Phenol annelation

Phenol annelation.1 This modified methyl vinyl ketone can be used for synthesis of 5,6,7,8-tetrahydro-2-naphthol or 5-indanol by reaction with the lithium enolate of cyclohexanone or cyclopentanone, respectively. The former reaction is formulated in equation (I). 

Phenol annelation.1 Methyl vinyl ketone (and substituted vinyl ketones) undergo Robinson annelation with the j8-keto sulfoxide (1) to afford the 5,6,7,8-tetrahydro-2-naphthol (2) with loss of benzenesulfenic acid. Sodium methoxide is used as base, and the reaction proceeds at 0 -> 25°. 

Phase-transfer catalysts, 220, 221,305-306 Phenanthrenes, 319, 320 9-Phenanthrol, 431 Phenol annelation, 272 Phenoxysulfonyl azide, 377-378 Phenylacetaldehyde, 217 Phenylacetylene, 7 2 (S)-3-Phenyl-1-butene, 36 Phenyl chlorothionocarbonate, 306-307 Phenyl cyanate, 307-308 Phenyldiazomethane, 308 o-Phenylene phosphorochloridate, 91-92 o-Phenylglydne methyl ester, 308 Phenyl isocyanate, 309 Phenyl isocyanide, 309-310 Phenyl iso thiocyanate, 122 Phenyllithium, 5... 

The coupling of o-bromobenzoic acid and phenols leads directly to annelated coumarins (75CJC343). The formation of a similar quantity of salicylic acid, formed through a competitive... 

The reaction of 2,2-dimethyl-4,6-dioxo-l,3-dioxane (Meldrum s acid 394) and its analogues with 3-dialkylaminophenols has been used to prepare some fluorescent 7-dialkylamino-4-hydroxycoumarins (Scheme 127) (77M499). The substituted malonic acid (395) or its dehydration product is a possible intermediate, since it is known that diaryl-malonic esters are accessible from phenols and the 1,3-dioxane. 3-Methoxyphenol yields the pyrano[3,2-c]benzopyran-2,5-dione (396) in this reaction, presumably by annelation of another ring on to initially formed 4-hydroxy-7-methoxycoumarin. 

Replacement of a further coordinated water molecule by the remaining phenolic oxygen atom in the azo compound gives a complex in which the metal atom is a member of two annelated chelate rings. Proton loss from the chelated azo compound, again promoted by the polarization associated with coordination to the positively charged metal ion, then leads to the 1 1 chromium complex (37). 

Fig (14) Olefin (107) has been converted to cyclic ether (114) by standard reactions. Its transformation to enone (115) is accomplished by annelation with methyl vinyl ketone and heating the resulting diketone with sodium hydride in dimethoxyethane. The ketoester (116) is subjected to Grignard reaction with methyllithium, aromatization and methylation to obtain the cyclic ether (117). Its transformation to phenolic ester (119) has been achieved by reduction, oxidation and esterification and deoxygenation. 

Thiation is used predominantly for the synthesis of annelated thiazoles (e.g., (109)—(111)) from heterocyclic acylamides bearing either adjacent phenol or halogen substituents (Equations (33)— (35)) (70KGS1624, 77KGS1495, 87KGS410). The thieno[3,2-c]isothiazolium perchlorate (113) was obtained from the 2-benzoyl-3-(phenylamino)thiophene (112) by sequential reaction with phosphorus pentasulfide and perchloric acid (Equation (36)) <77CJC1123>. 

When the annellated heteroaromatic group is a five-member ring (43, 44), the properties are best described as intermediate between a naphtho and benzopyran. The standard method of synthesis for diaryl naphthopyrans (acid-catalyzed condensation between a diaryl propargyl alcohol and a naphthol, Scheme 8) is reported not to work for heteroaromatic fused phenols. This is true especially in cases where the heteroaromatic phenol contains a (basic) nitrogen. Alternatively, these pyrans can be prepared by the method of Casiraghi69 outlined in Scheme 16. 

Alkynyl complexes. These complexes, which are readily available by reaction of an alkynyllithium with chromium carbonyl followed by methylation with CH3OSO2F, undergo facile Diels-Alder reactions with dienes to provide a general route to ,p-un-saturated chromium carbene complexes. The latter undergo benzannelation or cyclo-hexadienone annelation on reaction with an alkyne. A (trimethylsilyl)ethynyl complex is useful because benzannelation results in migration of silicon from carbon to oxygen to provide a protected phenol. 

The estimation of thebaine in the analysis of opium is described by Klyachkina [55] and Anneler [56], The alkaloid has been estimated in opium residues by condensation with benzoquinone, isolation of the very sparingly soluble adduct, and iodimetric titration of this in chloroform solution. This method is reported to be accurate to 0-5 per cent., provided resins, dyeing substances, and phenolic alkaloids are first removed [57]. Thebaine can also be estimated as its silicotungstate [53] or salicylate [54]. 

Intramolecular bis-alkyne annelations.2 A typical reaction of this type generally leads to a mixture of a phenol and a cyclohcxadicnone (equation I). However this annclation can be adapted to a construction of the steroid ring system by a... 

Fig. (16). The alcohol (171) was converted to the keto ether (185) applying the standard organic reactions and this on subjection to Robinson annelation. The resulting adduct on treatment with sodium methoxide in methanol afforded the tricyclic ketone (187) which is converted to another keto ether (188). It is converted to tertiary alcohol (189) by treatment with methyllithium. Acid treatment of the alcohol produced the phenol (190). Its methyl derivative (191) is converted to pisiferol (192) by treatment with zinc and zinc iodide. Its methyl derivative (193) was converted to ester (195) via oxidation, reduction, tosylation and detosylation. The reagents mentioned accomplished its conversion to pisiferic acid (196).

When reacting with l,2,4-triazin-5-ones 34, benzo-annelated crown ethers 40 and their open-chain analogs, the podands 42, behave like phenol ethers, thus yielding C-adducts 41 and 43 (Scheme 24) <2001H(55)2349>. 

In a similar fashion, compounds 34 react with benzo-annelated crown ethers, which contain the phenol moiety, to form adducts 41, which can be transformed into Sn products through elimination of aldehyde (see also Section 9.02.5.7.l(i)). Indeed, thermolysis of the a -adducts 41 affords l,2,4-triazin-5-ones 113 (Scheme 60) <2001H(55)2349>. Yields of 113 are poor, but can be improved when the reaction is carried out in an argon atmosphere <2001H(55)2349>. 

This reaction can also be used to obtain an annelated phenol 7. The reaction of 2 with 1 under a CO atmosphere provides the phenol 8 via a rhodacycle. 

The annelation of phenols with 2,3-epoxycycloalkanones via a Lewis acid-promoted intramolecular acylation-rearrangement of a lactone intermediate, e.g. (184), has been shown to give tricyclic benzofurans, e.g. (183), in excellent yields (Scheme 38). The methyl-substituted furan double bond in (183) is effectively a masked ketone carbonyl that is easily liberated by ozonolysis, producing the diketone (182). 

C-Acylation, intramolecular (s.a. 1,4-Addition-acylation, intramolecular Phenol ring annelation-acylation, -) -, -, asym. 44, 734 N-Acylation 43,197... 

The second communication of that year [24] is now cited more than 225 times, which also represents a remarkable number. This communication also comprised new reactivity patterns (Scheme 2). Based on the results from the first communication discussed above, a furan ring is formed from an allenyl ketone. Then the furanyne intermediate underwent a previously unknown transformation to an annelated phenol. Since they are easily accessible, furanynes can also be used directly. 

Benzisoxazoles.—The reaction of salicylaldehyde oxime with thionyl chloride in pyridine to yield 1,2-benzisoxazole (539 R = H) constitutes a new synthesis of this ring system.Thermolysis of the azido-ketone (540) affords the linearly annelated anthranil (541). ° The benzisoxazoles (539 R = H, Me, or Ph) rearrange photochemically to the benzoxazoles (543) via intermediate azirines (542). ° Irradiation of an aqueous solution of the benzisoxazolium salt (544) gives the phenolic ketone (545). ° ... 

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