نتایج جستجو برای: cyclizations

تعداد نتایج: 570  

2014
Tulaza Vaidya Ryan Cheng Peter N. Carlsen Alison J. Frontier Richard Eisenberg

A heterogeneous gold catalyst with remarkable activity for promoting the electrophilic reactions of aryl vinyl ketones and aryl dienyl ketones is described. The catalyst is easy to prepare, is robust, and can be recycled. Low loadings are effective for different types of cationic reactions, including Nazarov cyclizations, lactonizations, and [1,2] shifts.

Journal: :Chemical communications 2012
Zhongxue Fang Haiyan Yuan Ying Liu Zixun Tong Huiqin Li Jin Yang Badru-Deen Barry Jianquan Liu Peiqiu Liao Jingping Zhang Qun Liu Xihe Bi

gem-Dialkylthio vinylallenes were obtained for the first time and applied to the divergent synthesis of fully-substituted pyrroles and thiophenes by domino cyclizations. These two cyclization pathways were regulated by alkylthio groups. Plausible reaction mechanisms were presented and supported by DFT calculations. An unprecedented metal-free carbothiolation was discovered in the formation of t...

2017
Daniel Rackl Viktor Kais Eugen Lutsker And Oliver Reiser

The synthesis of chiral tetrahydrofurans and pyrrolidines starting from 1,2-diols or β-amino alcohols, respectively, by visible-light-mediated deoxygenation is described. Easily accessible monoallylated/propargylated substrates were activated either as inexpensive ethyl oxalates or as recyclable 3,5-bis(trifluoromethyl)benzoates to generate alkyl radicals suitable for 5-exo-trig/5-exo-dig cycli...

Journal: :Advanced Synthesis & Catalysis 2018

Journal: :Journal of Synthetic Organic Chemistry, Japan 1992

2007
Jose Luis Chiara Ángela García

Cyclic hydrazones are efficient ketyl radical acceptors in reductive coupling cyclizations mediated by samarium diiodide, affording cyclic amino alcohols with controlled stereochemistry at the new aminated stereocenter. This approach has been successfully applied to the stereoselective synthesis of a fully functionalized trehazolin cyclitol starting from D-glucose, where the required cyclic hyd...

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