The cycloadditions of carbon dioxide into epoxides to afford cyclic carbonates by H-bond donor (HBD) and onium halide (X) cocatalysis have emerged as a key strategy for CO 2 fixation. However, if the HBD is also a halide receptor, the two will quench each other, decreasing the catalytic activity. Here, we propose a strained ion pair tris(alkylamino)cyclopropenium halide (TAC•X), in which TAC repels X. TAC possesses a positively charged cyclopropenium core that makes the vicinal C−H or N−H a nonclassical HBD. The interionic strain within TAC•X makes TAC a more electrophilic HBD, allowing it to activate the oxygen of the epoxide and making X more nucleophilic and better able to attack the methylene carbon of the epoxide. NMR titration spectra and computational studies were employed to probe the mechanism of the cycloaddition of CO 2 to epoxides reactions under the catalysis of TAC•X. The 1 H and 13 C{ 1 H}NMR titration spectra of the catalyst with the epoxide substrate unambiguously confirmed H-bonding between TAC and the epoxide. DFT computational studies identified the transition states in the ring-opening of the epoxide (TS1) and in the ring-closure of the cyclic carbonate (TS2).

A simple Ni(cod)2 and carbene mediated strategy facilitates the efficient catalytic cross‐coupling of methoxyarenes with a variety of organoboron reagents. Directing groups facilitate the activation of inert C−O bonds in under‐utilized aryl methyl ethers enabling their adaptation for C−C cross‐coupling reactions as less toxic surrogates to the ubiquitous haloarenes. The method reported enables C−C cross‐coupling with readily available and economical arylboronic acid reagents, which is unprecedented, and compares well with other organoboron reagents with similarly high reactivity. Extension to directing group assisted chemo‐selective C−O bond cleavage, and further application towards the synthesis of novel bifunctionalized biaryls is reported. Key to the success of this protocol is the use of directing groups proximal to the reaction center to facilitate the activation of the inert C−OMe bond.

A copper-catalyzed regioselective [3 + 2] annulation of malonate-tetherd acyl oximes with isatins was developed, affording valuable 2,3-dihydrooxazole-spirooxindoles in moderate to good yields with excellent diastereoselectivity. The reaction sequence involves...