2//-Naphtho furans, 2-hydroxy

H-Cyclopenta[7,8]naphtho[2,3-6]furan-7-yl glyoxylate, 2,3,6,10-tetrahydro-6-hydroxy-6-methyl-3,10-dioxo-, methyl ester H NMR. 4, 560 (66JCS(C)743) Cyclopenta[6]quinoline, 6,7,8,9-tetrahydro- C NMR, 2, 122 (77JOC300, 77JOC2742)... 

Naphtho[bc]furan derivatives are formed from peri-hydroxy-naphthylbenzyl ketone 49 by acidic or basic catalysis (83ZOR41I ... 

TL4391). The benzologs of naphtho[bc]furan-6-ones 60 (so-called furan-anthrones) are obtained by cyclization of anthracene peri-hydroxy ketones 58 or carbomethoxychloromethylanthraquinones 59 (80MI3 84ZOR818). 

Ci2Hg02 (Continuation) Naphtho l,2-b furan 3-Hydroxy-E6b/1. 92 (ArO — CH2 — COOH/ PCl5/SnCl4)... 

Dihydro-5-hydroxy-2,2,4-trimethyl-naphtho[l,2- ]furan, as antioxidant 863... 

The fast fade rate shown by 2-(4-trifluoromethyl)-2-phenyl-5-trifluorophenyl-[l]benzofuran[2,3-(]naphtho[l,2-6]pyran is attributable to the bulky 5-substituent rather than to the fused benzofuran ring <01WOP36424>. Its synthesis follows from the preparation of 9-hydroxy-7-trifluoromethylbenzo[6]naphtho[ f]furan from 4-chloromethyldibenzofuran (Scheme 18). 

Sikkimotoxin, 3a,4,9,9a-Tetrahydro-4-hydroxy-6,7-dunethoxy-9-(3,4,S-trimethoxyphenyt)naphtho 2,3-c -furan-I(3H) >ne 1 -hydroxy-2-hydroxymethyl-6,7-dimeth -oxy-4-(3 4 5 -trim ethoxy phenyl)-1,2,3,4-let rahydro-naphthalene-3-carboxylic acid lactone, C Hj p, mol wt 430.44. C 64.17%, H 6.09%, O 29.74%. Isoln from roots and rhizomes of Podophyllum sikkimeitsis R. Chatterjee et Mukerjee, Berberidaceae Chatterjee. Datta, Indian J. Physiol Allied Set 4, 6l (1950). Structnre Chatterjee. Chakra-varti, J. Am. Pharm. Assoc. Scl Ed. 4l, 415 (1952) Schreier, Helv. Chim. Acta 47, 1529 (1964). 

The structures of the seven naphthoquinones were identified as (2S, 3S)-3-hydroxy-5,6-dimethoxydehydroiso-a-lapachone (94), (2R)-5,6-dimethoxydehydroiso-a-lapachone (95), (2R)-5-methoxydehydroiso-a-lapachone (96), 2-(1-hydroxyethyl)-naphtho[2,3-b]furan-4,9-dione (97), 5-hydroxy-2-(1-hydroxyethyl)naphtho 2,3-b furan-4,9-dione (98), 2-isopropenylnaphtho 2,3-b furan-4,9-dione (99), and 5-hydroxy-dehydroiso-a-lapachone (100), all of which were found to be bioactive [73],... 

Marrubiin (6-[2-(3-furanyl)ethyl]decahydro-6-hydroxy-2a,5a,7-tri-methyl-2H-naphtho[l,8-fcc]furan-2-one from Lamiaceae species) 13MOL9049. 

Constit. of Crescentia cujete. Cytotoxic. Mp 217-218°. 9-Hydroxy [150994-77-7]. 9-Hydroxy-3- hydroxymethyl) furo[3,2-h]naphtho[2,3-d]furan-5,10-dione CisHgO M 284.225 Constit. of C. cujete. Cytotoxic. Mp 221-223°. 

Dihydro-6-hydroxy-2-[5-hydroxy-4-carboxynaphtho[l,2-6]furan-2-yl]-2-methyl-2//-naphtho[l, 2-6]pyran-5-carboxylic acid, D-20061... 

Hydroxy-2-(3-hydroxy-3-methylbutyl)-5-methoxybibenzyl, in H-20173 11 -Hydroxy-3-( 1 -hydroxy-3-methylbutyl)-4-methoxy-9-methyl-5//,7//-dibenzo[/ ,g][l,5] dioxocin-5-one, see P-10025 1 -[4-[2-Hydroxy-1 -(hydroxymethyl)ethoxy]-3-methoxyphenyl]-2-[4-(3-hydroxypropyl)-2-methoxyphenoxy]- ,3-propanediol, H-30157 9-Hydroxy-3-(hydroxymethyl)furo[3,2-/ ] naphtho[2,3- furan-5,10-dione, in H-30185... 

In a related transformation, the same group described a three-component domino reaction of 2-hydroxy-l,4-naphthoquinone, acting as a P-dicarbonyl surrogate, aromatic aldehydes and 1-(2-oxo-2-phenylethyl)pyridinium bromides in the presence of ammonium acetate, in water under microwave irradiation, that affords naphtho[2,3-Z)]furan-4,9-diones 31 [22]. Mechanistically, this domino reaction probably follows the same Knoevenagel-Michael intramolecular S 2 pathway described for the preparation of compounds 28, with ammonium acetate acting in this case as the base, to give intermediates 33. These compounds, which can be considered as tautomers of a hydroquinone species, would be finally transformed into the observed quinones by air-promoted oxidation, yielding the final products 31 (Scheme 1.16). 

Dihydro-5-hydroxy-6-methoxy-2-methylnaphtho[l,2-b]furan shaken 5 min. with FeGls in water-acetone 2-j -hydroxypropyl-5-methoxy-l,4-naphtho-quinone (startg. m. f. 599). Y 91.5%. W. Eisenhuth and H. Schmid, Helv. 41, 2021 (1958). 

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