نتایج جستجو برای: cyclizations
تعداد نتایج: 570 فیلتر نتایج به سال:
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.
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...
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...
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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