Synthesis 1990; 1990(8): 697-701
DOI: 10.1055/s-1990-26986
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Asymmetrische Diels-Alder-Reaktionen mit chiralen 2-Methyl-1-(1-arylethoxy)-1,3-butadienen

Rainer Rieger* , Eberhard Breitmaier
  • *Institut für Organische Chemie und Biochemie der Universität Bonn, Gerhard-Domagk-Str.1, D-5300 Bonn 1, Federal Republic of Germany
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Publication History

Publication Date:
17 September 2002 (online)

Asymmetric Diels-Alder Reactions with Chiral 2-Methyl-1-(1-arylethoxy)-1, 3-butadienes Chiral 1-arylethanols 2, prepared by enantioselective reduction of phenones 1 with lithium aluminium hydride and Chirald [(2S,3R)-(+)-4-dimethylamino-1, 2-diphenyl-3-methylbutanol], are converted to the chiral 2-methyl-1-(1-arylethoxy)-1,3-butadienes 5 by vinylogous transesterification with 2-methyl-1-ethoxyacrolein (3) and subsequent Wittig methylenation of the intermediate chiral (3-(1-arylethoxy)-2-methylacroleins 4. The 1-arylethyl isoprenyl ethers 5 undergo [4+2] cycloadditions as donor-activated 1,3-dienes with numerous electron-deficient dienophiles in good chemical yields and high diastereomeric excesses (≥95%). The chiral inductor is removed optically pure from the cycloadducts by hydrogen chloride and silica gel in dichloromethane suspension at room temperature.