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1.
Manojit Pal 《Tetrahedron letters》2003,44(45):8221-8225
An efficient synthesis of 2-alkyl/aryl substituted benzo[b]furans/nitrobenzo[b]furans in water has been accomplished via Pd/C catalyzed reaction of o-iodophenols with terminal alkynes in the presence of PPh3, CuI and prolinol. This method can tolerate a variety of functional groups present in the alkynes as well as base labile nitro group in the o-iodophenols. The protocol does not require the use of a phase transfer catalyst or water-soluble phosphine ligands and is free from the use of any organic co-solvent. 相似文献
2.
Naphtho[1,2-b]furans 1a-f, naphtho[2,1-b]furans 2a-f, benzo[1,2-b:5,4-b′]difurans 3a-b, benzo[1,2-b:4,5-b′]difurans 4a-b, and benzo[1,2-b:4,3-b′]difurans 5a-b were synthesized by base-catalyzed cyclization reaction of the corresponding o-alkoxybenzoylarene derivatives. The o-alkoxybenzoylarenes were obtained from the etherification reaction of the o-hydroxybenzoylarenes, which were prepared either by the reaction of methoxyarenes with benzoyl chloride in the presence of aluminum chloride or by photo-Fries rearrangement of aryl benzoates. 相似文献
3.
Antonella Bochicchio Maria Funicello Maria Teresa Lopardo Paolo Lupattelli 《Tetrahedron letters》2010,51(21):2824-971
Acetylation/Sonogashira cross-coupling reaction/cyclization has been carried out in one-pot using a Na2PdCl4/2-(di-tert-butylphosphino)-N-phenylindole/CuI system in TMEDA to give 5-nitro-2-substituted benzo[b]furans in excellent yields. We also describe the extension of this method to 4-EWG-2-bromo-phenols obtaining 2,5-disubstituted-benzo[b]furans in good yields. 相似文献
4.
An efficient and practical method for construction of 2-arylbenzo[b]furans from 2-methoxychalcone epoxides has been reported. Catalyzed by 2 mol % of BF3·Et2O, 2-methoxychalcone epoxides went through the Meerwein rearrangement, followed by deformylation in one-pot to successfully afforded 2-methoxydeoxybenzoins. Afterward, 2-arylbenzo[b]furans were obtained in high yields (87%–100%) via intermolecular cyclodehydration of 2-methoxydeoxybenzoins with 48% HBr. By utilization of this approach, the natural product stemofuran A and the key intermediate of eupomatenoid 6 have been synthesized conveniently. 相似文献
5.
An efficient one-pot synthesis of 12H-benzo[b]xanthen-12-ones via an oxidant initiated and base promoted tandem reaction of 2-(4-(2-haloaryl)-4-hydroxybut-1-ynyl)benzaldehydes has been developed. By using similar strategy, a one-pot synthesis of naphtha[2,3-b]furans from the cascade reaction of 2-(4-hydroxy-but-1-ynyl)benzaldehydes with 2-bromoacetonitrile or α-bromocarbonyl compounds has also been achieved. 相似文献
6.
An efficient and metal-free method was developed to synthesize 3-chalcogen benzo[b]furans via the iodine-mediated electrophilic cyclisation of 2-alkynylanisoles with disulfides or diselenides. In the presence of I2, various 3-sulfenylbenzofurans or 3-selenenylbenzofurans were obtained in moderate to high yields. 相似文献
7.
V.S. Prasada Rao LingamDnyaneshwar H. Dahale Kagga MukkantiBalasubramanian Gopalan Abraham Thomas 《Tetrahedron letters》2012,53(42):5695-5698
An efficient two-step approach for the synthesis of naphtho[1,2-b]furans and naphtho[2,1-b]furans has been developed. Various functionalized propargyl alcohols were etherified with α- or β-naphthol under Mitsunobu reaction conditions to give naphthyl 2-propynyl ethers, which underwent a facile microwave-assisted Claisen rearrangement and concomitant anionic cyclization to yield naphthofuran derivatives under basic reaction conditions. 相似文献
8.
Reaction of 3-amino-2-benzoylbenzo[b]furan with bromoacetyl bromide followed by cyclization in methanolic ammonia gave 5-phenyl-1,3-dihydrobenzo[d′] furo[3,2-e] [1,4]diazepin-2-one, a representative of a new ring-system. The corresponding chloro substituted diazepin-2-one was similarly prepared from 3-amino-2-(4-chlorobenzoyl) benzo[b] furan. Some alkylation and thionation reactions of these diazepines have been investigated. 相似文献
9.
Doug Vaughan 《Tetrahedron letters》2009,50(41):5709-5712
Reaction of 2,2-dialkylacetaldehydes with electron-rich 2-naphthols in presence of p-TSA under closed-vessel solvent-free microwave irradiation conditions resulted in formation of corresponding dihydronaphtho[2,1-b]furans in good to excellent yields. In several cases, small amounts of 14-alkyl-14H-dibenzo[a,j]xanthenes were also formed. 相似文献
10.
Pyrolytic conversion of [1,2,4]triazino[3,4-b][1,3,4]thiadiazin-4-ones, [1,3,4]thiadiazino[2,3-b]quinazolin-10-ones and [1,2,4]triazolo[3,4-b][1,3,4]thiadiazines into their corresponding pyrazolo[5,1-c][1,2,4]triazin-4-ones, pyrazolo[4,3-b]quinazolin-9-ones and pyrazolo[5,1-b][1,2,4]triazoles via desulfurization ring contraction is described. The starting condensed 1,3,4-thiadiazines were prepared from the corresponding readily available 4-amino-3-thioxo-1,2,4-triazin-5(4H)-ones, 3-amino-2,3-dihydro-2-thioxoquinazolin-4(1H)-one and 4-amino-3(2H)-thioxo-1,2,4-triazoles upon reaction with the appropriate α-haloketones in two steps, or directly in one step in ethylpyridinium tetrafluoroborate (ionic liquid, IL). 相似文献
11.
Yi Wang 《Journal of fluorine chemistry》2007,128(9):1052-1057
A site-specific synthesis of 4-substituted-6-fluoro(carboalkoxyl)benzo[b]furans and benzo[b]thiophenes is described. The reactions of heterocyclic aromatic aldehydes with a Wittig reagent, followed by Sonogashira reaction with terminal alkynes, and subsequent base-catalyzed cyclization site-specifically provide 4-substituted-6-fluoro(carboalkoxyl)benzo[b]furans and benzo[b]thiophenes in good yields. 相似文献
12.
T. I. Mukhanova O. A. Lykova L. M. Alekseeva V. G. Granik 《Chemistry of Heterocyclic Compounds》1998,34(6):651-657
Derivatives of 2-methyl-3-benzoyl-5-hydroxynaphtho[1,2-b]furans and 3-acetonyl-4-benzoylhydroxynaphthols were synthesized by the reaction of tertiary enaminoketones withp-naphthoquinone. The transformations of derivatives of 2-methyl-3-benzoyl-5-hydroxynaphtho[1,2-b]furans into naphthofurandiones with nitric acid and transformation into the corresponding enamines with DMF acetal were investigated. It was shown that when the latter react withp-benzoquinone, derivatives of 2-(5-hydroxybenzofuryl-3)naphthofurans are formed. 相似文献
13.
V.S. Prasada Rao Lingam Ramanatham Vinodkumar Abraham Thomas 《Tetrahedron letters》2008,49(27):4260-4264
A variety of mono- and disubstituted phenols are alkylated with propargyl bromide to give phenyl 2-propynyl ethers, which were further coupled with aryl iodides under Sonogashira reaction conditions to give 3-phenoxy-1-aryl-1-propyne derivatives. The latter compounds underwent an initial Claisen rearrangement followed by ring closure to give functionalized benzo[b]furans in moderate to good yields. 相似文献
14.
Antonio Arcadi Federico Blesi Sandro Cacchi Giancarlo Fabrizi Antonella Goggiamani 《Tetrahedron letters》2011,52(40):5149-5152
A straightforward approach to the synthesis of 2,5,7-trisubstituted benzo[b]furans from 2-bromo- and 2-chloro-6-iodo-4-substituted phenols through a consecutive copper- and/or palladium-catalyzed assembly and functionalization process is described. Functionalization at the C(7) position is carried out by Suzuki-Miyaura cross-coupling and C-N bond forming reactions. 相似文献
15.
An efficient domino process for the construction of 2,3-disubstituted benzo[b]furans has been developed via copper-catalyzed three-component coupling reactions of salicylaldehydes, amines, and alkynes followed by base-assisted O-annulation reaction. 相似文献
16.
We describe here a novel synthesis of benzo[b]naphtho[2,3-d]furan-6,11-diones based on the heteroannulation of 2-(2-bromophenyl)-3-hydroxy-1,4-naphthoquinones. The naphthoquinones were prepared from 3-(2-bromophenyl)naphthalen-2-ols, which were obtained by intramolecular aldol condensation of 2-[3-(2-bromophenyl)-2-oxo-propyl]benzaldehydes. Alternatively, benzo[b]naphtho[2,3-d]furan-6,11-diones were obtained more directly and efficiently by cyclization of 3-(2-bromophenyl)naphthalen-2-ols to benzo[b]naphtho[2,3-d]furans and oxidation of the resulting compounds. Furthermore, the first 6-oxabenzo[a]anthracen-5-one described was similarly obtained from 2-[3-(2-formylphenyl)-2-oxopropyl]benzoic acid and oxidized to 6-oxa-benzo[a]anthracene-5,7,12-trione. 相似文献
17.
Tadatsugu Yamaguchi Manabu HosakaToru Ozeki Masakazu MorimotoMasahiro Irie 《Tetrahedron letters》2011,52(43):5601-5604
Photochromic benzo[b]silole derivatives, 1-(1,1-dimethyl-2-phenylbenzo[b]silol-3-yl)-2-(2-phenylbenzo[b]thien-3-yl)perfluorocyclopentene and 1-(1,1-dimethyl-2-phenylbenzo[b]silol-3-yl)-2-(2-phenyl-1-benzofuran-3-yl)perfluorocyclopentene, were synthesized and their photochromic performance was examined in solution. 相似文献
18.
Alya Al-EtaibiElizabeth John Maher R. IbrahimNouria A. Al-Awadi Yehia A. Ibrahim 《Tetrahedron》2011,67(34):6259-6274
Intramolecular base catalyzed C-C bond formation led to exclusive stereoselective syntheses of trans-6,7-dihydro-5H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines, trans-7,8-dihydro-6H-[1,2,4]triazino[3,4-b][1,3,4]thiadiazin-4-ones, and trans-3,4-dihydro-2H-[1,3,4]thiadiazino[2,3-b]quinazolin-10-one. trans-6,7-Dihydro-5H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines isomerize slowly in CDCl3 and more rapidly in DMSO-d6 into the corresponding cis-stereoisomers. The other trans-6,7-dihydro-[1,3,4]thiadiazines isomerize also in DMSO-d6 into the corresponding cis-stereoisomers. Pyrolytic conversion of these heterocyclic condensed dihydrothiadiazines into their corresponding pyrazolo[5,1-b][1,2,4]triazoles, pyrazolo[5,1-c][1,2,4]triazin-4-ones and pyrazolo[4,3-b]quinazolin-9-ones via desulfurization ring contraction is described. 相似文献
19.
Claudia Feberero Cintia Virumbrales Carlos Sedano Lorena Renedo Samuel Surez-Pantiga Roberto Sanz 《Molecules (Basel, Switzerland)》2022,27(2)
A straightforward and transition metal-free one-pot protocol to synthesize halobenzo[b]furans has been developed employing simple and easily available starting materials such as O-aryl carbamates and alkynylsulfones. The fine-tuning of the different steps involved was key to achieving a successful one-pot procedure. Initially, a directed ortho-lithiation process, which uses the carbamate as the directed metalation group, was crucial in providing access to O-2-alkynylaryl N,N-diethyl carbamates by a direct alkynylation of the o-lithiated carbamate, with arylsulfonylalkynes as electrophilic reagents. Cyclization of the generated o-alkynylaryl carbamates was successfully accomplished through a strategy involving in situ carbamate alkaline hydrolysis under conventional heating or microwave irradiation, coupled with a subsequent heterocyclization step delivering the desired benzo[b]furans. A wide variety of new halobenzo[b]furans has been synthesized and their utility has been demonstrated by their further transformation. 相似文献
20.
2-Alkylaminobenzo[b]furans were isolated and characterized by X-ray crystal structural analysis, for the first time, from the Cu-catalyzed intramolecular amidation of hindered secondary amides under controlled microwave heating. A mechanism was proposed to account for competing Cu-catalyzed intramolecular N- and O-arylation pathways, which were controlled by the bulkiness of substituents on the nitrogen atom of secondary amides. 相似文献