Highly diastereoselective Michael addition reactions of butane-2,3-diacetal desymmetrized glycolic acid. Preparation of alpha-hydroxy-gamma-amino acid derivatives.

[reaction--see text] The butane-2,3-diacetal (BDA) desymmetrized glycolic acid building block undergoes efficient and highly diastereoselective lithium enolate Michael additions to alpha,beta-unsaturated ketones, lactones, and nitro olefins. Subsequent deprotection of these Michael adducts gives alpha-hydroxy acids in very high yield. Hydrogenation of the nitro group in some of the adducts leads to gamma-lactams, which can be easily converted into alpha-hydroxy-gamma-amino acid derivatives.