Aliphatic Carboxylic Anhydrides Research Articles

The synthesis of derivatives of tetra(hexa)hydro[1,2,3]triazolo-[4,5-e][1,4]diazepines and their acylation

Aim. To study the conditions for reduction of 5-hydroxy[1,2,3]triazolo[4,5-e][1,4]diazepines and develop the method for the synthesis of their tetra- and hexahydroderivatives.Results and discussion. It has been found that the functional hydroxy and carbonyl groups of 5-hydroxy[1,2,3]triazolo[4,5-e][1,4]diazepines tend to selective reduction with complex metal hydrides, and it has allowed to develop methods for the synthesis of their hydrogenated derivatives and to carry out the acylation of the diazepine cycle.Experimental part. The selective reduction of the hydroxy group was obtained by the interaction of 5-hydroxy[1,2,3]triazolo[4,5-e][1,4]diazepines with a 2-fold excess of NaBH4 in the boiling isopropanol. It allowed obtaining derivatives of tetrahydro[1,2,3]triazolo[4,5-e][1,4]diazepine-8(3H)-one with the yield of 61-82 %. The complete reduction of the diazepine cycle can be achieved only by using a 5-fold excess of LiAlH4-Me3SiCl hydration system and long-term boiling in THF. It has been shown that the tetrahydroderivatives synthesized with aliphatic carboxylic anhydrides are prone to selective acylation of the N4 diazepine ring atom, while hexahydroderivatives form a product of acetylation at N4 and N6 atoms.Conclusions. The conditions for the partial and complete reduction of 5-hydroxy[1,2,3]triazolo[4,5-e][1,4]diazepines have been found, convenient methods for the synthesis of tetrahydro- and hexahydroderivatives have been developed, and their directed functionalization by acyl groups has been performed.

Nickel-Catalyzed Decarboxylative Alkylation of Aryl Iodides with Anhydrides

We present the anhydride-based decarboxylative alkylation of aryl iodides catalyzed by nickel. This method of decarboxylative coupling works with a broad scope of aliphatic carboxylic anhydrides and tolerates synthetically useful aromatic substituents. Assisted by a redox system of pyridine N-oxide and zinc additives, the current reaction occurs under mild conditions and without the assistance of photocatalyst. Notably, this method features high chemoselectivity toward alkyl migration with mixed aliphatic/aromatic anhydrides. Thus, it provides a powerful synthetic tool to modify high-valued aliphatic carboxylic acids by converting them into mixed anhydrides using readily available aryl carboxylic acids such as p-toluic acid. We propose a catalytic cycle that involves the key steps of free radical-based decarboxylation and subsequent alkyl transfer to nickel that precedes an oxidatively induced C–C reductive elimination from Ni(III).

Kinetic Resolution of Racemic α-Arylalkanoic Acids with Achiral Alcohols via the Asymmetric Esterification Using Carboxylic Anhydrides and Acyl-Transfer Catalysts

A variety of optically active carboxylic esters are produced by the kinetic resolution of racemic alpha-substituted carboxylic acids using achiral alcohols, aromatic or aliphatic carboxylic anhydrides, and chiral acyl-transfer catalysts. The combination of 4-methoxybenzoic anhydride (PMBA) or pivalic anhydride with the modified benzotetramisole-type catalyst ((S)-beta-Np-BTM) is the most effective for promotion of the enantioselective coupling reaction between racemic carboxylic acids and a novel nucleophile, bis(alpha-naphthyl)methanol, to give the corresponding esters with high ee's. This protocol was successfully applied to the production of nonracemic nonsteroidal anti-inflammatory drugs from racemic compounds utilizing the transacylation process to generate the mixed anhydrides from the acid components with the suitable carboxylic anhydrides.

Friedel-Crafts Acylation of Aromatic Hydrocarbons Using Zeolites

A convenient heterogeneous catalytic methodology for Friedel-Crafts acylation of benzene and toluene using various aliphatic carboxylic anhydrides over zeolites at 250 °C is described. An interesting para selectivity is observed in the case of acylation of toluene over HZSM-5.

Electroreductive acylation of activated olefins using a reactive metal anode

Electroreductive acylation of 3-aryl substituted α,β-unsaturated esters and nitriles in the presence of aliphatic carboxylic anhydrides using areactive metal anode (Mg, Al, Zn) in an undivided cell afforded the corresponding β-acyl compounds in moderate to good yields. It was found that anionic species formed by electron transfer from a cathode may be stabilized by metal ions freshly formed from an anode and undergo electrophilic attack of carboxylic anhydrides to give the β-acyl products in high yields as compared with the previously reported method using a divided cell.

ChemInform Abstract: Formation of Cyanines from Pyrylium Salts and Aliphatic Carboxylic Anhydrides.

AbstractReaction of the pyrylium salts (I) with the carboxylic anhydrides (II) produces the cyanines (III).

ChemInform Abstract: Synthesis and Reactions of Benzo(b)furo(2,3‐c)pyrylium Salts.

AbstractCyclization of the acetonyl‐ and phenacylbenzofurans (I) with the aliphatic carboxylic anhydrides (II) in the presence of perchloric acid gives the pyrylium salts (III) which react with ammonia, producing the fused pyridines (IV).

Revisitation of the reaction between aniline and formaldehyde. VI. The accumulated amide ester function from Addition of Carboxylic Anhydrides to N‐methyleneamines or their trimers

AbstractSome aliphatic carboxylic anhydrides gave excellent yields of the novel addition products to both aliphatic and aromatic N‐methyleneimines, starting from their aliphatic and aromatic trimeric cyclic oligomers. A preliminary positive ion mass spectrometric study is here reported. They hydrolyze surprisingly faster than the corresponding acid amides, making necessary the intervention of a special mechanism. The reduction of the acetylamideester of cyclohexylmethyleneimine (3c) with LiAlH4 was also “abnormal”, as it yielded N‐methyl‐N‐ethylcyclohexylamine in quantitative yield.