Studies of the Enantiocontrolled Synthesis of the C(10)-C(25) Subunit of Amphidinolide C.

A stereocontrolled synthesis of , the C(10)-C(25) component of amphidinolide C (), has been efficiently achieved. Reaction of the dithiane component with nonracemic bis(epoxide) directly affords functionalized 2,5--disubstituted tetrahydrofuran . Propargylation is highly diastereoselective for the formation of the desired C(12)-C(13) stereochemistry, and the resulting terminal alkyne is utilized for a regioselective -silylstannylation.

1-alkoxyallene as an effective precursor for regio- and stereocontrolled allylation reactions with aliphatic aldehydes via bis-stannylation.

Bis-stannylation of 1-(methoxy)methoxyallene yields (E)-(3-(methoxymethoxy)prop-2-ene-1,2-diyl) bis-tributylstannane (2) as a highly reactive allylation reagent. Stereoselective reactions of functionalized stannane 2 with a variety of aldehydes provide good yields of 1,2-diol derivatives. Reactions with alpha-alkoxyaldehydes proceed with chelation-controlled addition to afford efficient constructions of 3,4-anti-4,5-syn-relationships in stereotriads bearing three differentiated oxygen (alkoxy and hydroxy) substituents.