A One-Pot Azido Reductive Tandem Mono-N-Alkylation Employing Dialkylboron Triflates: Online ESI-MS Mechanistic Investigation

An efficient one-pot reductive tandem mono-N-alkylation of both aromatic and aliphatic azides using diallcylboron triflates as allcylating agents has been examined under standardized reaction conditions. This methodology after optimization has been employed toward the syntheses of various secondary alkyl as well as aryl amines, including the synthesis of N10-butylated pyrrolo [2,1-c] [1,4]benzodiazepine-5,11-diones via in situ azido reductive-cydization process. This protocol is particularly attractive to provide an environmentally benign and practical method for mono-N-alkylation from organic azides without the use of toxic catalysts or corrosive alkylating agents. In addition, the mechanistic aspects have been investigated and the intermediates associated with this selective transformation have been intercepted and characterized by online monitoring of the reaction by ESI-MS/MS.