Nickel‐Catalyzed, Regio‐ and Enantioselective Benzylic Alkenylation of Olefins with Alkenyl Bromide
作者:Jiandong Liu、Hegui Gong、Shaolin Zhu
DOI:10.1002/anie.202012614
日期:2021.2.19
A NiH‐catalyzed migratory hydroalkenylation reaction of olefins with alkenyl bromides has been developed, affording benzylic alkenylation products with high yields and excellent chemoselectivity. The mild conditions of the reaction preclude olefinic products from undergoing further isomerization or subsequent alkenylation. Catalytic enantioselective hydroalkenylation of styrenes was achieved by using
Silver-catalyzed Double Decarboxylative Radical Alkynylation/Annulation of Arylpropiolic Acids with α-keto Acids: Access to Ynones and Flavones under Mild Conditions
Ynones are privileged buildingblocks in various organic syntheses of heterocyclicderivatives due to their multifunctional nature, and flavones are an important class of natural products with a wide range of biological activities. We describe the catalytic double decarboxylative alkynylation of arylpropiolic acids with α‐keto acids. With Ag(I)/persulfate as the catalysis system, the valuable ynones
3α-Hydroxy-3β-(phenylethynyl)-5β-pregnan-20-ones: Synthesis and Pharmacological Activity of Neuroactive Steroids with High Affinity for GABA<sub>A</sub> Receptors
作者:Ravindra B. Upasani、Kevin C. Yang、Manuel Acosta-Burruel、Chris S. Konkoy、James A. McLellan、Richard M. Woodward、Nancy C. Lan、Richard B. Carter、Jon E. Hawkinson
DOI:10.1021/jm9605344
日期:1997.1.1
Neuroactive steroids that allosterically modulate GABAA receptors have potential uses as anticonvulsants, anxiolytics, and sedative-hypnotic agents. Recently, a series of pregnanes substituted with simple alkyl groups at the 3 beta-position were synthesized and found to be active in vitro. The present report describes the synthesis of a series of substituted 3 alpha-hydroxy-3 beta-(phenylethynyl)pregnan-20-ones
Palladium catalyzed hydrogenolysis of 1,1-dibromo-1-alkenes by tributyltin hydride proceeds smoothly to give (Z)-1-bromo-1-alkenes with excellent stereoselectivity in good yields. Dibromomethylenation of aldehydes by a combination of CBr4 and Ph3P in methylene chloride and the successive hydrogenolysis affords (Z)-1-bromo-1-alkenes in one-pot.
successfully employed to convert aromatic and heteroaromaticaldehydes and ketones efficiently to the corresponding dibromoolefins. Exemplified by the successful dibromoolefination of traditionally inert pyridyl‐flanked carbonyls, MW activation significantly broadens the scope of this valuable transformation, although some limitations especially with electron‐rich aromaticketone derivatives remain.