Studies toward the Synthesis of Amphidinolide C1: Stereoselective Construction of the C(1)-C(15) Segment.

An enantioselective synthesis of the C(1)-C(15) segment of the marine natural product amphidinolide C has been accomplished by a route that includes a stereoselective boron-Wittig reaction to furnish a trisubstituted alkenylboronate. In addition, the route employs enantioselective alkene diboration to install the C(6) hydroxyl group which undergoes intramolecular conjugate addition to establish a tetrahydrofuran ring. Lastly, a catalytic Suzuki-Miyaura cross-coupling is accomplished to construct the C(9)-C(10) bond.

Reactions of organoboron compounds enabled by catalyst-promoted metalate shifts.

This tutorial review describes recent developments in catalytic reaction design that involve catalyst-promoted 1,2-metalate shifts as a critical part of the reaction mechanism. Issues pertaining to catalysis, stereoselectivity, and reaction mechanism are discussed.

Stereoselective Synthesis of Trisubstituted Alkenylboron Reagents by Boron-Wittig Reaction of Ketones.

Application of the boron-Wittig reaction to ketone electrophiles provides a straightforward route to trisubstituted alkenylboronic esters. With either a pentamethyldiethylenetriamine or trimethyl-1,4,7-triazacyclononane additive, the olefination can occur with very high levels of stereocontrol and in good chemical yield.

Enantioselective Conjunctive Cross-Coupling of Bis(alkenyl)borates: A General Synthesis of Chiral Allylboron Reagents.

Palladium-catalyzed conjunctive cross-coupling is used for the synthesis of enantioenriched allylboron reagents. This reaction employs nonsymmetric bis(alkenyl)borates as substrates and appears to occur by a mechanism that involves selective activation of the less substituted alkene followed by migration of the more substituted alkene during the course of a Pd-induced metalate rearrangement.