Pyrrolizidinone and Indolizidinone Synthesis: Generation and Intramolecular Addition of α-Acylamino Radicals to Olefins and Allenes

Article abstract of DOI:10.1021/ja00338a033

α-Acylamino radicals can be generated by treatment of phenylthio, methylthio, or phenylselenyl lactams of type 7, 8, and 17 with tri-n-butyltin hydride in the presence of AIBN.The radicals add intramolecularly to olefins and allenes to give indolizidinones and pyrrolizidinones.The product distribution depends on the substitution patterns of the unsaturated moiety and the legnth of the chain connecting the radical and olefinic centers.Product ratios appear to reflect the kinetic partitioning of the radical between cyclization pathways.These reactions are potentially useful in the area of pyrrolizidine alkaloid synthesis.The conversion of cyclization produts 50 and 51 to (+/-)-supinidine (1) serves as an example.