Base-Controlled Chemodivergent [4 + 1] and [2 + 1]/[4 + 2] Annulations of -Aminochalcones with Bromocrotonates.

Controlling the selectivity of reactions is a significantly attractive strategy in synthetic organic chemistry. Herein, an efficient base-controlled chemodivergent domino reaction between -aminochalcones and bromocrotonates has been developed. A series of -2,3-disubstituted indolines and cyclopropane-fused tetrahydroquinolines were obtained via two pathways with a broad substrate scope in moderate to excellent yields under transition-metal-free conditions. It is noteworthy that the bromocrotonates could be used as C1 or C2 synthons by modulating the base; in particular, the bromocrotonates were used as both nucleophiles and electrophiles to generate cyclopropanes for the first time.