Benzaldehyde 2-hydroxy

Reactions of the Aromatic Ring. The aromatic ring of hydroxybenzaldehydes participates in several typical aromatic electrophilic reactions. Ha.logena.tlon, Chlorination and bromination yield mono- and dihalo derivatives, depending on reaction conditions. Bromination of / -hydroxy-benzaldehyde in chloroform yields 65—75% of the product shown (39). 

Further substitution of benzoic acid leads to a drug with antiemetic activity. Alkylation of the sodium salt of p-hydroxy-benzaldehyde (8) with 2-dimethylaminoethyl chloride affords the so-called basic ether (9). Reductive amination of the aldehyde in the presence of ammonia gives diamine, 10. Acylation of that product with 3,4,5-trimethoxybenzoyl chloride affords trimetho-benzamide (11). ... 

Mit Natrium-bis-[2-methoxy-athoxy]-dihydrido-aluminat konnen in sieden-dem Xylol Hydroxy-benzaldehyde und -acetophenone innerhalb weniger Stunden zu Al-kyl-phenolen reduziert werden (Vorschrift S. 171) z.B.2 ... 

Methoxy-4-hydroxy-benzaldehyd 4-Hydroxy-3-methoxy-l- melhyl-benz.ol 85% d.Th. 

In groBerem MaBstab wird die reduktive Dimerisierung von 4-Hydroxy-benzaldehyd zu l,2-Bis- 4-hydroxy-phenyl]-glykol an Quecksilber durchgefiihrt6. 

The Reimer-Tiemann reaction of phenol with chloroform, in the presence of 50% NaOH, gives a much higher ratio of para to ortho hydroxy benzaldehyde when polyethylene glycol is used as compared to the established procedure without any addition of a hydrotope. A para to ortho ratio of 1 1 has been realized (Neumann and Sasson, 1986). 

Dhurrin Taxi- phyllin p-hydroxy- benzaldehyde Prunasin Root washings ... 

Acetal handle 78 synthesized from Merrifield resin and 4-hydroxy-benzaldehyde was applied to the solid-phase synthesis of carbohydrates and 1-oxacephams (Scheme 41) [90]. For the latter, a 1,3-diol was initially anchored to the support to form a cyclic acetal. A ring opening reaction with DIBAL generated a resin-bound alcohol which was converted to the corresponding triflate for A-alkylation with 4-vinyl-oxyazetidin-2-one. A Lewis acid catalyzed ring closure released 1-oxa-cephams from the support. 

The structure of the antibiotic, 9, which has been variously named lacto-quinomycin-A and medermycin, was first reported by Okabe and coworkers in 1985.58 In early 2002,59 a communication was published reporting that the original structure, 9, was incorrect based on synthesis and that the substituted tetrahydropyran ring was attached to the 6-position to give 10, rather than the 8-position as originally reported. The authors based their conclusion on the fact that a key intermediate was identified as 6-bromo-3-hydroxybenzaldehyde rather than the 4-bromo-3-hydroxy benzaldehyde as previously reported.60... 

Alkaline Nitrobenzene Oxidation of Cornstalks. Isolation of p-Hydroxy-benzaldehyde. J. Amer. chem. Soc. 66, 37 (1944). 

A first application using ferroceneboronic acid as mediator [45] was described for the transformation of p-hydroxy toluene to p-hydroxy benzaldehyde which is catalyzed by the enzyme p-cresolmethyl hydroxylase (PCMH) from Pseudomonas putida. This enzyme is a flavocytochrome containing two FAD and two cytochrome c prosthetic groups. To develop a continuous process using ultrafiltration membranes to retain the enzyme and the mediator, water soluble polymer-bound ferrocenes [50] such as compounds 3-7 have been applied as redox catalysts for the application in batch electrolyses (Fig. 12) or in combination with an electrochemical enzyme membrane reactor (Fig. 13) [46, 50] with excellent results. 

In an electrochemical enzyme membrane reactor an electrochemical flow-through cell using a carbon-felt anode is combined with an enzyme-membrane reactor. The residence time is adjusted by the flow of the added substrate solution. The off-flow of the enzyme membrane reactor only contains the products p-hydroxy benzaldehyde and p-hydroxy benzylalcohol. By proper adjustment of the residence time and the potential, total turnover of the p-hydroxy toluene, which is introduced into the reactor in 13 mM concentration, can be obtained. In a 10-day run, the enzyme underwent 400000 cycles and the polymer-bound mediator, which was present in a higher concentration than the enzyme, underwent more than 500 cycles. At the end, the system was still active. By proper selection of the residence time, one can either... 

The terf-butoxy group was chosen as the protective group for the formation of p-hydroxy benzaldehyde [29]. 

The sediment concentrations of anthropogenic compounds in the cove were somewhat less variable than upstream this probably reflects the greater bottom uniformity of the cove. Fewer of the plant s compounds were detected in sediment from the channel where the cove leads into the brackish river (Point 18, Figure 1). Found at this location were various phenols (no. 28, 30a, 30b, 31, 33, 38, 39), di-t-butyl-benzoqui-none (no. 57), 3,5-di-t-butyl-4-hydroxy-benzaldehyde (no. 35), three benzotriazoles (no. 6, 10, 12), 4,4 -dichloro-3(trifluoromethyl) carbanilide (no. 77), and 2-chloro-4,6-bis-isopropylamino-s-triazine (no. 14). The only compounds from the plant detected in the sediment sample from the brackish river (Point 19) were the two high molecular weight benzotriazoles (no. 10 and 12) and methyl 3-(3 ,5 -di-t-butyl-4 -hydroxphenyl) propionate (no. 46). 

The stereoselective synthesis of c/.v-fused pyrano and furanobenzopyran can be achieved through the one-pot three-component reaction of o-hydroxy benzaldehyde, aromatic amines, and cyclic enolethers in the presence of catalytic amounts of Bi(OTf)3 (10 mol%) in air and the moisture-stable ionic liquid [bmim]PF6 [116]. The reaction of salicilaldehyde, aniline and 2,3-dihydrofuran furnishes the c/.v-fused furanochroman. In a similar fashion, various substituted salicilaldehydes and... 

The plausible mechanism of the reaction is shown in Fig. 25. The reaction probably proceeds through the activation of imine (formed in situ from the o-hydroxy benzaldehyde and the aromatic amine) by the catalyst followed by the addition and subsequent cyclization of the enol ether, resulting in the formation of the fused acetal. Ionic liquids are stable enough with amines and water and also effectively activate the imines to undergo cyclization. The recovered ionic liquid can be re-used with gradual decrease in the efficiency of the method. The hydro-phobic nature of the ionic liquid also helps in recovery of the catalyst. 

A closer inspection of A. luteoviolaceus by different groups provided a further variety of highly active metabolites, tetrabromopyrrole, hexabromo-2,2 -bipyrrole, tetrabromobiphenol, several simple phenols including 4-hydroxy-benzaldehyde and n-propyl-4-hydroxybenzoate, violacein (5) and related pigments, and the extremely strong siderophore alterobactin [97]. 

Unangst and co-workers condensed 104 with several 3,5-dialkyl-4-hydroxy-benzaldehydes followed by alkylation and hydrolysis to afford 110 and other... 

Apart from these above mentioned compounds, courmains, iridoids, and alkaloids have also been obtained from semi-mangroves distributed in China. For example, cerbinal, p-hydroxy-benzaldehyde, benzamide, n-hexadecane acid monoglyceride, loliolide, 3-sitosterol, et al. 

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