Letter from the President

Abstract

Deprotonation of RCO2CH2Ph (R = Me, Et, iso Pr) with HO− in the gas phase yields the two (M-H)− ions (R-H)−-CO2CH2Ph and RCO2−-CHPh which do not interconvert under conditions of collisional activation. When R = tert Bu, deprotonation forms the benzylic anion exclusively. Both anions undergo fragmentation following extensive rearrangement. The enolate anions (R-H)-−CO2CH2Ph lose CO2 following a Claisen type rearrangement. The benzylic anion RCO2−-CHPh undergoes two complex rearrangements, viz (i) a 1,2 Wittig type rearrangement yielding (Ph)(R)CHO− and CO, and (ii) loss of the elements of R. The latter reaction is not a simple cleavage of R·: deuterium labelling supports stepwise loss of [H· + (R-H)] and product ion studies suggest the reaction proceeds through the complex rearrangement pathway RCO2-−CHPh → RCOCH(Ph)O− → RCH(O−)COPh → [PhCOCHO]−· + H· + (R-H). The last step may proceed via a cyclic radical anion/radical intermediate.