Dehydration of 1-Substituted Secondary and Tertiary Bicyclononan-9-ols. A Substituent-Driven Rearrangement to 4-Substituted and/or Angularly Substituted Hexahydroindenes

Article abstract of DOI:10.1021/jo00152a030

The acid-catalyzed dehydration of substituted bicyclo<3.3.1>nonan-9-ols (1-9) has been studied as a route to substituted hexahydroindenes via skeletal rearrangement.The nature of the substituent at C1 strongly affects the rearrangement.Thus 1-substituted secondary alcohols 1-3 (R = Ph, CH3, H) afford 4-substituted 2,3,4,5,6,7-hexahydroindenes 1b-3b, while a mixture of 3a-carbethoxyhexahydroindenes (4a,b) is produced from 4 (R = CO2Et).Tertiary alcohols 5-9 afford cis-3a-substituted 2,3,3a,6,7,7a-hexahydroindenes 1a-9a.These processes are discussed in terms of relative stabilities of the intermediate carbonium ions.