A De Novo Approach for the Atroposelective Synthesis of C5 Aryl Pyrazoles via 5- endo - dig Cyclization

Herein we present a chiral silver phosphate-catalyzed 5-endo-dig nucleophilic cyclization of alkynyl β-alkoxy naphthalene-substituted hydrazones under mild conditions, leading to the synthesis of various C-C axially chiral pyrazoles in excellent yields and enantioselectivities. While the silver salt accelerates the desired transformation, the chiral phosphoric acid plays a key role in inducing enantioselectivity. Moreover, this work also explores the synthetic applications and conformational stability of the obtained product.