Ja. Marshall et Mr. Palovich, COMPARATIVE-STUDIES ON THE SYNTHESIS OF AN ANTI,SYN STEREOTRIAD WITH CHIRAL ALLENYLSTANNANE AND ALLENYLINDIUM REAGENTS, Journal of organic chemistry, 62(17), 1997, pp. 6001-6005
Addition of the chloroallenylstannane derived from the Bu3Sn allene (S
)-2 and SnCl4 to nonracemic alpha-methyl-beta-oxygenated aldehyde 1a a
fforded mixtures of anti,syn and anti,anti adducts 3a and 3b. When InC
l3 was employed in the transmetalation of allenylstannane (S)-2, a mix
ture of adducts 3a and ent-3b was produced. Experiments with the beta-
ODPS aldehydes 1b and 5 showed that InBr3 and InI3 yield a transient I
nXn species from allenylstannane (S)-2 with mainly retention of config
uration. In contrast, transmetalation of (S)-2 with SnCl4 or BuSnCl3 a
ffords an intermediate allenyl species of inverted configuration. The
(S)-2/BuSnCl3 reagent showed high enantio-and diastereoselectivity in
addition to aldehydes 1a, 1b, and 5. The (S)-2/InBr3 or InI3 reagent,
while somewhat less selective, afforded enantiomeric or diastereomeric
adducts.