Ja. Marshall et al., HIGHLY SYN-SELECTIVE ADDITIONS OF ALLYLIC STANNANES TO PROTECTED ALPHA-AMINO ALDEHYDES, Journal of organic chemistry, 59(18), 1994, pp. 5139-5140
The gamma-oxygenated allylic stannane (R)-8b adds to the threonine- an
d serine-derived N-BOC aldehydes 1 and 14 in the presence of MgBr2 to
afford the syn adducts 9b and 15b as the sole products.