Highly Diastereoselective Lithium Enolate Aldol Reactions of Butane-2,3-diacetal Desymmetrized Glycolic Acid and Deprotection to Enantiopure <i>anti</i>-2,3-Dihydroxy Esters
作者:Darren J. Dixon、Steven V. Ley、Alessandra Polara、Tom Sheppard
DOI:10.1021/ol016707n
日期:2001.11.1
[reaction--see text] The butane-2,3-diacetal (BDA) desymmetrized glycolic acid building block 1 undergoes efficient and highlydiastereoselective lithium enolate aldol reactions with both aromatic and aliphatic aldehydes to afford, after an acidic methanolysis deprotection step, the enantiopure anti-2,3-dihydroxy esters in good yield.
According to a chiral memory protocol, a chiral glycolic acid equivalent, the butane-2,3-diacetal-desymmetrized glycolate 2, is obtained from chiral 3-halopropane-1,2-diols 1. Compound 2 is a new and effective building block for the synthesis of mono- and dialkylated α-hydroxy acids 3, which constitute a biologically and pharmacologically important structural motif.