Controlled Release of Volatile Secondary and Tertiary Alcohols by Neighboring Group Participation: Stepwise Cyclization and Re-Opening of 2,2 '-Bis(carbamoyl)dibenzoates at Neutral pH

摘要

Bioactive, volatile, secondary and tertiary fragrance alcohols are efficiently released by intramolecular neighboring-group-assisted hydrolysis of 2,2'-bis(carbamoyl)dibenzoates at neutral pH. The stepwise cyclization of 2,2'-[(methylimino)bis(propane-3,1-diylcarbamoyl)]dibenzoates is followed by the re-opening of the intermediately formed diphthalimide and proceeds in an overall four-step consecutive reaction sequence. Kinetic rate constants for all four reaction steps could be determined pairwise by reversed-phase HPLC. At neutral pH, secondary alcohols were released by one order of magnitude faster than the tertiary alcohols, and the rate constants for the re-opening of the diphthalimides were found to be in the same order of magnitude as the release of the tertiary alcohols. Dynamic headspace analysis on a dry cotton surface finally confirmed the efficient release of tertiary alcohols under mild reaction conditions generally encountered for applications in functional perfumery.