Anhydrides, as acylating agents

Silica sol-gel inunobihzed La(OTf)3 (Scheme 48.2B) previously used in the acylation of a series of alcohols and activated aromatic compounds using acetic anhydride as acylating agent, showed a poor activity compared with other various sihca sol-gel inunobihzed triflate derivatives (tert-butyl-dimethylsilyl-trifluoromethane-sulfonate (BDMST), or trifhc acid (HOTf)). Acylation at the aromatic ring occurred over the BDMST and HOTf catalysts, while the La(OTl)3 catalysts only led to O-acetylated products [22]. Such behavior is characteristic... 

The typical reaction with benzoic anhydride as acylating agent was carried out as follows a solution of 20 mmol of aromatic substrate in 50 ml dry chlorobenzene were introduced in the flask and magnetically stirred under nitrogen atmosphere. 

Tables 14.1 and 14.2 show the dramatic improvement brought by the substitution of the old technology with AICI3 catalyst and acetylchloride as acylating agent in a batch reactor by the new technology with a HBEA zeolite catalyst, acetic anhydride as acylating agent in a fixed bed reactor (12). The fixed bed reactor process constitutes a major break-through in anisole acetylation.

The reaction was carried out at 100°C with sulpholane as solvent and acetic anhydride as acylating agent [9]. The results conversion of 2MN and the ratio of the two ketone products, l-acetyl-2-methoxynaphthalene (lAC) over 2-acetyl-6-methoxy-naphthalene (2AC), are given in Table 2. The selectivity for the two products was better than 95% in all cases. 

Diethyl benzoylmalonate has been prepared by treatment of the copper derivative of ethyl benzoylacetate with ethyl chlorocarbonate.9 It has also been obtained by the action of benzoyl chloride on a mixture of malonic ester and sodium ethoxide 1benzoyl chloride and the ethoxymagnesium derivative.14 The present method has been described in a previous communication and is of interest as an illustration of the use of mixed carbonic anhydrides as acylating agents.8... 

Mixed esters of hydrolysed starch have been prepared in pyridine using anhydrides as acylating agents. The mixed esters are hydrophobic and organic-soluble, but may be readily solubilized in aqueous base through the half-ester groups. The solutions show surface activity which varies according to the type and extent of substitution. 

There is only one example of trifluoroacylation in the series of benzoindolizines. 3-Perfluoroacyl derivatives 15 and 16 were obtained in high yield [12] using trifluo-roacetic and perfluorosuccinic anhydride as acylating agents. 

Ethyl chloroformate/triethylamine Carboxylic alkoxyformic anhydrides as acylating agents... 

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