Preferred endo-attack on hexamethyldewarbenzene by protons kinetic vs. thermodynamic control
✍ Scribed by H. Hogeveen; P.W. Kwant
- Book ID
- 104245083
- Publisher
- Elsevier Science
- Year
- 1972
- Tongue
- French
- Weight
- 277 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0040-4039
No coin nor oath required. For personal study only.
✦ Synopsis
HexamethylDewarbenzene (1) is attacked by various reagents from the exo side of the molecule. 1 Only recently* has en unambiguous example of endo attack been presented. Another example of endo attack is claime d, but it is doubtful whether this is correct, because it is possible, as shown in analogous cases 4,5 , that intermediates of the type & and & occur, which interconvert rapidly thereby destroying information about the orientation of the initial attack. We wish to report here the protonation of 1 by HCl under conditions wherein interconversion of the intermediate bicyclic C2.1.1.1 ions occurs only for a minor part. The data show that the protonation occurs for at least 80$ from the endo side. It will further be shown that the initially formed bicyclic C2.1.1.1 addition products of 1 and HCl undergo a number of reactions depending on the experimental conditions, such as temperature and acidity. Ions a and 2 are formed by dissolving 1 in an excess of an equimolar mixture of HCl and methylene chloride in the temperature range of -50' to-lOO°C.