Base catalysed intermolecular cyclisation of N-protected o-amino benzaldehyde/acetophenone with phosphorus/sulphur based allenes: facile synthesis of substituted quinolines?

Organic & Biomolecular Chemistry Pub Date: 2016-03-03 DOI: 10.1039/C6OB00259E

Abstract

Reaction of N-Bz protected o-aminobenzaldehyde or acetophenone with allenylphosphonates in the presence of a simple base leads to quaternary carbon substituted phosphono-quinolines which undergo thermal rearrangement to O-phosphorylated quinolines. The present one-pot reaction involves intermolecular cyclisation, dehydration, and benzoyl group rearrangement followed by a novel phosphoryl group migration. The migration was less facile/not observed in the reactions using allenylphosphine oxides and sulphur based allenes wherein only substituted quinolines were obtained in good yields. X-ray structures have been determined for the key products.

Graphical abstract: Base catalysed intermolecular cyclisation of N-protected o-amino benzaldehyde/acetophenone with phosphorus/sulphur based allenes: facile synthesis of substituted quinolines
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