Total synthesis of haliclamine A, a macrocyclic marine alkaloid related to the key biogenetic intermediate of manzamines
作者:Yoshiki Morimoto、Chiho Yokoe
DOI:10.1016/s0040-4039(97)10368-9
日期:1997.12
The first total synthesis of haliclamine A (1), a macrocyclic marine alkaloid closely related to the key bisdihydropyridine intermediate 3 of the biogenetically unique manzamine family, has been efficiently achieved via stepwise inter- and intramolecular N-alkylations of 3-alkylpyridine derivatives 26 and 28.
A new convergent and unified synthesis of the marine natural alkaloid haliclamine A is described. The synthesis of 3-alkylpyridine monomers 8 and 9 was first achieved from a common thiophene intermediate 5. These syntheses make use of thiophene chemistry and the ability of cyclopropylcarbinols 20 and 21 to rearrange to the homoallylic bromides 22 and 23, respectively. The Zincke procedure for the synthesis of pyridinium salts was then applied to the corresponding amino derivatives 8 and 9 to give efficiently unsymmetrical bis-pyridinium macrocycle 1, whose reduction afforded haliclamine A.
Haliclamines A and B, cytotoxic macrocyclic alkaloids from a sponge of the genus