Die Cyclopropylcarbinyl-Cyclobutyl-Homoallyl-Umlagerung II. Teil. Produkte und Geschwindigkeit der Umlagerung von Tricyclo[3.2.1.02,7]octan-3-ol-, endo- und exo-Tricyclo-[3.2.1.03,6]octan-4-ol und exo-Bicyclo[3.2.1.]oct-2-en-7-ol-Derivaten

✍ Scribed by Manfred Geisel; Cyril A. Grob; Werner Santi; Werner Tschudi

• Publisher: John Wiley and Sons
• Year: 1973
• Tongue: German
• Weight: 524 KB
• Volume: 56
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19730560323

✦ Synopsis

Abstract

Solvolyses of the 2,4‐dinitrobenzoates of the cyclopropylcarbinol 1a, the cyclo‐butanol 2a and the homoallylic alcohol 3a in buffered 70% aqueous dioxane lead to the same product mixture consisting of 78% cyclopropylcarbinol 1a and 22% homoallylic alcohol 3a. Approximately the same product mixture is optained when the homoallylic chloride 3b and the cyclopropylcarbinyl p‐nitrobenzoate 1c are solvolyzed. A common cationic intermediate is indicated in these kinetically controlled rearrangement reactions. Under conditions of thermodynamic control only homoallylic products are formed.

The 2,4‐dinitrobenzoates 1d and 2d react 7.2 × 10^3^ and 7.7 times, respectively, as fast as the homoallylic isomer 3d. Since the homoallylic chloride 3b reacts ca. 10^5^ times as fast as its saturated analogue, 7‐exo‐bicyclo[3.2.1]octyl chloride 4, all three esters react with the enhanced rates which are characteristic of these structural types.

The endo‐cyclobutyl dinitrobenzoate 2d reacts more than 60 times as fast as its exo‐isomer 6d. The rate difference is ascribed to a stereoelectronically more favorable orientation of the participating σ bonds in the puckered cyclobutane ring in the endo isomer 2d.