spirocyclization forming spirooxindoles and spirodihydrobenzofurans has been achieved. Mechanistic studies suggest that the transformation proceeds through sequential carbopalladation, C–Hactivation, and benzyne insertion. Both classes of spirocycles have been synthesized in good to excellent yields, and the procedure is readily scalable.
Formation of allylated quaternary carbon centers <i>via</i> C–O/C–O bond fragmentation of oxalates and allyl carbonates
作者:Haifeng Chen、Yang Ye、Weiqi Tong、Jianhui Fang、Hegui Gong
DOI:10.1039/c9cc07072a
日期:——
emphasizes Fe-promoted cross-electrophile allylation of tertiaryalkyl oxalates with allyl carbonates that generates all C(sp3)-quaternary centers. The reaction involves fragmentation of tertiaryalkyl oxalate C-O bonds to give tertiaryalkyl radical intermediates, addition of the radicals to less hindered alkene terminals, and subsequent cleavage of the allyl C-O bonds. Allylation with 2-aryl substituted
Enantioselective CuH-Catalyzed Hydroallylation of Vinylarenes
作者:Yi-Ming Wang、Stephen L. Buchwald
DOI:10.1021/jacs.6b02527
日期:2016.4.20
The enantioselective, intermolecular hydroallylation of vinylarenes employing allylic phosphate electrophiles has been achieved through a copper hydride catalyzed process. The protocol described herein can be applied to a diverse set of vinylarene substrates and allows for the installation of the parent allyl group as well as a range of 2-substituted allylic fragments.
Nickel-catalyzed enantioselective hydrovinylation of silyl-protected allylic alcohols: An efficient access to homoallylic alcohols with a chiral quaternary center
Asymmetric hydrovinylation of silyl-protected allylicalcoholscatalyzed by nickel complexes of chiral spiro phosphoramidite ligands was developed. A series of homoallylicalcohols with a chiral quaternary center were produced in high yields (up to 97%) and high enantioselectivities (up to 95% ee). The reaction provides an efficient method for preparing bifunctional compounds with a chiral quaternary
The cyclopentadienyl (Cp) group is a very important ligand for many transition‐metal complexes which have been applied in catalysis. The availability of chiralcyclopentadienyl ligands (Cpx) lags behind other ligand classes, thus hampering the investigation of enantioselective processes. We report a library of chiral CpxIrIII complexes equipped with an atropchiral Cp scaffold. A robust complexation
环戊二烯基(Cp)基团是许多在催化中应用的过渡金属配合物的重要配体。手性环戊二烯基配体(Cp x)的可用性落后于其他配体类别,因此妨碍了对映选择性过程的研究。我们报告了配备手性Cp支架的手性Cp x Ir III复合物的库。强大的络合程序可为Cp x Ir III络合物可靠地提供可调节的抗衡离子。在概念验证的应用中,含碘化物对烯炔的环异构化反应具有很高的选择性。脱氢哌啶稠合的环丙烷产物以良好的产率和对映选择性形成。