Total synthesis of (±)-fangchinoline

(±)-Fangchinoline was synthesized by condensation of (±)-1-(3-bromo-4-methoxy-benzyl)-2-methyl-6-methoxy-7-hydroxy-8-bromo-1,2,3,4-tetrahydroisoquinoline ( 2 ) and (±)-1-(4-hydroxy-benzyl)-2-methyl-6-methoxy-7-hydroxy-1,2,3,4-tetrahydroisoquinoline ( 3 ) in the presence of copper, pyridine and potassium carbonate.     

Cycloaddition of 1-Aryl-3-trimethylsiloxy-1,3-butadienes in the Synthesis of Natural Quinone Analogs

7-Hydroxy-5-(2-methoxyphenyl)-2-methyl-6-R-1,4-naphthoquinones, 8-hydroxy-1-(2-methoxyphenyl)-3-oxo-1,2,3,4-tetrahydro-9,10-anthraquinone, and 2-ethoxycarbonyl-8-hydroxy-1-(2-methoxyphenyl)-3-trimethylsiloxy-1,1a,4,4a-tetrahydro-9,10-anthraquinone were synthesized by reactions of 1-(2-methoxyphenyl)-2-R-3-trimethylsiloxy-1,3-butadienes with 2-bromo-5-methyl-1,4-benzoquinone and juglone. 1-Aryl-2-ethoxycarbonyl-3-trimethylsiloxy-1,3-butadienes reacted with 1,4-naphthoquinone to afford 1-aryl-2-ethoxycarbonyl-3-hydroxy-9,10-anthraquinones and their 4,4a-dihydro derivatives.     

Comparative Sites for Coordination of Naphthoquinones and its Derivatives: Studies on the Synthesis of a Series of 1,4-Naphthoquinone Derivatives and Their Ni(II) Complexes

Abstract

New derivatives (5–8) of 5-amino-8-hydroxy-1,4-naphthoquinone (1) have been synthesized and characterized by IR, UV-Vis, ¹H NMR, mass spectra and CNH. These new ligands and the 5-amino-8-hydroxy-l,4-naphthoquinone (1), the 5-amino-6-bromo-8-hydroxy-1,4-naphtho-quinone (2), the 5-acetylamino-8-hydroxy-1,4-naphthoquinone (3) and the 5-dodecanoylamino-8-hydroxy-1,4-naphthoquinone (4), were complexed with Ni(II) giving the chelates (1a–8a). The structure and site of coordination of these complexes are discussed in relation to their spectroscopic data and thermal analysis.     

Total synthesis of cryptophycin-24 (Arenastatin A) amenable to structural modifications in the C16 side chain

Two efficient protocols for the synthesis of tert-butyl (5S,6R,2E, 7E)-5-[(tert-butyldimethylsilyl)oxy]-6-methyl-8-phenyl-2, 7-octadienoate, a major component of the cryptophycins, are reported. The first utilized the Noyori reduction and Frater alkylation of methyl 5-benzyloxy-3-oxopentanoate to set two stereogenic centers, which became the C16 hydroxyl and C1' methyl of the cryptophycins. The second approach started from 3-p-methoxybenzyloxypropanal and a crotyl borane reagent derived from (-)-alpha-pinene to set both stereocenters in a single step and provided the dephenyl analogue, tert-butyl (5S,6R,2E)-5-[(tert-butyldimethylsilyl)oxy]-6-methyl-2, 7-octadienoate, in five steps. This compound was readily converted to the 8-phenyl compound via Heck coupling. The silanyloxy esters were efficiently deprotected and coupled to the C2-C10 amino acid fragment to provide desepoxyarenastatin A and its dephenyl analogue. The terminal olefin of the latter was further elaborated via Heck coupling. Epoxidation provided cryptophycin-24 (arenastatin A).     

Isolation and identification of a major impurity in a new bulk drug candidate by preparative LC, ESI-MS(n), LC-MS-MS, and NMR

A simple preparative liquid chromatography (LC) method is developed to isolate a major impurity in a new bulk drug candidate, 6-bromo-4-(carbamidinemethyl)-5-hydroxy-1-methyl-2-(phenylthiomethyl)-1H-indole-3-carboxylic acid ethyl ester hydrochloride monohydrate (carmidole). The carmidole solution for preparation is exposed to daylight before isolation. Based on the electrospray ionization (ESI)-mass spectroscopy (MS(n)) spectral data of the impurity fraction and carmidole, the impurity is preliminarily characterized as 6-bromo-4-(carbamidinemethyl)-5-hydroxy-1-methyl-2-methyl-1H-indole-3-carboxylic acid ethyl ester. LC-MS-MS is used to analyze a carmidole sample. The impurity, lyophilate, is obtained from the fraction of preparative LC, and the impurity standard is synthesized. By comparison of the retention times of high-performance liquid chromatography, ESI-MS(n), and (1)H-nuclear magnetic resonance of the impurity lyophilate with impurity standard and carmidole itself, the structure of the impurity is confirmed and its formation is discussed.     

Syntheses of 5-hydroxy-2-(phenyl or styryl)chromones and of some halo derivatives

One-pot syntheses of 5-hydroxy-2-(phenyl or styryl)chromones and the corresponding 6- and 8-monoiodo- and 6,8-diiodochromones have been developed. The procedures involve oxidative cyclization of 2′-benzyloxy-6′-hydroxychalcones and 2′-benzyloxy-6′-hydroxy-2-cinnamylideneacetophenones and electrophilic substitution processes on the chromone moieties; such procedures were also applied to the syntheses of 6,8-dibromochromone derivatives.     

Anthraquinones from the roots of Prismatomeris malayana

A novel anthraquinone, 1,3-dihydroxy-5,6-dimethoxy-2-methoxymethyl-9,10-anthraquinone (9) and a new natural product, 2-hydroxymethyl-1-methoxy-9,10-anthraquinone (8) were isolated from the roots of Prismatomeris malayana together with seven known anthraquinones, tectoquinone (1), 1-hydroxy-2-methyl-9,10-anthraquinone (2), rubiadin (3), rubiadin-1-methyl ether (4), 1,3-dihydroxy-5,6-dimethoxy-2-methyl-9,10-anthraquinone (5), nordamnacanthal (6), and damnacanthal (7). Their structures were determined on the basis of spectroscopic data. Some of the anthraquinones were tested for anticancer, antifungal, and antimalarial activities.     

Prenylisoflavone derivatives from the roots of Hedysarum scoparium

Four new prenylisoflavone derivatives, namely, 5-hydroxy-4'-methoxy-8-prenyl-2'-hydroxyisopropyldihydrofurano[4,5:6,7]-isoflavone (1), 5-hydroxy-4'-methoxy-6-prenyl-2'-hydroxyisopropyldihydrofurano[4,5:8,7]-isoflavone (2), 5-hydroxy-4'-methoxy-8-prenyl-1',2'-peroxyl-3',3'-dimethyldihydropyrano[5,6:6,7]-isoflavone (3), and 5-hydroxy-4'-methoxy-6-prenyl-1',2'-peroxyl-3',3'-dimethyldihydropyrano[5,6:8,7]-isoflavone (4), together with three known ones 5-7, were isolated from the roots of Hedysarum scoparium. Their structures were established by means of detailed spectroscopic analysis (IR, EI- or HR-ESI-MS as well as 1D- and 2D-NMR), and by comparison of their spectroscopic data with those reported for structurally related compounds.     

Anthraquinones with antiplasmodial activity from the roots of Rennellia elliptica Korth. (Rubiaceae)

Dichloromethane root extract of Rennellia elliptica Korth. showed strong inhibition of Plasmodium falciparum growth in vitro with an IC?? value of 4.04 μg/mL. A phytochemical study of the dichloromethane root extract has led to the isolation and characterization of a new anthraquinone, 1,2-dimethoxy-6-methyl-9,10-anthraquinone (1), and ten known anthraquinones: 1-hydroxy-2-methoxy-6-methyl-9,10-anthraquinone (2), nordamnacanthal (3), 2-formyl-3-hydroxy-9,10-anthraquinone (4), damnacanthal (5), lucidin-ω-methyl ether (6), 3-hydroxy-2-methyl-9,10-anthraquinone (7), rubiadin (8), 3-hydroxy-2-methoxy-6-methyl-9,10-anthraquinone (9), rubiadin-1-methyl ether (10) and 3-hydroxy-2-hydroxymethyl-9,10-anthraquinone (11). Structural elucidation of all compounds was accomplished by modern spectroscopic methods, notably 1D and 2D NMR, IR, UV and HREIMS. The new anthraquinone 1, 2-formyl-3-hydroxy-9,10-anthraquinone (4) and 3-hydroxy-2-methyl-9,10-anthraquinone (7) possess strong antiplasmodial activity, with IC?? values of 1.10, 0.63 and 0.34 μM, respectively.     

Formation of the benzo[f]pyrazolo[3,4-c][1,2,5]-triazepine system in the template reaction of o-amino-o′-halophenylazopyrazoles

The substance isolated from the template cyclization of 4-(2-bromo-4-methyl-1-phenylazo)-5-amino-3-methyl-1-propylpyrazole was identified by spectroscopic methods as 5-(2-bromo-4-methylphenyl)-3,7-dimethyl-1-propyl-1,5-dihydrobenzo[f]-pyrazolo[3,4-c][1,2,5]triazepine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 802–804, June, 1979.     

Synthesis, structure and spectroscopy of new thiopyrone and hydroxypyridinethione transition-metal complexes

The coordination chemistry of several O,S mixed donor ligands, namely thiopyrone and hydroxypyridinethione chelators, with a variety of middle and late first-row transition-metal ions is described. Complexes of 3-hydroxy-2-methyl-4-thiopyrone (thiomaltol) with cobalt(II), copper(II) and zinc(II); 3-hydroxy-1,2-dimethyl-4(1H)-pyridinethione (3,4-HOPTO) with iron(III), nickel(II), copper(II) and zinc(II); and 3-hydroxy-1-methyl-2(1H)-pyridinethione (3,2-HOPTO) with iron(III), nickel(II), copper(II) and zinc(II) have been synthesized and characterized. The structures, absorbance spectroscopy, cyclic voltammetry and superconducting quantum interferometer device (SQUID) measurements of selected metal complexes, as well as ligand protonation constants, are reported. Most of the metal complexes show coordination geometries indicative of a strong trans influence by the O,S chelators. The data presented herein provide the most detailed study of the transition-metal coordination chemistry of both thiopyrone and hydroxypyridinethione O,S donor ligands to date, and provide the basis for the investigation of these ligands in realm of biological inorganic chemistry.     

新型苯并吡喃类FSH拮抗剂的合成

以2-溴-4,5-二甲氧基苄溴为起始原料,依次经取代、Sonogoshira偶联、水解、酰化和氧化反应合成了新型FSH拮抗剂——(R)-N-[1-羟基-3-(1H-吲哚-3-基)丙烷-2-基]-3-异丙氧基-8,9-二甲氧基-6H-苯并[c]苯并吡喃-2-甲酰胺,总收率16.8%,其结构经~1H NMR和MS(ESI)确证。     

Adsorption-photomertic and test determination of cadmium(II) with hetarylformazans

Procedures were developed for the solid-phase spectroscopic and test determination of cadmium(II) using 1-(2-hydroxy-5-nitrophenyl)-3-isopropyl-5-(benzoxazol-2-yl)- and 1-(2-hydroxy-5-sulfophenyl)-3-methyl-5-(benzothiazol-2-yl)formazans on a Polyorgs-34n solid-phase fibrous adsorbent (under batch conditions) and a Diasorb-100-TA silica gel with trimethylammonium groups (under dynamic conditions). Optimum conditions were determined for the complexation of these reagents on solid supports. The procedure for the rapid determination of cadmium(II) on Polyorgs-34n was tested for natural water and snow cover.     

Bromination and diazo-coupling of pyridinethiones; microwave assisted synthesis of isothiazolopyridine, pyridothiazine and pyridothiazepines

Isothiazolopyridines, pyridothiazines and pyridothiazepines are important compounds that possess valuable biological activities. This paper reports on the synthesis of these compounds using both conventional chemical methods and modern microwave techniques. 3-Bromo-6-hydroxy-4-methyl-2-thioxo-2,3-dihydropyridine-3-carboxamide, 5-arylazo-6-hydroxy-4-methyl-2-thioxo-1,2-dihydropyridine-3-carboxamides, 3,5-bis-arylazo-6-hydroxy-4-methyl-2-thioxo-2,3-dihydropyridine-3-caboxamide, 4-methyl-2,3,6,7-tetra-hydroisothiazolo[5,4-b]-pyridine-3,6-dione, 2,2'-(methylene-bis-(sulfanediyl))bis(4-methyl-6-oxo-1,6-dihydropyridine-3-carboxamide), 2-hydroxy-5-methyl-4H-pyrido[3,2-e][1,3]-thiazine-4,7(8H)-dione and 2-arylmethylene-8-hydroxy-6-methyl-2,3,4,5-tetrahydropyrido-[3,2-f][1,4]thiazepine-3,5-diones have been prepared from 6-hydroxy-4-methyl-2-thioxo-2,3-dihydropyridine-3-carboxamide. Some of these compounds were prepared using microwave-assisted reaction conditions, that provided higher yields in shorter times than the conventional methods.     

6-芳甲氧基-7-甲基-4-羟基-3-喹啉羧酸乙酯类化合物的合成及抗球虫活性研究

本文通过亚硝化、催化氢化、EMME缩合、醚化和关环五步反应合成了3个未见文献报道的6-芳甲氧基-7-甲基-4-羟基-3-喹啉羧酸乙酯类化合物。所有化合物的结构均经1H NMR,IR和HRMS等方法确证。对三个化合物进行了抗球虫活性实验,实验结果表明,在27 mg/kg的使用浓度下,化合物6-苄氧基-7-甲基-4-羟基-3-喹啉羧酸乙酯(5a)具有抗球虫活性。     

Determination of 2-hydroxy-5-methyl-4′-methoxy chalkone oxime (HMMCO) and substituted oximes by enthalpimetric and potentiometric titrations

Enthalpimetric and potentiometric titrations of 2-hydroxy-5-methyl-4′-methoxy chalkone oxime (HMMCO), 2-hydroxy-5-chloro-4′-methoxy chalkone oxime (HCMCO), and 2-hydroxy-3-bromo-5-methyl-4′-methoxy chalkone oxime (HBMMCO) were carried in acetone medium using tetra-n-butyl ammonium hydroxide, potassium hydroxide in isopropyl alcohol, and potassium tertiary butoxide in tertiary butyl alcohol, as titrants. Alcoholic KOH was found to be the most suitable titrant. Enthalpimetric titrations could be used for 1–8 mg of oximes where as potentiometric titrations gave accurate results for 1–20 mg.     

Isolation of tetraprenyltoluquinols from the brown alga Sargassum thunbergii

Thunbergols A (4) and B (5), tetraprenyltoluquinols, along with three known compounds (1-3) have been isolated from the brown alga Sargassum thunbergii. The structures of these two new compounds were determined to be 9-(3,4-dihydro-2,8-dimethyl-6-hydroxy-2H-1-benzopyran-2-yl)-6-methyl-2-(4-methyl-3-pentenyl)-(2E,6E)-nonadienoic acid (4) and 10-(2,3-dihydro-5-hydroxy-7-methyl-1-benzofuran-2-yl)-10-hydroxy-6-methyl-2-(4-methyl-3-pentenyl)-(2E,6E)-undecadienoic acid (5), respectively, by combined spectroscopic methods. Both of them exhibited significant scavenging activities on radical and potently inhibited generation of ONOO(-) from morpholinosydnonimine (SIN-1).     

Total synthesis of the proposed structure of the anthrapyran metabolite delta-indomycinone

The first total synthesis of the proposed structure of delta-indomycinone has been accomplished. The key steps involve the Diels-Alder reaction of a bromonaphthoquinone (6) and 1-methoxy-3-methyl-1-trimethylsiloxy-1,3-butadiene (7) to access the anthraquinone skeleton, representing a common building block of other naturally occurring anthraquinone antibiotics, regioselective bromination of anthraquinone (14) and a highly diastereoselective alkylation of enantiomerically pure dioxolanone 8. The reported synthetic approach has the advantage of high yields, excellent selectivity and a remarkable general applicability for the total synthesis of other anthrapyran natural products. The spectroscopic data obtained for the synthetic compounds 2 and 36 are not in agreement with those reported for the natural product, and therefore revision of the assigned structure is required.     

Studies on the Synthesis of (2R,4′R,8′R)-α-Tocopherol Alternative Syntheses of 2-Chroman-acetic Acid Intermediates

As an extension of previous studies on the total synthesis of (2R,4′R,8′R)-α-tocopherol ( 1 ) [1] [2], (S)-(?)-2-(6-benzyloxy-2,5,7,8-tetramethylchroman)acetic acid ( 6 ), a pivotal intermediate, possessing the absolute configuration required for construction of 1 was prepared by optical resolution of the racemic modification 11 . the latter substance was obtained by two routes, one emanating from the hydroxy acetal 7 [1] and the other based upon the Lewis acid mediated cycloaddition of trimethylhydroquinone to rac.-3-hydroxy-3-methylpent-4-en-l-yl acetate ( 16 ) giving rac. ethyl 2-(6-hydroxy-2,5,7,8-tetramethyl-chroman)acetate ( 12 ).     

1,3-dipolar cycloaddition chemistry for the preparation of novel indolizinone-based compounds

[Chemical reaction: See text] Starting from methyl 5-oxo-6-trifluoromethanesulfonyloxy-1,2,3,5-tetrahydroindolizine-8-carboxylate, obtained by a Rh(II)-catalyzed 1,3-dipolar cycloaddition reaction of 1-(2-benzenesulfonyl-2-diazoacetyl)pyrrolidin-2-one and methyl acrylate, several indolo- and furano-fused indolizinones were efficiently prepared. In the first case, a palladium-mediated C-N coupling of the triflate with a variety of substituted anilines provided the desired methyl 5-oxo-6-(arylamino)-1,2,3,5-tetrahydroindolizine-8-carboxylates in high yield. Methyl 6-(2-bromophenylamino)-5-oxo-1,2,3,5-tetrahydroindolizine-8-carboxylate as well as its decarboxylated analogue, 6-(2-bromophenylamino)-2,3-dihydro-1H-indolizin-5-one, were synthesized in excellent yield and were found to undergo an intramolecular Heck cyclization to give 1,2,3,6-tetrahydroindolizino[6,7-b]indol-5-ones. To prepare furano-fused indolizinones, methyl 6-hydroxy-5-oxo-1,2,3,5-tetrahydroindolizine-8-carboxylate was etherified with different allyl halides, and the resultant allyl ethers were subjected to a thermal Claisen rearrangement to give the corresponding methyl 7-allyl-6-hydroxy-5-oxo-1,2,3,4-tetrahydroindolizine-8-carboxylates. Cyclization under Wacker oxidation conditions afforded methyl 2-methyl-8-oxo-5,6,7,8-tetrahydro-1-oxa-7a-aza-s-indacene-4-carboxylates in near-quantitative yield.