Different enynols and propargyl derivatives were sumitted to radical hydrostannylation (Bu 3 SnH/ AIBN), Pd(0)-catalyzed hydrostannylation [Bu 3 SnH/Pd(0)], and stannylcupration [Bu 3 Sn(R)CuCNLi 2 ] conditions. Except for the radical stannylation reaction, high regio-and stereoselective formation of vinyl-and dienylstannanes are obtained. Results are tentatively explained in terms of steric Interactions between the alkyne or enyne substituents and the palladium or cuprate moieties in the different reaction intermediates.

The total synthesis of the marine macrolide bryostatin 2 is described. The synthesis plan relies on aldol and directed reduction steps in order to construct the anti-1,3-diol array present in each of the principal subunits (A, B, and C). These fragments were coupled using a Julia olefination and subsequent sulfone alkylation. A series of functionalization reactions provided a bryopyran seco acid, which was macrolactonized under Yamaguchi conditions. Installation of the two enoate moieties took advantage of asymmetric phosphonate and aldol condensation strategies. Reduction of the C20 ketone and simple protecting group operations then completed the synthesis of bryostatin 2. This flexible approach should provide access to a series of new analogues of this clinically important marine natural product.