Trienyl side chain

The first total synthesis of racemic indolizomycin was accomplished by S.J. Danishefsky et a. The natural product s trienyl side chain was elaborated using the classical J-L olefination. The macrocyclic a, 3-unsaturated aldehyde was treated with an ( )-allylic lithiated sulfone to give epimeric acetoxy sulfones upon acetylation. The mixture of epimers was exposed to excess sodium amalgam in methanol to afford the desired ( , , ) triene stereospecifically. 

The well-known series of natural tocopherols consists of methylated tocols derived from phytol. Recently Green ct al. (1959a, 1960) showed the existence of a second, closely related series of natural tocopherols containing an unsaturated (trimethyltrideca-3,7,ll-trienyl) side chain, as represented by e- and fi-tocopherol (Table II). Further chromanols, chromenols, and benzoquinones which may play a role together with or similar to that of vitamin E in the living cell are also listed in Table II. 

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