Simple and Economical Process for Producing Amantadine Hydrochloride.

A simple and economical process for producing amantadine hydrochloride (1) on a 250 g scale, an antiviral and anti-Parkinson drug, has been developed. Several methods for the preparation of 1 through intermediate N-(1-adamantyl)-acetamide (4) in four or three steps were reported. These procedures started with adamantine (2) or 1-bromoadamantane (3), acetonitrile, and sulfuric acid by using the Ritter-type reaction to obtain N-(1-adamantyl)-acetamide, which was deacetylated to afford 1-amino-adamantane (5) and then the salt formed with anhydrous HCl gives 1 with the overall yield of 1 being 50-58%. In this article, a two-step procedure for the synthesis of 1 from 1-bromadamantane (3) and formamide via N-(1-adamantyl)-formamide (6) in two steps with an overall yield of 88% was reported. In this procedure, the preparation of 6 from 3 is a key step with a yield of 94%, followed by the hydrolysis of 6 with an aq. solution of HCl to give 1 in high yield (93%). The procedure was also carried out under optimal conditions established to reduce the use of toxic reagents or solvents and was carried out in one pot to make it more environmentally friendly. The procedure can be considered as more suitable for the large-scale production of 1. The structures of product 1 and intermediate 6 were confirmed by IR, MS, 1H NMR, 13C NMR.

A new method for synthesis of N,N-diethyl-m-methylbenzamide

RESUMEN Introducción: La N,N-dietil-m-metilbenzamida o N,N-dietil-m-toluamida (DEET), es muy conocida como repelente de insectos. Además, se utiliza para mejorar la administración dérmica y transdérmica de muchos fármacos. Objetivos: Presentar un procedimiento factible para sintetizar DEET a partir de ácido m-toluico y dietilamina. Métodos: El ácido m-toluico fue activado con 1,1'-carbonil-diimidazol, para obtener el producto intermedio 1- (m-toluoil) imidazol que continúa reaccionando con dietilamina, para producir DEET. De este modo, se mejoran los factores que afectan la síntesis de N, N-dietil-m-toluamida. Resultados: Se obtuvo DEET mediante un procedimiento óptimo. Los subproductos de la reacción son solubles en agua; se eliminan fácilmente mediante el método de extracción líquido-líquido con agua y diclorometano. La mayor parte del DEET obtenido tiene gran pureza. Los rendimientos fueron del 94 al 95 %. Conclusiones: Se ha proporcionado una ruta mejorada para una síntesis simple y eficaz de DEET a partir de ácido m-toluico y dietilamina en presencia de 1,1'-carbonil-diimidazol. El procedimiento de síntesis se realizó en un solo reactor y el aislamiento de DEET se logró mediante extracción líquido-líquido. El tiempo total de procedimiento se redujo significativamente. Este método de síntesis es fácilmente escalable y factible industrialmente.

ABSTRACT Introduction: N, N-diethyl-m-methylbenzamide or N, N-diethyl-m-toluamide (DEET), is well known as an insect repellent. In addition, it is used to improve the dermal and transdermal delivery of many drugs. Objectives: To present a feasible procedure to synthesize DEET from m-toluic acid and diethylamine. Methods: The m-toluic acid was activated with 1,1'-carbonyl-diimidazole, to obtain the intermediate product 1- (m-toluoyl) imidazole that continues to react with diethylamine, to produce DEET. In this way, the factors affecting the synthesis of N, N-diethyl-m-toluamide are improved. Results: DEET was obtained through an optimal procedure. The by-products of the reaction are soluble in water; they are easily removed by the liquid-liquid extraction method with water and dichloromethane. Most of the DEET obtained has high purity. The yields were 94 to 95 %. Conclusions: An improved route has been provided for a simple and efficient synthesis of DEET from m-toluic acid and diethylamine in the presence of 1,1'-carbonyl-diimidazole. The synthesis procedure was carried out in one-pot, and the isolation of DEET was achieved by liquid-liquid extraction. The total procedure time was significantly reduced. This synthesis method is easily scalable and industrially feasible.

Correction to "Simple Two-step Procedure for the Synthesis of Memantine Hydrochloride from 1,3-Dimethyl-adamantane".

[This corrects the article DOI: 10.1021/acsomega.0c01589.].

Simple Two-step Procedure for the Synthesis of Memantine Hydrochloride from 1,3-Dimethyl-adamantane.

Memantine hydrochloride is a medicine used for the treatment of Alzheimer's disease. A number of methods for the preparation of memantine hydrochloride have been reported. These procedures started from 1,3-dimethyl-adamantane by as many as using three or four reaction steps to produce memantine hydrochloride with overall yields ranging from 54 to 77%. In this article, a simple, concise two-step synthesis of memantine hydrochloride from 1,3-dimethyl-adamantane via N-formamido-3,5-dimethyl-adamantane with an improved overall yield of 83% was developed. In step 1, 3,5-dimethyl-adamantane was reacted with formamide and nitric acid to afford 1-formamido-3,5-dimethyl-adamantane in 98% yield, followed by hydrolysis of 1-formamido-3,5-dimethyl-adamantane with aq hydrochloride to give memantine hydrochloride in 85% yield. The procedure can be easily deployed at an industrial scale.

Synthesis and Bioactivity of Thiosemicarbazones Containing Adamantane Skeletons.

Reaction of 4-(1-adamantyl)-3-thiosemicarbazide (1) with numerous substituted acetophenones and benzaldehydes yielded the corresponding thiosemicarbazones containing adamantane skeletons. The synthesized compounds were evaluated for their in vitro activities against some Gram-positive and Gram-negative bacteria, and the fungus Candida albicans, and cytotoxicity against four cancer cell lines (Hep3B, HeLa, A549, and MCF-7). All of them showed good antifungal activity against Candida albicans. Compounds 2c, 2d, 2g, 2j and 3a, 3e, 3g displayed significant inhibitory activity against Enterococcus faecalis. Compounds 2a, 2e, 2h, 2k and 3j had moderate inhibitory potency against Staphylococcus aureus. Compounds 2a, 2e and 2g found so good inhibitory effect on Bacillus cereus. Compounds 2d and 2h, which contain (ortho) hydroxyl groups on the phenyl ring, were shown to be good candidates as potential agents for killing the tested cancer cell lines, i.e., Hep3B, A549, and MCF-7. Compounds 2a-c, 2f, 2g, 2j, 2k, 3g, and 3i were moderate inhibitors against MCF-7.

Synthesis and Bioactivity of Hydrazide-Hydrazones with the 1-Adamantyl-Carbonyl Moiety.

Reaction of 1-adamantyl carbohydrazide (1) with various substituted benzaldehydes and acetophenones yielded the corresponding hydrazide-hydrazones with a 1-adamantane carbonyl moiety. The new synthesized compounds were tested for activities against some Gram-negative and Gram-positive bacteria, and the fungus Candida albicans. Compounds 4a, 4b, 5a, and 5c displayed potential antibacterial activity against tested Gram-positive bacteria and C. albicans, while compounds 4e and 5e possessed cytotoxicity against tested human cancer cell lines.