Recent advances in transition-metal catalyzed reactions using molecular oxygen as the oxidant

Abstract

For green and sustainable chemistry, molecular oxygen is considered as an ideal oxidant due to its natural, inexpensive, and environmentally friendly characteristics, and therefore offers attractive academic and industrial prospects. This critical review introduces the recent advances over the past 5 years in transition-metal catalyzed reactions using molecular oxygen as the oxidant. This review highlights the scope and limitations, as well as the mechanisms of these oxidation reactions (184 references).

Merger of Visible Light Induced Oxidation and Enantioselective Alkylation with a Chiral Iridium Catalyst

“…[7] We were wondering if this class of chiral iridium photocatalysts would also be capable of catalyzing asymmetric photoredox processes which instead proceed through oxidative chemistry and we chose the well-established oxidation of a-silylamines as our model system. [8][9][10][11][12] To start with, 2-phenylacetyl-1-methylimidazole (1 a'') was treated with N,N-diphenyl-N-(trimethylsilyl)methylamine (2 a) in the presence of the enantiomerically pure iridium complex L-IrO [13] (2 mol %), while exposed to air. Encouragingly, irradiation with visible light in the form of a standard 12 W energy saving household lamp for 20 h afforded the expected aminoalkylation product 3 a'' with 91 % ee, albeit with a low yield of just 34 % (Table 1, entry 1).…”

Eosin Y Catalyzed Visible-Light-Promoted Aerobic Oxidative Cyclization of 2-Aminobenzothiazole

“…Meanwhile the aerobic oxygen has received a great importance in research during present time. [29][30] In general, organosulfur / nitrogen compounds have been frequently used as precursors in radical reactions because they form radicals very readily. [31][32][33] Encouraged by organocatalytic visiblelight-mediated aerobic oxidative transformations [34,35] and in continuation of our work on development of novel environmentally benign synthesis [36][37][38][39] herein we report a simple, visible light irradiated, efficient and green protocol for the synthesis of 2-aminobenzothiazole, using eosin Y as photocatalyst with excellent yield as depicted in Scheme 1.…”

Liquid phase oxidation chemistry in continuous-flow microreactors

“…Thus, the design of new and improved catalysts and oxidants to increase the selectivity remains a vigorous research discipline. [5][6][7][8][9][10][11] Furthermore, reaction mechanisms are often complex for oxidation processes. [12][13][14][15] The complexity is further aggravated by complex mass transport processes in e.g., multiphase oxidation processes using oxidants such as oxygen, ozone or hydrogen peroxide.…”