The alkyne pathway to keramadine from the marine sponge Agelas sp.
作者:Thomas Lindel、Matthias Hochgürtel
DOI:10.1016/s0040-4039(98)00341-4
日期:1998.4
A novel synthesis of the pyrrole-imidazole alkaloid keramadine (1) from the marine spongeAgelassp. is described. Regiocontrol is reached by the Pd-catalyzed alkynylation of 1-benzenesulfonyl-4-iodoimidazole, followed by N-methylation employing trimethyloxonium tetrafluoroborate. Key step is the double hydrogenation of a 5-alkynyl-2-azidoimidazole which simultanously generates the (Z)-double bond