Heterocycle acylation

So-called aryl values have been introduced by Imoto et ai. - for the piu pose of systematizing the reactivities of different aromatic systems by means of the linear free-energy relationship, which however, could not be applied to the decomposition rates of heterocyclic acyl azides in toluene. ... 

Professor D Auria (Basilicata University) summarizes the photochemical isomerization of pentaatomic heterocycles, providing a unified description in terms of the five conceivable mechanisms. R. Alan Aitken and Andrew W. Thomas of the University of St. Andrews, Scotland, summarize the substantial recent progress in heterocyclic acyl and formyl anion equivalents. 

MISCELLANEOUS FIVE-MEMBERED HETEROCYCLES Acylation with 3-chloropropionyl chloride of the... 

Heterocycle Acyl chloride Methoda Yield of Reissert compound (%)... 

Direct thiation is used predominantly for the synthesis of annelated thiazoles, most often from heterocyclic acyl-amides. Examples are highlighted in CHEC-II(1996) <1996CHEC-II(7)49> no further examples have been reported in this period. 

Review papers have covered (81RCR336 84KGS579) the field of rotational isomerism in carbonyl-containing derivatives of five-membered aromatic heterocycles. This article aims to report a critical account of the results appearing in the literature concerning conformational information on heterocyclic acyl derivatives. 

Zhao and co-workers43 have described a method which utilises heterocyclic acyl hy-drazides and heterocyclic 1,2-diketones to afford 1,2,4 triazines. The resulting triazines were obtained in low yields, even under solvent-free microwave conditions. By adopting the conventional thermal conditions, for example, using acetic acid as the solvent instead under microwave heating conditions at 180°C for 5 min (60°C above the boiling point for acetic acid), high yields (75-92%) of the products were obtained, Scheme 5.25. 

Several aromatic and heterocyclic acyl trimethylsilanes have been used as acyl anion equivalents by treatment with fluoride ion (Scheme 81, path a)23 133 154b160191192. Provided that the acyl substituent is electron-withdrawing, and that there are no aryl substituents on the silicon atom, acyl anions can be trapped by various electrophiles in moderate to good yields indeed, acyl anions and pentacoordinate silicon anionic species have both been detected in gas-phase reactions of acyl silanes with fluoride ion193. 

Aitken, A. R., Thomas, A. W., Heterocyclic Acyl and Formyl Anion Equivalents, 79,89. 

Heterocyclic betaine derivatives of alternant hydrocarbons, 26, 1 Heterocyclic acyl and formyl anion equivalents, 79, 89 Heterocyclic betaines pyridinium... 

This naphthalene synthesis has several attractive features. The intermediate or-ganometallics need not be isolated it is regiospecific and aliphatic, aromatic, or heterocyclic acyl groups can be introduced efficiently. 

Five- to seven-membered O-, N-, and S-heterocycles Acyl ylides with a tethered terminal ester function requisite for the construction of five- to seven-membered heterocycles are very conveniently accessible by reaction of the cumulated ylide ketenylidenetriphenylphosphorane 11 with various carboxylic esters bearing OH-, NHR-, and SH-groups in a-, -, or y-position. 

Natural heterocyclic -acyl acrylates, synthesis of 86YGK819. 

Heterocyclic acyl and formyl anion equivalents 01AHC(79)89. 

Table 4.10 Heterocycle acylation with AAN in the presence of BEA zeolite...

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