The First Highly Enantioselective Alkynylation of Chloral: A Practical and Efficient Pathway to Chiral Trichloromethyl Propargyl Alcohols

A new, inexpensive chiral amino alcohol‐based ligand, (1S,2S)‐2‐N,N‐dimethylamino‐1‐(4‐nitrophenyl)‐3‐(tert‐butyloxy)propan‐1‐ol, was developed for the asymmetric alkynylation of chloral in high yield with up to 98% ee. The resulting chiral adduct (S)‐1‐trichloromethyl‐3‐phenyl‐2‐propyn‐1‐ol was hydrogenated over 10% Pd/C to give the useful intermediate chiral trichloromethyl carbinol in quantitative yield, which was efficiently transformed into the pharmaceutically important building blocks 2‐hydroxy‐4‐phenylbutanoate and homophenylalanine in high yield with excellent enantiomeric excess.