startdate><enddate>20020531</enddate><creator>Deetz, Martin J</creator><creator>Forbes, Christopher C</creator><creator>Jonas, Marco</creator><creator>Malerich, Jeremiah P</creator><creator>Smith, Bradley D</creator><creator>Wiest, Olaf</creator><general>American Chemical Society</general><scope>BSCLL</scope><scope>IQODW</scope><scope>NPM</scope><scope>AAYXX</scope><scope>CITATION</scope><scope>7X8</scope></search><sort><creationdate>20020531</creationdate><title>Unusually Low Barrier to Carbamate C−N Rotation</title><author>Deetz, Martin J ; Forbes, Christopher C ; Jonas, Marco ; Malerich, Jeremiah P ; Smith, Bradley D ; Wiest, Olaf</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-a445t-fa3f36ac79898fadbca3dffae3f719eea78618d9bb79ed65b6717eb89677d1f23</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2002</creationdate><topic>Chemistry</topic><topic>Exact sciences and technology</topic><topic>Heterocyclic compounds</topic><topic>Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings</topic><topic>Organic chemistry</topic><topic>Preparations and properties</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Deetz, Martin J</creatorcontrib><creatorcontrib>Forbes, Christopher C</creatorcontrib><creatorcontrib>Jonas, Marco</creatorcontrib><creatorcontrib>Malerich, Jeremiah P</creatorcontrib><creatorcontrib>Smith, Bradley D</creatorcontrib><creatorcontrib>Wiest, Olaf</creatorcontrib><collection>Istex</collection><collection>Pascal-Francis</collection><collection>PubMed</collection><collection>CrossRef</collection><collection>MEDLINE - Academic</collection><jtitle>Journal of organic chemistry</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Deetz, Martin J</au><au>Forbes, Christopher C</au><au>Jonas, Marco</au><au>Malerich, Jeremiah P</au><au>Smith, Bradley D</au><au>Wiest, Olaf</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Unusually Low Barrier to Carbamate C−N Rotation</atitle><jtitle>Journal of organic chemistry</jtitle><addtitle>J. Org. Chem</addtitle><date>2002-05-31</date><risdate>2002</risdate><volume>67</volume><issue>11</issue><spage>3949</spage><epage>3952</epage><pages>3949-3952</pages><issn>0022-3263</issn><eissn>1520-6904</eissn><coden>JOCEAH</coden><abstract>The barrier for rotation about an N-alkylcarbamate C(carbonyl)−N bond is around 16 kcal/mol. In the case of an N-phenylcarbamate, the rotational barrier is lowered to 12.5 kcal/mol, but with N-(2-pyrimidyl)carbamates the barriers are so low (<9 kcal/mol) that the syn and anti rotamers cannot be observed as separate signals by 500 MHz NMR spectroscopy at 183 K. X-ray and computational data show that the N-(2-pyrimidyl) carbamates have C(carbonyl)−N bonds that are on average 0.03 Å longer than for related N-phenylcarbamates. The computational results trace the origin of the effect to increased single bond character for the C(carbonyl)−N bond due to the increased electron-withdrawing ability of the pyrimidyl ring.</abstract><cop>Washington, DC</cop><pub>American Chemical Society</pub><pmid>12027723</pmid><doi>10.1021/jo025554u</doi><tpages>4</tpages></addata></record> |
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| source | American Chemical Society Journals |
| subjects | Chemistry Exact sciences and technology Heterocyclic compounds Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings Organic chemistry Preparations and properties |
| title | Unusually Low Barrier to Carbamate C−N Rotation |
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