A radical mediated approach to the stereoselective formal total synthesis of (+)-Sch 642305
摘要:
A formal total synthesis of (+)-Sch-642305 is described. The synthesis, which commenced from a simple chiral synthon (5S)-5-(hydroxymethyl)dihydrofuran-2(3H)-one, employed, as a key step, a radical mediated opening of a chiral epoxy alcohol intermediate with Cp(2)Ti(III)Cl following an efficient method developed by us earlier. The resultant intermediate radical was intramolecularly trapped by the electron deficient double bond present in the molecule to give rise to its highly functionalized six-membered carbocyclic ring in stereoselective manner. (C) 2009 Elsevier Ltd. All rights reserved.
Total synthesis of (4S,10R)-4-hydroxy-10-methyl-11-oxododec-2-en-1,4-olide and related bioactive marine butenolides
作者:Wei-Min Dai、Lei Shi、Yannian Li
DOI:10.1016/j.tetasy.2008.06.028
日期:2008.7
Marine-derived microorganisms produce structurally diverse butenolides possessing a variety of bioactivities. Described here is the total synthesis of (4S, 10R)-4-hydroxy-10-nnethyl-11-oxododec-2-en-1,4-olide and a related butenolide containing anti stereochemistry at C10-C11. A three-module coupling strategy has been established for synthesis of the stereoisomers of the naturally Occurring butenolides by assembling the C3-C7 and C9-C12 fragments via double alkylation of a 1,3-dithiane. The C10-C11 stereochemistry could be easily controlled by an asymmetric aldol condensation, while the butenolide unit was efficiently constructed according to the ring-closing metathesis protocol. (C) 2008 Elsevier Ltd. All rights reserved.