7134-09-0Relevant academic research and scientific papers
Cornforth and Corey-Suggs reagents as efficient catalysts for sulfonation of aromatic and heteroaromatic compounds using NaHSO3 under solvent free and microwave conditions
Fatima, Touheeth,Duguta, Govardhan,Purugula, Venkanna,Yelike, Hemanth Sriram,Kamatala, Chinna Rajanna
, p. 1001 - 1006 (2020/07/27)
Cornforth and Corey-Suggs reagents Pyridinium Dichromate (PDC) and Pyridinium Chlorochromate (PCC) were explored as efficient catalysts for sulfonation of aromatic and heteroaromatic compounds using NaHSO3 in aqueous acetonitrile medium at room temperature within 1–4 h, while microwave assisted reactions took place within 1–4 min under solvent-free conditions. These observations indicate significant rate accelerations in microwave assisted reactions. which were explained due to the bulk activation of molecules induced by insitu generated high temperatures and pressures when microwaves are transmitted through reaction medium.
METHOD AND COMPOSITIONS FOR TREATING HIV INFECTIONS
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Page/Page column 43, (2008/12/08)
Described herein are compounds and compositions that are useful in the treatment of HIV, AIDS, and AIDS-related diseases. In addition, compounds are described herein that are capable of inhibiting the dimerization of HIV proteases.
DPPH (=2,2-diphenyl-1-picrylhydrazyl) radical-scavenging reaction of protocatechuic acid (=3,4-dihydroxybenzoic acid): Difference in reactivity between acids and their esters
Saito, Shizuka,Kawabata, Jun
, p. 1395 - 1407 (2007/10/03)
Prolocatechuic acid (=3,4-dihydroxybenzoic acid; 1) exhibits a significantly slow DPPH (=2,2-diphenyl-1-picrylhydrazyl) radical-scavenging reaction compared to its esters in alcoholic solvents. The present study is aimed at the elucidation of the difference between the radical-scavenging mechanisms of protocatechuic acid and its esters in alcohol. Both protocatechuic acid (1) and its methyl ester 2 rapidly scavenged 2 equiv. of radical and were converted to the corresponding o-quinone structures 1a and 2a, respectively (Scheme). Then, a regeneration of catechol (=benzene-1,2-diol) structures occurred via a nucleophilic addition of a MeOH molecule to the o-quinones to yield alcohol adducts 1f and 2c, respectively, which can scavenge additional 2 equiv. of radical. However, the reaction of protocatechuic acid (1) beyond the formation of the o-quinone was much slower than that of its methyl ester 2. The results suggest that the slower radical-scavenging reaction of 1 compared to its esters is due to a dissociation of the electron-withdrawing carboxylic acid function to the electron-donating carboxylate ion, which decreases the electrophilicity of the o-quinone, leading to a lower susceptibility towards a nucleophilic attack by an alcohol molecule.
Reactions of the dihydroxybenzenes and their methyl ethers with sulfur trioxide. The effect of initial sulfation on the sulfonation product distribution
Cerfontain, Hans,Coenjaarts, Norbert J.,Koeberg-Telder, Ankie
, p. 7 - 13 (2007/10/02)
The sulfation and sulfonation resulting from the reaction of the dihydroxybenzenes and their mono- and dimethyl ethers with SO3 in nitromethane have been studied, and their product distributions are reported.As to the non-hydroxy-substituent-containing substrates, 1,2-dimethoxybenzene (3) yields the 4-sulfonic acid (3-4-S) which, upon further sulfonation, yields a 1:4 mixture of the 3,5- and 4,5-S2.The 1,3- (6) and 1,4-isomer (9) yield initially the 4- and 2-S, respectively, and subsequently exclusively 6-4,6- and 9-2,5-S2, respectively.With the substrates containing one hydroxy substituent, the sulfonation isomer distribution is dependent on the SO3 to substrate ratio if the OH and OMe substituents are in ortho or para orientation, due to increasing sulfonation of the corresponding methoxyphenyl hydrogen sulfate.Thus, 2-methoxy- (2) and 4-methoxyphenol (8) with one equiv of SO3 at 0 deg C yield a 3:1 mixture of 2-4-S and 2-5-S and a 9:1 mixture of 8-2-S and 8-3-S, respectively, but, with >/= 4 equiv of SO3, the former reactant yields only 2-5-S and the latter only 8-3-S. 3-Methoxyphenol (5) yields initially a 1:1 mixture of the 4- and 6-sulfonic acid.Further sulfonation yields only 5-O,4,6-S3 which slowly cyclizes to the 1,3,2,4-benzodioxadithiin 2,2,4,4-tetraoxide derivative 11.As to the dihydroxy-containing substrates, 1,2-dihydroxybenzene (1) with 1 equiv of SO3 first yields the hydrogen sulfate 1-O-S which rearranges to 1-4-S; on using an excess of SO3, the eventual product is 1-O(2),4-S2.Similarly, the 1,4-isomer (7) with 1 equiv of SO3 yields initially 7-O-S which isomerizes to 7-2-S.With 6 equiv of SO3, initially 7-O,O-S2 is formed and subsequently its 2-sulfonic acid, which eventually cyclizes slowly to the 1,3,2,4-benzodioxadithiin 2,2,4,4-tetraoxide derivative 12.The 1,3-isomer 4 with 1 equiv of SO3 yields the 4-sulfonic acid.With 4 equiv of SO3, initially 4-O,O-S2 is formed and subsequently 4-4,O,O-S3, which is converted into both 4-O,O,4,6-S4 and the cyclization product 10.Eventually, small amounts of 4-O,2,4,6-S4 and 14-2,6-S2 are formed by transsulfonation.
Sulfonation and sulfation on reaction of 1,2-dihydroxybenzene and its methyl ethers in concentrated aqueous sulfuric acid
Cerfontain, Hans,Coenjaarts, Norbert J.,Koeberg-Telder, Ankie
, p. 325 - 330 (2007/10/02)
The homogeneous sulfonation of 1,2-dihydroxybenzene (1), its monomethyl (2) and dimethyl ether (3) in concentrated aqueous sulfuric acid at 25 deg C has been studied and isomer distributions, as well as rate coefficients for the sulfonation of 1-3 and their monosulfonic acids, have been determined.In 73.5-87.5percent H2SO4, 1 yields the 3- and 4-sulfonic acids in a ratio of 25:75, 2 yields the 4-, 5- and 6-sulfonic acids in a ratio of 46:36:18 in 73.5percent H2SO4 and 50:39:11 in 87.5percent H2SO4, whereas 3 yields only the 4-sulfonic acid.The remarkable absence of the 3-sulfonic acid (87.5percent H2SO4, the 4-sulfonic acid of 1 and the 5-sulfonic acid of 2 are present in part in the form of their hydrogen sulfate.In that acid region, the 3- and 4-sulfonic acids of 1 both yield the 3,5-disulfonic acid, the 4- and 6-sulfonic acids of 2 both yield the 4,6-disulfonic acid and the 4-sulfonic acid of 3 mainly yields the 4,6- together with some 4,5-disulfonic acid.
Antihypertensive 4-amino-2-[4-(1,4-benzodioxan-2-carbonyl) piperazin-1-yl or homopiperazin-1-yl]quinazolines
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, (2008/06/13)
Compounds having the formula STR1 and pharmaceutically acceptable salts thereof wherein R represents 6,7-di(lower alkoxy) or 6,7,8-tri(lower alkoxy); m is 1 or 2, X is --CHR1 -- or --CH2 CH2 --; each R1 and R0 may be the same or different and is hydrogen or lower alkyl; each of R2 and R3 is hydrogen, lower alkoxy, lower alkyl, halogen, lower alkanoyl, lower alkoxycarbonyl, --CONR4 R5 or --SO2 NR4 R5 wherein each of R4 and R5 is hydrogen or lower alkyl; processes for their preparation; and their use as regulators of the cardiovascular system, and particularly in the treatment of hypertension.
