Routes to Mitomycins. Chirospecific Synthesis of Aziridinomitosenes

Article abstract of DOI:10.1021/jo00223a019

The syntheses of ethyl (1R,2R)-1,2-(N-benzylaziridino)-7-methoxy-6-methyl-2,3,5,8-tetrahydro-5,8-dioxo-1H-pyrrolo<1,2-a>indole-9-carboxylate (59) and a regioisomeric aziridinoindoloquinone 60 are presented.Aziridine ring closure on a tricyclic indoloquinone nucleus and on monocyclic pyrrolidine derivatives was unsuccessful but did succeed with the acyclic educt.Thus the synthesis of the target aziridinomitosene was achieved by aziridine ring closure on the asymmetric 2-amino-3-hydroxy-4-azidobutanoate 49 followed by homologation and reductive ring closure to the bicyclic aziridinopyrrolidine 54.Subsequent reduction, regiospecific addition to 2,3-dibromo-5-methoxy-6-methylbenzoquinone (27), photochemical rearrangement, oxidation, and palladium-catalyzed ring closure afforded the (R,R)-aziridinomitosene 59.Regioisomeric aziridinoindoloquinone 60 was obtained directly by the addition of bicyclic aziridine 54 to dibromoquinone 27 followed by copper(II)-catalyzed ring closure.