This paper summarizes the application of bis(alpha-chloroamide)s for the preparation of azamacrocyclic ligands. Bis(alpha-chloroamide)s look like crabs with two reactive claws so the method is called the crablike cyclization reaction. This cyclization strategy-has been used;to,prepare many different types of macrocyclic compounds over the past 10 years including cyclens, cyclams, perazamacrocycles, diazadithiamacrocycles, and some cage compounds. The method is particularly valuable where no other method will work. In general, the crablike cyclization reaction produces the macrocyclic diamides in 40-70% yields.