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Asymmetric Diels-Alder reaction catalysed by some chiral Lewis acids

✍ Scribed by F. Rebiere; O. Riant; H.B. Kagan

Publisher
Elsevier Science
Year
1990
Tongue
English
Weight
906 KB
Volume
1
Category
Article
ISSN
0957-4166

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✦ Synopsis

Diels-Alder reaction between cyclopentadiene and various dienophiles (mainly methacrolein) at -78°C was catalysed by various chiral aluminum alcoholates. The catalysts were prepared by reaction of EtAICl2 with several families of dial (or their monoether monoalcohol derivatives) . The most enantioselective catalyst is derived from diol Sa. A detailed investigation in that case gives some light on the experimental parameters of the system, especially the reproductible preparation of the catalyst. Enantiomeric excess up to 86% (in exo cycloadduct 2a) could be achieved. Tentative structures are proposed for the transition state of the reaction.

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Asymmetric Diels–Alder reactions of N-su
Asymmetric Diels–Alder reactions of N-sulfinyl dienophiles using chiral Ti(IV) Lewis acids
✍ Annette Bayer; Lars K. Hansen; Odd R. Gautun 📂 Article 📅 2002 🏛 Elsevier Science 🌐 English ⚖ 407 KB

Enantioselective hetero Diels-Alder (HDA) reactions of 1,3-cyclohexadiene with benzyl N-sulfinylcarbamate 1a and with N-sulfinyl-p-toluensulfonamide 1b promoted by chiral Ti(IV)-based Lewis acids are reported. The obtained yields and enantiomeric excesses obtained are heavily dependant on the mode o