M. Arifuddin

An efficient reduction of azides to amines: synthesis of DNA interactive pyrrolo(2,1-c)(1,4)benzodiazepines †

Abstract Reaction of a variety of azido compounds with FeSO4·7H2O/NH3 results in quantitative yields of the corresponding amino compounds. This reductive methodology has been extended towards the synthesis of pyrrolo[2,1-c][1,4]benzodiazepine antibiotics.

Enantioselective ring opening of epoxides with trimethylsilyl azide (TMSN3) in the presence of β-cyclodextrin: an efficient route to 1,2-azido alcohols

Abstract The ring opening of epoxides with nucleophiles such as TMSN 3 and isopropylamine takes place enantioselectively in the presence of β-cyclodextrin under extremely mild conditions and the azido alcohols and amino alcohols are formed as ( S )-isomers.

Improved Efficient Conversion of Aldehydes to Nitriles via Their N, N-Dimethyl Hydrazones

Abstract Aldehyde N, N-dimethylhydrazones undergoes facile oxidative cleavage to nitriles on reaction with DMS and K2CO3 in quantitative yields. Nitriles can also be easily obtained in high yields in a “one-pot” process starting from the corresponding aldehydes.

Discovery of 4-sulfamoyl-phenyl-β-lactams as a new class of potent carbonic anhydrase isoforms I, II, IV and VII inhibitors: The first example of subnanomolar CA IV inhibitors

A series of benzenesulfonamides incorporating 1,3,4-trisubstituted-β-lactam moieties was prepared from sulfanilamide Schiff bases and in situ obtained ketenes, by using the Staudinger cycloaddition reaction. The new compounds were assayed as inhibitors of four human isoforms of the metalloenzyme carbonic anhydrase (hCA, EC 4.2.1.1) involved in various physiological/pathological conditions, hCA I, II, IV and VII. Excellent inhibitory activity was observed against all these isoforms, as follows: hCA I, involved in some eye diseases was inhibited with KIs in the range of 7.3-917nM; hCA II, an antiglaucoma drug target, with KIs in the range of 0.76-163nM. hCA IV, an isoform involved in several pathological conditions such as glaucoma, retinitis pigmentosa and edema was potently inhibited by the lactam-sulfonamides, with KIs in the range of 0.53-51.0nM, whereas hCA VII, a recently validated anti-neuropathic pain target was the most inhibited isoform by these derivatives, with KIs in the range of 0.68-9.1nM. The structure-activity relationship for inhibiting these CAs with the new lactam-sulfonamides is discussed in detail.

FACILE TRANSFORMATION OF N, N-DIMETHYLHYDRAZONES AND TOSYLHYDRAZONES TO KETONES WITH DIMETHYL SULFATE AND POTASSIUM CARBONATE

Abstract N,N-Dimethylhydrazones and tosylhydrazones can be converted to their ketones in good to excellent yields with dimethylsulfate and K2CO3.

Sulfocoumarin-, Coumarin-, 4-Sulfamoylphenyl-Bearing Indazole-3-carboxamide Hybrids: Synthesis and Selective Inhibition of Tumor-Associated Carbonic Anhydrase Isozymes IX and XII

A series of sulfocoumarin‐, coumarin‐, and 4‐sulfamoylphenyl‐bearing indazole‐3‐carboxamide hybrids were synthesized and investigated as inhibitors of the human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms I and II (cytosolic isozymes), as well as hCA IX and XII (transmembrane, tumor‐associated enzymes). Compounds 6 a–g (amide derivatives) and 7 a–h (triazoles) act as “prodrugs”, and their hydrolysis products are the de facto CA inhibitors. These compounds displayed sub‐micromolar to high‐nanomolar inhibitory activity against hCA isoforms IX and XII, which were recently validated as antitumor drug targets. Moreover, no inhibition of the off‐target hCA I and II isoforms was observed. Compounds 8 a–f (another set of triazoles) exhibited nanomolar inhibition against hCA isoforms I, II, IX and XII, among which compounds 8 c, 8 d, and 8 f were found to inhibit the tumor‐associated hypoxia‐induced hCA isoform IX with Ki values of 1.8, 2.3, and 2.0 nm respectively. Further exploration of these compounds could be useful for the development of novel antitumor agents with selective mechanisms of CA inhibitory action.

Discovery of curcumin inspired sulfonamide derivatives as a new class of carbonic anhydrase isoforms I, II, IX, and XII inhibitors

Abstract A series of curcumin inspired sulfonamide derivatives was prepared from various chalcones and 4-sulfamoyl benzaldehyde via Claisen–Schmidt condensation. All new compounds were assayed as inhibitors of four human isoforms of the metalloenzyme carbonic anhydrase (hCA, EC 4.2.1.1) isoforms hCA I, II, IX and XII. Interesting inhibitory activities were observed against all these isoforms. hCA I, an isoform involved in several eye diseases was inhibited moderately with KIs in the range of 191.8–904.2 nM, hCA II, an antiglaucoma drug target was highly inhibited by the new sulfonamides, with KIs in the range of 0.75–8.8 nM. hCA IX, a tumor-associated isoform involved in cancer progression and metastatic spread was potently inhibited by the new sulfonamides, with KIs in the range of 2.3–87.3 nM, whereas hCA XII, and antiglaucoma and anticancer drug target, was inhibited with KIs in the range of 6.1–71.8 nM. It is noteworthy that one of the new compounds, 5d, was found to be almost 9 times more selective against hCA II (KI = 0.89 nM) over hCA IX and hCA XII, whereas 5e was 3 and 70 times more selective against hCA II (KI = 0.75 nM) over hCA IX and hCA XII, respectively.

Development of sulfonamides incorporating phenylacrylamido functionalities as carbonic anhydrase isoforms I, II, IX and XII inhibitors

A series of novel sulfonamides incorporating phenylacrylamido functionalities were synthesized and investigated for the inhibition of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). The physiologically and pharmacologically relevant human (h) isoforms hCA I and II (cytosolic isozymes), as well as the transmembrane tumor-associated hCA IX and XII were included in the study. These compounds showed low nanomolar or sub-nanomolar inhibition constants against hCA II (KIs in the range of 0.50-50.5nM), hCA IX (KIs of 1.8-228.5nM), and hCA XII (KIs of 3.5-96.2nM) being less effective as inhibitors of the off target isoform hCA I. A detailed structure-activity relationship study demonstrates that the nature and position of substituents present on the aromatic part of the scaffold strongly influence the inhibition of CA isoforms. As hCA II, IX and XII are involved in pathologies such as glaucoma and hypoxic, and metastatic tumors, compounds of the type reported in this work may be useful preclinical candidates.

Iodine-mediated one-pot intramolecular decarboxylation domino reaction for accessing functionalised 2-(1,3,4-oxadiazol-2-yl)anilines with carbonic anhydrase inhibitory action

Abstract A practical and transition metal-free one-pot domino synthesis of diversified (1,3,4-oxadiazol-2-yl)anilines has been developed employing isatins and hydrazides as the starting materials, in the presence of molecular iodine. The prominent feature of this domino process involves consecutive condensation, hydrolytic ring cleavage, and an intramolecular decarboxylation, in a one-pot process that leads to the oxidative formation of a C–O bond. Fluorescence properties of some of the representative molecules obtained in this way were studied. The synthesised 2-(1,3,4-oxadiazolo-2-yl)aniline-benzene sulphonamides (8a–o) were screened for their carbonic anhydrase (CA, EC 4.2.1.1) inhibitory activity. Most of the compounds exhibited low micromolar to nanomolar activity against human (h) isoforms hCA I, hCA II, hCA IV, and XII, with some compounds displaying selective CA inhibitory activity towards hCA II with KIs of 6.4–17.6 nM.

Synthesis and Biological Evaluation of 4-sulfamoylphenyl/sulfocoumarin carboxamides as selective inhibitors of carbonic anhydrase isoforms hCA II, IX and XII

With the aim to develop potent and selective human carbonic anhydrase inhibitors (hCAIs), we synthesized 4‐sulfamoylphenyl/sulfocoumarin benzamides (series 5 a–r and series 7 a–q) and evaluated their inhibition profiles against five isoforms of the zinc‐containing human carbonic anhydrase (hCA, EC 4.2.1.1): cytosolic hCA I and II, and the transmembrane isozymes hCA IV, IX, and XII. Compounds 5 a–r were found to selectively inhibit hCA II in the nanomolar range, while being less effective against the other hCA isoforms. As noted from the literature, sulfocoumarin (1,2‐benzoxathiine 2,2‐dioxide) acts as a “prodrug” inhibitor and is hydrolyzed by the esterase activity of hCA to form 2‐hydroxyphenylvinylsulfonic acid, which thereafter binds to the enzyme in a manner similar to that of coumarins and sulfoxocoumarins. All these sulfocoumarins (compounds 7 a–q) were found to be very weak or ineffective as inhibitors of the housekeeping off‐target hCA isoforms I and II, and effectively inhibited the transmembrane tumor‐associated isoforms IX and XII in the high nanomolar to micromolar ranges. Further structural modifications of these molecules could be useful for the development of effective hCA inhibitors used for the treatment of glaucoma, epilepsy, and cancer.