Reactions of Arynes

A Diels-Alder reaction of arynes with 1,2,4-triazines 102 allows the preparation of isoquinolines substituted with electron-withdrawing groups in the nitrogen-containing ring. The isoquinoline-1-carboxylic esters bearing additional substituents are of particular interest because they are not readily available by the usual routes [100,101] (Scheme 2.42). 

Grushin VV, Alper H (1999) Activation of Otherwise Unreactive C-Cl Bonds. 3 193-225 Guitian E, Perez D, Pena D (2005) Palladium-Catalyzed Cycloaddition Reactions of Arynes. 14 109-146... 

The availability of the tetrahalogenoanthranilic acids, in particular tetrachloroanthranilic acid, suggested that an investigation of reactions with carbonyl compounds would be worthwhile. The reactions of arynes... 

In a study of the formation and reactions of arynes at high temperatures. Fields and Meyerson plyrolyzed a thiophene solution of phthalic anhydride at 690° by mass spectrometry and gas chromatography they found benzene, naphthalene, benzo[b]thiophene, phenylthiophenes, bithienyls, thienothiophene 1, and naphthothiophene in the pyrolysis products. Pyrolysis of thiophene itself produced benzo-[Z lthiophene, thienothiophene 1, phenylthiophene, and bithienyl. The... 

As mentioned in the introductory section, arynes behave as soft acids . Therefore, the relative reactivity of a nucleophile should be governed by basicity as well as polarizability. The following gradations, established through competitive reactions of arynes with different nucleophiles, are more or less in line with this expectation.1 (i) BuLi > PhSLi > PhNMeLi > PhGaCLi > ROLi > ArOLi, for 9,10-phe-nanthryne in ether (ii) PhS- > Ph3C > PhC=C > enolates > PhO- > RO" > I, CN, for benzyne in liquid ammonia (iii) I- > Br > Cl- > EtOH for benzyne in alcohol. 

There has been a summary of the use of insertion reactions of arynes into a-bonds to prepare nrt/io-disubs tituted arenes. A key to the success of these processes is the ability to generate benzyne under mild conditions by the reaction of readily available o-(trimethylsilyl)phenyl triflate with fluoride ions.61 Reaction of amines and their derivatives with benzynes generated in this way has been shown to be an efficient method for the production of N-arylated derivatives, as illustrated in Scheme 8. The method also works well in the O-arylation reactions of phenols and carboxylic acids 62... 

Two different carbon functional groups can be introduced simultaneously into 1,2-positions of aromatic skeletons based on a novel insertion reaction of arynes (101) into a carbonyl-cyanomethyl a-bond of a-cyanocarbonyl compounds (102) to produce 1,2-disubstituted aromatics (103).134... 

Mechanisms, reaction, use of volumes of activation for determining, 2, 93 Mechanisms of formation and reactions of arynes at high temperatures, 6, 1 Mechanisms of reactions in solution, entropies of activation and, 1, 1 Mechanistic studies, heat capacities of activation and their uses in, 5, 121 Meisenheimer complexes, 7, 211... 

MECHANISMS OF FORMATION AND REACTIONS OF ARYNES AT HIGH TEMPERATURES... 

The major products from the reaction of arynes with thiophene and benzothiophene by addition and insertion are shown in Table 11. Benzyne from phthalic anhydride reacted with thiophene at 690° to give naphthalene and benzothiophene by 1,4-addition and loss of sulfur, and by 1,2-addition and loss of acetylene, respectively, as well as phenyl-thiophene by insertion (Fields and Meyerson, 1966d, 1967e) (Scheme 19). The ratio of naphthalene to benzothiophene was about 9 1, nearly the same preference for 1,4-over 1,2-addition as was inferred from the reaction of benzyne with dichlorobenzenes and pyridine at the same temperature, and again reflects the strong tendency of benzyne to act as a dienophile. 

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