Total synthesis of jimenezin was achieved via radical cyclization of beta-alkoxyacrylate and beta-alkoxyvinyl sulfoxide intermediates and intramolecular olefin metathesis reaction. (c) 2005 Published by Elsevier Ltd.
Total Synthesis of Jimenezin via an Intramolecular Allylboration
作者:Nina G. Bandur、David Brückner、Reinhard W. Hoffmann、Ulrich Koert
DOI:10.1021/ol0614471
日期:2006.8.1
[structure: see text] An efficient total synthesis of the annonaceous acetogenin jimenezin was achieved. The key steps used were a highly stereoselective intramolecularallylboration to establish the tetrahydropyran ring and an intramolecular Williamson reaction to close the tetrahydrofuran ring.
thus revising the proposed structure 1 to 2. The key steps in this synthesis include an efficient construction of the THP-THF fragments 3 and 16 through a stereoselective condensation between the pyranyl aldehyde 5 and the acetylene derivative 6, and a palladium-catalyzed coupling reaction of 3 or 16 with a terminal butenolide 4.
A highlystereoselective asymmetric total synthesis of (−)-jimenezin (1), a potent anticancer acetogenin, was efficiently completed with the key feature being a sequential intramolecular amide enolate alkylation (IAEA). Our investigation to probe the origin of the complete stereoselectivity in the second IAEA step to form the conformationally flexible tetrahydrofuran with perfect stereocontrol identified