A highly enantioselective and diastereoselective synthesis of cyclobutanes via boronic esters.
[formula: see text] 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.
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Department of Chemistry, Washington State University, Pullman 99164-4630, USA.
Hiscox
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Matteson
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D001897:Boronic Acids / Q000737:chemistry*; D002087:Butyrates / Q000138:chemical synthesis*; D002384:Catalysis; D003500:Cyclization; D003503:Cyclobutanes / Q000138:chemical synthesis*; D004952:Esters; D008274:Magnesium / Q000737:chemistry; D013058:Mass Spectrometry; D009570:Nitriles / Q000138:chemical synthesis*; D013237:Stereoisomerism
D001897:Boronic Acids; D002087:Butyrates; D003503:Cyclobutanes; D004952:Esters; D009570:Nitriles; D008274:Magnesium