Methylaluminum bis(4-substituted-2,6-di-tert-butylphenoxide) as an efficient nonchelating Lewis acid: Application to asymmetric Diels-Alder reaction and diastereoselective alkylation to alkoxy carbonyl substrates
✍ Scribed by Keiji Maruoka; Masataka Oishi; Kei Shiohara; Hisashi Yamamoto
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- French
- Weight
- 884 KB
- Volume
- 50
- Category
- Article
- ISSN
- 0040-4020
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✦ Synopsis
The exceptionally bulky methylaluminum bis(4-substituted-2$-di-6-di-tert-butylphenoxide) such as MAD or MABR can be successfully utilized as a highly efficient nonchelating Lewis acid for achieving high stereoselectivity in 1,n asymmetric induction in cyclic as well as acyclic systems. Thus, Diels-Alder reaction of the acrylate of D-pantolactone and cyclopentadiene in the presence of such bulky organoaluminum reagents exhibits high diastereoselectivity not observable with oniinary Lewis acids. Furthemmm, high levels of nonchelation conlrolled diaste~~~~selectivity are present in Grignaxd-and organolithium-types of addition to a-and palkoxy cyclic ketones in the presence of MAD or MABR