RESUMO
Here, we report a general copper-catalyzed C(sp3) carboboration of 1,3-diynes, providing access to an array of tetra-substituted boryl enynes in a regioselective manner. All four positions of enyne can be efficiently manipulated using this methodology. The reaction was smoothly applied in the conjugation of complex bioactive molecules to the enyne scaffold. Cross-coupling reactions were carried out with boron end groups on densely substituted 1,3-enynes, opening avenues for the modular synthesis of highly functionalized enynes. Control experiments and density functional theory studies supported the proposed mechanism.
RESUMO
We demonstrate for the first time a nickel-catalyzed diastereoconvergent reductive coupling of a heteroatom-attached allyl moiety with aldehydes, viz., O-allyl, O-cinnamyl salicylaldehydes, and others, to afford syn-chromanols exclusively. The reaction proceeds through a [2 + 2 + 1] oxidative cycloaddition involving the active catalyst. This method is applicable to both terminal and internal olefin substrates. The formal syntheses of CP-199.330, CP-199.331, and CP-85.958 have been demonstrated. Control experiments, mass spectrometric analysis, and DFT studies supported the plausible mechanism and the origin of exclusive syn-selectivity.
RESUMO
In the present work, we demonstrate a regioselective [2 + 2 + 2] cyclotrimerization of 1,3-diynes catalyzed by Ni0 to provide hexasubstituted benzenes (HSBs). HSBs have significant applications as functional materials and pharmaceuticals. The present protocol exhibited remarkable versatility, transforming 1,3-diynes with diverse alkyl, aryl, and heterocyclic groups to the corresponding HSBs. With the help of control experiments and density functional theory (DFT), the mechanism of the reaction and the origin of regioselectivity were elucidated.