Water-promoted synthesis of fused bicyclic triazolines and naphthols from oxa(aza)bicyclic alkenes and transformation via a novel ring-opening/rearrangement reaction

An efficient three-component domino reaction among oxa(aza)bicyclic alkenes, sodium azide, and primary haloalkanes is reported, which offers a mild access to 1,2,3-triazolines in an aqueous medium with excellent diastereoselectivities and yields. Further studies show that, water-promoted isomerization of oxa(aza) bicyclic alkenes can afford 1-naphthol derivatives in good yields. Water not only promotes the reaction, but also provides a recyclable and sustainable approach to the desired product. In addition, a novel metal-free cascade ring-opening/rearrangement reaction of the obtained bicyclic triazolines to form multifunctionalized indenes has been discovered.