Strategic use of nitrogen free radicals in natural product synthesis: Total synthesis of agelastatin A

The present review describes our endeavor to access agelastatin alkaloids wherein new means of radical nitrogenation of carbon-carbon double bonds have been developed. The first topic presents the development of intramolecular iron (II)-mediated radical aminohalogenation reactions of allyl azido formates and allyl N-tosyloxy carbamates, which culminated in the establishment of the 2nd- A nd 3rd-generation approaches to (-)-agelastatin A (AA). The second topic deals with the radial azidation reaction of carbon-carbon double bond with KMnO4/BnEt3NCl/TMSN3, a new reagent that produces an azido radical, by which the 4th-generation synthesis of AA has been successfully accomplished.