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6- pyrans are prepared from the appropriate 4-substituted 2H-naphtho[1,2-b]pyran-2-ones and either methylmagnesium iodide or phenylmagnesium bromide; some related compounds and derivatives are also prepared and dimerisation of cylized products from the methylmagnesium iodide reactions affords dimers including a relative of isolapachenole through addition reactions of the intermediate carbonium ion.

Diphen yl-6H-nap htho( 2',3 ' : 2,S)p yran and 4,6-Diphen yl-4 Hnaphtho (2', 3': 2,3)p yran B y J . COTTAM and R. LIVINGSTONE DECOMPOSITION of the Grignard complex from 6,7-benzocoumarin (I) and phenylmagnesium bromide gave a gum, which on trituration with ether yielded 3-(3-hydroxy-2-naphthyl)-1,3-diphenylpropan-l-one (11) as a solid, difficult to purify owing to the ease of cyclisation and dehydration to 4,6-diphenyl-4H-naphtho(2',3':2,3)pyran (111). Complete conversion into (111) occurred when compound (11) was boiled with acetic acid.2 Compound (11) was shown to be a ketone by the carbonyl absorption (1655 cm.-l) in the infrared region. 3-(3-Hydroxy-2-naphthyl)-l,l-diphenylprop-2-en-l-ol (IV) was isolated from the ether-soluble fraction, and when boiled with acetic acid, dehydrated, and cyclised gave 6,6-diphenyl-GH-naphtho-(2',3':2,3) pyran (V) .2The naphthopyran (V) was prepared from 2-acetyl-3-naphth01,~ which condensed with