... N-ACYLIMINIUM CYCLIZATIONS VIA REVERSIBLE 2-AZA-COPE REARRANGEMENTS * Hugo Ent, Henk de Koning and W.Nico Speckamp Laboratory of Organic Chemistry, University of Amsterdam, Nieuwe Achtergracht 129, 1018 WS ... However, when la was stirred in HCO2H/AcOH (2:3) for ~1O mm at 20C and subsequently treated with ethanolic KOH, the alcohols !1a3 (X=OH) and 5a3 (X=&H) could be isolated in ~49.5% and 25% yield, respectively. ...