Effect of structural rigidity on the photoreduction of imines

Abstract

Upon irradiation in 2-propanol, A1-9-octahydroquinoline (1) gives trans-decahydroquinoline, 2-methyl-A1-piperideine (2) gives 2-methylpiperidine, AMsopropylidenepropylamine (7) gives Ar-propyl-2-aminopropane, and 2phenyl-A+pyrroline (8) gives 2,2,-diphenyl-2,2'-bipyrrolidine (9). Comparative photolyses of 2 and 7 and 8 and A-benzylidenecyclohexylamine (10) show that cyclic imines 2 and 8 do not show enhanced reactivity toward photochemical hydrogen abstraction reactions when compared with acyclic analogs. It is concluded that the low reactivity of the carbon-nitrogen double bond toward photochemical hydrogen abstraction reactions is not due only to rapid radiationless decay by twisting about the carbon-nitrogen bond.

Unveiling the Role of DMAP for the Se-Catalyzed Oxidative Carbonylation of Alcohols: A Mechanism Study

“…This transition-state structure shows general characteristics of the S N 2-type nucleophilic substitution reaction. 42 The formed intermediate [DMAP···HSe] δ− [DMAP-(CO)OR] δ+ ( IV ) ( Figure 2 ) is stabilized by the ionic interaction as confirmed by the Bader charge analysis ( Table S3 ) and charge density isosurface ( Figure S6b ).…”

“…The charge density isosurface for TS III–IV shows that a covalent C ( III ) –Se ( III ) bond is maintained with the formation of the C ( III ) –N (DMAP) bond, resulting in the tetrahedral coordination of carbonyl carbon (Figure S6b). This transition-state structure shows general characteristics of the S N 2-type nucleophilic substitution reaction . The formed intermediate [DMAP···HSe] δ− [DMAP-(CO)­OR] δ+ ( IV ) (Figure ) is stabilized by the ionic interaction as confirmed by the Bader charge analysis (Table S3) and charge density isosurface (Figure S6b).…”

2,3,4,5-Tetrahydropyridine (Δ1-piperideine) and its derivatives. Synthesis and chemical properties

“…90,122,123 The irradiation of a mixture of 2-methyl-3,4,5,6-tetrahydropyridine 1b and propan-2-ol with the light of a Hanovia-450W high-pressure mercury lamp through a quartz filter results in a redox process giving 2-methylpiperidine (yield 72%), acetone and the product of reductive dimerisation of acetone, 2,3-dimethylbutane-2,3-diol. 124…”