Reaction of dialkyl carbonates with alcohols: Defining a scale of the best leaving and entering groups*

A series of dialkyl and methyl alkyl carbonates has been synthesized and their re- activity investigated. The behavior of preferential leaving and entering groups for the newly synthesized carbonates has been accurately investigated. Both experimental and computa- tional studies agreed that the scale of leaving groups follows the trend: PhCH 2 O - , MeO - ≥ EtO - , CH 3 (CH 2 ) 2 O - , CH 3 (CH 2 ) 7 O - > (CH 3 ) 2 CHO - > (CH 3 ) 3 CO - . Accordingly, the scale of the entering group has the same trend, with t-butoxide being the worst entering group. A preliminary attempt to rationalize the nucleofugality trends, lim- ited to the (CH 3 ) 3 CO - and CH 3 O - groups, has indicated that a likely origin of the observed trends lies in the different entropic contributions and solvation effects.