Solid-phase synthesis of 1,3-dialkyl quinazoline-2,4-diones

Design and Molecular Docking Studies of Some 2,3 Di-Substituted Quinazolin-4-One Analogues Against Staphylococcus aureus UDG

BACKGROUND

In this present investigation, some 2, 3 disubstituted-quinazolin-4-one derivatives are designed and docked against chain A and chain B of (3WDF) receptor.

METHODS

The heterocyclic fused rings quinazolinone have drawn a great attention owing to their expanded applications in the field of pharmaceutical chemistry. The diverse range of molecules with quinazoline/quinazolinone moieties have been reported to exhibit a broad spectrum of biological activities.

RESULTS

The results designate that the quinazolinone ring forms hydrophobic and hydrogen bond contacts with ASN 127 A, ALA 126 A, and SER 83 B, SER 183 B amino acid residue.

CONCLUSION

Molecular docking is safe and straightforward to use tool which facilitates in investigating, interpreting, enplaning and identification of molecular properties using 3D structures.

Efficient solid-phase synthesis of 3-substituted-5-oxo-5H-thiazolo[2,3-b]-quinazoline-8-carboxamides under mild conditions with two diversity positions

Highly efficient solid-phase synthesis of thiazolo[2,3,b]quinazolines under mild conditions was developed using resin-bound 2-amino-terephthalamic acid, Fmoc-NCS, and bromoketones. Primary amines immobilized to an acid-cleavable backbone amide linker were acylated with 1-methyl-2-aminoterephtalate. Following cleavage of the methyl ester, Fmoc-NCS was used to form a resin-bound thiourea. Bromoketones were subsequently added to form an aminothiazole ring and the cyclization was performed using DIC/HOBt to afford thiazolo[2,3,b]quinazolines. Highly efficient solid-phase synthesis is amenable to high throughput/combinatorial synthesis.

Studies on quinazolines. 11. Intramolecular imidate-amide rearrangement of 2-substituted 4-(omega-chloroalkoxy)quinazoline derivatives. 1,3 -O --> N shift of chloroalkyl groups via cyclic 1,3-azaoxonium intermediates

The omega-chloroalkylation of 2-substituted quinazolin-4(3H)-one derivatives 1 and 2 with Br-(CH(2))(n)-Cl (n = 2-4) and the intramolecular imidate-amide rearrangement of the alkylated products are described. At room temperature, the 2-phenyl substituent promoted O-alkylation, whereas the less steric 2-benzyl group led to a higher ratio of N-alkylation. The investigation of the O-alkylated products, 4-omega-chloroalkoxyquinazolines, revealed that the migration of omega-chloroethyl and omega-chloropropyl groups from oxygen to nitrogen should be intramolecular via five- and six-membered cyclic 1,3-azaoxonium intermediates, respectively. Competition between rearrangement and nucleophilic substitution results in the formation of 7a,b and 8a,b from the nucleophilic substitution of 4a,b and 6a,b, respectively.

Efficient synthesis of 2,4-disubstituted 1,2,4-benzothiadiazin-3-one 1,1-dioxides on solid support

The first solid-phase synthesis of 1,2,4-benzothiadiazin-3-one 1,1-dioxides has been developed. Synthesis of the title compounds was achieved by the reduction of 2-nitrobenzenesulfonamides, followed by cyclization with carbonyldiimidazole. Because 1,2,4-benzothiadiazin-3-one 1,1-dioxides have been known to possess various bioactivities, this method is useful from the viewpoint of new drug discovery. In addition to the excellent purity of the title compounds, a large number of compounds can be synthesized with this method, because this synthesis includes four diversity points.

Solid-phase combinatorial synthesis and cytotoxicity of 3-aryl-2,4-quinazolindiones

A series of 3-aryl-2,4-quinazolinediones with various substitution on aromatic rings has been prepared by solid-phase synthesis. Several compounds showed cytotoxicity on human colon carcinoma (Col2) tested by SRB method.

Combinatorial chemistry as a tool for drug discovery

The question 'will combinatorial chemistry deliver real medicines' has been posed [96]. First it is important to realise that the chemical part of the drug discovery process cannot stand alone; the integration of synthesis and biological assays is fundamental to the combinatorial approach. The results presented in Tables 3.1 to 3.8 suggest that so far smaller directed combinatorial libraries have obtained equivalent results to those obtained previously from traditional medicinal chemistry analogue programs. Unfortunately, because of the long time it takes to develop pharmaceutical drugs there are no examples yet of marketed drugs discovered by combinatorial methods. There are interesting examples where active leads have been discovered from the screening of the same library against multiple targets (e.g. libraries 13, 39, 43, 66, 71 and 76). It is now possible to handle much larger libraries of non-oligomeric structures and the chemistry required for such applications is becoming available. Whether combinatorial approaches can also be adapted to deal with all the other requirements of a successful pharmaceutical (lack of toxicity, bioavailability etc.) is open to question but there are already examples such as cassette dosing [235-237]. However we can still be optimistic about the possibility of larger libraries producing avenues of investigation for the medicinal chemist to develop into real drugs. Combinatorial chemistry is an important tool for the medicinal chemist.

Palladium-catalyzed cyclocarbonylation of o-iodoanilines with heterocumulenes: regioselective preparation of 4(3H)-quinazolinone derivatives

A catalyst system comprising palladium acetate-bidentate phosphine is effective for the cyclocarbonylation of o-iodoanilines with heterocumulenes at 70-100 degrees C for 12-24 h to give the corresponding 4(3H)-quinazolinone derivatives in good yields. Utilizing o-iodoaniline with isocyanates, carbodiimides, and ketenimines for the reaction, 2,4-(1H,3H)-quinazolinediones, 2-amino-4(3H)-quinazolinones and 2-alkyl-4(3H)-quinazolinones were obtained, respectively. The nature of the substrates including the electrophilicity of the carbon center of the carbodiimide, and the stability of the ketenimine, influence the product yields of this reaction. Urea-type intermediates are believed to be generated first in situ from the reaction of o-iodoanilines with heterocumulenes, followed by palladium-catalyzed carbonylation and cyclization to yield the products.

Solid-phase synthesis of phenolic steroids: from optimization studies to a convenient procedure for combinatorial synthesis of biologically relevant estradiol derivatives

During the course of our studies on therapeutic agents for the treatment of breast cancer, we became interested in the solid-phase combinatorial synthesis of estradiol derivatives that contain a functionalized side chain at either position 16 beta or 7 alpha. Both types of compounds have already demonstrated inhibitory activity toward both biosynthesis and action of estradiol. As a first step, two versatile precursors bearing an azidoalkyl side chain at either position 16 beta or 7 alpha of estradiol were synthesized using standard solution-phase methods. Afterward, the effectiveness of five linkers to attach the phenolic function of these estradiol derivatives to a polystyrene resin was investigated; they were benzylic ether (Merrifield), 4-alkoxy-benzylic ethers (Wang, Sheppard), tetrahydropyranyl ether (Ellman), benzoic ester, and o-nitrobenzyl ether. To test the linker in a synthetic context, a short sequence of reactions, including reduction of the azide and acylation of the corresponding amine, was performed on the polymer-bound estradiol derivative. While all of the tested linkers proved effective in attaching the phenol functionality of the precursor, only the o-nitrobenzyl ether photolabile linker enabled the release of the final products in acceptable purities. Consequently, this linker was used to perform successfully the solid-phase synthesis of four different classes of estradiol derivatives in acceptable yields and excellent purities. This study was preliminary to the combinatorial synthesis of larger libraries of biologically relevant estradiol derivatives.

Combinatorial approaches to harmacophoric heterocycles: A solid-phase synthesis of 3,1-benzoxazine-4-ones

An efficient solid-phase synthesis of 3,1-benzoxazine-4-ones is described. Immobilized amino acid based functionalized urea derivatives 2 undergo a high yielding heterocyclization under mild conditions in presence of coupling reagents (DIC, TsCl/Py, or Ac2O) to afford 3,1-benzoxazine-4-ones 6. The method offers broad scope for structural and chemical diversity, and is amenable for combinatorial synthesis of 3,1-benzoxazine-4-ones libraries with potential for discovery of novel serine protease inhibitors. Copyright 1998 John Wiley & Sons, Inc.

Solid phase synthesis of benzylamine-derived sulfonamide library

Using solid phase synthesis, a library has been constructed of benzylamine-derived sulfonamides which have strong inhibitory activity against the blood coagulant thrombin. The library compounds were obtained in good yield and high purity; four of these thrombin inhibitors showed nanomolar potency (Ki 600-10 nM).