Camphor-Derived N-Acryloyl and N-Crotonoyl Sultams: Practical Activated Dienophiles in Asymmetric Diels-alder Reactions. Preliminary Communication
✍ Scribed by Wolfgang Oppolzer; Christian Chapuis; Gérald Bernardinelli
- Publisher
- John Wiley and Sons
- Year
- 1984
- Tongue
- German
- Weight
- 292 KB
- Volume
- 67
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
Abstract
Starting from (+)‐camphor‐10‐sulfonyl chloride (5), the crystalline sultam 8 was easily prepared. Lewis‐acid‐promoted Diels‐Alder additions of the crystalline N‐acry‐loyl and N‐crotonoyl derivatives 9 and 10, respectively, to cyclopentadiene and 1,3‐butadiene at −130 to −78° furnished adducts 11, 12 and 17 with high chiral efficiency. Crystallization of the adducts and nondestructive removal of 8 gave either alcohols 13, 14 and 18 ir acid 19 in 99% enantiomeric purity. The sense of induction was reversed on using the enantiomer of 8 as the auxiliary. The structure of 10 was established by X‐ray diffraction analysis.