645-36-3Relevant articles and documents
Synthesis of substituted anilinesviaa gold-catalyzed three-component reaction
Ueda, Hirofumi,Yamamoto, Ryota,Yamaguchi, Minami,Tokuyama, Hidetoshi
, p. 765 - 769 (2021/02/09)
A three-component reaction for the synthesis of substituted anilines by a gold(i)-catalyzed domino reaction was developed. Cationic gold catalysts selectively and sequentially activated two different alkynes, which were involved in pyrrole synthesis and subsequent Diels-Alder reaction. The sequential formal (3 + 2) annulation/Diels-Alder reaction of three components provided a variety of substituted anilines in a modular fashion. Moreover, utility of the aniline products was demonstrated by derivatization to substituted benzoxazines, which are pharmaceutically important heterocycles.
Les dialkoxy-2,2 ethanals, synthons difonctionnels a deux carbones : preparation par acetalisation du glyoxal et quelques applications en synthese
Stambouli, Abdelhamid,Hamedi-Sangsari, Farid,Amouroux, Roger,Chastrette, Francine,Blanc, Alain,Mattioda, Georges
, p. 95 - 100 (2007/10/02)
Known for a long time, 2,2-dialkoxy ethanals had to be prepare by rather tedious indirect pathways since monoacetalization of glyoxal was unknown.We discovered that it is possible to acetalize only one of the glyoxal functions using a great excess of alcohol, in the presence of an active enough catalyst.With careful monitoring of the reaction, 50 to 70 percent yield of monoacetals is obtained.The monoacetal is formed much quicker than the diacetal and the maximum yield is rather quickly obtained; with further elimination of water, diacetalization proceeds at the expense of the monoacetal.Depending on azeotropic compositions and boiling points, one of the following methods is used: 1.General method: 40 percent aqueous glyoxal (1 mol), alcohol (10 mol), catalyst (0.01 to 0.1 equivalent) and solvent are refluxed with azeotropic water extraction.The monitored (GC) reaction is stopped at the most favourable moment. 2.Method without solvent, convenient for unreactive alcohols, such as i-butanol: water is evaporated from glyoxal solution (1 mol); the residue, alcohol (10 mol) and catalyst are refluxed with water azeotropic extraction. 3.Method without solvent and without water azeotropic extraction: dehydrated glyoxal (1 mol) is refluxed with alcohol (10 mol) and catalyst.This method is the most convenient for methanol and ethanol.This sample and inexpensive preparation of 2,2-dialkoxy ethanals prompted us to perform syntheses of difunctional molecules otherwise only tediously accessible, since easily obtained functionalized acetals can be hydrolysed to functionalized aldehydes which constitute interesting synthons.Hydride or catalytic reduction as well as organometallic reactions lead to alcohols, further hydrolysed into 2-hydroxy aldehydes or oxidized to give way finally to α-ketoaldehydes for which this method provides a general synthetic pathway.From the oximes, prepared by classical methods, nitriles and amines can be obtained.Starting directly from the aldahydes, amines may be prepared by hydrogenation in the presence of ammonia or amines.The reaction of 2,2-dialkoxy ethanals with amides provides hydroxy and alkoxy acetal amides.The Cannizzaro reaction was also investigated; the same reactivity is displayed by formaldehyde and glyoxal monoacetals.Other reactions, among which Wittig and Wittig-Horner, are presently being studied in our laboratory.
THE CHEMICAL SIMULATION OF THE "ATP-IMIDAZOLE" CYCLE
Ranganathan, Darshan,Farooqui, Firdous,Bhattacharyya, Diphti,Mehrotra, Sanjiv,Kesavan, K.
, p. 4481 - 4492 (2007/10/02)
The synthetic strategy inherent in the "ATP-Imidazole" cycle and centred around the vicinal disposition of -NH2 and -CONH2 functions, has been demonstrated with anthranilamide (2) and 1-benzyl-5-aminoimidazole-4-carboxamide (1) as regeneratable carriers involving specifically N-alkylated quinazolin-4-ones, hypoxantines and adenines, as key intermediates.The isolation and characterization of the enamine (22) coupled with other observations has made it possible to rationalize the pathways involved in these cyclic operations.The practical utility of the synthetic strategy using regeneratable carriers has beem illustrated with the synthesis of a range of 1,5-disubstituted imidazoles.Whilst pathways leading to specific N-alkylation in the Natural cycle and in simulation studies are comparable, the subsequent events take place in a reverse order, primarily because of the divergence in the hydrolitic profile of the alkylated substrates.The action of dilute alkali on 3-alkylated quinazolin-4-ones leads to 2-3 rather than 3-4 bond rupture.Endeavours to promote the latter path, by blocking the 2 position gave unexpected results. 2-Methyl-3-phenacyl quinazolin-4-one gave with dilute alkali the novel aromatic tricyclic system (32) from trans-annular cyclization.On the other hand the 2-blocked 3-benzamido quinazolin-4-ones (33) and (34) gave triazoles (35) and (36) arising from the desired 3-4 rupture followed by cyclization initiated by the resulting amidine unit. 2-Phenil-3-benzamidoquinazolin-4-one (34) with distilled water at 200 deg C gave a number of products whicc have been identified and their formation explained.
Thiohemiacetal formation by inhibitory aldehydes at the active site of papain.
Lewis,Wolfenden
, p. 4890,4891 (2007/10/05)
Papain is strongly inhibited by aldehydes resembling carboxylic acids, released by hydrolysis of specific substrates (Westerik, J. O''C., and Wolfenden, R. (1972), J. Biol. Chem. 247, 8195-8197). Inhibitory complexes might involve binding of the aldehyde intact or as a covalent hydrate, or the aldehyde might undergo covalent addition of an active site sulfhydryl group to form a thiohemiacetal derivative. In an attempt to distinguish between these possibilities, benzamidoacetaldehyde-1-d has been synthesized, and its properties compared with those of the undeuterated inhibitor. After correction for differences in hydration, the observed effect on inhibition is found to be compatible with formation of a thiohemiacetal. In keeping with this conclusion, benzamidoethanol (a partial analogue of the covalent hydrate) and benzamide, N-methylbenzamide and N-ethylbenzamide (somewhat similar to the free aldehyde in size and hydrophobic character) are found to exhibit negligible affinity for the active site.
