Pectenotoxin-2 Synthetic Studies. 3. Assessment of the Capacity for Stereocontrolled Cyclization To Form the Entire C1−C26 Subunit Based upon the Double Bond Geometry Across C15-C16
摘要:
Second-generation synthetic routes to enantiopure sulfone 21 and aldehyde 24 are described. The union of these two intermediates by means of a Julia-Kocienski coupling gave rise to a series of E-configured building blocks that did not prove amenable to transannular cyclization. Alternatively, when the C15-C16 double bond was introduced with Z-geometry by Wittig olefination, spontaneous closure to generate a tetrahydrofuran culminated an ensuing direct dihydroxylation step. The structural assignment to 35, undergirded by detailed H-1 and C-13 NMR studies, is consistent with proper transannular bonding so as to deliver the entire C1-C26 fragment of PTX2.
Pectenotoxin-2 Synthetic Studies. 2. Construction and Conjoining of ABC and DE Eastern Hemisphere Subtargets
作者:Dmitriy Bondar、Jian Liu、Thomas Müller、Leo A. Paquette
DOI:10.1021/ol0504291
日期:2005.4.1
[reaction: see text] Practical asymmetric synthesis of aldehyde 2 and tetrazolyl sulfone3 has allowed for their coupling via Julia olefination to generate 32 as a single product. This substance possesses the entire carbon backbone of the A-E substructure of pectenotoxin-2.