Notizen: Influence of Counter Ion Structure on the Direction of the Phase Transfer Catalytic Methylation of an Enol [1]
Open Access
- 1 March 1990
- journal article
- Published by Walter de Gruyter GmbH in Zeitschrift für Naturforschung B
- Vol. 45 (3) , 409-412
- https://doi.org/10.1515/znb-1990-0320
Abstract
Phase transfer catalytic (PTC) methylations of deoxybenzoin by dimethyl sulfate can be steered towards enol ether formation by large, sterically shielded ammonium ions or – more strongly – by large highly delocalized phospho-iminium (and presumably other large) cations. The C-alkylation direction is favoured by small, hard ammonium ions of the type RNMe3 + and by crown ethers, particularly benzo-crowns. O/C ratios can be varied between 0,75 and 63, the largest effects so far reported for ambident anions. These results should give guide-lines for alkylations of other ambident ions.Keywords
This publication has 0 references indexed in Scilit: