Portal de Periódicos da CAPES

Iridium-Mediated Isomerization−Cyclization of Bicyclic Pauson−Khand Derived Allylic Alcohols

2008; American Chemical Society; Volume: 73; Issue: 21 Linguagem: Inglês

10.1021/jo8017439

1520-6904

Yvonne Kavanagh, Cíara M. Chaney, Jimmy Muldoon, Paul Evans,

Advanced Synthetic Organic Chemistry

Treatment of 2-(toluene-4-sulfonyl)-2,3,4,4a,5,6-hexahydro-1H-[2]pyrindin-6-ol 10, accessed from the diastereoselective Luche reduction of a Pauson-Khand derived bicylic cyclopentenone, with a catalytic amount of (1,5-cyclooctadiene)(pyridine)(tricyclohexylphosphine)iridium(I) hexafluorophosphate 1 (Crabtree's catalyst) under a hydrogen atmosphere resulted in the formation of 4-(toluene-4-sulfonyl)-2-oxa-4-azatricyclo[5.2.1.0(3,8)]decane 12 as a single diastereoisomer. This process is likely to proceed via an initial Ir(I)-mediated isomerization of the alkene to form an N-sulfonyl enamine 11, followed by cyclization. Evidence to support this came when, after short reaction periods, 11 was isolated, characterized spectroscopically, and on resubmission to the reaction conditions formed 12.