Diversity-oriented and diastereoselective synthesis of diverse polycyclic thieno(2,3-b)-quinoline derivatives using a synergistic strategy.

A cascade spiroannulation of 2-mercaptoquinoline-3-carbaldehydes with α,α-dicyanoalkenes as well as a cascade spiroannulation of 2-mercaptoquinoline-3-carbaldehydes aldehydes with α-bromocarbonyl compounds was investigated based on a synergistic strategy, providing a series of diverse spiro-fused heterocyclic compounds containing more different functional groups. The features of this strategy directed towards molecular complexity and diversity include step economy, mild conditions, and high bond-forming efficiency, but important polycyclic heterocyclic products, which could be transformed into potential biologically interesting heterocyclic structures.