Acylation and sulfonylation

Nevertheless, they are stable to standard work-up and purification methods. The benzenesulfonyl group can be introduced using base and an aprotic solvent[3] or under phase transfer conditions[4], Table 9.2 gives some representative examples of acylation and sulfonylations. 

Indole (10mmol) was added to dry CH3CN (20 ml) and the mixture stirred while DMAP (122 mg, 1,00 mmol) and di-tert-butyl dicarbonate (2.62 g. 12 mmol) were added. Evolution of gas was noted and stirring was continued 

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4 1-Phenylsulfonyl CgHjSOjCl, benzene, 50% NaOH, (C4H9)4N+HS04-(10mol%) 96 m 

Takechi, M. Machida and Y. Kanaoka, Chem. Pharm. Bull. 36, 3770 (1988). 

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The 4-piperazinyl nitrogen in pipemidic acid (69) has been alkylated, acylated and sulfonylated in the search for enhanced antibacterial activity, whilst the 3-pyrrolidinyl position in piromidic acid (68) is hydroxylated metabolically and enzymically to (74) (75MI21503), from which acyloxy derivatives have been prepared. 

Although the chemical shifts of most commonly encountered orga-nofluorine compounds are upheld of CFC13 and thus have negative values, there are a number of structural situations for fluorine that lead to positive chemical shifts (downfield from CFC13). These include acyl and sulfonyl fluorides as well as the fluorines of SF5 substituents. 

Friedel-Crafts (FC) alkylation, acylation, and sulfonylation reactions are important C-C or C-S bond forming reactions in organic chemistry [60-64], Since the seminal works of Charles Friedel and James Mason Crafts published in 1877 in which they report the use of A1C13 for alkylation reactions [65], the search for more active catalysts, especially for acylation reactions, continues. Due to increasing environmental concerns, the need for green catalysts and processes for the FC reaction has gained significant importance. Bi(III) salts have shown to be efficient and recoverable catalysts with applicability in this area [13]. 

Other reactions have been studied for synthesizing these polymers, including the electrophilic aromatic substitution of acyl and sulfonyl halides on aromatic reactants and the nickel-catalyzed aromatic coupling of aromatic dihalides [Yonezawa et al., 2000]. 

Although pyrrole is much less acidic than phenol (pAT ca. 10), many reactions of the pyrrole anion are reminiscent of those of the phenolate anion. Examples include A-alkylation, -acylation and -sulfonylation (Scheme 6.9). For the phenolate anion these reactions occur at oxygen. 

A -Aminopyrimidinones and quinazolinones can be acylated and sulfonylated to give amide and sulfonamide derivatives, and also reacted with isocyanates to give ureas, and with aldehydes and ketones to give imines. They can also participate in cyclization reactions to form fused pyrimidine heterocycles. 

While the use of acyl and sulfonyl protecting groups led to mediocre yield, masking of the nitrogen in the form of a carbamate led to improved yields.15... 

Aminoethanol Derivatives, Proposed by E. von Hert for use as/or in ex pis included among other compds the acyl- and sulfonyl-derivs of nitrated aminoethanol. As an example of an acyl derivative may be cited the compd,[OaNO CHa CHa N(NOa )CO]a, mp 88°, prepd by the condensation of HO ... 

Acyl and sulfonyl halides and anhydrides react instantaneously with pyridine to form quaternary salts which are excellent acylating and sulfonylating agents. The familiar use of pyridine as a solvent in such reactions reflects this. While usually used in situ, stable A-acylpyridinium and N-acylisoquinolinium salts, e.g. (63), have been isolated and their structures confirmed by single crystal... 

Whereas aryl, acyl, and sulfonyl azides decompose in the presence of aluminum trichloride in benzene solution only with evolution of N , alkyl azides also split oif significant amounts of N,-.1 -18 At 50° alkylbenzenes and azomethines are obtained. In order to explain these results, Kreher and Jager suggested that two intermediate complexes may be formed (Scheme IV). According to Goubeau, Allenstein, and... 

Two modes of dimerization of the 2-alkyl-6-methyl-4//-l,3-thiazine-4-one (249) have been observed (83CC56). One mode gave the linearly combined dimer 250, and the other led to a spiro compound (251). The structure of one of the spiro compounds was confirmed by X-ray crystallography (Scheme 101). The reactions occurred when the 2-alkyl group was methyl, ethyl, or n-propyl, but not when it was isopropyl. 4-Acyloxy-and 4-p-tosyloxy-l,3-thiazine-6-ones (253) have been prepared by acylation and sulfonylation starting from thiazine-4,6-diones (252), in a solvent, at temperatures from room temperature to reflux (Scheme 102) (79KGS44). 

Synthesis of heterocycles, from acyl and sulfonyl isocyanates ... 

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