Remote Stereochemical Control of Both Reacting Centers in Ketyl-Olefin Radical Cyclizations: Involvement of a Samarium Tridentate Ligate
作者:Gary A. Molander、J. Christopher McWilliams、Bruce C. Noll
DOI:10.1021/ja963195c
日期:1997.2.1
diastereoselection in a samarium(II) iodide-promoted ketyl-olefin cyclization reaction has been achieved using tartramide-derived keto allylic acetals as chiral auxiliaries. The unique features of the reaction include the fact that remote diastereoselection is achieved in a radical process and that high levels of stereochemical induction are observed at both new stereocenters created in the transformation. The source
Ring-Expansion of Thioacetal Ring via Bicyclosulfonium Ylide. Effect of Protic Nucleophile on Ylide Intermediate
作者:Takashi Mori、Yuichi Sawada、Akira Oku
DOI:10.1021/jo991775x
日期:2000.6.1
reaction of 2-(3-diazo-2-oxopropyl)-2-methyl-3-oxathiolane 9f in the absence of AcOH gave 4-oxa-7-thiocan-2-en-1-one 19 via a sulfonium ylideintermediate, whereas, in the presence of AcOH, an alternative regioisomer 20 was also formed competitively with 19 via an oxonium ylideintermediate.