First asymmetric synthesis of chiral beta-iodo Baylis-Hillman esters via tandem 1,4-conjugate addition/carbonyl coupling reactions

A new asymmetric approach to chiral beta-iodo Baylis-Hillman hydroxy esters was developed via a tandem asymmetric I-C/C-C formation reaction. The reaction was conveniently carried out by slow addition of diethylaluminum iodide into a mixture of aldehyde and alpha,beta-acetylenic menthyl ester in dichloromethane at -23 degrees C. Excellent geometric selectivity, promising diastereoselectivity and modest to high yields (up to 91%) were obtained.