A novel skeletal rearrangement of the A ring of the immonium salt derived from norditerpenoid alkaloid yunaconitine

作者：Xu, LA; Chen, QH; Wang, FP^*

来源：Tetrahedron, 2002, 58(21): 4267-4271.

DOI：10.1016/S0040-4020(02)00356-3

• norditerpenoid alkaloid
• yunaconitine
• immonium salt
• rearrangement

Treatment of 3-acetylyunaconitine 2 from yunaconitine I with NBS at 40degreesC for 12 h afforded the 3-acetylyunaconitine azomethine 3 (48%). Reaction of 3 with CH3I 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 20 min produced the rearrangement alkaloid 5 (38%) besides other unidentified compounds. Acetylation of 5 with Ac2O/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.

• 出版日期2002-5-20
• 单位四川大学