Synthese substituierter N‐Hydroxylactame, Lactame, Chinolin‐N‐oxide und Chinoline durch katalysierte Reduktive Cyclisierung von 2‐Nitrocinnamoyl‐Verbindungen mit Wasserstoff/Platinschwarz

Abstract

Synthesis of Substituted N‐Hydroxylactams, Lactams, Quinoline‐N‐oxides, and Quinolines by Catalyzed Reductive Cyclization of 2‐Nitrocinnamoyl Derivatives with Hydrogen/Platinum Black Substituted nitrobenzenes 1a–1m , consisting of two series of 6 analogous compounds, containing the structural unit of an α,β‐substituted 2‐nitrocinnamoyl group have been reductively cyclized by means of hydrogen in the presence of platinum black catalyst to form four types of heterocycles: N‐hydroxylactams 2a and b , lactams 3 and 4 , quinoline‐N‐oxides 5a–d , and quinolines 6a and b . The type of substituents at the 2‐nitrocinnamoyl group is of significance for the type of heterocycle formed in this reaction. It is of special interest that by the use of the reduction system hydrogen/platinum black the probability to obtain N‐hydroxylactams or quinoline‐N‐oxides, which are difficult to obtain by alternative procedures, becomes much higher than by the use of many reducing agents acting noncatalytically.