Self aryl-groups

The highly evolved catalyst 20 combines several features that have proved successful in simpler cases. The ionic sulfonate groups make the substrate sufficiently soluble for the reaction to be run in water. (The four hydrophilic cyclodextrins perform the same service for the catalyst.) The target reaction, the seledive oxidation of the steroid skeleton, goes back to the early days of enzyme models,1711 and the choice of porphyrin and of manganese as the metal cation are based on many years experience. The aryl groups are perfluorinated because an earlier version of the catalyst suffered self-oxidation. 

Self-coupling of aryl groups when cross-couphng is very slow [77, 78, 79]... 

Two syntheses involving cycloaddition reactions were the self-condensation of N-aryltrichloroacetimido chlorides, in the presence of antimony pentachloride, which gave 45-63% yields of 3-aryl-2,4-6wtrichloromethyl-3,4-dihydroquinazolines, and the dimerization of A-aryl dialkylketen-imines (71). The imines 71, in the latter reaction, required a temperature of 125°C for several days to give the 4-methylene-3,4-dihydroquinazolines (72) in ca. 50% yields. Quinazolines could not be formed in this reaction when both the ortho positions of the A-aryl group were substituted. 

In a detailed study, Ikeda et al. reported that a zincporphyrin bearing a pyrazol-4-yl group in the 5-position and an ort/zo-ethoxycarbonylphenyl group in the 15-position, self-assembles into the cyclic trimer 26 (meso-aryl groups omitted) in CH2CI2 with a stability constant iCsa = 6.0 x 10 moH P... 

In recent years, there has been a considerable effort to expand the range of iodonium salts that can be employed as photoinitiators for cationic polymerizations. Stable iodonium salts can be obtained when one of the aryl groups in 51 is replaced by a moiety that can provide resonance stabilization to the positively charged iodine atom. For example, Koser et prepared stable aryl (phenyl ethynyl)iodonium salts, 55, that were shown by Kitamura et al. and by Hofer and Liska to exhibit good activity as cationic photoinitiators. Similarly, iodonium salts, 56, in which the positively charged iodine atom is attached to the central carbon of a resonance-stabilized 1,3-diketone moiety such as dimedone are also isolable compounds that display the ability to serve as photoinitiators for cationic polymerization. Finally, it has been reported that diaryl(oxo)iodonium salts, 57, can be readily prepared by the base-catalyzed self-condensation of diaryliodyl compounds. Replacement of the initial... 

The name adopted for this group of highly reactive (and in some circumstances intramolecularly self-reactive) compounds is intended to cover both arylmetal halides (halogen bonded to the metal) and haloaryl metals (halogen attached to the aryl nucleus). Individually indexed compounds are ... 

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