syn-Diastereoselective Homoaldol Reactions: γ-Hydroxyalkylation of (Z)-2-Butenyl Carbamates and Synthesis of β,γ-cis-Di- and -Trisubstituted γ-Lactones
✍ Scribed by Prof. Dr. Dieter Hoppe; Dr. Florian Lichtenberg
- Publisher
- John Wiley and Sons
- Year
- 1984
- Tongue
- English
- Weight
- 352 KB
- Volume
- 23
- Category
- Article
- ISSN
- 0044-8249
No coin nor oath required. For personal study only.
✦ Synopsis
In the crystal, the molecule has C, symmetry (Fig. ); its conformation essentially corresponds to that which, according to MNDO calculations and NMR data, is the more stable of the two conformations in The benzene ring has an unsymmetric boat conformation, whose most striking characteristic is the marked bending of the "bow" (Fig. ; al =26.8"); to our knowledge this is the strongest deviation from planarity known so far in a benzene ring. The angle at the "stern" is smaller (a2 = 12 O ) , and the sum al+a2=38.8" is close to that found in the [6]paracyclophane system (41.3 '[Ia1, 38.9 '[Ib1). A remarkable feature is the large angle Dl = 48 O ; the strain at the bridgehead carbon atoms C-6 and C-10 also manifests itself in marked pyramidalization (sum of the bond angles: 354").