The multicomponent reaction between 2-naphthol, arylaldehydes and ammonia yields aminobenzylnaphthols in a process known as the Betti reaction, which was first uncovered at the beginning of the 20th century.
Abstract:The acid-catalyzed cyclocondensation of N,N'-bisaryl (aryl = 2-pyrimidinyl, 2-pyrazinyl and 4-nitrophenyl) methanediamines 5a-c with aqueous formaldehyde in refluxing acetonitrile leads to the formation of the corresponding 1,3,5-triaryl-1,3,5-hexahydrotriazines 6a-c. The stoichiometric reactions of 2-aminopyrimidine and 2-aminopyrazine with aqueous formaldehyde in acetonitrile under reflux conditions also afforded 6a and 6b, respectively. Treatment of 2-aminopyrimidine with aqueous formaldehyde in a 3:2 ratio yielded N,N',N"-tris(2-pyrimidinyl)dimethylenetriamine (7a) as a sole product, which upon subsequent reaction with formaldehyde also afforded 6a. The reaction of N,N'-biphenylmethanediamine with formaldehyde was also investigated.
A simple and efficient synthesis of novel 6,6′‐(arylmethylene)bis(benzo[a]phenazin‐5‐ol) derivatives has been developed via a sequential one‐pot, two‐step, pseudo‐five‐component tandem reaction starting from 2‐hydroxynaphthalene‐1,4‐dione, o‐phenylenediamine, and aromatic aldehydes in the presence of 2‐aminopyridine as co‐catalyst and p‐TsOH as catalyst at 90°C under solvent‐free conditions. This sequential green process offers several advantages, such as operational simplicity, high yield, low cost, easy handling, clean reactions, absence of any tedious work‐up, and purification of products by non‐chromatographic methods.
An efficient synthetic procedure for the preparation of novel (E)‐3‐(3,8a‐dihydro‐2H‐oxazolo[3,2‐a]pyridin‐2‐ylidene)chroman‐2‐one derivatives was developed. A sequential one‐pot, two‐step tandem reaction starting from 3‐(2‐bromoacetyl)‐2H‐chromen‐2‐one derivatives synthesized, pyridine, and naphthols in the presence of triethylamine proceeded smoothly in acetonitrile under reflux conditions. In this process, 2‐oxo‐2H‐chromen‐3‐yl)ethyl)pyridinium bromide derivatives as intermediate produced in situ, followed by Michael addition of naphthoxide anion and intramolecular cylization, resulted the corresponding products in good to high yields. All of the compounds were obtained in high purity without any use of more purification.
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