A series of symmetrically disubstituted compounds, with substituents linked to the ring through a carbon atom, has been prepared from 2,9-dimethyl-l,lO-phenanthroline. Nmr data are also reported.

Elatenyne (3,7-dibromo-6-ethyl-2-(pent-2′-en-4′-ynyl ) octahydropyrano [3,2-b] pyran ) was isolated as an oil from the marine red alga Laurencia elata. Its structure and those of three derivatives were assigned on the basis of spectroscopic, predominantly n.m.r ., data.

The preparation of a series of macrocycles, formed by reaction of HO‐(‐CH2‐CH2‐O‐)nH with 1,10‐phenanthroline‐2,9‐dicarbonyl chloride (n = 2,3,4) and 1,8‐naphthyridine‐2,7‐dicarbonyl chloride (n = 3,4), is described. An improved synthetic route to 2,7‐dimethyl‐1,8‐naphthyridine 9 is also reported.

The DNA‐sequence specificity of daunomycin was investigated by DNase I footprinting and an E. coli RNA polymerase transcription‐inhibition assay. The 5′‐CA sequence was identified as being the highest affinity binding site, although other modest affinity (5′‐GC, CG, CT, TC, AC) and poor affinity sites (5′‐AA, AT, TA) were also observed. The preference of daunomycin for 5′‐CA nucleotide sequence suggests that its biological activity may arise from association with the 5′‐CA‐containing sequences thought to be associated with genetic regulatory elements in eukaryotes.

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