Page 1. Tetrahedron Letters,Vo1.30,No.20,pp 2619-2622,1989 oo40-4039/89 $3.00 + .OO Printed in Great Britain Pergamon Press plc ... 4-dimethylaminopyridine (Steglich reagent)." We have obtained better results by using a catalytic (15-20%) amount of N-hydroxysuccinimide ...