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.
A novel catalyst system—a combination of the readily available 2,2′-biphenol with the inexpensive, nontoxic, and eco-friendly B(OH)3—promoted the Nazarov cyclization of activated and inactivated divinyl ketones to afford the corresponding cyclopentenones up to 96% yield under, in a cis-selective manner. Compared with the conventional harsh conditions with hazardous reagents, user-friendly method was established with bench-stable and easy-to-handle reagents.
Efficient Nazarov Cyclizations of 2-Alkoxy-1,4-pentadien-3-ones
作者:Guangxin Liang、Stefan N. Gradl、Dirk Trauner
DOI:10.1021/ol036019z
日期:2003.12.1
[GRAPHICS]Expeditious and high-yielding Nazarov cyclizations of 2-alkoxy-1,4-pentadien-3-ones are described. An example of a catalytic asymmetric Nazarov cyclization is presented.
Nazarov-type Reactions in Water
作者:Masaya Kokubo、Shū Kobayashi
DOI:10.1002/asia.200800461
日期:2009.4.6
AbstractDifferent in water! We have developed Nazarov‐type reactions in water. Different reaction courses compared with those in organic solvents are observed in water. In the presence of a scandium based, surfactant‐type catalyst, water‐trapping products are obtained exclusively. The results presented are unprecedented and provide a valuable extension to information available regarding organic reactions in water.magnified image