Dihydro-4-hydroxy-2 benzofuran

Fluorophenyl)-l ]-hydroxy-2,3,4,1 ]-tetrahydro-6/7-pyrimido[],2-Z)]-isoquinolin-6-one was obtained in the reaction of l-(4-fluorophenyl)-3-oxo-],3-dihydro-2-benzofuran-l-carboxamide and 1,3-diaminopropane in boiling toluene (01BMCL339). 

Aryliden-3-oxo-2,3-dihydro-l-benzofurane addieren Benzonitril-phenylimin und stabilisie-rensich unter Aromatisierungzu4-Aryl-l, 3-diphenyl-5-(2-hydroxy-benzoyI)-l H-pyr-azolen2443. 

Formation of the methylcarbamate of 2,3-dihydro-2,2- dimethyl-4-hydroxy benzofuran in 57% yield has been reported from the N-methylamido derivative of saccharin through nucleophilic substitution by the addition of triethylamine in aqueous acetone (1 2) at ambient temperature over 2 hours (ref.29). 

Dihydro-2-hydroxy-6-methyl-3-methylenebenzofuran,42,43 a simple natural benzofuran, has nematocidal properties. 

Benzofuranic acids iraws-meranzinic acid (56).162 Euparinoid benzofurans the important class of euparinoids (extracts of plants of the Compositae family), contains benzofurans, dihydro-benzofurans, and also includes compounds with a hydronaphthofuran ring. We mention euparin (the earliest known) (5-acetyl-6-hydroxy-2-isopropenylbenzofuran) (57, R6=OH, R =H) 163 166, dehydro-tremetone (5-acetyl-2-isopropenylbenzofuran) (57, R6—R —H),167,168... 

The synthesis of the (i) 4-hydroxy-6-methoxytetrahydrofuro[2,3-6]-benzofuran ring (116), a degradation product of natural substances of the sterigmatocystin series, is similar,318 as is the synthesis of the dihydro derivative (117) from the o-acetylated acetaldehyde (118), a nonisolated intermediate which is ring-closed to 119 and then heated in toluene to give 117. The last is the starting point for the synthesis of aflatoxin M4 (49).153... 

Bcnzofuran-4,7-dioncs have been synthesized regioselectively by [3 + 2] photoaddition of 2-hydroxy-1,4-benzoquinones with a range of alkenes (equation 185)664. The reaction occurs in 30-60% yield and is a useful method for the synthesis of the benzofuran ring system, which is important in natural products like acamelin665. Substituted naphthoquinones may also be used in this reaction666,667 and this has lead to a very simple two-step synthesis of maturinone. In a similar reaction, a [3 + 2] photoaddition reaction of 2-amino-1,4-naphthoquinones with electron-rich alkenes gave 13-82% yields of 2,3-dihydro-177-bcn/ /]indole-4,9-diones in a single-step process which involved photolysis followed by oxidation (equation 186)668,669. 

Benzoesaure 2-Hydroxy-5-(3-oxo-butanoylamino)- XI/2, 20 2-Benzofuran 6,7-Dimethoxy-3-nitromethyl-1-oxo-1,3-dihydro-VI/2, 576 Bernsteinsanre Benzoylamino- IV/lb, 644 2-(2-Hydroxy-benzylidenamino)- XI/ 2, 327... 

V. Enamines. Reactions of the enamines from condensation of piperidine or morpholine with an aldehyde with p-benzoquinone gives 2,3-dihydro-5-hydroxy-2-piperidino(or morpholino)benzofurans (146),... 

A 4,5-dihydro-2,5-methano-l,3-benzodioxepine together with a furo[2,3-Z)]benzofuran have been reported to arise on treatment of 5-hydroxy-3-methyl-3//-benzofuran-2-one with LiAlILt followed by acidification with oxalic acid <05JOC6171>. 

Acetyl-2-ethyl-benzofuran reagiert mit Hydrazin bzw. Methyl-hydrazin zu 3(5)-Ethyl-4-(2-hydroxy-phenyl)-5(3) -methyl- bzw. 1,3-Ditnethyl-5-ethyl-4- (2-hydroxy-phenyl) - IH-pyrazol [Bd. VI/lc, S.382 (1976)]. Das gleiche Prinzip liegt der Reaktion von 4-Acetyl-2-ethoxy-5-me-thyl-2,3-dihydro-furan mit Phenyl-hydrazin zugrunde979. 

Im Falle des 2-Carboxy-l-benzofurans wird der Furan-Ring so aufgespalten, daB nach Hydrierung 3,4-Dihydro-cumarin vorliegt nach dem Ansauern der Reduktionslosung wird 3-(2-Hydroxy-phenyl)-propansaure4 erhalten ... 

Steynberg, PJ., J.R Steynberg, R.W. Hemingway, D. Ferreira, and G.W. McGraw Acid-catalyzed Rearrangements of Flavan-4-phloroglucinol Derivatives to Novel 6-Hydroxyphenyl-6a, 1 lb-dihydro-6//-[l]-benzofuro[2,3-c]chromenes and Hydroxy-phenyl-3,2 -spirobidihydro[l]benzofurans. J. Chem. Soc., Perkin Trans. 1, 2395 (1997). 

Bujons J, Sanchez-Baeza F, Messeguer A (1994) A Study of the Interconversion Between 3,4-Dihydro-4-formyl-2-hydroxy-2/7-benzopyran and 2,3,3a,8a-Tetrahydro-2-hydroxyfuiio-[2,3-6]benzofuran Moieties, and its Application to a Formal Synthesis of ( )-Aflatoxin Bl. 

Me ether [159686-23-4]. 2,3-Dihydro-4-hydroxy-6-methoxy-5- l-oxobuty[)benzofuran... 

Dihydro-2-(4-hydroxy-3-methoxyphenyl)-3-methyl-5-( 1 -propenyl)benzofuran, in C-60161... 

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