Oxidation of Trialkylamines by BrCCl₃: Scope, Applications and Mechanistic Aspects

Abstract

The catalyst‐free photochemical reaction of trialkylamines and BrCCl3 induced by visible light was investigated. The outcome of the reaction was found to depend strongly on the nature of the amine substrates. N‐Methyl‐1,2,3,4‐tetrahydroisoquinolines give 3,4‐dihydroisoquinolinium salts, whereas aliphatic trialkylamines produce hydrohalide salts and streptocyanines as the major products. The addition of KCN inhibits streptocyanine formation, and results in the clean formation of α‐aminonitriles instead. The light‐absorbing species and the underlying reaction mechanism were studied by DFT calculations and experimental observations.

Redox and photocatalytic properties of a NiII complex with a macrocyclic biquinazoline (Mabiq) ligand

“…The above reaction is induced by visible light as no conversion occurs without irradiation (entry 6). In the absence of the Ni II catalyst, 17 only 12% of a product mixture was obtained, which was composed of the cyclized product 4 and the reduced product 5 in a 55/45 ratio (entry 7). In the absence of the reductant, no reaction was observed (entry 8).…”

Synthesis of highly substituted fluorenones via metal-free TBHP-promoted oxidative cyclization of 2-(aminomethyl)biphenyls. Application to the total synthesis of nobilone

“…Benzylamines and derivatives thereof have been described in literature to be susceptible to oxidation by diverse reagents (tritylium ion [40], silver [38] and cerium salts [41], peroxides [42][43][44] and persulfates Scheme 2: Overview of published cyclization methodologies for the synthesis of fluorenones starting from functionalized biaryls. [45], nitroxyls [46], hypervalent iodine compounds [39,47], or tetrahalomethanes [48]) to give imines, iminium salts, aldehydes and other, in some cases dimeric products [49]. Here, oxidation of the benzylic amino moiety should lead either to iminium ions (or N-acyl iminium ions) 4a as strong electrophiles or to stabilized radicals 4b which could undergo cyclization to give the fluorenone backbone.…”

‐Aminonitriles: From Sustainable Preparation to Applications in Natural Product Synthesis

“…In the latter case, the use of the abundant chromium instead of the common ruthenium‐ or iridium‐based sensitizers provides an ecological and economical benefit. Photoorganocatalytic protocols were developed as well as an inexpensive and simple flow reactor using sunlight …”