Sequenced elimination–reduction and elimination–cyclopropanation reactions of 2,3-epoxyamides promoted by samarium diiodide. Synthesis of 2,3-dideuterioamides and cyclopropanamides
摘要:
An easy and general sequenced elimination/reduction or elimination/cyclopropanation process promoted by samarium diiodide or/and CH2I2/Sm provide an efficient method for synthesising 2,3-dideuterioamides 3 or cyclopropanamides 8, respectively. The transformations take place in high yields and with total or high selectivity from the easily available 2,3-epoxyamides. (C) 2004 Elsevier Ltd. All rights reserved.
Stereoselective beta -elimination of 2-chloro-3-hydroxyamides 1 is achieved by using samarium diiodide to yield alpha,beta -unsaturated amides 2, in which the C=C bond is di- tri-, or tetrasubstituted. The starting compounds a are easily prepared by reaction of the corresponding lithium enolates of alpha -chloroamides with aldehydes or ketones at -78 degreesC. The influence of the reaction conditions and the structure of the starting compounds on the stereoselectivity of the beta -elimination reaction is also discussed.
Sequenced elimination–reduction and elimination–cyclopropanation reactions of 2,3-epoxyamides promoted by samarium diiodide. Synthesis of 2,3-dideuterioamides and cyclopropanamides
作者:José M. Concellón、Mónica Huerta、Eva Bardales
DOI:10.1016/j.tet.2004.07.051
日期:2004.10
An easy and general sequenced elimination/reduction or elimination/cyclopropanation process promoted by samarium diiodide or/and CH2I2/Sm provide an efficient method for synthesising 2,3-dideuterioamides 3 or cyclopropanamides 8, respectively. The transformations take place in high yields and with total or high selectivity from the easily available 2,3-epoxyamides. (C) 2004 Elsevier Ltd. All rights reserved.
Synthesis of Aromatic (<i>E</i>)- or (<i>Z</i>)-α,β-Unsaturated Amides with Total or Very High Selectivity from α,β-Epoxyamides and Samarium Diiodide
作者:José M. Concellón、Eva Bardales
DOI:10.1021/jo0349577
日期:2003.11.1
stereoselective synthesis of aromatic alpha,beta-unsaturated amides was achieved by treatment of aromatic alpha,beta-epoxyamides with samariumdiiodide. The starting compounds 1 and 3 are easily prepared by the reaction of enolates derived from alpha-chloroamides with carbonylcompounds at -78 degrees C. A mechanism to explain this transformation is proposed.