Structure-activity study of 5-substituted 1-carbobenzoxy-2-iminohydantoins as potential anticonvulsant agents

De novo design and synthesis of dipyridopurinone derivatives as visible-light photocatalysts in productive guanylation reactions

Described here is the de novo design and synthesis of a series of 6H-dipyrido[1,2-e:2',1'-i]purin-6-ones (DPs) as a new class of visible-light photoredox catalysts (PCs). The synthesized DP1-5 showed their λ _Abs(max) values in 433-477 nm, excited state redox potentials in 1.15-0.69 eV and -1.41 to -1.77 eV (vs. SCE), respectively. As a representative, DP4 enables the productive guanylation of various amines, including 1°, 2°, and 3°-alkyl primary amines, secondary amines, aryl and heteroaryl amines, amino-nitrile, amino acids and peptides as well as propynylamines and α-amino esters giving diversities in biologically important guanidines and cyclic guanidines. The photocatalytic efficacy of DP4 in the guanylation overmatched commonly used Ir and Ru polypyridyl complexes, and some organic PCs. Other salient merits of this method include broad substrate scope and functional group tolerance, gram-scale synthesis, and versatile late-stage derivatizations that led to a derivative 81 exhibiting 60-fold better anticancer activity against Ramos cells with the IC₅₀ of 0.086 μM than that of clinical drug ibrutinib (5.1 μM).

Designed Synthesis of Diversely Substituted Hydantoins and Hydantoin-Based Hybrid Molecules: A Personal Account

Hydantoin and its analogues such as thiohydantoin and iminohydantoin have received substantial attention from both a chemical and a biological point of view. Several compounds of this class have shown useful pharmacological activities such as anticonvulsant, antitumor, antiarrhythmic, and herbicidal properties that have led, in some cases, to clinical applications. Because of these broad-spectrum activities, intensive research efforts have been dedicated in industry and academia to the synthesis and structural modifications of hydantoin and its derivatives. Realizing the importance of hydantoin in organic and medicinal chemistry, we also initiated a research program that successfully designed and developed new routes and methods for the formation of hydantoin, thiohydantoin, and iminohydantoin substituted at various positions, particularly at the N-1 position without following a protection–deprotection strategy. Because combinations of two or more pharmacophoric groups can lead to hybrid molecules that display a mixed mechanism of action on biological targets, we extended our developed strategy to the syntheses of new types of hydantoin-based hybrid molecules by combining hydantoin with a triazole, isoxazoline, or phosphate scaffold as a second pharmacophore to exploit their diverse biological functions.

1 Introduction

2 Chemistry and Properties

2.1 Physical Properties

2.2 Chemical Properties

2.3 Biological Properties

3 General Synthetic Methods

4 Synthesis of Diversely Substituted Hydantoins

5 Synthesis of Diversely Substituted Thiohydantoins

6 Synthesis of Diversely Substituted Iminohydantoins

7 Fused or Bicyclic (Thio)hydantoins

8 Di- or Multivalent (Thio)hydantoins

9 Hydantoin-Based Hybrid Molecules

9.1 Hydantoin–Isooxazoline Hybrids

9.2 Hydantoin–Triazole Hybrids

9.3 Hydantoin–Phosphate Hybrids: Phosphorylated Hydantoins

10 Summary and Outlook

Hydantoin-bridged medium ring scaffolds by migratory insertion of urea-tethered nitrile anions into aromatic C-N bonds

Bicyclic or tricyclic nitrogen-containing heterocyclic scaffolds were constructed rapidly by intramolecular nucleophilic aromatic substitution of metallated nitriles tethered by a urea linkage to a series of electronically unactivated heterocyclic precursors. The substitution reaction constitutes a ring expansion, enabled by the conformationally constrained tether between the nitrile and the heterocycle. Attack of the metallated urea leaving group on the nitrile generates a hydantoin that bridges the polycyclic products. X-ray crystallography reveals ring-dependant strain within the hydantoin.

Synthesis and pharmacological evaluation of novel 1'-[2-(difluoromethoxy)benzyl]-2'H,5'H-spiro[8-azabicyclo[3.2.1]octane-3,4'-imidazolidine]-2',5'-diones and their derivatives

A series of novel 1'-[2-(difluoromethoxy)benzyl]-2'H,5'H-spiro[8-azabicyclo[3.2.1]octane-3,4'-imidazolidine]-2',5'-dione substituted hydantoins (5-32) were synthesized using an appropriate synthetic route and characterized by elemental analysis and spectral data. The novel molecules were screened for anticonvulsant activity in mice by maximal electroshock (MES) and subcutaneous pentylenetetrazol (ScPTZ)-induced seizure tests. The neurotoxicity was assessed using the rotarod method. Compounds 9, 10, 18, 30, and 31 exhibited anticonvulsant potency against MES seizure and in the ScPTZ model, with lesser neurotoxicity. Some title compounds showed lesser central nervous system depression compared to phenytoin.

Vibrational spectra and normal coordinate analysis of diazepam, phenytoin and phenobarbitone

Vibrational spectroscopy is an important tool for the structural investigation of the organic molecules. In the present investigation, a normal coordinate analysis has been carried out on some anti-epileptic drugs, viz. diazepam, phenytoin and phenobarbitone. Diazepam is a derivative of benzodiazepine, phenytoin is a derivative of hydanation and pheonobarbitone is a barbiturate. The infrared spectra of the compounds are recorded in the region 4000-400 cm(-1) and Raman spectra are recorded in the region 3500-50 cm(-1). From the structural point of view, diazepam, phenytoin and phenobarbitone have been assumed to C(s) point group. A systematic set of symmetry coordinates has been constructed for these compounds and Wilson's FG matrix method has been applied for the normal coordinate analysis using general quadratic valance force field. The potential energy distribution is also calculated to check the vibrational band assignments.

Synthesis of macrocyclic analogues of the neuroprotective agent glycyl-l-prolyl-l-glutamic acid (GPE)

The syntheses of seven macrocyclic analogues of the neuroprotective tripeptide glycyl-L-prolyl-L-glutamic acid (GPE) are described. Macrocycles 6 and 7 mimic the cis conformer of GPE whereas macrocycles 2-5, 8, and 9 mimic the trans conformer of GPE. The macrocyclic peptides of well-defined geometry were prepared via Grubbs ring closing metathesis of an appropriate diene precursor. In turn each of the diene precursors were prepared from the readily available allyl-substituted amino acid building blocks 12, 13, 14, 27, 36 and 51.

Synthesis of double headed imidazoline acyclo C-nucleosides: 1,4-bis[1-amino-5-oxo-4-substituted(imidazolin-2-yl)]galacto-tetritols

Condensation of 2,3,4,5-tetra-O-acetyl-galactaroyl dichloride (1) with two equivalents of the alpha-amino esters 2a-c gave the corresponding 2,3,4,5-tetra-O-acetyl-galactaric acid diamides 3a-c. Heterocyclization of 3a-c by heating with hydrazine hydrate took place with concomitant de-O-acetylation of the polyacetoxyalkyl chain to give 1,4-bis[1-amino-5-oxo-4-substituted(imidazolin-2-yl)] galacto-tetritols (5a-c) and not the theoretically possible 1,2,4-triazinones 4 as indicated by spectral data. Compounds 5a-c readily reacted with p-nitrobenzaldehyde to give the corresponding p-nitrobenzylideneamino derivatives 6a-c. Acetylation of 5a-c afforded the 2,3,4,5-tetra-O-acetyl-1,4-bis[1-acetamido-5-oxo-4-substituted(imidazolin-2-yl)]galacto-tetritols (7a,b,d). De-O-acetylation of 7a,b,d gave 1,4-bis[1-acetamido-5-oxo-4-substituted (imidazolin-2-yl)]galacto-tetritols (8a-c).