1069114-64-2Relevant academic research and scientific papers
Gold(I)-Catalyzed Enantioselective Desymmetrization of 1,3-Diols through Intramolecular Hydroalkoxylation of Allenes
Zi, Weiwei,Toste, F. Dean
, p. 14447 - 14451 (2016)
A gold(I)-catalyzed enantioselective desymmetrization of 1,3-diols was achieved by intramolecular hydroalkoxylation of allenes. The catalyst system 3-F-dppe(AuCl)2 /(R)-C8-TRIPAg proved to be specifically efficient to promote the desymmetrizing cyclization of 2-aryl-1,3-diols, which have proven challenging substrates in previous reports. Multisubstituted tetrahydrofurans were prepared in good yield with good enantioselectivity and diastereoselectivity by this method.
Copper-Catalyzed Intramolecular Desymmetric Aryl C-O Coupling for the Enantioselective Construction of Chiral Dihydrobenzofurans and Dihydrobenzopyrans
Yang, Wenqiang,Liu, Yangyuan,Zhang, Shasha,Cai, Qian
, p. 8805 - 8808 (2015/11/27)
O-Heterocyclic structures such as 2,3-dihydrobenzofurans are key motifs in many natural compounds and pharmaceuticals. Enantioselective formation of chiral dihydrobenzofurans and analogues was achieved through a copper-catalyzed desymmetrization strategy with a chiral cyclic 1,2-diamine. A broad range of substrates are compatible with this CuI-diamine catalytic system and afford the desired coupling products with chiral tertiary or quaternary carbon centers in high yields and good to excellent enantioselectivities under mild conditions. O-Heterocyclic structures such as chiral dihydrobenzofurans can be formed enantioselectively through a copper-catalyzed desymmetrization strategy with a chiral cyclic 1,2-diamine ligand. A broad range of substrates is compatible with this CuI-diamine catalytic system and afford the desired coupling products with chiral tertiary or quaternary carbon centers in high yields and good to excellent enantioselectivities under mild conditions.
Synthesis of benzocyclobutenes by palladium-catalyzed C-H activation of methyl groups: Method and mechanistic study
Chaumontet, Manon,Piccardi, Riccardo,Audic, Nicolas,Hitce, Julien,Peglion, Jean-Louis,Clot, Eric,Baudoin, Olivier
supporting information; experimental part, p. 15157 - 15166 (2009/03/12)
An efficient catalytic system has been developed for the synthesis of benzocyclobutenes by C-H activation of methyl groups. The optimal conditions employed a combination of Pd(OAc)2 and PtBu3 as catalyst, K2CO3 as the base, and DMF as solvent. A variety of substituted BCB were obtained under these conditions with yields in the 44-92% range, including molecules that are hardly accessible by other methods. The reaction was found limited to substrates bearing a quaternary benzylic carbon, but benzocyclobutenes bearing a tertiary benzylic carbon could be obtained indirectly from diesters by decarboxylation. Reaction substrates bearing a small substituent para to bromine gave an unexpected regioisomer that likely arose from a 1,4-palladium migration process. The formation of this "abnormal" regioisomer could be suppressed by introducing a larger subsituent para to bromine. DFT(B3PW91) calculations on the reaction of 2-bromo-tert-butylbenzene with Pd(PtBu3) with different bases (acetate, bicarbonate, carbonate) showed the critical influence of the coordination mode of the base to induce both an easy C-H activation and to allow for a pathway for 1,4-palladium migration. Carbonate is shown to be more efficient than the two other bases because it can abstract the proton easily and at the same time maintain κ1-coordination without extensive electronic reorganization.
