Novel method for preparation of poly(benzoxazinone‐imide)

A novel method was developed to prepare poly(benzoxazinone‐imide) by the dealcoholization of poly(amide‐imide), having pendent ethoxycarbonyl groups, which was prepared from poly(amide acid). The poly(amide acid) was prepared from the reaction of pyromellitic dianhydride and 4,4′‐diamino‐6‐ethoxycarbonyl benzanilide. The curing behavior of the poly(amide acid) was monitored by DSC, which indicated the presence of two broad endotherms, one with maximum at 153 °C due to imide‐ring formation and the other with maximum at 359 °C due to benzoxazinone‐ring formation. The poly(amide acid) was thermally treated at 300 °C/1 h to get poly(amide‐imide) with pendent ester groups, then at 350 °C/2 h to convert into poly(benzoxazinone‐imide) by dealcoholization. Viscoelastic measurements of the poly(amide‐imide) showed that the storage modulus dropped at about 280 °C with glass‐transition temperature (T_g ) at about 340 °C. The storage modulus of poly(benzoxazinone‐imide), however, was almost constant up to 400 °C and no T_g was detected below 400 °C. Also, the tensile modulus and tensile strength of the poly(benzoxazinone‐imide) was much higher than that of the poly(amide‐imide). The 5% decomposition of poly(benzoxazinone‐imide) film was at 535 °C, which reflects its excellent thermal stability. Also, poly(benzoxazinone‐imide) showed more hydrolytic stability against alkali in comparison to polyimides. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1647–1655, 2000     

Discovery of a potent,non-peptide bradykinin B1 receptor antagonist

Bradykinin (BK) plays an important role in the pathophysiological processes accompanying pain and inflammation. Selective bradykinin B1 receptor antagonists have been shown to be anti-nociceptive in animal models and could be novel therapeutic agents for the treatment of pain and inflammation. We have explored chemical modifications in a series of dihydroquinoxalinone sulfonamides to evaluate the effects of various structural changes on biological activity. The optimization of a screening lead compound, facilitated by a homology model of the BK B1 receptor, culminated in the discovery of a potent human BK B1 receptor antagonist. Results from site-directed mutagenesis studies and experiments in an animal pain model are presented.     

Discovery of a PCAF Bromodomain Chemical Probe

The p300/CBP‐associated factor (PCAF) and related GCN5 bromodomain‐containing lysine acetyl transferases are members of subfamily I of the bromodomain phylogenetic tree. Iterative cycles of rational inhibitor design and biophysical characterization led to the discovery of the triazolopthalazine‐based L‐45 (dubbed L‐Moses ) as the first potent, selective, and cell‐active PCAF bromodomain (Brd) inhibitor. Synthesis from readily available (1R,2S)‐(−)‐norephedrine furnished L‐45 in enantiopure form. L‐45 was shown to disrupt PCAF‐Brd histone H3.3 interaction in cells using a nanoBRET assay, and a co‐crystal structure of L‐45 with the homologous Brd PfGCN5 from Plasmodium falciparum rationalizes the high selectivity for PCAF and GCN5 bromodomains. Compound L‐45 shows no observable cytotoxicity in peripheral blood mononuclear cells (PBMC), good cell‐permeability, and metabolic stability in human and mouse liver microsomes, supporting its potential for in vivo use.     

Synthesis of novel heterocycles with antimicrobial and surface activity

A new series of anionic surfactants with dual type of activity antimicrobial and surface activity have been synthesized by reaction of 4H‐3,1‐benzoxazinone 3 and quinazolinethione 10 with nitrogen nucleophiles and activated olefinic compounds. The compounds were evaluated for their surface activity as well as their antimicrobial and biodegradability properties.     

Synthesis of Heterocycles Having Double Characters: As Antimicrobial and Surface Active Agents

A new series of anionic surfactants having double function as antimicrobial and surface active agents have been synthesized by reaction of 4(H)‐3,1‐benzoxazinone 3 and quinazolinethione 10 with nitrogen nucleophiles and activated olefinic compounds. The compounds were evaluated for their surface activity as well as the antimicrobial and biodegradability properties.     

6,7‐Dimethoxy‐quinazolin‐4‐yl‐amino‐thiophene‐2‐carboxamides as Potent Inhibitors of VEGF Receptors 1 and 2

The identification of agents with antiproliferative activity against endothelial cells has significant value for the treatment of many angiogenesis‐dependent pathologies. The vascular endothelial growth factor (VEGF) and its receptors have been implicated as key factors in tumor angiogenesis and are major targets in cancer therapy. A series of novel 6,7‐dimethoxy‐quinazolin‐4‐yl‐amino‐thiophene‐2‐carboxamides were synthesized and evaluated as antagonists of VEGFR‐1 and VEGFR‐2. More specifically, several analogues exhibited low micromolar to nanomolar potency in the inhibition of VEGFR‐1 and VEGFR‐2. The most potent compound in this series, compound 7b , was found to be a potent inhibitor of VEGFR‐2 in a homogeneous time‐resolved fluorescence enzymatic assay with an IC₅₀ as low as 87 nm.     

A Chemical Probe for the ATAD2 Bromodomain

ATAD2 is a cancer‐associated protein whose bromodomain has been described as among the least druggable of that target class. Starting from a potent lead, permeability and selectivity were improved through a dual approach: 1) using CF₂ as a sulfone bio‐isostere to exploit the unique properties of fluorine, and 2) using 1,3‐interactions to control the conformation of a piperidine ring. This resulted in the first reported low‐nanomolar, selective and cell permeable chemical probe for ATAD2.     

Design and Synthesis of Novel EGFR Inhibitors with L‐Rhamnose–Benzoxazinone Hybrids

Four L ‐rhamnose–benzoxazinone compounds as epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors were designed and synthesized. All structures of the compounds were characterized by ¹H‐NMR, ¹³C‐NMR, and high‐resolution mass spectrometry. The inhibition activities of the target compounds for the EGFR tyrosine kinase activity in vitro were determined. Compounds 6a , 6b , 6c , 6d displayed moderate activity in targeting EGFR.     

Regiospecific Isomerization of 2‐Benzoxazinon‐2‐yl Benzoic Acid Toward Some Nitrogen Nucleophiles as Environmental Insecticide

Based on the strategies of receptor structure‐guided benzoxazinone design, a series of nitrogen nucleophiles such as benzyl amine, sodium azide, 4,4‐bis o‐toluidine, 4‐butanolamine, glucosamine, 2‐amino pyridine, 2‐picolinyl amine, hydroxyl amine, and hydrazine derivatives, for example, hydrazine hydrate, semicarbazide, thiosemicarbazide, methylhydrazide, phenylhydrazide, could be reacted with 2‐benzoxazine‐2‐yl benzoic acid 1 . According the basicity of nucleophiles, regiospecific isomerization of benzoxazinone has been considered through formation of the spiro derivatives. Organic reagents can be controlled on the course of reaction of benzoxazinonyl benzoic acid 1 . Preliminary bioassays indicated that the insecticidal spectra of the synthesized compounds were ecofriendly biodegradable materials due to isomerization. Among these analogues, the quinazoline 2 – 4 showed 100% mortality against Nilaparvata lugens (LC₅₀ = 0.087 mg/L). The insecticidal potency of our designed analogues was dual‐controlled by isomerization to quinazolinone and spiro derivatives that observed in vitro and shed light on the novel insecticidal mechanism. The chemical structure of the products can be confirmed by microanalytical, spectral data, optimized and stimulated by quantum chemical parameters.     

Probing BRD Inhibition Substituent Effects in Bulky Analogues of (+)-JQ1

A series of bulky organometallic and organic analogues of the bromodomain (BRD) inhibitor (+)-JQ1 have been prepared. The most potent, N-[(adamantan-1-yl)methyl]-2-[(9S)-7-(4-chlorophenyl)-4,5,13-trimethyl-3-thia-1,8,11,12-tetraazatricyclo[8.3.0.02,6]trideca-2(6),4,7,10,12-pentaen-9-yl]acetamide, 2e , showed excellent potency with an K_D=ca. 130 nm vs. BRD4(1) and a ca. 2-fold selectivity over BRD4(2) (K_D=ca. 260 nm ). Its binding to the first bromodomain of BRD4 was determined by a protein cocrystal structure.     

Ring Opening of 2‐(Benzylamino)‐2H‐1,4‐benzoxazin‐3(4H)‐ones and 2‐Bromo‐2H‐1,4‐benzoxazin‐3(4H)‐ones

Substituted 2‐(benzylamino)‐2H‐1,4‐benzoxazin‐3(4H)‐ones are unstable under alkaline and acidic conditions, undergoing opening of the benzoxazinone ring. 2‐Bromo‐2H‐1,4‐benzoxazin‐3(4H)‐ones show similar degradation under alkaline conditions, while replacement of Br at C(2) to give 2‐hydroxy‐2H‐1,4‐benzoxazin‐3(4H)‐ones was observed only under mild alkaline conditions. Mechanisms of ring opening and degradation to 2‐aminophenol derivatives are proposed.     

LP99: Discovery and Synthesis of the First Selective BRD7/9 Bromodomain Inhibitor

The bromodomain‐containing proteins BRD9 and BRD7 are part of the human SWI/SNF chromatin‐remodeling complexes BAF and PBAF. To date, no selective inhibitor for BRD7/9 has been reported despite its potential value as a biological tool or as a lead for future therapeutics. The quinolone‐fused lactam LP99 is now reported as the first potent and selective inhibitor of the BRD7 and BRD9 bromodomains. Development of LP99 from a fragment hit was expedited through balancing structure‐based inhibitor design and biophysical characterization against tractable chemical synthesis: Complexity‐building nitro‐Mannich/lactamization cascade processes allowed for early structure–activity relationship studies whereas an enantioselective organocatalytic nitro‐Mannich reaction enabled the synthesis of the lead scaffold in enantioenriched form and on scale. This epigenetic probe was shown to inhibit the association of BRD7 and BRD9 to acetylated histones in vitro and in cells. Moreover, LP99 was used to demonstrate that BRD7/9 plays a role in regulating pro‐inflammatory cytokine secretion.     

Synthesis of 3‐[4‐Acyl‐2‐(1‐methoxy‐1‐methylethyl)morpholin‐3‐yl]‐benzonitriles as Novel Potassium Channel Openers

Potassium channel openers (KCO's) have been demonstrated to possess potent relaxant‐activity on smooth muscle. Tissue‐selective KCO's may find use in the treatment of a variety of diseases, such as hypertension, asthma, and urinary incontinence. We have previously reported a series of 1,9‐dioxa‐4‐aza‐phenanthrene‐6‐carbonitriles, including compounds 2 & 3 , as bladder‐selective KCO's. As a continuation of our efforts, we have designed 3‐[4‐acyl‐2‐(1‐methoxy‐1‐methylethyl)morpholin‐3‐yl]‐benzonitriles as ring‐opened analogs of compounds 2 & 3 . In this report, we describe the efficient construction of the novel 2,3‐disubstituted morpholine structure, as represented by the synthesis of compounds 4‐7 . Compounds 4‐7 showed potent and selective relaxant‐activity on rat bladder detrusor strip preparation. In this series, the most potent derivatives are Boc‐substituted analogs 4 & 6 (IC₅₀ = 3.9 and 2.9 μM, respectively).     

Design and Synthesis of Novel Pyrazole‐based Lp‐PLA2 Inhibitors

A series of novel pyrazole‐based lipoprotein‐associated phospholipase A₂ (Lp‐PLA₂) inhibitors have been designed and synthetized by a variety of acetophenones via a 10‐step convergent approach. The synthetic approach is carefully optimized, and an unsuccessful alternative route is also discussed. The in vitro biological activity reveals that all the synthesized compounds are potent Lp‐PLA₂ inhibitors with compound 13b being the most potent one (Lp‐PLA₂, IC₅₀=1.5 nmol/L).     

Fluorine Pseudocontact Shifts Used for Characterizing the Protein–Ligand Interaction Mode in the Limit of NMR Intermediate Exchange

The characterization of protein–ligand interaction modes becomes recalcitrant in the NMR intermediate exchange regime as the interface resonances are broadened beyond detection. Here, we determined the ¹⁹F low‐populated bound‐state pseudocontact shifts (PCSs) of mono‐ and di‐fluorinated inhibitors of the BRM bromodomain using a highly skewed protein/ligand ratio. The bound‐state ¹⁹F PCSs were retrieved from ¹⁹F chemical exchange saturation transfer (CEST) in the presence of the lanthanide‐labeled protein, which was termed the ¹⁹F PCS‐CEST approach. These PCSs enriched in spatial information enabled the identification of best‐fitting poses, which agree well with the crystal structure of a more soluble analog in complex with the BRM bromodomain. This approach fills the gap of the NMR structural characterization of lead‐like inhibitors with moderate affinities to target proteins, which are essential for structure‐guided hit‐to‐lead evolution.     

New Substituted 1‐Aryl‐4,4,6‐Trimethyl‐3,4‐Dihydropyrimidine‐2‐(1H)Thiones; A Metal‐Free and Solvent‐Free Synthesis,Characterization, and Lymphoid Tyrosine Phosphatase Inhibition Studies

A series of fourteen 3,4‐dihydropyrimidine‐2‐thiones ( 3a–n ) were synthesized by a green protocol, and their structures were characterized by spectroanalytical data. The compounds were obtained in high yields by efficient annulation of mesityl oxide (4‐methylpent‐3‐en‐2‐one) with anilines in the presence of potassium thiocyanate. The reaction is essentially metal‐catalyst‐ and solvent‐free, as mesityl oxide itself is the solvent as well as the reactant. The compounds were tested for their ability to inhibit the lymphoid tyrosine phosphatase PTPN22, and 5 of the 14 compounds exhibited IC₅₀ values in the mid‐micromolar range, with the most potent hit being the compound 3d , having a methoxy substituent at the 2‐position of the phenyl ring with an IC₅₀ = 18 ± 1 μM, and second most potent compound ( 3c ) with an IC₅₀ value of 45 ± 3 μM, having methyl substituents at both 2‐ and 4‐position of the phenyl ring.     

Synthesis and Biological Evaluation of 2‐substituted‐6‐(morpholinyl/piperidinyl)pyridazin‐3(2H)‐ones as Potent and Safer Anti‐inflammatory and Analgesic Agents

A series of 2‐substituted‐6‐(morpholinyl/piperidinyl)pyridazin‐3(2H )‐ones was synthesized and the structures were established using various spectroscopic techniques. The target compounds were screened for anti‐inflammatory and analgesic activities at 20 and 40 mg/kg. The safety of the synthesized derivatives was evaluated by assessing anti‐platelet activity and ulcer index. The obtained pharmacological data revealed that 6‐morpholinyl derivatives 4a–12a were found to be somewhat more potent than 6‐piperidinyl derivatives 4b–6b. The 6‐morpholinyl substituted pyridazinone 12a exhibited maximum anti‐inflammatory and analgesic activities. Homoveratrylamine substituted compounds 6a and 6b emerged as promising leads in both the series with good anti‐inflammatory and analgesic activities without any ulcerogenicity. Anti‐platelet activity results of the compounds of both the series showed significantly low bleeding time in comparison with standard drug aspirin indicating the cardiovascular safety of new pyridazinones.     

Renewable Molecular Flasks with NADH Models: Combination of Light‐Driven Proton Reduction and Biomimetic Hydrogenation of Benzoxazinones

Using small molecules with defined pockets to catalyze chemical transformations resulted in attractive catalytic syntheses that echo the remarkable properties of enzymes. By modulating the active site of a nicotinamide adenine dinucleotide (NADH) model in a redox‐active molecular flask, we combined biomimetic hydrogenation with in situ regeneration of the active site in a one‐pot transformation using light as a clean energy source. This molecular flask facilitates the encapsulation of benzoxazinones for biomimetic hydrogenation of the substrates within the inner space of the flask using the active sites of the NADH models. The redox‐active metal centers provide an active hydrogen source by light‐driven proton reduction outside the pocket, allowing the in situ regeneration of the NADH models under irradiation. This new synthetic platform, which offers control over the location of the redox events, provides a regenerating system that exhibits high selectivity and efficiency and is extendable to benzoxazinone and quinoxalinone systems.