7-Hydroxy-3- chromane

Detailed investigations (84TL5813) of 6- and 7-substituted 2-hydroxy-chromane-4-one 40B showed that in solution they exist in the three-... 

S526, 81T1437). m-Substituted dihydric phenols give a mixture of the 5- and 7-hydroxy-chromans. 

A special reaction of this type is the oxidation of 2,2,5,7,8-pentamethyl-6-hydroxy-chromane (X) for which the following reaction was suggested [92] on the basis of polaro-graphic data ... 

Both coumarin and chromone are converted by diborane then alkaline hydrogen peroxide into 3-hydroxy-chroman." " Catalytic reduction of conmarin or chromone satnrates the C-C double bond." For both systems, hydride reagents can of course react either at carbonyl carbon or at the conjugate position and mixtures therefore tend to be prodnced. Zinc amalgam in acidic solntion converts benzopyrones in 4-unsubstituted benzopyrylinm salts." ... 

H-Benzo[a]carbazole, 4,4a,5,l 1,1 la,l Ib-hexahydro-synthesis, 4, 283 Benzo[b]carbazole, N-acetyl-photochemical rearrangements, 4, 204 Benzo[/]chroman-4-one, 9-hydroxy-2,2-dimethyl-synthesis, 3, 851 Benzochromanones synthesis, 3, 850, 851, 855 Benzochromones synthesis, 3, 821 Benzocinnoline-N-imide ring expansion, 7, 255 Benzocinnolines synthesis, 2, 69, 75 UV, 2, 127 Benzocoumarins synthesis, 3, 810 Benzo[15]crown-5 potassium complex crystal stmcture, 7, 735 sodium complex crystal stmcture, 7, 735 Benzo[ 18]cr own-6 membrane transport and, 7, 756 Benzo[b]cyclohepta[d]furans synthesis, 4, 106 Benzocycloheptathi azoles synthesis, 5, 120... 

Chroman, 6-hydroxy-2,2-dimethyl- C NMR, 3, 587 Chroman, 2-hydroxymethylene-synthesis, 3, 781... 

Chroman-2-carboxylic acid, 2-hydroxy-4-oxo-ethyl ester synthesis, 3, 852... 

Chroman-2-carboxylic acid, 6-hydroxy-2,5,7,8-tetramethyl-as antioxidant, 3, 718 oxidation, 3, 725... 

Chroman-6-carboxylic acid, 8-hydroxy-2-methyl-4-0X0—see Rosellinic acid, 718 Chroman-2,7-dicarboxylic acid, 2,4,4-trimethyl-formation, 3, 733... 

Chroman-4-one, 5-acetoxy-3-hydroxy-2,2-dimethyl-synthesis, 3, 857 Chroman-4-one, 3-amino-synthesis, 3, 855 Chroman-4-one, 3-benzylidene-synthesis, 3, 829 Chroman-4-one, 3-bromo-... 

Chroman-4-one, 3-bromo-2-hydroxy-synthesis, 3, 856 Chroman-4-one, 2-/-butyl- H NMR, 3, 583 Chroman-4-one, 3-/-butyl- H NMR, 3, 583 Chroman-4-one, 2,3-dibromo-dehydrobromination, 3, 828 Chroman-4-one, 3,3-dibromo-dehydrobromination, 3, 828 Chroman-4-one, 2,3-dihalogeno-synthesis, 3, 856 Chroman-4-one, 2,2-dimethyl-mass spectra, 3, 617 Chroman-4-one, 2,2-diphenyl-synthesis, 3, 852 Chroman-4-one, 3-hydroxy-synthesis, 3, 856... 

Chroman-2-ylmethanol, (5)-6-hydroxy-2,5,7,8-tetramethyl-synthesis, 3, 779 Chromene, 3-acetyl-2-methoxy-synthesis, 3, 750 Chromene, 2-alkyl-synthesis, 3, 749 Chromene, 4-aryloxymethyl-synthesis, 3, 742-743 Chromene, bis(2,2-dimethyl-mass spectra, 3, 604 Chromene, 2,3-dichloro-synthesis, 3, 753 Chromene, 2,2-dimethyl-IR spectra, 3, 594 mass Spectra, 3, 604 molecular dimensions, 3, 621 synthesis, 3, 743, 749, 751 Chromene, 3-fluoro-2,2-dimethyl-synthesis, 3, 748 Chromene, 5-hydroxy-synthesis, 3, 745... 

Dicoumarol — see Coumarin, 3,3 -methylenebis(4-hydroxy-Dictamnine biosynthesis, 4, 992 occurrence, 4, 989 pharmacology, 4, 992 synthesis, 4, 990 Dicyanocobyrinic acid heptamethyl ester, 4, 422 Dicycloalkaselenophenes synthesis, 4, 968 Dicyclohexa-1,4-diselenins thermolysis, 4, 968 Dieckmann condensation chroman-3-one synthesis by, 3, 854 isochroman-4-one synthesis by, 3, 859 oxoindolizidine synthesis by, 4, 471... 

C25H27CIO3 /O/Oy-i -J) see Trenbolone acetate ( )-2-chioro-3-[4-[(6-hydroxy-2,5,7,8-tetramethyl-chroman-2-yl)incthoxy]phenyl]propionic acid (C23H27C10 97322-69-5) sec Troglitazone 4 -chloro-2 (24midazoUn-2-yl)benzophenone (Ci HjiClNjO 22590-J7-6) see Mazindo ... 

AXELSON M, KIRK D N, FARRANT R D, COOLEY G, LAWSON A M and SETCHELL K D R (1982) The identification of the weak oestrogen equol (17-hydroxy-3-[4-hydroxyphenyl]chroman) in human urine , Biochem J, 210, 353-7. 

Skinner, W. A. Alaupovic, P. Oxidation products of vitamin E and its model, 6-hydroxy-2,2,5,7 8-pentamethyl-chroman. V. Studies of the products of alkaline ferricyanide oxidation. J. Org. Chem. 1963, 28, 2854—2858. 

Equol [7-hydroxy-3-(4 -hydroxyphenyl)-chroman] is a nonsteroidal estrogen of the isoflavone class. It is exclusively a product of intestinal bacterial... 

McCleland has reported that 3-phenylpropan-l-ol [125] and 3-(p-methyl-phenyl)propan-l-ol 99 [126] cyclize to chromans when oxidized by the radical anion SO4, generated by redox decomposition of S20 with Fe. The intermediate arene radical cation 100 is attacked by the nucleophilic hydroxy group. Whereas 1,6-cyclization yields 7-methylchroman 102, 1,5-cyclization with subsequent C-migration leads to the regioisomer 6-methylchroman 105. A dependence of the isomeric ratio and the combined yields to the pH value is determined. While 7-methylchroman 102 is the main product over a wide pH range, 6-methylchroman 105 is only formed at low pH. When the pH is lowered, the combined yields decrease due to the formation of an a-oxidized non-cyclized product. 

White, W. F., Zhao, D. (3R,4S)-3-[4-(4-Fluorophenyl)-4-hydroxypiperidin-1-yl]chroman-4,7-diol a conformationally restricted analoque of the NR2B subtype-selective NMD A antagonist (1S,2S)-1-(4-hydroxyphenol)-2-(4-hydroxy-4-phenylpiperidino)-1-propanol, J. Med. Chem. 1998, 41, 1172-1184. 

It is possible to distinguish axial and equatorial hydroxy groups in chroman-4-ols on the basis of their chemical shifts in DMSO (79BCJ2163). The pseudoaxial OH proton resonates at a significantly higher field the different behaviour is attributed to solute-solvent hydrogen bonding. 

The 13C spectra indicate a preference for a pseudoaxial orientation of the hydroxy group in chroman-4-ol and frans-2-methylchroman-4-ol (78). The cis isomer (79) has a pseudoequatorial hydroxy group and the resonances for C-2, C-3 and C-4 appear at lower field than those of the trans compound (77JCS(P1)217). A similar situation obtains for the related flavanols. 

Chromenes result from the dehydration of chromanols. The ready availability of the hydroxy compounds by the reduction of chroman-4-ones and through their reaction with Grignard and related reagents makes this an attractive route. Amongst many available examples, the syntheses of ageratochromene (precocene II 125) (58BSB22), fluorinated... 

The dehydration of chroman-2-ols, the corresponding 3-hydroxy compounds or their acetates yields chrom-2-enes. The elimination of acetic acid may be achieved by pyrolysis (62JA813, 69BSF1715, 70JOC2282), whilst loss of water is usually achieved under acidic conditions (35JCS646, 56JCS4785, 60CB1025). 

The stereochemical consequences of the cyclization of some 3-(2,5-dihydroxyphenyl)pro-pan-l-ols (247) have been investigated, with a view to optimizing the chiral economy of a tocopherol synthesis from (S)-chroman-2-carboxylic acid (81JOC2445). It was observed that acid-catalyzed dehydration occurred with retention of configuration and it was proposed (79JA6710) that the process involved the formation of a hemiketal through nucleophilic attack by the side-chain hydroxy group on the keto tautomer. 

However, the related chloro (248) and the benzyl ether (249) analogues do not cyclize to chromans under the same conditions, implicating the second phenolic hydroxy group of... 

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