Synthesis and anti-human immunodeficiency virus activity of the skeleton isomers of 3',4'-Di-(O)-(-)-camphanoyl-(+)-khellactone.

Optically active structural isomers (1b-f and dst-1b-f) of 3',4'-di-(O)-(-)-camphanoyl-(+)-khellactone (DCK) were synthesized and their anti-human immunodeficiency virus (HIV) activity was investigated. The value of the sensitivity index (SI) of 1b was greater than that of DCK.

Synthesis of acinetobactin.

A structure involving the absolute configuration of acinetobactin (1b) was clarified. It was reconfirmed that preacinetobactin (1a) produced 1b by a rearrangement reaction.

Effects of sulfaphenazole derivatives on cardiac ischemia-reperfusion injury: association of cytochrome P450 activity and infarct size.

Cardiac ischemia-reperfusion injury is evoked by reactive oxygen species (ROS). We previously reported that sulfaphenazole (SPZ) attenuated cardiac ROS levels and ischemia-reperfusion injury in rats. SPZ has distinct two actions: a) elimination of ROS and b) inhibition of cytochrome P450 (CYP) that is responsible for ROS production. The aim of this study is to determine which action contributes to the attenuation of cardiac ischemia-reperfusion injury using SPZ and its derivatives [acetyl-SPZ (Ac-SPZ) and dichloro-SPZ (2Cl-SPZ)]. Administration of 2Cl-SPZ or SPZ prior to ischemia significantly reduced myocardial infarct size, myocardial lipid peroxides, and ROS levels. In addition, they inhibited rat cardiac CYP activity. However, Ac-SPZ neither reduced infarct size nor inhibited cardiac CYP activity. The three compounds had similar effects on ROS scavenging activity in that they scarcely scavenged hydrogen peroxide and superoxide anions but reduced hydroxyl radicals with the same efficacy. The serum concentration of each compound was almost the same until 24 h after reperfusion. Collectively, our findings indicate that the suppressive effects of SPZ and 2Cl-SPZ on ischemia-reperfusion injury are associated with the reduction of ROS levels, which is primarily due to a decrease in ROS production via inhibition of cardiac CYP, not via ROS scavenging activity.

Trifluoroacetylation-induced Houben-Hoesch-type cyclization of cyanoacetanilides: increased nucleophilicity of CN groups.

Trifluoroacetic anhydride-mediated tandem trifluoroacetylation/cyclization of cyanoacetanilides proceeded efficiently under mild conditions to give 4-hydroxy-3-trifluoroacetylquinolin-2(1H)-ones in good yields. Isolation and direct observation of the reaction intermediates revealed that alpha-trifluoroacetylation resulted in the shortening of C[triple bond]N bonds and that the electron density of CN groups was high. A plausible reaction mechanism based on the results is also described.

Synthesis of all-methylated isorugosin B.

All-methylated isorugosin B was synthesized via two-step esterification between optically active valoneic acid and glucose derivatives.

A concise and versatile synthesis of viridicatin alkaloids from cyanoacetanilides.

The efficient synthesis of 3-hydroxy-4-arylquinolin-2(1H)-ones through one-pot Knoevenagel condensation/epoxidation of cyanoacetanilides followed by decyanative epoxide-arene cyclization is described. A convergent assembly with functionalized aldehydes allows for rapid synthesis with diverse substitution patterns. Isolation of 3-hydroxy-4-arylquinolin-2(1H)-ones is readily accomplished by precipitation and filtration.

[Synthetic studies on aromatic heterocyclic compounds].

This review covers the concise synthesis of simple coumarin with salicyl aldehydes and Wittig reagent, and a convenient synthesis of polycyclic aromatic heterocyclic compounds using the aryl-aryl coupling reaction of aryl benzamides and aryl benzoates with a Pd reagent is presented. In the first section, the reactions of salicyl aldehydes with OMe, OH, Br, CO(2)Me, and NO(2) groups with carbethoxymethylenetriphenylphophorane are described. Specifically, the reaction of 3-nitrosalicylaldehyde with amines gave benzoxazoles in moderate yield. In the second section, the syntheses of benzo[c]phenanthridine alkaloids, quinazoline alkaloids, and graphislactones in the Pd-mediated biaryl coupling reaction are described. Moreover, the synthesis of benzonaphthazepine and pyrrolophenanthridine alkaloids utilizing regioselective C-H activation with intramolecular coordination of a benzylamine to Pd is described, and the effects of oxygen substituents in the benzoyl part of benzanilides on the coupling position in its biaryl coupling reaction are presented. An effective Pd reagent for the coupling reaction of aryl tolyflate and arene was developed.

Concise synthesis of dl-febrifugine.

Racemic compound (1) of the antimalarial agents febrifugine (d-1) was synthesized using an stereoselective Michael reaction of an omega-amidoenone (5) which was prepared by the Wittig reaction of piperidinediol (7).

Structure elucidation and synthesis of lycoposerramine-B, a novel oxime-containing Lycopodium alkaloid from Lycopodium serratum Thunb.

A new alkaloid, lycoposerramine-B (1), containing an oxime function, was isolated from the club moss Lycopodium serratum Thunb. The structure of 1 was elucidated by spectroscopic analysis, including J-resolved HMBC spectroscopy, and confirmed by its synthesis from the known alkaloid, serratinine (3).

Scandium(III) trifluoromethanesulfonate catalyzed aromatic nitration with inorganic nitrates and acetic anhydride.

The rare earth metal(III) trifluoromethanesulfonate (rare earth metal(III) triflate, RE(OTf)3) was found to be an efficient catalyst for aromatic nitration with carboxylic anhydride-inorganic nitrate as the nitrating agent. In the presence of a catalytic amount of RE(OTf)3, the nitration of substituted benzenes proceeded to afford the corresponding nitrobenzenes. Especially, scandium(III) trifluoromethanesulfonate (scandium(III) triflate, Sc(OTf)3) is the most active catalyst among our tested Lewis acids. It was also found that acetic anhydride-Al(NO3).9H2O is the most active nitrating agent in this system.

Re-revision of the stereo structure of piperidine lactone, an intermediate in the synthesis of febrifugine.

The stereo structure of piperidine lactone (3), an intermediate of the antimalarial agent febrifugine ((+)-1) prepared by a synthetic method, was re-revised to the cis-form from the trans-form.

Aryl-aryl coupling reaction using a novel and highly active palladium reagent prepared from Pd(OAc)2, 1,3-bis[diphenylphosphino]propane (DPPP), and Bu3P.

A palladium-assisted coupling reaction of aryl triflate with arene was investigated, and a novel Pd reagent prepared from equimolar Pd(OAc)2, 1,3-Bis[diphenylphosphino]propane (DPPP), and Bu3P was developed. This method is useful for intramolecular biaryl coupling reactions, not only between aryl triflate and arene (triflate-amide), but also between aryl halide and arene (halo-amide).

Rare earth metal trifluoromethanesulfonates catalyzed benzyl-etherification.

Rare earth metal trifluoromethanesulfonates [rare earth metal triflate, RE(OTf)3] were found to be efficient catalyst for benzyl-etherification. In the presence of a catalytic amount of RE(OTf)3, condensation of benzyl alcohols and aliphatic alcohols proceeded smoothly to afford the benzyl ethers. The condensation between benzyl alcohols and thiols also proceeded, and thio ethers were obtained in good yield. In these reactions, RE(OTf)3 could be recovered easily after the reactions were completed and could be reused without loss of activity.