Cyclization of the lactam carbonyl on the indole ring in tryptophanol-derived oxazolopiperidone lactams 2 and 6, under the classical POCl3-promoted Bischler–Napieralski conditions and under neutral conditions via the corresponding thiolactam, has been studied. Whereas tricyclic lactam 2 only leads to products coming from an α-amidoalkylation process, bicyclic lactam 6 undergoes cyclization on the lactam
Enantioselective Synthesis of Spiro[indolizidine-1,3′-oxindoles]
作者:Maria Pérez、Carlos Ramos、Lucia Massi、Silvia Gazzola、Chiara Taglienti、Nihan Yayik、Elies Molins、Antonio Viayna、F. Javier Luque、Joan Bosch、Mercedes Amat
DOI:10.1021/acs.orglett.7b01818
日期:2017.8.4
A three-step procedure for the enantioselective synthesis of spiro[indolizidine-1,3′-oxindoles], consisting of a stereoselective cyclocondensation reaction between (S)-tryptophanol and a prochiral or racemic δ-oxoester, bromination of the resulting oxazolopiperidone lactam, and a final stereoselective spirocyclization, is reported.