Synthesis of echinamines A and B, the first aminated hydroxynaphthazarins produced by the sea urchin Scaphechinus mirabilis and its analogues

J Nat Prod. 2006 Aug;69(8):1125-9. doi: 10.1021/np0502185.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Molecular Structure
  • Naphthoquinones* / chemical synthesis
  • Naphthoquinones* / chemistry
  • Naphthoquinones* / isolation & purification
  • Sea Urchins / chemistry*

Substances

  • Naphthoquinones
  • echinamine A
  • echinamine B