Papers by Arifudidn Mohammed
A series of 4b-arylamino-4%-O-demethylepipodophyllotoxins and 4b-arylaminopodophyllotoxins have b... more A series of 4b-arylamino-4%-O-demethylepipodophyllotoxins and 4b-arylaminopodophyllotoxins have been synthesized with significant stereoselectivity and improved yields by employing the BF 3 ·OEt 2 /NaI reagent system. Compounds NPF, GL-331 and other DNA topoisomerase II inhibitors have been prepared in good to excellent yields by employing this methodology.
An improved protocol for the cleavage of epoxides with aromatic amines in the presence of FeCl 3 ... more An improved protocol for the cleavage of epoxides with aromatic amines in the presence of FeCl 3 promoted by ultrasonic irradiation. This new methodology provides excellent yields in short reaction times (15-25 min) at room temperature.
Aromatic compounds (phenols), when treated with Vilsmeier Haack (V-H) reagent in the presence of ... more Aromatic compounds (phenols), when treated with Vilsmeier Haack (V-H) reagent in the presence of transition metal ions such as Cu(II), Ni(II), Co(II), Cd(II), and Zn(II) under reflux conditions, afforded corresponding ortho-formyl derivatives in good yields. Under normal conditions the metal-ion-free V-H reactions are too sluggish and resulted in poor yields. This protocol provides highly regioselective formylation under a mild and efficient condition with simple workup.
Reaction of a variety of azido compounds with FeSO 4 ·7H 2 O/NH 3 results in quantitative yields ... more Reaction of a variety of azido compounds with FeSO 4 ·7H 2 O/NH 3 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.
Amines are efficiently protected as their BOC derivatives under mild reaction conditions when rea... more Amines are efficiently protected as their BOC derivatives under mild reaction conditions when reacted with BOC anhydride in presence of ZnCl 2 . The present method is applicable to a variety of amines including aliphatic, aromatic as well as heteroaromatic amines. This protocol appears to be competitive and in some cases superior to previously reported procedures that work under basic conditions.
Some new 4β-N-heteroaryl analogues of podophyllotoxin have been prepared by employing Red Phospho... more Some new 4β-N-heteroaryl analogues of podophyllotoxin have been prepared by employing Red Phosphorous/I 2 reagent system. These 4β-N-heteroaryl analogues have been evaluated for their cytotoxicity against six human cancer cell lines and some representative ones have shown promising anticancer activity.
A new and efficient method for the regeneration of carbonyl compounds from their N,N-dimethylhydr... more A new and efficient method for the regeneration of carbonyl compounds from their N,N-dimethylhydrazones has been carried out by employing transition metal complexes under mild conditions and different complexes have been examined for this regeneration process.
The Vilsmeier-Haack formylation reactions with hydrocarbons are sluggish in acetonitrile medium. ... more The Vilsmeier-Haack formylation reactions with hydrocarbons are sluggish in acetonitrile medium. The VH reactions follows second-order kinetics and affords formyl derivatives under kinetic conditions that are also irrespective of the nature of the oxychloride (POCl 3 or SOCl 2 ) used for the preparation of VH reagent along with DMF. However, the reactions undergo significant rate accelerations in the presence of transition metal ions such as Cu(II), Ni(II), Co(II) and Cd(II). Transition metal ion catalyzed VH formylation is explained through the formation of a mixed ligand complex of the [M(II)S(VHR)] type prior to the rate determining rearrangement step, before yielding formyl derivatives of hydrocarbons.
To determine analgesic and anti-inflammatory activity of a oily formulation containing camphor, m... more To determine analgesic and anti-inflammatory activity of a oily formulation containing camphor, menthol and thymol as ingredients in wistar albino mice and rats.
The reaction of 1, 2-phenylenediamine with aromatic aldehydes in the presence of ammonium molybda... more The reaction of 1, 2-phenylenediamine with aromatic aldehydes in the presence of ammonium molybdate and ultrasonically accelerated to produce selectively 2-aryl-1-(arylmethyl)-1-H-1.3-benzimidazoles in good yields. The reaction is very efficient and proceeds under mild reaction conditions giving rise to pure products without further purification.
A series of benzenesulfonamides incorporating 1,3,4-trisubstituted-b-lactam moieties was prepared... more A series of benzenesulfonamides incorporating 1,3,4-trisubstituted-b-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 K I s in the range of 7.3-917 nM; hCA II, an antiglaucoma drug target, with K I s in the range of 0.76-163 nM. hCA IV, an isoform involved in several pathological conditions such as glaucoma, retinitis pigmentosa and edema was potently inhibited by the lactam-sulfonamides, with K I s in the range of 0.53-51.0 nM, whereas hCA VII, a recently validated anti-neuropathic pain target was the most inhibited isoform by these derivatives, with K I s in the range of 0.68-9.1 nM. The structure-activity relationship for inhibiting these CAs with the new lactam-sulfonamides is discussed in detail.
A series of C-4-anilino-and C-4-imido-substituted new podophyllotoxin congeners have been designe... more A series of C-4-anilino-and C-4-imido-substituted new podophyllotoxin congeners have been designed, synthesized, and evaluated for their cytotoxicity and DNA topoisomerase-II (topo-II) inhibition potential. Some of these compounds have exhibited promising in vitro anticancer and topo-II inhibition activity.
Substituted aryl oxiranes undergo the facile ring opening with phenols in the presence of catalyt... more Substituted aryl oxiranes undergo the facile ring opening with phenols in the presence of catalytic amount of bismuth(III) triflate to afford 1,3-diaryloxy-2-propanols in excellent yields under mild conditions. Bismuth(III) triflate is relatively nontoxic, easy to handle and inexpensive, which makes this procedure particularly attractive for large scale synthesis.
—Two moieties of epipodophyllotoxin have been linked at C4-position to provide novel bisepipodoph... more —Two moieties of epipodophyllotoxin have been linked at C4-position to provide novel bisepipodophyllotoxin analogues. These have been evaluated for their anticancer potential and DNA–topoisomerase II poisoning activity. Most of these analogues have exhibited promising in vitro anticancer activity against different human tumour cell lines and interestingly 4 0-O-methylated analogues have shown increased cytotoxic activity. Similarly, the DNA–topo II poisoning activity tested for these compounds has not only exhibited the DNA cleavage potential comparable to etoposide, but for some compounds this cleavage potential is superior to etoposide. Further, an interesting structure–activity relationship of these epipodophyllotoxin dimers have been generated on the basis of GI 50 values. The equations indicated that GI 50 activity is strongly dependent on structural and thermodynamic properties. These QSAR results are discussed in conjunction with conformational analysis from molecular modelling studies. QSAR models developed in these studies will be helpful in the future to design novel potent bispodophyllotoxin analogues by minor structural modifications.
—The new 4b-amido analogues of podophyllotoxin or 4 0-O-demethylepipodophyllotoxin have been prep... more —The new 4b-amido analogues of podophyllotoxin or 4 0-O-demethylepipodophyllotoxin have been prepared either by the coupling of 4b-amino podophyllotoxin or 4b-amino-4 0-O-demethyl epipodophyllotoxin with the corresponding acids in presence of DCC in dichloromethane or by treating the appropriate acid chloride or sulphonyl chloride in presence of Et 3 N. These 4b-amido and 4b-sulphonamido derivatives of podophyllotoxin have been evaluated for their cytotoxicity against six human cancer cell lines. Some of these analogues have shown promising anticancer activity.
Graphical Abstract Purpose: To report a new and efficient method for the regeneration of carbonyl... more Graphical Abstract Purpose: To report a new and efficient method for the regeneration of carbonyl compounds from their oximes and phenylhydrazones by employing transition metal complexes under mild conditions. Methods: Different oxime and phenylhydrazone complexes have been examined for this regeneration process and found effective. Results: A new method for the cleavage of oximes and phenylhydrazone into their corresponding carbonyl compounds has been done successfully. Conclusion: The present method is of practical significance as it is rapid, high yielding, involves simple work-up under the very mild condition, and it applicable to both aldehydes and ketones. Thus, it is believed that the present method appears to be viable alternative to existing procedures.
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Papers by Arifudidn Mohammed