Synthesis and some properties of mixed alkyldi-(-)-menthyltin hydrides

The synthesis and physical properties of methyldi-(-)-menthyltin 4 and neophyldi-(-)-menthyltin 7 hydrides as well as those of their organotin precursors are described. The reaction of hydrides 4 and 7 with carbon tetrachloride shows that the reactivity of 4 is within the range of the more common triorganotin hydrides while the organotin hydride 7 reacts more slowly. A study of the reduction of acetophenone with both hydrides shows that whereas the reduction with 4 leads to (-)-(S)-1-phenylethanol(8.8% optical purity), the reduction with 7 affords(+)-(R)-1-phenylethanol (6.6% optical purity); these results indicate that some degree of asymmetric induction can be achieved. Full H-1, C-13 and Sn-11 NMR data are given.