B. Hermans et L. Hevesi, LEWIS-ACID MEDIATED REACTION OF SELENOACETALS WITH ALLYLSILANES AND ALLYLSTANNANES - SYNTHESIS OF HOMOALLYLSELENIDES, Bulletin des Societes chimiques belges, 103(5-6), 1994, pp. 257-262
Selenoacetals react with allytrimethylsilane in the presence of tin te
trachloride to produce homoallyl selenides in moderate to good yields.
Aliphatic acetals react less efficiently than do aromatic ones, espec
ially when steric factors can play a significant role. The use of ally
l stannanes as nucleophiles is complicated by transmetallation side re
actions with Lewis acids; in the case of tin tetrachloride this is the
only observable transformation. However, non transmetallating Lewis a
cids such as BF3 . OEt2, ZnCl2, AlCl3, etc... also allow the synthesis
of homoallyl selenides from selenoacetals and allyl stannanes. The re
action of bis(methylseleno)phenylmethane with tributylcrotylstannane g
ave a diastereo-isomeric mixture of homoallyl selenides where the syn
isomer predominated (syn/anti = 70/30), whereas the reverse stereosele
ctivity was observed for the reaction of 1,1-bis(methylseleno)-2-pheny
lpropane with allyltributylstannane.