Iodomethylation of chiral alpha-amino aldehydes by means of samarium/diiodomethane. Application to the synthesis of various enantiomerically pure compounds

Chiral iodohydrins 2 have been obtained from alpha-amino aldehydes 1 and Sm/CH2I2. Treatment of compound 2 with acetic anhydride, NaH, or AgBF4 affords, with high diastereoselectivity, O-protected 3-(dibenzylamino)-1-iodoalkan-2-ol 3, amino epoxides 4, or azetidinium salts 5, respectively. The synthesis of enantiomerically pure allylamines 6 is also described by metallation of 3 with zinc. The reaction of a-amino aldehydes 1 with Sm/CH2I2 and further treatment with organocuprates affords chiral amino alcohols 7 in a one-pot process.