The use of some bifunctional reagents in organic synthesis

The preparation and synthetic uses of a number of bifunctional reagents (5-chloro-2-trimethylstannyl-2-pentene and related substances, (~)-1-bromo-4-methyl-3-trimethylstannyl-2-pentene, and alkyl (z)and (~)-2,3-bis(trimethylstannyl)-2-alkenoates) are described. In this work a number of useful annulation methods were developed and these annulation sequences played key roles in effecting total syntheses of the sesquiterpenoids (+)-axamide-1 and (+)-axisonitrile-1, the diterpenoid ( + ) ( 1 4 S ) dolasta-1(15),7,9-trien-l4-ol, and the sesterterpenoid (2)-palauolide. A versatile synthesis of functionalized, stereochemically defined tetrasubstituted alkenes, starting from cr,j3-acetylenic esters, has been developed.