181214-48-2Relevant academic research and scientific papers
Stereoselective hydrogenolysis of 1,1-dibromo-1-alkenes and stereospecific synthesis of conjugated (Z)-alkenyl compounds
Uenishi, Jun'ichi,Kawahama, Reiko,Yonemitsu, Osamu,Tsuji, Jiro
, p. 8965 - 8975 (1998)
The Pd-catalyzed hydrogenolysis of 1,1-dibromoalkenes with Bu3SnH occurs at room temperature stereoselectively to give (Z)-1-bromo-1-alkenes. We sought to determine the optimal reaction conditions and illustrate the scope of this method with 32 dibromoalkenes including alkenyl- and alkynyl- conjugated 1,1-dibromo-1-alkenes 7a-h and 2,2-disubstituted 1,1-dibromo-1- alkenes 9af. Triphenylphosphine was the best ligand for the Pd-catalyzed hydrogenolysis. A wide range of solvents can be used for this reaction excluding EtOH, AcOH, and CHCl3. However, the reaction proceeds even in these solvents with the addition of a cosolvent or radical scavenger. The reaction of 1,1-diiodo-1-alkene (3) gave a mixture of (Z)-1-iodo-1-alkene (4), (Z)-1-tributylstannyl-1-alkene (5), and a terminal alkene 6, while that of 1,1-dichloroalkene did not occur. This selectivity can be explained by the stereoselective insertion of Pd(0) to a trans bromine-alkenyl carbon bond, successive transmetalation with Bu3SnH, and reductive elimination. The Suzuki and Sonogashira couplings of the resulting (Z)-1-bromo-1-alkenes with alkenyl(dialkoxy)borane and terminal alkyne occurred to give conjugated polyenes and enynes stereospecifically. The Pd-catalyzed hydrogenolysis of 1,1-dibromo-1-alkene and successive cross-coupling can be carried out either in a stepwise manner or in one-pot under the same Pd catalysis. These two processes should be useful for the synthesis of geometrically pure polyene and enyne with a Z-alkenyl unit.
Tellurium-promoted stereoselective hydrodebromination of 1,1-dibromoalkenes: Synthesis of (: E)-bromoalkenes
Perin, Gelson,Barcellos, Angelita M.,Peglow, Thiago J.,Nobre, Patrick C.,Cargnelutti, Roberta,Lenard?o, Eder J.,Marini, Francesca,Santi, Claudio
, p. 103657 - 103661 (2016/11/13)
We describe herein an efficient and simple method for the stereoselective hydrodebromination of 1,1-dibromoalkenes by using a catalytic amount of the nucleophilic species of tellurium, generated in situ by the reaction of elemental tellurium with NaBH4. By this methodology, (E)-bromoalkenes were obtained in moderate to excellent yields under mild reaction conditions, without the use of transition metals or base. Furthermore, a high stereoselectivity for the (E)-isomer was observed when 1,1-dibromoarylalkenes were used, thus indicating a promising alternative for future applications in organic synthesis.
Domino Cu-catalyzed C-N coupling/hydroamidation: A highly efficient synthesis of nitrogen heterocycles
Martin, Ruben,Rivero, Marta Rodriguez,Buchwald, Stephen L.
, p. 7079 - 7082 (2007/10/03)
(Chemical Equation Presented) Working in tandem: Highly functionalized pyrroles and pyrazoles can be synthesized from a domino Cu-catalyzed C-N coupling/hydroamidation sequence. The scope and the generality of the method is noteworthy as a wide variety of substituents, either in the alkene or alkyne counterparts, are well tolerated.
