Abstract
6-exo-Methylbicyclo[3.2.0]hepten-7-ones and their 2-alkylidene analogues are readily prepared from dialkyl squarates. These compounds undergo facial oxy-Cope ring expansions upon treatment with vinyllithium; the former leads to bicyclo[4.2.1]non-1(4)-en-6-ones and the latter to the first examples of bicyclo[5.2.1]dec-1(10)-en-5-ones, compounds having exceptionally strained bridgehead double bonds. The transformations are controlled by the 6-exo- methyl group in the starting material along with the substituent at position- 1 (bridgehead) which force attack of the lithium reagent from the concave face of the starting material, thus allowing the cyclopentenyl or alkylidene groups to participate in the sigmatropic event.
Original language | English (US) |
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Pages (from-to) | 3379-3386 |
Number of pages | 8 |
Journal | Journal of Organic Chemistry |
Volume | 65 |
Issue number | 11 |
DOIs | |
State | Published - Jun 2 2000 |
Externally published | Yes |
ASJC Scopus subject areas
- Organic Chemistry