Hydrogen bonding of a hydroxy proton to an indenide carbanion observed by n.m.r. and i.r. spectroscopy. The use of cryptand to make the alcohol group less acidic than the carbon acid in aprotic solvents of low dielectric constant

Abstract

The indene moiety in 4-(inden-3′-yl)-2,3,4-trimethylpentan-2-ol (1) is a stronger acid than the hydroxy group in dipolar aprotic solvents but the acidity is reversed in non-polar aprotic solvents; addition of cryptand makes the hydrogen-bonded carbanion (2) the most favoured species in all solvents.