Photochemistry of a benzofuro-annulated oxanorbornadiene formation of propellanes by trapping of an intermediate carbonyl ylide with CN and CC dipolarophiles
✍ Scribed by Bussenius, Jörg ;Keller, Manfred ;Eberbach, Wolfgang
- Book ID
- 102904194
- Publisher
- John Wiley and Sons
- Year
- 1995
- Tongue
- English
- Weight
- 543 KB
- Volume
- 1995
- Category
- Article
- ISSN
- 0947-3440
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✦ Synopsis
Abstract
On photochemical excitation of the benzofuro‐annulated oxanorbornadiene 10 in the presence of dipolarophiles the 1:1 addition compounds 11, 22, 23a,b, and 24, respectively, are formed as the only monomeric products. The mechanistic interpretation is based on a reaction sequence which involves [2 + 2] photocycloaddition to the oxaquadricyclane 12, 1,3‐dipolar cycloreversion to the carbonyl ylide 13 and subsequent face‐selective trapping by the corresponding dipolarophile. No indication of the transformation of 13 to the highly strained [3]3,6‐oxepinophane 14 was obtained. With the formation of 11 one of the rare examples of the cycloaddition of a nitrile dipolarophile (i.e. acetonitrile) was uncovered.