Regioselective synthesis of allyltrimethylsilanes from allylic halides and allylic sulfonates. Application to the synthesis of 2,3-bis(trimethylsilyl)alk-1-enes
Sphinga-4,8-dienine derivatives were synthesized from a vinyl-epoxide 5 via three routes. First, reaction of 5 with 2-dodecenyl cyanocuprate afforded a 1:1 mixture of (4E,8E)- and (4E,8Z)-sphingadienine derivatives in high yield. Second, the (4E,8E)-isomer was selectively synthesized via allylic bromide-allylic sulfone coupling followed by desulfonylation. Third, the (4E,8Z)-isomer was selectively