Bio-inspired dimerisation of prenylated quinones directed towards the synthesis of the meroterpenoid natural products, the scabellones

Abstract

Stirring 2-geranyl-6-methoxy-1,4-hydroquinone in pyridine/O2 or 2-geranyl-6-methoxy-1,4-benzoquinone in pyridine/N2 affords the dimeric meroterpenoid natural products, scabellones A–C in modest to low yields and also identifies 2-methoxy-6-(4-methylpent-3-en-1-yl)-1,4-naphthoquinone (scabellone E) as a new natural product. The corresponding reaction of the des-methoxy analogue, 2-geranyl-1,4-benzoquinone in degassed pyridine for three days afforded the natural product cordiachromene A (15% yield) and 6-(4-methylpent-3-en-1-yl)-1,4-naphthoquinone (12%), the latter being a likely biosynthetic precursor to the marine meroterpenoid alkaloids, conicaquinones A and B.