7, R'= CH, CH= C (SR) Si (CH,), gioselectivity to give adducts 2 rather than adducts 3 (Scheme I). Exceptions to this generalization include the reactions of (alky1thio) allylcopper reagents with allylic halides, 38pb (ary1thio) allyllithium reagents with ketones in the presence of N, N, N', N'-tetramethylethylenediamine, hexamethylphosphoramide, or 1, 4- diazabicyc10 [2.2. 2] 0~-tane,'* and the doubly metalated derivative of 2-propenethiol with ...
