Syntheses of 3-acetoacetylaminobenzo[b]furan derivatives having cysteinyl leukotriene 2 receptor antagonistic activity

ZnCl2 -Catalyzed [4+1] Annulation of Alkylthio-Substituted Enaminones and Enaminothiones with Sulfur Ylides

Concise construction of furan and thiophene units has played an important role in the synthesis of potentially bioactive compounds and functional materials. Herein, an efficient Lewis acid ZnCl₂ catalyzed [4+1] annulation of alkylthio-substituted enaminones is reported, that is, α-oxo ketene N,S-acetals with sulfur ylides to afford 2-acyl-3-aminofuran derivatives. In a similar fashion, [4+1] annulation of the corresponding enaminothiones, that is, α-thioxo ketene N,S-acetals, with sulfur ylides efficiently proceeded to give multisubstituted 3-aminothiophenes. This method features wide substrate scopes as well as broad functional group tolerance, offering a concise route to highly functionalized furans and thiophenes.

The squaramide-catalyzed asymmetric Michael/cyclization tandem reaction for the synthesis of chiral trifluoromethylated hydroxyimino tetrahydrobenzofuranones

An enantioselective synthesis of trifluoromethylated hydroxyimino tetrahydrobenzofuranones has been developed. 1,3-Dicarbonyl carbocyclic compounds react with β-CF3-β-disubstituted nitroalkenes in the presence of a chiral squaramide catalyst, providing efficient access to diverse hydroxyimino tetrahydrobenzofuranones featuring a trifluoromethyl group at the C3-position of an all-carbon quaternary stereocenter with good yields (up to 81%) and enantioselectivities (up to 89% ee).

Discovery of Gemilukast (ONO-6950), a Dual CysLT1 and CysLT2 Antagonist As a Therapeutic Agent for Asthma

An orally active dual CysLT1 and CysLT2 antagonist possessing a distinctive structure which consists of triple bond and dicarboxylic acid moieties is described. Gemilukast (ONO-6950) was generated via isomerization of the core indole and the incorporation of a triple bond into a lead compound. Gemilukast exhibited antagonist activities with IC50 values of 1.7 and 25 nM against human CysLT1 and human CysLT2, respectively, and potent efficacy at an oral dose of 0.1 mg/kg given 24 h before LTD4 challenge in a CysLT1-dependent guinea pig asthmatic model. In addition, gemilukast dose-dependently reduced LTC4-induced bronchoconstriction in both CysLT1- and CysLT2-dependent guinea pig asthmatic models, and it reduced antigen-induced constriction of isolated human bronchi. Gemilukast is currently being evaluated in phase II trials for the treatment of asthma.

Discovery of Highly Potent Dual CysLT1 and CysLT2 Antagonist

The benzoxazine derivative, (2S)-4-(3-carboxypropyl)-8-{[4-(4-phenylbutoxy)benzoyl]amino}-3,4-dihydro-2H-1,4-benzoxazine-2-carboxylic acid (19, ONO-2050297), was identified as the first potent dual CysLT1 and CysLT2 antagonist with IC50 values of 0.017 μM (CysLT1) and 0.00087 μM (CysLT2), respectively.

Asymmetric Michael/cyclization tandem reaction of 4-hydroxycoumarin with β-nitroalkenes catalyzed by chiral bifunctional thioureas

The first asymmetric Michael/cyclization tandem reaction of 4-hydroxycoumarin with nitroolefins catalyzed by chiral bifunctional thioureas was reported and 2,3-dihydrofuro[3,2-c]-coumarin adducts have been obtained in moderate yields (53-75%) and good enantioselectivities (64-90% ee).

Preparation of novel (Z)-4-ylidenebenzo[b]furo[3,2-d][1,3]oxazines and their biological activity

A reaction of 2-acetyl-3-acylaminobenzo[b]furans (9d–o) with Vilsmeier (VM) reagent afforded a mixture of (E)- and (Z)-{(E)-2-aralkenylbenzo[b]furo[3,2-d][1,3]oxazin-4-ylidene}acetaldehydes (5) with a characteristic exo-formylmethylene group on the oxazine ring. The Z-isomer was more stable than the E-isomer. The Z-isomers ((Z)-5) were reacted with phosphonate reagents under two different conditions to obtain various butadiene derivatives (12) containing benzo[b]furo[3,2-d][1,3]oxazine skeleton. Typical compounds (5 and 12) were evaluated for their anti-osteoclastic bone resorption activity, antagonistic activity for the cysLT1 receptor and growth inhibitory activity for MIA PaCa-2 and MCF-7. Compounds 12f and 12j showed potent anti-osteoclastic bone resorption activity comparable to E₂ (17β-estradiol).

Degradation-promoters of cellular inhibitor of apoptosis protein 1 based on bestatin and actinonin

A series of hybrid compounds of bestatin (1) and actinonin (3), which promote degradation of cellular inhibitor of apoptosis protein 1 (cIAP1), were designed and synthesized. Structure-activity relationship studies indicated that absolute configuration, hydrophobicity at the alpha-position of the internal amide carbonyl group, and the presence of a small substituent at the alpha-position of the ester group are important factors for the expression of potent cIAP1 degradation-promoting activity. HAB-5A (30b) showed the most potent activity (IC(50)=0.53 microM) among the compounds prepared.

Preparation of 2-, 3-, 4- and 7-(2-alkylcarbamoyl-1-alkylvinyl)benzo[b]furans and their BLT1 and/or BLT2 inhibitory activities

Several 2-alkylcarbamoyl-1-alkylvinylbenzo[b]furans were designed to find a selective leukotriene B4 (LTB4) receptor antagonist. 2-(2-Alkylcarbamoyl-1-alkylvinyl)benzo[b]furans having a substituent group at the 3-position, 4-(2-alkylcarbamoyl-1-methylvinyl)benzo[b]furans having a substituent group at the 3-position, and 7-(2-alkylcarbamoyl-1-methylvinyl)benzo[b]furans and 3-(2-alkylcarbamoyl-1-alkylvinyl)benzo[b]furans were prepared and evaluated for LTB4 receptor (BLT1 and BLT2) inhibitory activities. (E)-3-Amino-4-[2-[2-(3,4-dimethoxyphenyl)ethylcarbamoyl]-1-methylvinyl]benzo[b]furan ((E)-17c) showed potent and selective inhibitory activity for BLT2. On the other hand, (E)-7-(2-diethylcarbamoyl-1-methylvinyl)benzo[b]furan ((E)-27a) showed potent inhibitory activity for both BLT1 and BLT2.

Preparation of 3-(4-chlorophenyl)-2-(2-aminothiazol-4-yl)-5-methoxybenzo[b]furan derivatives and their leukotriene B4 inhibitory activity

A series of 3-(4-chlorophenyl)-2-(2-aminothiazol-4-yl)benzo[b]furan derivatives 6-10 were prepared and their leukotriene B(4) inhibitory activity was evaluated. We found that several compounds showed strong inhibition of calcium mobilization in CHO cells overexpressing human BLT(1) and BLT(2) receptors. Among them, 3-(4-chlorophenyl)-2-[5-formyl-2-[(dimethylamino)methyleneamino]thiazol-4-yl]-5-methoxybenzo[b]furan 9b showed the most potent and selective inhibition for the human BLT(2) receptor, and its IC(50) value was smaller than that of the selected positive control compound, ZK-158252.

Synthesis and biological activities of novel furo[2,3,4-jk][2]benzazepin-4(3H)-one derivatives

A novel seven-membered lactam formation method has been established by intramolecular ring closure reaction of 4-bromo-(E)-3-[(2-alkylvinyl)carbonylamino]benzo[b]furans under Heck coupling conditions. A number of furo[2,3,4-jk][2]benzazepin-4(3H)-ones, tricyclicbenzo[b]furans, have been prepared by this method and evaluated for their leukotriene B(4) (LTB(4)) receptor and poly(ADP-ribose)polymerase-1 (PARP-1) inhibitory activities.

A novel oxazine ring closure reaction affording (Z)-((E)-2-styrylbenzo[b]furo[3,2-d][1,3]oxazin-4-ylideno)acetaldehydes and their anti-osteoclastic bone resorption activity

A novel oxazine ring formation method was established using the reaction of 2-acetyl-(E)-3-styrylcarbonylaminobenzo[b]furans (4) with Vilsmeier-Haack-Arnold reagent to afford (E and Z)-((E)-2-styrylbenzo[b]furo[3,2-d][1,3]oxazin-4-ylideno)acetaldehydes (5). (Z)-4-(8-Bromo-(E)-2-styrylbenzo[b]furo[3,2-d][1,3]oxazin-4-ylideno)but-(E)-2-enoic acid ethyl ester (6b), derived from (Z)-5a, showed significantly potent anti-osteoclastic bone resorption activity comparable to 17beta-estradiol (E2).

Synthesis of 2-, 4- and 5-(2-Alkylcarbamoyl-1-methylvinyl)-7-alkyloxybenzo[b]furans and their Leukotriene B4 Receptor Antagonistic Activity

Variable 7-carboxylpropoxy or (1-phenyl)ethoxybenzo[b]furan derivatives with (E)- and (Z)-2-alkylcarbamoyl-1-methylvinyl groups at the 2-, 4-, and 5-positions were prepared to find novel and selective leukotriene B(4) (LTB(4)) receptor antagonists. (E)-2-(2-Diethylcarbamoyl-1-methylvinyl)-7-(1-phenylethoxy)benzo[b]furan (4v) showed selective inhibition of the human BLT(2) receptor (hBLT(2)). On the other hand, (E)-2-acetyl-4-(2-diethylcarbamoyl-1-methylvinyl)-7-(1-phenylethoxy)benzo[b]furan (7c) inhibited both human BLT(1) receptor (hBLT(1)) and hBLT(2). The (E)-2-(2-diethylcarbamoyl-1-methylvinyl) group lay on approximately the same plane as the benzo[b]furan ring, whereas the (E)-4-(2-diethylcarbamoyl-1-methylvinyl) group had a torsion angle (45.7 degrees ) from the benzo[b]furan ring plane. However, the (Z)-(2-alkylcarbamoyl-1-methylvinyl)benzo[b]furans were inactive. The inhibitory activity depended on the conformation of the 2-alkylcarbamoyl-1-methylvinyl groups.

Synthesis of 2-, 4- and 5-(2-alkylcarbamoyl-1-methylvinyl)-7-alkyloxybenzo[b]furans and their leukotriene B4 receptor antagonistic activity

Variable benzo[b]furan derivatives having (E)- and (Z)-2-alkylcarbamoyl-1-methylvinyl groups at the 2-, 4- and 5-positions and a carboxylpropoxy or (1-phenyl)ethoxy group at the 7-position were prepared to find novel and selective leukotriene B4(LTB4) receptor antagonists. (E)-2-(2-diethylcarbamoyl-1-methylvinyl)-7-(1-phenylethoxy)benzo[b]furan (4v) showed selective inhibition to the human BLT2 receptor (hBLT2). On the other hand, (E)-2-acetyl-4-(2-diethylcarbamoyl-1-methylvinyl)-7-(1-phenylethoxy)benzo[b]furan (7v) inhibited both human BLT(1) receptor (hBLT1) and hBLT2. The (E)-2-(2-diethylcarbamoyl-1-methylvinyl) group lay on approximately the same plane as the benzo[b]furan ring, whereas the (E)-4-(2-diethylcarbamoyl-1-methylvinyl) group had the torsion angle (45.7 degree) from the benzo[b]furan ring plane. However, the (Z)-(2-alkylcarbamoyl-1-methylvinyl)benzo[b]furans were inactive. The inhibitory activity depended on the conformation of the 2-diethylcarbamoyl-1-methylvinyl group.