Homophthalic anhydride

Homofolic acid, 5,11-methenyl-tetrahydro-biological activity, 3, 327 Homofolic acid, tetrahydro-biological activity, 3, 327 Homoisoflavanones occurrence, 3, 722 thermoisomerization, 3, 722 thermolysis, 3, 728 Homolytic reactions heterocyclic compounds reviews, 1, 74 Homophthalic acid isocoumarins synthesis from, 3, 830 synthesis, 3, 830 Homophthalic anhydride isochroman-l-one synthesis from, 3, 860 20a-Homoporphyrin nomenclature, 1, 30 Homopterocarpin isolation, 4, 998 ( )- D- Homotestosterone synthesis, 1, 453 Homer-Emmons reaction chromene synthesis by, 3, 749 Hortiacine isolation, 3, 149 Hortiamine isolation, 3, 149... 

Homophthalic anhydride (5.0 g, 31 mmol) was added to a solution of 85% hydrazine hydrate (1.8 mL, 31 mmol) in EtOH (40 mL) and the mixture was heated under reflux for 6 h. The resulting precipitate was filtered off and washed with HOAc the product crystallized (EtOH) as colorless flakes yield 4.3 g (65 %) mp 298-300 JC. 

In a facile and rapid stereoselective, three-component, one-pot reaction, a series of cis-isoquinolonic acids 132 were synthesized using silica supported sulfuric acid to catalyze the reaction between homophthalic anhydride 133 with different aldehydes 134 and amines 135. This three-component cyclocondensation offers a variety of advantages including high yields, easy experimental work-up, and the use an inexpensive, non-toxic, readily available, and recyclable catalyst <06JHC187>. 

The achiral ionic liquid [bmim][BF ] was able to catalyze the three component reaction of benzaldehyde, aniline and homophthalic anhydride in 90% yield. Next to the major ciT-isomer, 10% tran.f-isomer was isolated after 3 h (Scheme 74) [196]. Control reactions in CH Cl with 10 mol% [bmim][BF ] and without catalyst showed that in the presence of the ionic hquid a high conversion in a short time was observed. Application of polar solvents like methanol or acetonitrile made it necessary to increase the reaction temperature to 70-80 °C, and the product was obtained in only 45-60% yield in a prolonged reaction time of 8-15 h. Further control reactions with [nBu NllCl] or [bmim] [Cl] showed that the anion played a comparable important role as the cation, since no product was formed. The author could demonstrate the generality of the reaction by the application of a broad variety of benzaldehyde and anihne derivatives. 

The ionic liquid [BMIM]BF4 was found to efficiently catalyze the three-component coupling reactions of aldehydes, amines, and homophthalic anhydride under ambient conditions to give the corresponding c/ -isoquinolonic acids in excellent yields with... 

Carboxybenzyl aryl ketones are formed together with the isocoumarin when homophthalic anhydride (isochroman-l,3-dione) is used to acylate aromatic molecules under Friedel-Crafts conditions (51JOC1064) and the 7-methoxy derivative behaves in a similar fashion (66JIC615). Some care in the choice of Lewis acid is necessary in view of the formation of the tropone derivative (504) in the acylation of hydroquinone (Scheme 181) (55JCS2244). 

The oriAo-benzoyl-benzoic acids readily yield anthraquinone and its derivatives (see p. 82). It may be noted that o-benzoyl-benzoic acid itself, with benzene and aluminium chloride, yields phthalophenone the same compound is made directly from phthalic anhydride by increasing the amount of the latter or by adding acetic anhydride. The same holds for p-toluoylbenzoic acid and ditoluoylphthalide. (Am. Soc., 43, 1965 J. C. S., 122, 539.) (For the use of carbomethoxylbenzoyl chlorides and of homophthalic anhydrides in these reactions, see Am. Soc., 43, 1950.)... 

In the reaction of monocyclic pyrylium salts with azomethines, however, an analogous para-bridged intermediate was excluded on the basis of experimental data. It is necessary to stress that the desired conversion is similar to the condensation of substituted homophthalic anhydrides with the same azomethines (77JOC1111 78JOC286 79JOC409 80S847) ... 

Benzopyrylium salts are more suitable than homophthalic anhydrides for the synthesis of dihydroisoquinolinium salts of type 237, by the method described previously, because of the easier availability and greater variety of the former compounds. 

Ab initio and density functional theoretical studies of the 4 + 2-cycloaddition of 2-azabutadiene with formaldehyde predict a concerted reaction that agrees well with experimental evidence.184 The azadiene A-plienyl-l-aza-2-cyanobuta-l,3-diene reacts with electron-rich, electron-poor, and neutral dipolarophiles under mild thermal conditions.185 5,6-Diliydro-4//-1,2-oxazines have been shown to be usefiil as synthon equivalents of 2-cyano-l-azabuta-1,3-dienes.186 The intramolecular Diels-Alder reaction of 1-aza-l,3-butadienes (106) can be activated by a 2-cyano substituent (Scheme 37).187 Stereoselectivity in the hetero-Diels-Alder reactions of heterobutadienes, nitrosoalkenes, and heterodienophiles has been extensively reviewed.188 The azadiene l-(f-butyldimethylsilyloxy)-l-azabuta-1,3 -diene (107) reacts with halobenzo-quinones, naphthoquinones, and A-phcnylmalcimidc to yield low to good yields of various pyridine heterocycles (108) (Scheme 38).189 The 4 + 2-cycloaddition of homophthalic anhydride with A-(cinnamylidcnc)tritylaminc produces the 3,4-adduct whereas with A -(cinnamylidcnc)bcnzylidinc the 1,2-adduct is produced.190... 

Methyl l-hydroxynaphthalene-2-carboxylate is formed in 19% yield when homophthalic anhydride and methyl propiolate are heated in toluene at 150° for 24 hours. 

Diels-Alder reactions. Homophthalic anhydride (1) undergoes Diels-Alder reactions with some alkynes and benzoquinones at 150-200° to give linear phenols, probably via the tautomer a.2 Examples ... 

Holacosamine, 269 Homoadditions, 495 Homogeraniol, 226 Homophthalic anhydride, 254 Hunsdiecker reaction, 515 Hydrazine, 255, 284... 

Xylopinine has been synthesized by the condensation of 3,4-dimethoxy-homophthalic anhydride and 6,7-dimethoxy-l-oxotetrahydroisoquinoline, followed by reduction of the resulting lactam.122 Xylopinine,123,124 scoulerine,124 isocoptisine,124 y/-epitetrahydroberberine,124 and govanine125 have been synthesized by cyclization of the appropriately substituted lactams (36), themselves prepared... 

Multi-component reactions were also utilized for the synthesis of isoquinolines. Yadav et al. reported the reaction of homophthalic anhydride 125, benzaldehyde 126, and anilines 127, under neutral conditions, in the presence of iodine in dichloromethane at room temperature to afford the desired cfs-oxoisoquinolinecarboxylic acid derivatives 128 in high yields <07S3191>. 

Cycloadditions with homophthalic anhydride. Homophthalic anhydride can undergo thermal cycloaddition with dienophilcs with loss of carbon dioxide, but the yields are generally low. The reaction can proceed at room temperature with dramatic improvement of the yield if the anhydride is first converted into the sodium salt (NaH) or lithium salt (LDA). The cycloaddition provides a regioseicctive route to pcri-hydroxy polycyclic compounds. 

Tetrahydroisoquinolonic acids are formed in good yields and enhanced rates from three-component coupling reactions of benzaldehydes, amines, and homophthalic anhydride. The key feature of this approach is the use of ionic liquids <03T1805>. 

The mass spectrum of homophthalic anhydride has a base peak at mje 118 which corresponds directly to benzocyclobuteneone, 49. The next most intense peak in the spectrum is mje 90 which corresponds to the elemental composition of fluoenyl allene, 50. 

These two molecules were the major products of hot wire pyrolysis of homophthalic anhydride, Eq. (38).79.80)... 

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