Aldehyde salicylic

In the strongly basic medium, the reactant is the phenoxide ion high nucleophilic activity at the ortho and para positions is provided through the electromeric shifts indicated. The above scheme indicates theorpara substitution is similar. The intermediate o-hydroxybenzal chloride anion (I) may react either with a hydroxide ion or with water to give the anion of salicyl-aldehyde (II), or with phenoxide ion or with phenol to give the anion of the diphenylacetal of salicylaldehyde (III). Both these anions are stable in basic solution. Upon acidification (III) is hydrolysed to salicylaldehyde and phenol this probably accounts for the recovery of much unreacted phenol from the reaction. 

The reaction of methoxybutenone with salicylic aldehyde (20°C, MeOK, toluene, MeOH, 15 h) affords 3-acetyl-2-methoxy-chromo-3-ene (291) in 14% yield (80MI1). 

The Dakin reaction proceeds by a mechanism analogous to that of the Baeyer-Villiger reaction. An aromatic aldehyde or ketone that is activated by a hydroxy group in the ortho or para position, e.g. salicylic aldehyde 12 (2-hydroxybenzaldehyde), reacts with hydroperoxides or alkaline hydrogen peroxide. Upon hydrolysis of the rearrangement product 13 a dihydroxybenzene, e.g. catechol 14, is obtained ... 

The formylation of a phenol 1 with chloroform in alkaline solution is called the Reimer-Tiemann reaction. It leads preferentially to formation of an ortho-formylated phenol—e.g. salicylic aldehyde 2 —while with other formylation reactions, e.g. the Gattermann reaction, the corresponding /jara-formyl derivative is obtained as a major product. The Reimer-Tiemann reaction is mainly used for the synthesis of o-hydroxy aromatic aldehydes. 

Salicylic aldehyde, C HgOj, is the simplest representative of the ortho-hydroxy aldehydes, which are, generally speaking, strongly odorous... 

Salicylic aldehyde is an almost colourless oil with a fragrant odour of meadowsweet. Its constitution is as follows —... 

Coumarin was first produced synthetically by Perkin. He made it by heating salicylic aldehyde, CgH (OH)i(COH), acetic anhydride, and sodium acetate. The whole solidifies to a crystalline mass, from which, on treatment with water, an oil separates containing coumarin and aceto-coumaric acid. This acid on heating is decomposed into acetic acid and coumarin, so that the product of distillation is principally coumarin. Perkin s synthesis proceeds according to the following equation —... 

Coumarin is sometimes adulterated with acetanilide, which should always be looked for the ease with which it yields aniline, on heating with potash solution, renders it very easy of detection. Some samples, otherwise pure, contain traces of unaltered salicylic aldehyde, which is revealed by the odour. 

S g of ethyl glycinate hydrochloride were dissolved in 400 cc of ethanol and 33.5 g of salicylic aldehyde were added. It is refluxed for half an hour and cooled. 38 cc of triethylamlne and 25 g of Raney nickel are then added whereafter hydrogenation is carried out at room temperature and under atmospheric pressure. After hydrogen adsorption was complete, the mixture was filtered and the alcohol evaporated off. The residue was taken up with acidified water, extracted with ether to eliminate part of the by-products, consisting mainly of o-cresol, then made alkaline with ammonia and extracted with ethyl acetate. The solvent was removed in vacuo and the residue crystallized from ether/petroleum ether. 36.7 g of o-hydroxybenzyl-aminoacetlc acid ethyl ester melting at 47°C are obtained. 

Chloroacetic acid, reaction with salicyl-aldehyde, 46, 28 Chloroacetone, 46, 3 Chloroacetyl fluoride, 45, 6 o-Chloroacetyl isocyanate, 46,16 -Chloroaniline, reaction with carbon disulfide and aqueous ammonia,... 

Besides the domino Michael/SN processes, domino Michael/Knoevenagel reactions have also been used. Thus, Obrecht, Filippone and Santeusanio employed this type of process for the assembly of highly substituted thiophenes [102] and pyrroles [103]. Marinelli and colleagues have reported on the synthesis of various 2,4-disubstituted quinolines [104] and [l,8]naphthyridines [105] by means of a domino Michael addition/imine cyclization. Related di- and tetrahydroquinolines were prepared by a domino Michael addition/aldol condensation described by the Hamada group [106]. A recent example of a domino Michael/aldol condensation process has been reported by Brase and coworkers [107], by which substituted tetrahydroxan-thenes 2-186 were prepared from salicylic aldehydes 2-184 and cycloenones 2-185 (Scheme 2.43). 

The interactions between the chiral Schiff bases being derivatives of 2-aminoalcohols and substituted salicylic aldehydes and titanium (IV) isopropoxide [33] have been monitored by aH NMR spectroscopy.81... 

The first use of room temperature ionic liquids as potential novel soluble phases for combinatorial synthesis has recently been described. As model reaction the Knoevenagel condensation of salicyl aldehyde grafted on to an imidazolium-derived ionic liquid was studied under the action of microwave irradiation (Scheme 12.19) [66]. Reactions were performed without additional solvent in the presence of a basic catalyst, utilizing microwave irradiation in a designated monomode microwave reac-... 

The possibility of carrying out a multistep synthesis makes it possible to obtain P,B-containing derivatives from unstable intermediate a-hydroxyalkylphosphines. Thus, phenylphosphine, salicylic aldehyde, phenylboric acid anhydride, and triethylamine interact to give a bicyc-lic product—2,8,9-trioxa-1 -borata-4-phospha-6,7 -benzobicyclo [3,3,3] nonane (115) [Eq. (74)] (87IZV2118 89IZV946). In this case an aldehyde takes part in the reaction opening up new synthetic possibilities. 

Analogous products have been obtained when salicylic aldehyde was replaced by o-hydroxynaphthaldehyde. 

The reaction of phenylphosphine with boric acid and 2 mol of salicylic aldehyde was carried out in the presence of pyridine with azeotropic removal of water and gave rise to the complex of pyridine with B(III) (116), bonded to three oxygen atoms (87IZV2118 89IZV946) [Eq. (75)]. 

More significant differences from the properties of cyclic boryloxyalkyl-phosphines were revealed for 5,6-benzo-4-diphenylphosphino-2-phenyl-l,3-dioxa-2-boracyclohexane (126), obtained by the interaction of diphe-nylphosphine, salicylic aldehyde, and phenylboric acid ester [Eq. (83)] (92IZV196). 

The stepwise condensation of 2-amino-5-ethyl-l,3,4-thiadiazole 83 with a mixture of salicylic aldehyde and acetylacetone in ethanol in a reagent mixture of 1 1 1 gave compound 84 in 36% yield <99RJOC624>. 

A similar coupling reaction of salicyl aldehydes with disubstituted alkynes, catalyzed by rhodium, is known... 

Hayashi et al.147 reported another highly enantioselective cyanohydrination catalyzed by compound 138. In this reaction, a Schilf base derived from fl-amino alcohol and a substituted salicylic aldehyde were used as the chiral ligand, and the asymmetric addition of trimethylsilylcyanide to aldehyde gave the corresponding cyanohydrin with up to 91% ee (Scheme 2-56). 

The chromium complexes of some azomethine derivatives are used as solvent dyes. Cl Solvent Yellow 32 (6.231) is an example, obtained by condensing one mole of salicyl-aldehyde with the appropriate amine, followed by treatment with one equivalent of chromium. 

Pyrrolidinone 126 and salicylic aldehyde in acetic acid under microwave irradiation gives in dioxopyrrolo[3,4-c]benzoxepine 127 as a mixture with phenyl chromeno[2,3- ]pyrrole 128 (8 and 13% yields, correspondingly. Equation (18)... 

In a manner similar to that of l-tosyl-4,6-dinitroindoline (see Scheme 28, Section 2.2.1), 4,6-dinitrobenzofuran undergoes condensation with salicylic aldehyde under basic conditions followed by nitro group substitution/cycliza-tion to afford a mono nitro compound with peri-fusion of the benzofuran ring in 68% yield (2005CHE796). 

Somewhat different type 2-amino-4H-chromene synthesis is represented by the interaction of CH-acidic nitriles 27 with salicylic aldehyde 157 where the phenolic OH and aldehyde groups are present in the same molecule. A conventional mechanistic scheme is represented (Scheme 58), where in the presence of a base nitrile 27 condenses with the aldehyde to give Knoevenagel intermediate 158. Then nucleophilic addition of the OH group leads to iminochromene 159, which then adds a nucleophile (as a rule, the second equivalent of nitrile 27) at position 4 to form 2-amino-4H-chromene 160. 

However, all the broad spectrum of products formed via the reaction of salicylic aldehydes with methylene-active nitriles cannot be shown on a one simple scheme. In the presence of ammonium acetate different chromenes 165 and 166 can be isolated, depending on the order of addition of reagents, the amount of catalyst, and temperature (77S871) (Scheme 60). 

Unusual polycyclic 169 was obtained from salicylic aldehyde 157 and cyanoacetylated bisindole derivative 170 (07JOC5886) (Scheme 62). 

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