PURPOSE: To alkylate by allowing an acylated azaglycine derivative to react with alcohol, diethylazodicarboxylate and a phosphine derivative in ether, and deprotecting the resulted compound.

CONSTITUTION: The alkylated azaglycine derivative of the formula X-(A)n-N(R)- NH-CO-NH2 is obtained by allowing the compound of the formula X-(A)n- NH-NH-CO-NH2 (X is an amino protective group, a 1-8C alkanoyl, 6-14C arylcarbonyl, etc.; A is amino acid or imino acid optionally protected in the third function group; (n) is 0-10) to react with a primary or secondary alcohol (e.g. methanol), diethyazodicarboxylate and a phosphine derivative (e.g. triphenylphosphine) in ether at 0-30°C, and then eliminating amino protective group X by a known method.