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Bicyclic (alkyl)(amino)carbene (BICAAC) is introduced as a metal- free catalyst for reduction of various nitriles to corresponding amine hydrochloride salts in the presence of pinacolborane. Mechanistic investigations combining experiments and...

Recent DFT based molecular engineering to obtain stable oxathiirane S-oxide derivatives evokes the recommencement of the use of carbenes for the sequestering of SO2, which has been kept separate so far. Carbene is one of the key chemicals for the sequestering of various premier greenhouse gases like CO2, CO, N2O, etc. In this respect, a comparative study of the reactivity of carbenes with variant greenhouse gases is highly demanding. The present investigation is engrossed in the comparative reactivity of SO2 and NO2 with carbenes. All three selected carbenes are highly susceptible to SO2 and NO2. Through an immaculate mechanistic study, we are able to corroborate that the end product of the carbene–SO2 reaction is an adduct which has a preferable structure having a six-membered ring with hydrogen bonding instead of ketone and SO with higher thermodynamic stability than the corresponding oxathiirane S-oxide derivative. Carbene reacts with NO2 to form a stable carbene N, N-dioxide derivative which forms vibrationally excited oxaziridine N-oxide which rapidly dissociates to form a ketone derivative. The formation of carbene S, S-dioxide and carbene N, N-dioxide is a barrierless process. The dissociation of oxaziridene N-oxide is also a barrierless process.

The sequestering and complete conversion of SO 2 to valuable chemicals in a metal-free pathway is highly demanded. The recent success of SO 2 fixation by N-heterocyclic carbenes instigated further studies in this regard. Previous reports were confined within the carbene−SO 2 reaction mechanism and the stability of oxathiirane S-oxide derivatives. The complete conversion of captured SO 2 to precious chemicals was not studied. The present inquisition has accomplished the scarcity of the earlier studies. It is observed that in the presence of an excess amount of carbene, the registered SO 2 is converted to the ketone derivative and thiocarbonyl S-oxide derivative. An electronic level investigation of these reactions is carried out. From the change of the molecular orbitals along the reaction path, it is concluded that the reaction between the oxathiirane S-oxide derivative and carbene follows a frog's hunting mechanism.

Herein, we report the first catalytic methylation of primary amides using CO2 as a C1 source. A bicyclic (alkyl)(amino)carbene (BICAAC) performs as an efficient catalyst exhibiting a dual role for...