2//-Naphtho furan

The method has been extended to o-hydroxylated naphthalenic and heterocyclic aldehydes, which leads to complex benzofurans, naphtho-furans,62,65,613,615 and furocoumarins.594... 

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[2,1 -6]furan, 1,5,8-trimethyl- H NMR, 4, 562 (75JCS(P1)478) Naphtho[l,2-6]phosphorin, 2-t-butyl-5,6-dihydro-4-... 

Naphtho[2,3-c]furan, 1,3-diphenyl-thiophene synthesis from, 4, 904 Naphthofurans aromaticity... 

Angular annulation of benzo[h]furan with a benzene ring leads to naph-tho[2,l-h]furan and naphtho[l,2-h]furan. 

Naphtho[2,l-h]furan-2-(3 -one 28 has been described as a keto tautomer (91JA2301). Naphtho[l,2-h]furan-3-(2//)-ones of type 29 (R = H, Me, Et, Pr, pentyl, heptyl) show keto-enol tautomerism with the enol form predominating (88RRC917). 

Chemical Name 5,6,9,17,19,21 -hexahydroxy-23-methoxy-2,4,12,16,18,20,22-heptamethyl-8-(N-(4-methyl-1-piperazinyl)formimidoyl] -2,7-(epoxypentadeca(1,11,13]trienimino)-naphtho[2,1-b] furan-1,11 (2H)-dione 21-acetate... 

Rhodococcus sp. Strain WU-K2R A Rhodococcus strain capable of sulfur-specific desulfurization of benzothiophene, naphthothiophene (NT), and some of their alkyl derivatives was reported [35]. The metabolites of BT desulfurization were BT sulfone, benzo[c][l,2]oxanthiin S-oxide, benzo[c][l,2]oxanthiin S,S-dioxide, o-hydroxystyrene, 2,(2 -hydroxyphenyl)ethan-l-al, and benzofuran. The NT metabolites were NT sulfone, 2 -hydroxynaphthyl ethene, and naphtho[2,l-b]furan [35], The exact biochemical pathway was not determined, however, part of the pathway for BT desulfurization was speculated to be similar to Paenibacillus All-2. 

Condensed benzo[i>]furan molecules can be prepared by inter- or intra-molecular Diels-Alder reactions from furo[3,4-b]benzofurans, and some interesting intermolecular examples are listed below. As can be seen, the furo[3,4-i>]benzofuran 60 underegoes Diels-Alder reactions with naphtho-l,4-quinone in the presence of Znl2 as a Lewis acid to form the aromatized cycloadduct. When the diene precursor reacts with benzo-l,4-quinone in the absence of Znl2, the product is obtained as an endo-exo mixture <00JCS(P1)1387>. 

Oxidation of several 1,1-bisphenols 78 with IBD gives spirobenzofuran derivatives of general formula 79 (Eq. 21). This approach, when applied to benzylidine l.l -bisnaphthols 80, leads to a stereospecific cyclization, thereby forming the less hindered naphtho[2,l-fi]furan-2(l//)-spiro-r-(2//)-naphthalene-2 -ones (82) [80JCS(P1)1978,80JCS(P1)1986]. The conversion 80 to 82 probably occurs through intermediate 81 (Scheme 25). 

Nitro-7-methoxy-naphtho[2,1-b]furan (R7000), a new highly potent mutagenic agent. Mutat Res 88 355-362. 

Terecamphene 3a,8a,9,9a-Tetrahydro-5,8a-dimethyl-3-inethylene-naphtho- [2,3-b]-furan-2,6(3H,4H)-dione (-)-Camphene Yomogin... 

Linear benz-annelation enhances the reactivity and decreases the stability of benzo[c]furan, as with other o-quinonoid heterocycles.1,3-Diphenyl-naphtho[2,3-e]furan (299) has been obtained from 297 via lactol 298 as deep red glistening plates with mp 148-154°C in 89% yield.Although dried crystals of 299 could be stored for several months in the absence of light and air, solutions in organic solvents decolorized slowly on standing... 

Angular benz-annelated benzo[c ]furans (naphtho[l,2-c]furans) are also known. Compounds 307 have been synthesized in the usual manner (Scheme 20). ... 

Benz-annelatedbenzo[c]furandiones—naphtho[2,3-c]furan-4,9-diones— (Table XIII) were prepared in moderate to good yields by a Friedel-Crafts... 

Wege and Moursounidis found that a linear Herndon relationship (log k vs log SC 82JCE371) is obeyed. Extrapolation to naphtho[2,3-c]furan gives ki = 3.15 x 104 mol-1 s-1, which is 415 times greater than the reactivity of isobenzofuran 2. The effects of substituents in isobenzofuran on a Diels-Alder reaction (with A-methylmaleimide, which gives nearly exclusively endo-adducts) was quantified by Rickborn and co-workers (Table III ... 

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