Selective monoacylation of symmetrical diamines via prior complexation with boron

Pretreatment of a symmetrical primary or secondary diamine with 9-BBN prior to the addition of an acyl chloride significantly suppressed undesired diacylation, and the product of monoacylation predominated. The reactive preference is interpreted as the result of a selective deactivation of one nitrogen atom of the diamine by 9-BBN.