Abstract:Cobalt(II) acetylacetonate-catalyzed isocyaA C H T U N G T R E N N U N G nide insertion reactions with amines utilizing tert-butyl hydroperoxide (TBHP) as an oxidant under ultrasound conditions have been developed, which lead to the synthesis of ureas, thioureas, as well as 2-aminobenzimidazoles, 2-aminobenzothiazoles, and 2-aminobenzoxazoles under the general reaction conditions in up to 96% yields, respectively. The intermediate amino methylidyneaminiums, initiated by cobalt(II) acetylacetonate-catalyzed reactions of isocyanides with amines, could be easily trapped by different nucleophiles such as water, sulfur, and intramolecular nucleophilic functional groups. This method provides a simple, general and practical protocol for the divergent synthesis of ureas, thioureas and azaheterocycles.
A Pd-catalyzed insertion and cycloaddition of CO and isocyanide into 2-iodoanilines under atmospheric pressure has been developed and affords quinazoline-2,4(1H,3H)-diones through the formation of new C-C, C-O, and C-N bonds under mild conditions. This reaction provides a new and practical method not only for the construction of quinazoline-2,4(1H,3H)-diones but also for the efficient utilization of carbon dioxide.
A novel and efficient protocol for the creation of 6-amino phenanthridine derivatives by Co(acac)2-catalyzed isocyanide insertion with 2-aryl anilines under an O2 atmosphere via homolytic aromatic substitution (HAS) type C-H functionalization has been developed. This reaction not only proceeds smoothly utilizing O2 as the oxidant but also provides a new approach to construct phenanthridine derivatives utilizing readily available 2-aryl anilines with isocyanides instead of 2-isocyanobiaryls with different radical precursors.
A novel and efficient cobalt-catalyzed oxidative isocyanide insertion with amines via two C À N bond formation reactions under ultrasound irradiation conditions has been developed. This protocol provides a simple, clean and general way to synthesize guanidines or their corresponding hydrochlorides from simple starting materials under ultrasonic conditions. This chemistry could also be applied to an efficient synthesis of optically active guanidines without loss of enantioselectivity.
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