Resorcinol, reaction with unsaturated

Thus, the unsubstituted starting compound 69 was treated with resorcinol in the presence of trifluoroacetic acid (TFA) to yield 70. Then, reaction of 69 with the cyclic a,/3-unsaturated ketone in the presence of lithium hydride gave the 7-substituted heteroaromatic compound 71, and ethyl cyanoacetate afforded the cross-conjugated product 72, whereas reaction with pyrimidine-2,4,6-trione in the presence of triethylamine yielded the addition product 73. Indole also been reacted with 69, and heating of the dichloromethane solution for 90 min in the presence of TFA yielded the addition product 74 in excellent yield (95%) <1998ZOR450> (Scheme 12). 

First isolated in 1892 and after several incorrectly proposed structures, the product obtained from the reaction of resorcinol and acetone is finally confirmed unequivocally from X-ray crystallographic studies as chroman 484 (Equation 198) <1997JOC737>. A study concerning the reaction of resorcinol with a variety of a,P-unsaturated ketones is available <1998JOC636>. 

Ketones arise from phenols by isomerization of unsaturated alcohols (37). Palladium is the most suited for this type of reaction because of its high isomerization activity coupled with a very low rate of reduction of the resulting ketones (6). Excellent yields of ketones often may be obtained rhodium will give at times quite substantial yields of cyclohexanones (50-65% methylcyclohexanones from cresols) (38), but in other reductions such as resorcinol, little ketone accumulates over either rhodium or platinum under conditions where it is a major product over palladium (29). 

A recent example of zeolite-catalyzed esterification involving biochemicals is the reaction of aminoacids with methanol. For instance, L-phenylalanine was converted to its methyl ester over H-USY at 130°C. However, the chiral carbon atom was racemized to a considerable extent, yielding an eventual ee of 52% (27). In the reaction of a, (3-unsaturated acids with phenols, the esterification over H-Beta is followed by an alkylation of the aromatic ring for instance resorcinol and acrylic acid react to form 7-hydroxy-3,4-dihydrocoumarin (28). 

The reaction of resorcinols with a,P-unsaturated aldehydes and ketones catalysed by ethylenediamine diacetate has been used to synthesise the naturally occurring chromenes confluentin and daurichromenic acid <05OBC3955, 05TL7539>. 2-Hydroxynaphthoquinone behaves similarly providing a useful route to pyranonaphthoquinones <05S3026>. 

A further example is the reaction of the magnesium salt of olivetol with 3-methylbut-2-enal when the yield of the 4-substitited product was 77% and that of the 2- was 3%. By contrast in the reaction of resorcinols with a,p-unsaturated carbonyl compounds in pyridine solution 2-substitution occurs as will be seen in the synthesis of deoxybruceol in section 12.6.5. 

Other epoxy resins are also being manufactured, but their commercial j utilization is not so far advanced as those based on bisphenol A and i epichlorohydrin. For instance, resorcinol and a mixture of diphenol-poly-(hydroxyphenyl)-pentadecanes, obtained by the addition reaction of phenol with an unsaturated phenol derived from cashew-nut oil (see structure below) can be reacted with epichlorohydrin to produce epoxy resins. ... 

The long-known acid catalysed reaction of resorcinol with acetone has been conclusively shown to give chroman (24) and probably proceeds through the formation of mesityl oxide. Other ketones and a,p-unsaturated ketones behave similarly. By altering the concentration of the HCl catalyst, spirobichroman (25) can become the major product, implicating phorone as an intermediate <97JOC737>. 

This reaction was first reported by Haddadin and Issodorides in 1965. It is the preparation of quinoxaline-1,4-dioxides from the cycloaddition between benzofuroxan (i.e., benzofu-razan A -oxide) and dienes, a.y -unsaturated ketones, enamines, or enolates. Unfortunately, this reaction is not named after the authors who discovered it instead it is known as the Beirut reaction after the city in which the inventors carried out is the initial work. In most cases, ketones," /3-diketones, j8-ketoesters, )8-ketonitrile, LS-dinitrile, and/8-ketoamides all are suitable for this reaction, and the corresponding enolates can be easily prepared in the presence of a weak base such as triethylamine. In addition, even phenolic enolates from phenol, resorcinol, hydroquinone, or benzoquinone undergo a similar dehydrative condensation with benzofuroxan under mild conditions (e.g., Na0H/H20, H2O, MeOH/RNH2, Si02/MeCN at room temperature), to give phenazine iV,iV -dioxide derivatives. ... 

Some of the curing adhesives require heat, whereas others react at room temperature with the help of catalysts, and in some instances with activation by light. Again, it is an advantage to make a bond without the aid of an oven. Among the adhesives which can be processed in the cold, with proper formulation, are resorcinol formaldehyde, unsaturated polyesters, methyl methacrylate, cyanoacrylate esters, epoxies, and urethanes. The polymerization reaction is usually exothermic, so that the glue line may become somewhat warmer than the ambient... 

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