Modification of natural coumarins reaction of khellactone esters with amines

The reaction of diesters of khellactone with primary and secondary amines under mild conditions has given derivatives of 4-aminodihydroseselin. Under more severe conditions, not only the replacement of a 4-acyloxy group by an amino group but also the opening of the lactone ring with the formation of the corresponding cinnamamide takes place. The ease of hydrolysis of the 3-acyloxy group and subsequent esterification of the alcohols formed and also the use of various amines makes it possible to obtain very diverse acyloxy and amino derivatives.All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 488–499, July–August, 1980.     

Influence of light on coumarins of the khellactone group

Summary The results of experiments on the UV irradiation of six coumarins and the study of the products formed have shown that acylated derivatives of khellactone undergo photolysis with the successive splitting out of acyl residues at C₄, and then at C₃, followed by the dehydration of the resulting diol and the formation of 3-hydroxyseselin. The hypothesis has been put forward that dihydrocoumarins containing a more voluminous substituent in the 4 position are the most sensitive to light.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 614–617, September–October, 1973.     

The aminoethanolysis reaction of khellactone derivatives

Summary 1. The aminoethanolysis of diesters of khellactone has been investigated and the methods of obtaining water-soluble amino derivatives of khellactone has been developed.2. The sequence of occurrence of the reactions has been studied, and three substances have been obtained and characterized.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 462–466, July–August, 1975.     

The preparation of aromatic amidino esters and their reaction with primary amines

A series of aromatic amidino esters were prepared from the respective anthranilic acids by reaction with DMF acetal. These amidino esters were then condensed with a variety of primary amines to give the corresponding 3-substituted quinazolin-4-ones. Based on substituent effects, and the application of acid catalysis, a unifying mechanism is proposed.     

Reactions of some pyranylidene esters with amines

The reactions of 4-(2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-ylidene)-2,6-diphenyl-4H-pyran ( 1 ) with primary amines gave the corresponding 1-substituted 1,4-dihydropyridine derivatives. The related benzo derivative of 1 (12) and primary amines gave 3-substituted 3,4-dihydro-2-phenyl-5H-[1]benzopyrano[3,4-c] pyridine-4,5-dione derivatives. With secondary amines, 12 gave 2-phenyl-4H,5H-pyrano[3,4-c] [1]benzopyrane-4,5-dione, and with isopropylamine, N,N-dimethylhydra-zine, and methanolic potassium hydroxide, 12 gave 4-phenacylcoumarin. Some reaction intermediates were isolated which indicate probable reaction paths. The reactions with amines were extended to a naphtho derivative of 1 (19) and to a thia homolog of 12 (24).     

Mass-spectrometric investigation of natural coumarins

Summary The mass spectra of coumarin, umbelliferone, herniarin, and ostol have been studied.     

A copper-catalyzed Petasis reaction for the synthesis of tertiary amines and amino esters

We have developed a copper-catalyzed process for the coupling of aldehydes, amines, and boronic acids. This allows greater reactivity with simple aryl boronic acids and allows coupling reactions to proceed that previously failed. Initial mechanistic studies support a process involving transmetalation from boron to copper.     

General molecular weight-lowering side reaction in the thermal condensation of aromatic methyl esters with aromatic amines and hydrazides

The direct thermal condensation of aromatic methyl esters with aromatic amines and hydrazides was studied. Using model compounds, it was learned that N-methylation of amines (both aromatic and aliphatic) and hydrazides is inherent at temperatures required for condensation polymerization. This side reaction prevents attainment of high molecular weight polyamides, polyhydrazides, or polyoxadiazoles from the corresponding difunctional aromatic monomers by heat alone. Reported catalysts for the condensation reaction do not prevent the side reaction.     

Study of natural coumarins by mass spectroscopy

Conclusions The mass spectra of six compounds have been obtained: kamolone, kamolol, [D₃]kamolone, [D]kamolol, kamolol acetate, and the terpene diol derived from kamolol. The fragmentation of these compounds under the action of electron impact have been discussed. The mass spectra of kamolone and kamolol agree well with the structures provided for them previously.Khimiya Prirodnykh Soedinenii, Vol. 6, No. 3, pp. 296–300, 1970     

The transformation products of some natural coumarins

Summary Products of the reactions of natural coumarins have been studied for the first time: the products of the reaction of osthole with a mixture of concentrated acetic and hydrochloric acid, of oxypeucedanin hydrate with acetone and thionyl chloride, and of decursinol with chromium trioxide. A total of eight new compounds not previously described in the literature has been obtained.The structures of seven of the substances have been established on the basis of their IR, PMR, and mass spectra and chemical reactions.Leningrad Sanitary-Hygienic Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 562–566, September–October, 1978.     

Platinum/scandium-cocatalyzed cascade cyclization and ring-opening reaction of tertiary amines with substituted salicylaldehydes to synthesize 3-(aminoalkyl)coumarins

The synthesis of 3-(aminoalkyl)coumarins starting with a platinum/scandium-cocatalyzed oxidative dehydrogenation of α,β-C(sp(3))-H bonds of tertiary amines in the presence of ambient oxygen followed by reactions with substituted salicylaldehydes is revealed. The in situ formed enamines reacted with various salicylaldehydes, which resulted in the development of a one-pot synthetic protocol involving aldol reaction, cyclization, and then ring-opening.     

The reaction of pentachloropyridine with aromatic amines

The reaction of pentachloropyridine with aromatic amines in dimethylformamide in the presence of sodium carbonate leads to 4-arylaminotetrachloropyridines. The product of the reaction of pentachloropyridine with aniline in pyridine is 4-amino-2,3,5,6-tetrachloropyridine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 7, pp. 963–965, July, 1970.