Treatment of 3-acetylyunaconitine 2 from yunaconitine 1 with NBS at 40C for 12h afforded the 3-acetylyunaconitine azomethine 3 (48%). Reaction of 3 with CHsI in MeOH at room temperature overnight gave the iminium salt 4 (100%). Unexpectedly, treatment of 4 with 5% NaOH in methanol at room temperature for 20min produced the rearrangement alkaloid 5 (38%) besides other unidentified compounds. Acetylation of 5 with AczO/pyridine containing a small amount of TsOH gave its two derivatives 6 (28%) and 7 (56%). The structure of 5 was confirmed using 2D NMR spectra and single crystal X-ray analysis of its acetyl derivative 7. 2002 Elsevier Science Ltd. All rights reserved.