New reactivities of deltaline analogs: an efficient O-demethylation at C-1 and an unusual extrusion of the C-14 atom

作者：Tang, Pei; Chen, Qi-Feng; Wang, Ling; Chen, Qiao-Hong; Jian, Xi-Xian; Wang, Feng-Peng^*

来源：Tetrahedron, 2012, 68(27-28): 5668-5676.

DOI：10.1016/j.tet.2012.04.055

• C-19-Diterpenoid alkaloids
• Deltaline
• O-Demethylation
• Extrusion

O-Demethylation at C-1 in the C-19-diterpenoid alkaloids is very challenging. In this paper, it was firstly observed that 10-OH group in deltaline (1) is a determining factor for the O-demethylation reaction. After removal of this hydroxyl group, 1-O-methyl group in the corresponding deltaline analogs can be readily removed by treatment with HBr-HOAc. Meanwhile, the C-14 atom in bromides 18 or 20 can be extruded under basic condition probably via a sequence, including Grob fragmentation, aerobic oxidation, deformylation, and S(N)2 nucleophilic substitution, to give enone 21 (70%) and oxetane 22 (14%). The structure of compound 22 was confirmed by X-ray crystallographic analysis of its derivative 21.

• 出版日期2012-7-8
• 单位四川大学