Asymmetricconjugatealkynylation of α,β-unsaturated ketones with (triisopropylsilyl)ethynylsilanols giving β-alkynylketones took place in high yields with high enantioselectivity in the presence of chiral rhodium catalysts.
Asymmetric Organocatalytic Double-Conjugate Addition of Malononitrile to Dienones: Efficient Synthesis of Optically Active Cyclohexanones
作者:Xue-ming Li、Bo Wang、Jun-min Zhang、Ming Yan
DOI:10.1021/ol102570b
日期:2011.2.4
9-Amino-9-deoxyepiquinine efficiently catalyzed the double-conjugate addition of malononitrile to dienones. A number of 1,1,2,6-tetrasubstituted cyclohexanones were prepared in good yields, diastereoselectivities, and excellent enantioselectivities.
Hexamethonium bis(tribromide) (HMBTB) a recyclable and high bromine containing reagent
作者:Bappi Paul、Bishal Bhuyan、Debraj D. Purkayastha、Siddhartha S. Dhar、Bhisma K. Patel
DOI:10.1016/j.tetlet.2015.08.063
日期:2015.10
A recyclable and high bromine containing di-(tribromide) reagent, hexamethonium bis(tribromide) (HMBTB) has been synthesized and utilized for the bromination of various organic substrates. The spent reagent hexamethonium bromide (HMB) can be effectively recycled by regenerating and reusing it without significant loss of activity. The crystalline and stable bis(tribromide) is an effective storehouse of very high percentage of active bromine requiring just half an equivalent of it for complete bromination. Both the Br-3(-) moieties in HMBTB are nearly linear with Br-Br-Br angle of 179.55 degrees. Published by Elsevier Ltd.
Tungsten(0)- and Rhenium(I)-Catalyzed Tandem Cyclization of Acetylenic Dienol Silyl Ethers Based on Geminal Carbo-Functionalization of Alkynes
Tungsten(0)‐ and rhenium(I)‐catalyzed reactions of acetylenic dienolsilylethers based on the concept of geminal carbo‐functionalization of alkynes are reported. Treatment of 3‐siloxy‐1,3‐diene‐7‐ynes with catalytic amounts of [W(CO)6] or [ReCl(CO)5] under photoirradiation conditions gives synthetically useful bicyclo[3.3.0]octane derivatives in good yields. Extremely high catalytic activity is noted
Synthesis of cis-2,6-tetrahydropyran-4-one via diastereoselectively intramolecular cyclization of β-hydroxy allyl ketone
作者:Adam Shih-Yuan Lee、Li-Shin Lin、Yu-Ting Chang
DOI:10.1016/j.tet.2012.02.076
日期:2012.5
A series of cis-2,6-tetrahydropyran-4-ones was synthesized from the intramolecular cyclization reaction of β-hydroxy allylketones in the presence of Me3SiOTf as catalyst. The β-hydroxy allylketone was prepared from allylation reaction with β-hydroxynitrile without protection of hydroxy functionality under the Barbier-type reaction condition.