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.
Enantiospecific Total Synthesis and Absolute Configuration Assignment of Chabrolobenzoquinone H
作者:Stergios R. Rizos、Konstantinos A. Ouzounthanasis、Alexandros E. Koumbis
DOI:10.1021/acs.joc.1c02634
日期:2022.1.21
meroditerpene metabolite with cytotoxic activity, is synthesized via a stereoselective Julia–Kocienski olefination between a chiral pool derived aliphatic PT-sulfone and a benzoquinone aldehyde partner. The latter was obtained via consecutive chain extension steps involving a Stille coupling and a stereospecific olefin cross-metathesis reaction followed by malonic ester synthesis and a Krapcho decarboxylation
Molecular Complexity via C–H Activation: A Dehydrogenative Diels–Alder Reaction
作者:Erik M. Stang、M. Christina White
DOI:10.1021/ja2059704
日期:2011.9.28
Traditionally, C-H oxidation reactions install oxidized functionality onto a preformed molecular skeleton, resulting in a local molecular change. The use of C H activation chemistry to construct complex molecular scaffolds is a new area with tremendous potential in synthesis. We report a Pd(II)/bis-sulfoxide-catalyzed dehydrogenative Diels-Alder reaction that converts simple terminal olefins into complex cycloadducts in a single operation.
WENDER, P. A.;SNAPPER, M. L., TETRAHEDRON LETT., 28,(1987) N 20, 2221-2224