- Asymmetric total synthesis of (?)-javaberine A and (?)-epi-javaberine A based on catalytic intramolecular hydroamination of N-methyl-2-(2-styrylaryl)ethylamine
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Asymmetric total synthesis of (?)-javaberine A and its epimer was achieved by utilizing two methods for isoquinoline synthesis, asymmetric hydroamination of N-methyl-2-(2-styrylaryl)ethylamine and Bischler-Napieralski cyclization. Intramolecular asymmetric hydroamination of N-methyl aminoalkene 4 was catalyzed by lithium amide–chiral bisoxazoline to give tetrahydroisoquinoline (S)-laudanosine with good enantioselectivity in excellent yield. N-Demethylation of (S)-laudanosine was accomplished by Polonovski-type reaction to give (S)-norlaudanosine. Condensation of (S)-norlaudanosine with homoveratric acid, and subsequent Bischler-Napieralski cyclization, LiAlH4 reduction, and O-demethylation furnished (8R,14S)-(?)-javaberine A, corresponding to antipode of natural javaberine A. (8S,14S)-(?)-Javaberine A, which corresponds to C14-epimer of natural javaberine A, was also successfully synthesized.
- Uenishi, Saho,Kakigi, Rina,Hideshima, Kumiko,Miyawaki, Akari,Matsuoka, Junpei,Ogata, Tokutaro,Tomioka, Kiyoshi,Yamamoto, Yasutomo
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- Preparation method of neuromuscular blocking agent intermediate
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The invention relates to a preparation method of a neuromuscular blocking agent intermediate. The preparation method is characterized by including: adding specific chiral organic acid into a mixture containing a compound as shown in formula (I) to form sa
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Paragraph 0066
(2018/07/30)
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- Organocatalytic Enantioselective Pictet-Spengler Approach to Biologically Relevant 1-Benzyl-1,2,3,4-Tetrahydroisoquinoline Alkaloids
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(Figure Presented) A general procedure for the synthesis of 1-benzyl-1,2,3,4-tetrahydroisoquinolines was developed, based on organocatalytic, regio- and enantioselective Pictet-Spengler reactions (86-92% ee) of N-(o-nitrophenylsulfenyl)-2-arylethylamines with arylacetaldehydes. The presence of the o-nitrophenylsulfenyl group, together with the MOM-protection in the catechol part of the tetrahydroisoquinoline ring system, appeared to be a productive combination. To demonstrate the versatility of this approach, 10 biologically and pharmaceutically relevant alkaloids were prepared using (R)-TRIP as the chiral catalyst: (R)-norcoclaurine, (R)-coclaurine, (R)-norreticuline, (R)-reticuline, (R)-trimemetoquinol, (R)-armepavine, (R)-norprotosinomenine, (R)-protosinomenine, (R)-laudanosine, and (R)-5-methoxylaudanosine.
- Ruiz-Olalla, Andrea,Würdemann, Martien A.,Wanner, Martin J.,Ingemann, Steen,Van Maarseveen, Jan H.,Hiemstra, Henk
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p. 5125 - 5132
(2015/05/27)
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- Total synthesis of 8-epi-javaberine A and javaberine A
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The total synthesis of berberine alkaloid javaberine A was examined. The B/C ring of berberine was successfully constructed by sequential Bischler-Napieralski cyclization-reduction protocols, and final demethylation afforded both javaberine A and its epimer.
- Yamamoto, Yasutomo,Tabuchi, Yuri,Baba, Ayana,Hideshima, Kumiko,Nakano, Mai,Miyawaki, Akari,Tomioka, Kiyoshi
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p. 1311 - 1321
(2016/11/07)
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- Method of Analyzing Optical Isomers or Method of Resolving the Same
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Provided are a method of quickly and simply confirming the success or failure of resolution of optical isomers with the use of a column for resolving optical isomers and a method of simply designing the conditions of the eluent composition under isocratic elution conditions. In resolving optical isomers, the success or failure of the resolution can be simply and quickly confirmed by employing an HPLC gradient elution analysis method with the use of a column for resolving optical isomers. When the resolution is successfully conducted, the eluent composition under isocratic elution conditions can be estimated from the elution time in the gradient elution analysis.
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Page/Page column 1; 4; Sheet 5/6
(2009/07/17)
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- Enantioselective synthesis of (+)-(S)-laudanosine and (-)-(S)-xylopinine
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The study presents a new pathway for the enantioselective synthesis of benzylisoquinoline alkaloids. The key steps of the synthesis of (+)-(S)-laudanosine (1) and (-)-(S)-xylopinine (2) are a Sonogashira coupling that builds up the C1-C8a bond of the benzylisoquinoline skeleton, an intramolecular Ti-catalyzed hydroamination of an alkyne, and a subsequent enantioselective imine reduction according to Noyori's protocol.
- Mujahidin, Didin,Doye, Sven
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p. 2689 - 2693
(2007/10/03)
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- Stereoselective synthesis of aporphine alkaloids using a hypervalent iodine(III) reagent-promoted oxidative nonphenolic biaryl coupling reaction. Total synthesis of (S)-(+)-glaucine
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The aporphine alkaloid (+)-glaucine (8a) and two other analogues 8b,c have been synthesized in good yield and high ee from the appropriate 1,2-diarylethylamine derivatives, which were in turn prepared using (S)-(+)-phenylglycinol as chiral support. Next, a sequence of simple transformations: N-alkylation with bromoacetaldehyde diethyl acetal, N-methylation, Pommeranz-Fritsch cyclization, and ionic hydrogenation led to the key intermediate, optically active, 1-benzyltetrahydroisoquinolines 7a-c. The final C-ring closure step was performed by C-C biaryl bond formation by an hypervalent iodine(III) reagent promoted oxidative coupling, affording the target heterocycles 8a-c in good yields and with no racemization at the formerly created stereogenic center.
- Anakabe, Eneritz,Carrillo, Luisa,Badia, Dolores,Vicario, Jose L.,Villegas, Maite
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p. 1093 - 1101
(2007/10/03)
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- A novel straightforward synthesis of enantiopure tetrahydroisoquinoline alkaloids
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A novel, direct, and high-yielding stereoselective method for enantiopure 1-substituted tetrahydroisoquinolines (THIQ) is described. The successful approach, which creates the stereocenter during the formation of the THIQ nucleus is based on (i) formation of chiral 2,3-substituted perhydro-1,3-benzoxazines derived from (-)-8-aminomenthol, (ii) diastereoselective intramolecular ring opening of the N,O-acetal moiety by an arylmetal generated from the substituent at the nitrogen atom in the perhydrobenzoxazine ring, and (iii) removal of the chiral auxiliary appendage. The starting perhydrobenzoxazines are easily prepared from (-)-8-aminomenthol and two different aldehydes, and the intramolecular opening is stereospecific, leading to a single stereoisomer. The method allows the preparation of a wide variety of enantiopure 1-substituted THIQ, with different substituents at C-1, by changing the nature of the starting aldehydes.
- Pedrosa,Andres,Iglesias
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p. 243 - 250
(2007/10/03)
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- Chiral auxiliary mediated pictet-spengler reactions: Asymmetric syntheses of (-)-laudanosine, (+)-glaucine and (-)-xylopinine
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Cyclohexyl-based chiral auxiliaries can be used effectively in an asymmetric Pictet-Spengler synthesis of tetrahydroisoquinoline, aporphine and protoberbine alkaloids. Using this strategy, concise asymmetric syntheses of (-)-laudanosine, (+)-glaucine and (+)- xylopinine have been accomplished.
- Comins, Daniel L.,Thakker, Paresh M.,Baevsky, Matthew F.,Badawi, Mohamed M.
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p. 16327 - 16340
(2007/10/03)
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- Enantioselective synthesis of (R)-(-)-laudanosine and (R)-(-)-glaucine from L-ascorbic acid
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L-Ascorbic acid 1 was converted into L-gulonolactone 2 by catalytic hydrogenation. Treatment of 2 with 3,4-dimethoxyphenylethyl amine 3 afforded amide 4, which in several steps was transformed into the title alkaloids in good enantiomeric excesses. Also, chromium(III) oxide is proposed as an effective catalyst for the conversion of (R)-(-)-laudanosine into (R)-(-)-glaucine.
- Czarnocki, Zbigniew,Mieczkowski, Jozef B.,Ziolkowski, Marek
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p. 2711 - 2720
(2007/10/03)
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- The in vitro degradation of cisatracurium, the R, cis-R'-isomer of atracurium, in human and rat plasma
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Objective: To assess the mechanism and rate of in vitro degradation of cisatracurium in aqueous buffer and in human and rat plasma. Methods: Cisatracurium was incubated in aqueous buffer at various pH values or in human and rat plasma maintained at pH 7.4 with HEPES buffer. Cisatracurium and the degradation products, laudanosine and the monoquaternary alcohol, were quantitated by HPLC with use of fluorescence detection. Results: In Soerenson's phosphate buffer, cisatracurium degraded spontaneously by a chemical process commonly reffered to as "Hofmann elimination." The rate of degradation increased with increasing pH. From pH 6.4 to 7.8 there was a 6.5-fold increase in the rate of degradation of cisatracurium and, on a molar basis, the final decomposition product laudanosine accounted for all of the drug. At a pH of 7.4, cisatracurium degraded with a half-life of about 34.1 +/- 2.1 minutes. Cisatracurium incubated in human plasma degraded with a mean (+/- SD) half-life of 29.2 +/- 3.8 minutes, which is consistent with Hofmann elimination. Besides laudanosine, and unlike that observed in Soerenson's phosphate buffer, significant amounts of the monoquaternary alcohol were formed that slowly degraded to laudanosine. The micromoles of laudanosine formed eventually accounted for the total amount of cisatracurium incubated with human plasma. The monoquaternary alcohol appears to be a product of ester hydrolysis of a monoquaternary acrylate formed during the firts step in Hofmann elimination. Evidence for esterase involvement at this step in the degradation of cisatracurium was based on inhibition studies with O-cresyl benzodioxaphosphorin oxide (CBDP), a specific carboxylesterase inhibitor. The addition of CBDP to human plasma completely blocked the formation of monoquaternary alcohol and converted the degradation of cisatracurium to total Hofmann elimination. In rat plasma cisatracurium was hydrolyzed, with a half-life of only 3 1/2 minutes, by carboxylesterases. The addition of CBDP increased the half-life to 25 minutes, which is consistent with Hofmann elimination. Conclusion: In human plasma the rate-limiting step in the degradation of cisatracurium is Hofmann elimination, with the initial formation of a monoquaternary acrylate. The observation that the monoquaternary alcohol results from ester hydrolysis of the monoquaternary acrylate by plasma esterase(s) explains the presence of the monoquaternary alcohol metabolite in human plasma during clinical studies with cisatracurium. The rapid hydrolysis of cisatracurium by rat plasma relative to human indicates a major species difference in plasma esterase(s).
- Welch, Richard M.,Brown, Alan,Ravitch, Josh,Dahl, Ray
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p. 132 - 142
(2007/10/03)
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- Asymmetric pictet-spengler synthesis of tetrahydroisoquinolines. An enantioselective synthesis of (-)-laudanosine
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A chiral auxiliary mediated Pictet-Spengler reaction was utilized in a synthesis of the tetrahydroisoquinoline alkaloid, (-)-laudanosine.
- Comins, Daniel L.,Badawi, Mohamed M.
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p. 2995 - 2996
(2007/10/02)
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