3//-Naphtho furans, 4,5-dihydro

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-... 

Analogous photorearrangements have been reported for other cyclic peroxides,194 and the conversion of the peroxide (243) to the benzo-furo[3,2-h]naphtho[l,2-d]furan (244) is believed to involve an intermediate oxiran.195 Studies of the photodecomposition of 3,4-dihydro-2/f-pyrans,196 tetrahydropyran,197 and 1,4-dioxan198 have been reported. 

Similar results are found with 2-allyloxy-l-chloro-naphthalene, that affords the diphenylphosphine (98% yield) and trimethylstannane (84% yield) of (l,2-dihydro-naphtho[2,l-Z>]furan-l-ylmethyl) derivatives. 

The photostimulated reaction of 2-allyloxy-l-bromo-naphthalene 27 under the same experimental conditions, affords l-(2-nitro-ethyl)-l,2-dihydro-naphtho[2,l-Z ]furan 28 in good yield (Sch. 26) [98]. 

Pentafluorophenyl propargyl ether isomerizes in the gas phase on silica gel at 370°C to give 2-monofluoromethyl-4,5,6,7-tetrafluorobenzo[6]-furan [81JCS(P1)1417]. Via the same route, naphtho[2,l-/ ]furans [82JCS(P1)107, 82JFC(20)173] and 4,5,6,7-tetrafluoro-2,3-dihydro-2-methyl-1-benzothiophene [81JCS(P1)1659] can be synthesized (Scheme 54). 

Furan 5-(4-Chlor-phenyl)-2-cyan-E6a. 106 (H -> Ar) Naphtho[l,8a,8-b,c pyrrot l-Chlor-2-oxo-1,2-dihydro- XI/2, 574... 

Synthetically, compound 152 was prepared by the Friedel-Crafts procedure from furan-3,4-dicarbonyl chloride and a tetralin derivative (85JCR (S)338). 1,4-Dihydro-l,4-epoxy-5,8-naphthoquinone, when treated with 3,6-di(2-pyridyl)-l,2,4,5-tetrazine, yielded the quinone 153 (75JCS(P1)1339) derivatives of 153 are also known (74CC1034). The parent compound (153) is a stable derivative of the unstable isobenzofuran. Finally, 3-acetyl-2-furyl-1,4-benzo- (or -naphtho-) quinones are isomerized photochemically in aprotic solvents into the quionones 154 (66HCA1806). 

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

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... 

In the presence of BQ, the Pd(PhCN)2Cl2-catalyzed reaction of l-(5,6-dihydro-4//-pyran-2-yl)-2-vinylcyclohexanol or l-(4,5-dihydrofuran-2-yl)-2-vinylcyclohexanol formed 3,4,7,8,9,10-hexahydro-2//-naphtho [1,2-6] pyran or 2,3,6,7,8,9-hexahydronaphtho[l,2-b]furan via nucleophilic carbopalladation of the C=C bond with the C=C bond in the allylic alcohol unit and triple elimination process (eqs 98 and 99). ... 

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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