Simple and selective one-pot replacement of the N-methyl group of tertiaryamines by quaternization and demethylation with sodium sulfide or potassium thioacetate: an application to the synthesis of pergolide
L. Anastasia et al., Simple and selective one-pot replacement of the N-methyl group of tertiaryamines by quaternization and demethylation with sodium sulfide or potassium thioacetate: an application to the synthesis of pergolide, J CHEM S P1, (19), 2001, pp. 2398-2403
The paper describes a mild, selective, and rapid replacement of an N-methyl
group of tertiary amines with other alkyl groups via a simple one-pot proc
edure. This transformation is easily achieved by preparation of the appropr
iate quaternary ammonium salt in sulfolane and in situ treatment with sodiu
m sulfide or potassium thioacetate. The protocol is successfully applied to
the transformation of dihydrolysergol, dextromethorphan and laudanosine (a
s models of ergot and opium N-methyl alkaloids) into various A-alkyl congen
ers.