A mild, selective and efficient Nazarov cyclization of divinyl ketones catalyzed by phosphomolybdic acid (PMA) is described. The process demonstrates a broad substrate scope with functional group tolerance under short reaction times. PMA supported on silicagel is more efficient than the bulk catalyst and is recycled up to three times without significant activity loss.
Cationic bromonium complex: NBS/P(OPh)3 as an efficient catalyst for Nazarov cyclization
作者:Fenglou Guo、Limin Wang、Song Mao、Chi Zhang、Jianjun Yu、Jianwei Han
DOI:10.1016/j.tet.2012.06.107
日期:2012.9
A general, catalytic method for Nazarovcyclization of dihydropyran derivatives has been developed. Cationic bromonium complex: NBS/P(OPh)3 was identified as an efficientcatalyst for the synthesis of a number of different cyclopentenones in high yields with an excellent level of diastereocontrol.
Benzotriazolium Salts: Emergent Readily Accessible Bench-Stable Lewis Acid Catalysts
作者:Tobias Danelzik、Sumi Joseph、Christian Mück-Lichtenfeld、Constantin G. Daniliuc、Olga García Mancheño
DOI:10.1021/acs.orglett.2c01697
日期:2022.8.26
benzotriazolium salts have been introduced as efficient, readily accessible, bench-stable Lewisacid catalysts. Though these sorts of N-heterocyclic compounds have found wide applications as ionic liquids or electrolytes, their Lewisacid catalytic activity remained unexplored. Herein, their potential as Lewisacid catalysts was demonstrated in two prototypical allylic and Nazarov cyclization reactions, showing