Isoflavones were synthesized from the reaction of 3‐bromochromone derivatives and aryltributylstannanes via Stillecoupling catalyzed by a water‐soluble and reusable PdCl2(NH3)2/2,2′‐cationic bipyridyl system in aqueous solution. For prototype 3‐bromochromone, the coupling reaction was performed at 80°C for 24 hr with 2.5 mol% catalyst in water in the presence of tetrabutylammonium fluoride. After
A reductive cross coupling reaction process for functionalization of a nucleophilic alkene can be achieved. The nucleophilic alkene and a nucleophilic cross coupling partner compound can be reacted in the presence of an oxidizable alcohol and a suitable catalyst to form a reductive coupling product. Various additives can also be useful to refine the process such as by mitigating certain undesirable intermediates, facilitating specific site selectivity for various substitutions or reaction sites, etc. Chiral additives can be optionally used which act to provide asymmetric catalysis, e.g. allow for regioselective and stereoselective production of reductive coupling products. A reductive cross coupling pathway can include oxidizing the oxidizable alcohol to form a catalyst hydride. The nucleophilic alkene can be inserted into the catalyst hydride to form a catalyst-alkyl intermediate. Further, the catalyst-alkyl intermediate can be transmetallized with the nucleophilic cross coupling partner compound to form a transmetallated intermediate. The catalyst can be reductively eliminated to form the reductive coupling product and a reduced catalyst. Finally, the reduced catalyst can be oxidized under aerobic conditions, for example with oxygen, to form the oxidized catalyst and subsequent repetition through the cyclic pathway.
A new approach to carbon–carbon bond formation: development of aerobic Pd-catalyzed reductive coupling reactions of organometallic reagents and styrenes
作者:Keith M. Gligorich、Yasumasa Iwai、Sarah A. Cummings、Matthew S. Sigman
DOI:10.1016/j.tet.2009.03.096
日期:2009.6
Alkenes are attractive starting materials for organic synthesis and the development of new selective functionalization reactions is desired. Previously, our laboratory discovered a unique Pd-catalyzed hydroalkoxylation reaction of styrenes containing a phenol. Based upon deuterium labeling experiments, a mechanism involving an aerobicalcoholoxidationcoupled to alkene functionalization was proposed
Palladium-Catalyzed Reductive Coupling of Styrenes and Organostannanes under Aerobic Conditions
作者:Keith M. Gligorich、Sarah A. Cummings、Matthew S. Sigman
DOI:10.1021/ja076746f
日期:2007.11.1
We report a highly regioselective PdII-catalyzed reductive coupling of an alkene with an organostannane using a tandem alcohol oxidation under aerobic conditions. Both aryl- and vinylstannanes are competent coupling partners with a variety of styrene derivatives. Mechanistic experiments support a tandem alcohol oxidation/alkene functionalization process. The ability to trap a palladium hydride derived
Novel resorcinol derivatives and methods of preparation and use are presented. These compounds can stimulate angiogenesis as a biological function triggered by the activation of one cannabinoid receptor distinct from CB1 and CB2. Thus, these compounds are specific ligands for one cannabinoid receptor distinct from CB1 and CB2. The invented compounds, when administered in a therapeutically effective amount to an individual or animal, results in a sufficiently high level of that compound in the individual or animal to cause a physiological response. The physiological response may be useful to treat a number of physiological conditions.