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

Herein we present a chiral silver phosphate-catalyzed 5-<i>endo</i>-<i>dig</i> 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.