Synthesis of Echinamines A and B, the First Aminated Hydroxynaphthazarins Produced by the Sea Urchin <i>Scaphechinus </i><i>m</i><i>irabilis</i> and Its Analogues
作者:Nataly D. Pokhilo、Maria I. Shuvalova、Maxim V. Lebedko、Galina I. Sopelnyak、Alla Ya. Yakubovskaya、Natalia P. Mischenko、Sergey A. Fedoreyev、Victor Ph. Anufriev
DOI:10.1021/np0502185
日期:2006.8.1
The first total synthesis of two marine aminated hydroxynaphthazarins, echinamines A (3-amino-7-ethyl- 2,5,6,8-tetrahydroxy-1,4- naphthoquinone) and B (2-amino-7-ethyl- 3,5,6,8-tetrahydroxy-1,4- naphthoquinone), produced by the sea urchin Scaphechinus mirabilis is described. This was achieved from 1,2,4-triacetoxybenzene (13) through a sequence involving double Fries rearrangement of 13, reduction of 3,5-diacetyl-1,2,4-trihydroxybenzene (14), methylation of 3,5-diethyl-1,2,4- trihydroxybenzene (15), simultaneous double acylation of 3,5-diethyl-1,2,4- trimethoxybenzene ( 16) with a dichloromaleic anhydride-ethyl radical elimination process, methylation of 6,7-dichloro-3-ethyl-2-hydroxynaphthazarin (17), nucleophilic substitution of a chlorine atom by the methoxy group in 6,7-dichloro-3-ethyl-2-methoxynaphthazarin (18), introduction of an amino group via direct substitution of a chlorine atom in 7-chloro-3-ethyl-2,6- dimethoxy- (11) and 7-chloro-2-ethyl-3,6-dimethoxynaphthazarins (12) by an azido group, and functional group deprotection. The synthesis of amino analogues of spinazarin and spinochrome D is also described.