Synthesis of Polycylic Fused Indoline Scaffolds through a Substrates-Guided Reactivity Switch

Zn(II)-catalyzed divergent synthesis of functionalized polycyclic indolines through formal [3+2] and [4+2] cycloadditions of indoles with 1,2-diaza-1,3-dienes (DDs) is reported. Nature and type of substituents of substrates are found to act as chemical switch to trigger two distinct reaction pathways and to obtain two different types of products upon the influence of the same catalyst. The mechanism of both [4+2] and [3+2] cycloadditions was investigated and fully rationalized by density functional theory (DFT) calculations.