The pinacol coupling is one of the most significant methods to synthesize vic-diols. The combination of samarium diiodide (SmI2) and samarium metal successfully induces the selective pinacol couplings of not only aromatic aldehydes and ketones but also aliphatic ones in the presence of trimethylchlorosilane (Me3SiCl) in 1,2-dimethoxyethane (DME). DME is the most suitable solvent for the reduction system
Stereoselective Access to Alkylidenecyclobutanes through γ-Selective Cross-Coupling Strategies
作者:Michael Eisold、Dorian Didier
DOI:10.1021/acs.orglett.7b01803
日期:2017.8.4
Alkylidenecyclobutanes (ACBs) containing all-carbon quaternary stereocenters were simply and efficiently synthesized by combining boron-homologation and γ-selective cross-coupling strategies. This unique sequence led to excellent regio- and diastereoselectivities in the generation of targeted four-membered rings with up to 99% enantiomeric excess using chiral substrates. In addition to the original
作者:Helen C. Aspinall、Nicholas Greeves、Carine Valla
DOI:10.1021/ol050256f
日期:2005.5.1
of samarium diiodide (SmI(2)) with tetraglyme catalyzes the intermolecular pinacolcoupling of aromatic or aliphatic aldehydes at loadings of 10 mol % in the presence of Me(2)SiCl(2) and Mg. Diastereoselectivity of up to 95/5 (+/-/meso) has been achieved for aliphatic aldehydes and up to 19/81 (+/-/meso) for aromatic aldehydes. De values of up to 99% have been achieved in intramolecular pinacol coupling
A Highly Enantioselective and Diastereoselective Synthesis of Cyclobutanes via Boronic Esters
作者:Hon-Wah Man、William C. Hiscox、Donald S. Matteson
DOI:10.1021/ol990579+
日期:1999.8.1
Deprotonation of enantiopure (R,R)-1,2-dicyclohexyl-1,2-ethanediol 1-chloro-4-cyanobutylboronates 5 with LDA followed by treatment with anhydrous magnesium bromide yields (R)-(trans-2-cyanocyclobutyl)boronic esters 7 in high diastereomeric and enantiomeric purity. No cyclobutane formation has been observed in the absence of at least a catalytic amount of magnesium halide.
Facile pinacol coupling of aliphatic ketones by Brook rearrangement in the presence of samarium species
作者:Xincan Wang、Guanqun Xie、Yanfei Zhao、Ke Zheng、Yanxiong Fang、Xiaoxia Wang
DOI:10.1016/j.tetlet.2021.153069
日期:2021.5
Herein we report a practical pinacol coupling reaction, in which ketones (aldehydes) react smoothly with Sm and TMSBr to afford the diol products with Sm(II) or (III) siliyl species generated in situ. This reported method affords poor yields for aromatic ketone substrates and good yields for aliphaticketones. Therefore, it distinguishes from most reductive coupling approaches that are more effective for