Studies toward the Synthesis of Furanocembrane Bipinnatin J: Synthesis of a 2,3,5-Trisubstituted Furfuryl Ether Intermediate
摘要:
Synthesis of 2,3,5-trisubstituted furfuryl ether (29), a potential intermediate in a synthetic approach to bipinnatin J, was achieved by a combination of etherification and Stille cross-coupling reaction. Unexpectedly, an intramolecular coupling reaction of 29 proceeded through S(N)2' substitution to give 15-membered furfuryl ether (30). Formation of gamma-butenolide (34) was also accomplished by a ruthenium-catalyzed carbonylation of allenic alcohol (33).
Stereoselective Aldol-Type Cyclization Reaction Mediated by Dibutylboron Triflate/Diisopropylethylamine
作者:Sanjib Das、Lian-Sheng Li、Subhash C. Sinha
DOI:10.1021/ol036229b
日期:2004.1.1
[reaction: see text] Dibutylboron triflate/diisopropylethylamine mediated aldol-type cyclization provides an expedient route for the stereoselective synthesis of cyclic ethers in a single step. The method is highly efficient for the stereoselective synthesis of 4-cis-tetrahydropyranones. The reaction is proposed to proceed via an S(N)1-type mechanism through a chair-like transition state, in which