Total Synthesis and Absolute Configuration of Curvularides A-E

Abstract

The first total synthesis of curvularides A-E, isolated from a culture broth of the endophytic fungus Curvularia geniculata, is described. The divergent total synthesis reported herein confirmed the absolute configurations of curvularides A-E and supported that these natural products might be obtained from a common biosynthetic pathway. The key steps involved in the synthesis were the diastereoselective hydrogenation of exo-methylene-γ-butyrolactone to α-methyl-γ-butyrolactone, Sharpless kinetic resolution, Sharpless asymmetric epoxidations, and intramolecular and intermolecular epoxide openings.

Chemoselective Lewis pair polymerization of renewable multivinyl-functionalized γ-butyrolactones

“…A potential solution to overcome the brittleness of such polymers is through additional vinyl functionalization of MBL monomers, followed by subsequent chemoselective polymerization to produce functionalized MBL polymers. A few vinyl-functionalized MBLs, γ-vinyl-α-methylene-γbutyrolactone (VMBL) [38], γ-vinyl-γ-methyl-α-methylene-γ-butyrolactone ( γ VMMBL) [39] and γ-diallyl-α-methylene-γ-butyrolactone (DAMBL) [40,41], are known in the literature, but their syntheses involve laborious multistep low-yield reactions and employ petroleum-based starting reagents. Accordingly, one of the objectives of this research was to develop an efficient and sustainable synthesis of such vinyl-functionalized MBLs starting from biorenewable feedstocks.…”

Regio‐ and Enantioselective Copper‐Catalyzed 1,4‐Conjugate Addition of Trimethylaluminium to Linear α,β,γ,δ‐Unsaturated Alkyl Ketones

“…The chiral products resulting from 1,4‐ACA, especially linear α,β,γ,δ‐unsaturated ketones which contain a C=C double bond, are versatile building blocks that can be easily transformed into many other functional groups (Figure ). Such chiral intermediates, particularly methyl‐substituted derivatives, are often found in natural products and biologically active compounds (Figure ) . Therefore the ACA of methyl organometallic reagents represents a particularly important synthetic methodology .…”

Enantioselective Synthesis of α-exo-Methylene γ-Butyrolactones via Chromium Catalysis

“…The allylation and lactonization of propionaldehyde under standard conditions proceeded smoothly to give compound 1t in 90% yield with 95% ee. Subsequent hydrogenation delivered compound 2 in 90% yield with 10/1 dr, which was the advanced intermediate in the synthesis of a family of natural products curvularides A–E . This protocol could be applied to aldehyde with a terminal diene moiety to generate lactone 1u in 60% yield with 94% ee.…”