Reactions of Iron Carbenes with α,β-Unsaturated Esters by Using an Umpolung Approach: Mechanism and Applications
An Umpolung approach, in which a phosphorus ylide moiety was introduced to increase the electron density of the double bond, was developed to activate electron‐deficient alkenes for reaction with electrophilic iron carbenes. In tandem with the Wittig reaction, the reactions of α,β‐unsaturated esters...
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Published in | Chemistry : a European journal Vol. 19; no. 21; pp. 6766 - 6773 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Weinheim
WILEY-VCH Verlag
17.05.2013
WILEY‐VCH Verlag |
Subjects | |
Online Access | Get full text |
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Summary: | An Umpolung approach, in which a phosphorus ylide moiety was introduced to increase the electron density of the double bond, was developed to activate electron‐deficient alkenes for reaction with electrophilic iron carbenes. In tandem with the Wittig reaction, the reactions of α,β‐unsaturated esters with in situ generated Fecarbene complexes delivered formal CH insertion products through cyclopropanation/ring‐opening reactions. DFT calculations and cross‐experiments indicate that, in this process, the ring opening of the cyclopropylmethyl ylide intermediate is rapid and reversible and the subsequent proton transfer is the rate‐determining step. Further studies revealed that, based on the choice of the ylide and ester groups, as well as the base, the reaction could be steered towards either the ring‐opening pathway or to the production of vinyl cyclopropanes.
Plenty of irons in the fire: An Umpolung approach was employed to activate electron‐deficient alkenes for reaction with electrophilic iron carbenes. The reaction pathway can be steered by the carbanion‐stabilizing groups, the esters, and the base (see scheme). |
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Bibliography: | Major State Basic Research Development Program - No. 2009CB825300 National Natural Science Foundation of China - No. 21121062; No. 21272248; No. 20932008 ArticleID:CHEM201204182 ark:/67375/WNG-F4WGMSSD-3 istex:4A29803B4BDFDA66547D7C390E5C8B3F15E6F197 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0947-6539 1521-3765 |
DOI: | 10.1002/chem.201204182 |