Cleavage of tert-Butyl Benzoates with NaH in DMF: Comments on the Mechanism and a Simple and Safe Alternative Procedure

The hazardous and inconvenient Schmidt procedure for tert-butyl benzoate ester cleavage by NaH in DMF has been reinvestigated. The reaction is suggested to involve B(AC)2 ester cleavage, facilitated by adventitious, NaH-derived NaOH, rather than the proposed E2 elimination of isobutylene by DMF-derived NaNMe2. Powdered KOH in THF is a significantly safer and simpler alternative that effects cleavage of tert-butyl benozoates, at ambient temperature, in excellent yield (94-99%).