3,4-Dihydroxy benzaldehyde

Ethoxy-3-hydroxybenzaldehyde (isobourbonal) has been prepared in good yield (84%) by ethylation of 3,4-dihydroxybenzaldehyde [Benzaldehyde, 3,4-dihydroxy-] with diethyl sulfate [Sulfuric acid, diethyl ester] in dimethylformamide.2... 

Benzaldehyde, 9, 39 Benzaldehyde, 3,4-dihydroxy-, 48 BENZALDEHYDE, 4-ETHOXY-3-HYDROXY-, 44... 

Atractyligenin-2-O-P-D-glucoside Sd 220 A083 Avenasterol, 5-dehydro Sd Ai07 Benzaldehyde, 3-4-dihydroxy Sd Ai22 Benzaldehyde Sd Hu aosz Benzofuran, 2-3-dihydro Sd Hu aosz... 

Benzaldehyde, 4-rm-butyl-, 55, 10 Benzaldehyde, diethylamine, 58,119 Benzaldehyde, dihexylamine, 58, 119 Benzaldehyde, 3,4-dihydroxy-, 56, 48 Benzaldehyde, dimethylamire, 58, 118 BENZALDEHYDE, 4-ETHOXY-3-HY-DROXY, 56, 44... 

Benzaldehyde, 3,4-dihydroxy- (protocatechualdehyde), Benzaldehyde, 4-hydroxy-Benzaldehyde, 4-hydroxy-3-methoxy- (vanillin), Benzaldehyde, 3,5-dimethoxy-4-hydroxy- (syringaldehyde)... 

Pyruvic Acid Compounds.—Lubrzynska and Smedley have recently shown that a number of aldehydes such as heliotropin, anisic aldehyde, benzaldehyde, and cinnamic aldehyde, condense with pyruvic acid in slightly alkaline solution, with the formation of )8-unsaturated-a-ketonic acids. For example, if heliotropin and pyruvic acid in alkaline solution be left standing for about eight days at ordinary temperature, dihydroxy-methylene-benzal-pyruvic acid is formed. This body forms yellow needles, melting at 163° Similarly, anisic aldehyde yields methoxy-benzal-pyruvic acid, melting at 130° and cinnamic aldehyde yields cinnamal-pyruvic acid, melting at 73°. 

Scheme 31) [109]. 4-Chlorobutanal, cyclopropylaldehyde, and m-phenoxyl-benzaldehyde are also prepared in the two-phase system [110]. Indirect electrooxidation of 6y3-methyl-3y3, 5a-dihydroxy-16a, 17a-cyclohexanopregnan-20-one are indirectly electrooxidized to the corresponding 5a-hydroxy-3,20-dione using sodium bromide and substituted TEMPO as the mediating couple [111]. 

Figure 2. Scores of 17 volatile phenols on two PLS factors. 1 = eug ol, 2 = iso-eugenol, 3 = 4-meUiyl-guiacol, 4 = 4-ethyl-guiacol, 5 = 4-hydroxy-benzaldehyde, 6 = 2,4-dihydroxy-benzaldehyde, 7 =...

NOTE No highs r nitrated derivs of Dihydroxy-benzaldehyde were found in Beil or in CA thru... 

Reactions of 4,7-phenanthroline-5,6-dione have been the subject of considerable study. It is reduced to 5,6-dihydroxy-4,7-phenanthroline by Raney nickel hydrogenation226,249 or by aromatic thiols in benzene,262 and oxidized by permanganate to 3,3 -bipyridyl-2,2 -dicarboxylic acid.263 It forms bishemiketals with alcohols226 and diepoxides with diazomethane.226 The diepoxides by reaction with hydrochloric acid form diols of type 57, R = Cl, which on oxidation with lead tetraacetate give 3,3 -bipyridyl diketones of type 58, R = Cl. Methyl ketones of type 58, R = H, are also obtained by lead(IV) acetate oxidation of the diol 57, R = H, obtained by lithium aluminum hydride reduction of 57, R = Cl. With phenyldiazomethane and diphenyldiazomethane the dione forms 1,3-dioxole derivatives,264,265 which readily hydrolyze back to the dione with concomitant formation of benzaldehyde and benzophenone, respectively. 

Reaction of 2-acyl-l,2,3,4,ll,lla-6H-hexahydropyrazino[l,2-fr]isoqui-noline-l,4-diones with aromatic aldehydes in the presence of KOfBu in CH2CI2 afforded 2-unsubstituted-3-arylidene derivatives (09T2201). From a similar reaction of czs-6H,llaH-6-benzyloxymethyl-9-methyl-7,8,10-trimethoxy-2-pivaloyl-l, 2,3,4,11,11 a-6H-hexahydropyrazino[l, 2-b] isoquinoline-1,4-dione and 3-methyl-2,4,5-benzaldehyde 2-unsubsti-tuted-3-(3-methyl-2,4,5-trimethoxyphenyl)methylene and 2-pivaloyl-3,3-dihydroxy derivatives were isolated in 20% and 39% yields, respectively. 

The last compound was prepared as follows the hydroxyl groups of 3,4-dihydroxy-benzaldehyde was protected using t-butyldimethylsilylchloride (1). 100 mg (0.26 mmol) of 3,4-di(t-butyl-methylsiloxy)benzaldehyde was dissolved in 1 ml tetrahydrofurane under atmosphere of argon at -40°C, and 0.30 ml of metal complex from (S)-6,6 -bis(triethylsilylethynyl)-l,l-dihydroxy-2,2 -binaphtalene (2) mixed with a solution of n-butyllitium in hexane.After stirring for 30 minutes, 79.4 mg (1.3 mmol) of nitromethane was added dropwise to the mixture. After 67 hour reaction time, 2 ml of 1 N aqueous solution of hydrochloric acid added to stop the reaction. Product was extracted with 50 ml ethyl acetate, dehydrated with anhydrous sodium sulfate and concentrated within evaporator followed by silica gel chromatography (n-hexane/acetone = 10/1), after which (R)-l-(3,4-di(t-butyldimethylsiloxy) phenyl)-2-nitroethanol with an optical purity of 92% e.e. was obtained in a yield of 93%. 

The irans-benzylidene derivative (188), obtained as the major product of condensation of 3-methylpiperazine 2,5-dione and benzaldehyde in the presence of acetic anhydride, undergoes photoisomerization to the cis isomer (191) on irradiation in methanol. Both isomers have been converted into tetrahydropyrazine imino ethers (189) and (192) by treatment with triethyloxonium fluoroborate. The trans compound reacts more slowly and gives a lower yield of imino ether and this is attributed to steric hindrance. Compounds 188 and 191 are de-acetylated on treatment with methanolic 2 N potassium hydroxide. The trans and cis isomers (187) and (190), so produced are converted into 3-benzyl-2,5-dihydroxy-6-methylpyrazine (144) when heated at 100° with sodium hydroxide.384 Treatment of the dichloroacetyl derivative of phenylalanine with methylamine gives l-methyl-3-benzylidenepiperazine 2,5-dione with the stereochemistry shown.384a... 

Adedeji et al. (1993) used a direct thermal desorption technique (220°C) to analyse the volatiles from beans that might cause the thermal degradation and transformation of sugar into common volatile compounds such as 3,5-dimethyl-2,4(3H,5H)-furandione and 3,5-dihydroxy-6-methyl-2,3-dihydro-4H-pyran-4-one. This last compound was detected at a high concentration (3880 ppm) in Mexican vanilla, being the third most abundant compound after vanillin and 2-furfural, and far more abundant than vanillic acid, p-hydroxy-benzaldehyde or p-hydroxybenzoic acid. 

Zhdanov and Polenov have reported58 a synthesis of the first sugar phosphorane (70), which was shown to react with p-nitro-and o-hy-droxy-benzaldehyde, forming unsaturated ketoses 71 and 72, respectively. Attempted reactions with p-dimethylamino-, p-hydroxy-, and 2,4-dihydroxy-benzaldehyde were unsuccessful. The formation of the dienic ketose 72 is undoubtedly caused by /3-elimination of a methoxyl group during treatment of the reaction mixture with aqueous sodium hydroxide during isolation. 

Azin of 2,4,6-trinitro-3-hydroxy-benzaldehyde. also called 2,4,6,2, 4 ,6 -Hexanitro-3,3 -dihydroxy benzadazin (also called Azin des 2,4,6-Trinit robenzaldehyds in Ger). [H0C6H(N02)3CH N-] 2 >mw 510.28, N 21.96%, OB -53.0% in the form of bright yellow needles that are sol in ale or 50% HAc, but insol in benz. Prepd by treating1 2,4,6-Trinitro-3-hydroxybenzaldehyde in hot aq NaOH with hydrazine sulfate Refs l) Beil 8, [63] 2) H.H. Hodgson ... 

Hydroboration is faster than cleavage with borane, but H2BCI etherate cleaves unsaturated acetals without giving hydroboration (equation 10). Lower yields are obtained with the less reactive Me2S complex, but that reagent gives good yields of dihydroxy diethers from chiral bisacetals (equation 11). The diethyl acetal of benzaldehyde can be reduced to ethyl benzyl ether in moderate yield by decaborane in toluene at 120-130 C (equation 12). °... 

Reduction of 2,2,3,3,5,6-hexamethyl-2,3-dihydropyrazine 1,4-dioxide (78) with sodium borohydride gave l,4-dihydroxy-2,2,3,3,5,6-hexamethylpiperazine (555) and attempted deoxygenation of (78) by zinc and hydrochloric acid gave the bishydroxylamine (79) (555). Compound (78) did not form benzylidene derivatives with benzaldehyde (555) and it was only slowly attacked by selenium dioxide one equivalent of selenium dioxide required 5 days boiling under reflux before the nitrone was completely reacted, and the product was thought to be 6-formyl-... 

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