Lipase-catalysed synthesis of olvanil in organic solvents

The release rate of vanillylamine from its hydrochloride salt was the limiting step in the lipase-catalysed synthesis of olvanil, a capsaicin analogue amide, in organic solvents. When the tertiary amine base concentration (N,N-diisopropylethylamine) was increased from 20 mM to 360 mM, the initial rate of amide synthesis increased proportionally. At a 12 molar excess of N,N-diisopropylethylamine and 30 min of preincubation, both the initial rate and total conversion were the same as those with free vanillylamine (80% conversion in 20 h). This result was independent of the organic solvent used. It is also shown that N,N-diisopropylethylamine does not enhance lipase activity.