ChemInform Abstract: Reaction of N‐Vinyliminophosphoranes. Part 16. A New Synthesis of 5H‐ Indeno(1,2‐b)pyridines and 5H‐Indeno(1,2‐b)pyridin‐5‐ones.

Abstract

Reaction of N-Vinyliminophosphoranes. Part 16. A New Synthesis of 5H-Indeno(1,2-b)pyridines and 5H-Indeno(1,2-b)pyridin-5-ones.-Thermal reaction of the in situ generated tributyl(inden-3-ylimino) phosphorane (Ia), which is more reactive than its stable phenyl analogue (Ib), with α,β-unsaturated ketones and aldehydes leads to a Michael-type C-C bond formation and subsequent aza-Wittig reaction to give the title compounds (III). These products are oxidized conveniently to yield the indenopyridinones (IV), including the 4-azafluorenone alkaloid onychine (IVb). - (NITTA, M.; OHNUMA, M.; IINO, Y.; J. Chem. Soc., Perkin Trans. I (1991) 5, 1115-1118 Dep. Chem., Sch. Sci. Eng., Waseda Univ., Shinjuku, Tokyo 169, Japan; EN)