Compelling evidence for a stepwise mechanism of the alkaline cyclisation of uridine 3?-phosphate estersElectronic supplementary information (ESI) available: Tables of rate parameters and Br�nsted plots for the alkaline cyclisation of RP uridine-3?-phosphorothioate esters and 2-hydroxypropylphosphate esters (HOCH(CH3)CH2OPO2OX). See http://www.rsc.org/suppdata/ob/b4/b406926a/While this article was being prepared we learnt of a paper in press which indicated similar conclusions and also obtained prima facie evidence for an intermediate in the metal ion complex-catalysed formation of methyl aryl phosphate esters.31