Tandem condensation of chiral α -alkoxy and α,β-dial-koxy aldehydes with allylic sulphinylanion, and thiophile promoted desulphurization of the resulting α-substituted allylic sulphoxide afford (E)-5-alkoxy-(or 5,6-dialkoxy)-2--alkene-1, 4-diols, advanced polyols precursors, the major stereochemical path occuring via a Felkin-Ahn (non chelation control) mode.
Ligand coupling through σ-sulfurane — complete retention of configuration of 1-phenylethyl group in the reaction of 1-phenylethyl 2-pyridyl sulfoxide with grignard reagent1
作者:Shigeru Oae、Tsutomu Kawai、Naomichi Furukawa
DOI:10.1016/s0040-4039(01)91150-5
日期:1984.1
The reaction of benzyl or 1-phenylethyl 2-pyridyl sulfoxide with Grignard reagent proceeds via a σ-sulfurane as an intermediate to give the coupling product, 2-benzylpyridine or 2-(1-phenylethyl)pyridine in quantitative yield. Stereochemistry for this reaction is complete retention at the benzylic carbon atom.
The ligand coupling reaction was extended to 3- and 4-pyridyl sulfoxides as well as the 2-pyrimidyl moiety with Grignard reagents. It was found that both 4-pyridyl and 2-pyrimidyl sulfoxides nicely underwent the ligand coupling reactions, but 3-pyridyl sulfoxide underwent ligand exchange.