No abstract

We report here a regiospecific [3 + 2] annulation between aminocyclopropanes and various functionalized alkynes enabled by a P/N-heteroleptic Cu(I) photosensitizer under photoredox catalysis conditions. Thus, a divergent construction of 3-aminocyclopentene derivatives including methylsulfonyl-, arylsulfonyl-, chloro-, ester-, and trifluoromethyl-functionalized aminocyclopentenes could be achieved with advantages of high regioselectivity, broad substrate compatibility, and mild and environmentally benign reaction conditions.

The reactivity umpolung of the CN bond in the quinoxaline scaffold has been successfully realized for the first time by introduction of a formyl or an acyl group adjacent to the C-position of the CN moiety. The reversed reactivity of the CN bond thus enabled direct nucleophilic attack of alkyl Grignard reagents at the N-terminus rather than the C-terminus, thereby providing an unprecedented and efficient method for the synthesis of quinoxalin-2­(1H)-one derivatives involving a tandem N-alkylation/CC bond cleavage process.