1. One-pot preparation of Oxazol-5(4H)-ones from amino acids in aqueous solvents
Hikaru Fujita, Munetaka Kunishima Chem Pharm Bull (Tokyo). 2012;60(7):907-12. doi: 10.1248/cpb.c12-00291.
A method for one-pot synthesis of oxazol-5(4H)-ones has been developed using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM), which is available for the activation of carboxylic acids in an aqueous solvent. The oxazolones were prepared by the N-acylation of amino acids with carboxylic acids and the subsequent cyclodehydration of the resulting N-acylamino acids by the addition of N,N-diethylaniline. Since both these reactions proceed effectively with the same coupling reagent, DMT-MM, in aqueous solvents, the procedure is simplified and becomes easy to perform. In addition, 5-(triazinyloxy)oxazole derivatives have been synthesized by controlling the basicity of the reaction system.
2. A one-flask synthesis of Weinreb amides from chiral and achiral carboxylic acids using the deoxo-fluor fluorinating reagent
A R Tunoori, J M White, G I Georg Org Lett. 2000 Dec 14;2(25):4091-3. doi: 10.1021/ol000318w.
[structure] The reagent [bis(2-methoxyethyl)amino]sulfur trifluoride (Deoxo-Fluor reagent) converts carboxylic acids to the corresponding acid fluorides, which then react with N,N-dimethylhydroxylamine to give the corresponding Weinreb amides in high yields. The reaction proceeds without racemization when optically active acids are used as the starting material. This method is operationally simple and provides the products in high purity.
3. Convenient one-pot synthesis of 2-oxazolines from carboxylic acids
Kazuhito Hioki, Yumiko Takechi, Noriyo Kimura, Hiroyuki Tanaka, Munetaka Kunishima Chem Pharm Bull (Tokyo). 2008 Dec;56(12):1735-7. doi: 10.1248/cpb.56.1735.
Simple one-pot methods for preparation of 2-oxazolines have been developed using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM). Treatment of a mixture of carboxylic acids and 2-haloethylammonium salts with DMT-MM in methanol followed by refluxing in the presence of KOH gives oxazolines.
