- A concise total synthesis of amphidinolide T2
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RCM+AD=T2: In the presence of the C16-methylene group, regioselective ring-closing metathesis (RCM) formed the (12E)-endocyclic double bond, which underwent Os-catalyzed asymmetric dihydroxylation (AD) to give the desired 12,13-diol intermediate required
- Li, Huoming,Wu, Jinlong,Luo, Jialu,Dai, Wei-Min
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supporting information; experimental part
p. 11530 - 11534
(2010/11/24)
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- STEREOSELECTIVE SYNTHESIS OF 1-[6-ETHYL-1,2-DIHYDROXY-PROPYL)-PYRIDIN-3-YL]-3-[2-(4-METHYL-PIPERAZIN-1-YL)-BENZYL]-PYRROLIDIN-2-ONE
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The present invention is related to the stereospecific preparation of 1-[6-(1- ethyl-1,2-dihydroxy-propyl)-pyridin-3-yl]-3-[2-(4-methyl-piperazin-1-yl)-benzyl]- pyrrolidin-2-one, and the intermediates thereof. Another aspect of the invention relates to 1-[6-(1 -ethyl- 1,2-dihydroxy-propyl)-pyridin-3-yl]-3-[2-(4-methyl-piperazin-1- yl)-benzyl]-pyrrolidin-2-one, wherein the carbon atoms having the 1,2-dihydroxy substituents are any of the four diastereomers selected from (R,R), (R,S), (S,R), and (S, S), wherein the carbon three of the pyrrolidin-2-one is (R) or (S), pharmaceutically acceptable salts thereof, solvates thereof, pharmaceutical compositions containing them, and methods using them for in treating or preventing depression, anxiety, obsessive compulsive disorder (OCD) and other disorders for which a 5-HT1 agonist or antagonist is indicated.
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Page/Page column 14; 34
(2008/12/06)
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- The effects of sulfur substitution for the nucleophile and bridging oxygen atoms in reactions of hydroxyalkyl phosphate esters
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(Graph Presented) The effects of sulfur substitution on the reactions of hydroxyalkyl phosphate esters are examined. These compounds are models for the intramolecular phosphoryl transfer reaction involved in the cleavage of the internucleotide bond in RNA. The models studied here lack the ribose ring and their conformational flexibility results in greater stability and the availability of different reaction pathways. Sulfur in the nucleophilic position shows no nucleophilic reaction at phosphorus, instead rapidly attacking at the beta carbon atom, forming thiirane with departure of a phosphomonoester. Sulfur substitution at either of the two bridging positions leads to cleavage of the diester via formation of a cyclic intermediate, but with significant rate acceleration when compared to the oxygen analogues. The bridge-substituted models react substantially slower than the analogous ribose compounds with sulfur substitution at comparable positions. Kinetic isotope effects reveal significant differences in the transition state depending on which bridging position sulfur occupies. When sulfur is in the scissile bridging position, a highly associative transition state is indicated, with a largely formed bond to the nucleophile and the scissile P-S bond is little changed. When sulfur occupies the other bridging position, the isotope effects imply a very early transition state in a concerted reaction.
- Iyer, Subashree,Hengge, Alvan C.
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p. 4819 - 4829
(2008/12/20)
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- Altered transition state for the reaction of an RNA model catalyzed by adinuclear zinc(II) catalyst
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The cyclization of 2-(hydroxypropyl)-4-nitrophenyl phosphate (HpPNP) catalyzed by the dinuclear zinc complex of 1,3-bis(1,4,7-triazacyclonon-1-yl)-2- hydroxypropane (1) proceeds by a transition state that is different from that of the uncatalyzed reaction. Kinetic isotope effects (KIEs) measured in the nucleophilic atom and in the leaving group show that theuncatalyzed cyclization has a transition state (TS) with little phospho rus-oxygen bond fission to the leaving group 18klg= 1.0064 ± 0.0009 and 15k = 1.0002 ± 0.0002) a nd that nucleophilic bond formation occurs in the rate-determining step (18knuc ) 1.0326 ( 0.0008). In the catalyzed reaction, larger leaving group isotope effects ( 18klg ) 1.0113 ± 0.0005 and 15k = 1.0015 ± 0.0005) and a smaller nucleophile isotope effect (18k nuc = 1.0116 ± 0.0010) indicate a later TS with greater leaving group bond fission and greater nucleophilic bond formation. These observed nucleophile KIEs are the combined effect of the equilibrium effect on deprotonation of the 2′-hydroxyl nucleophile and the KIE on the nucleophilic step. An EIE of 1.0245 for deprotonation of the hydroxyl group of HPpNP was obtained computationally. The different KIEs for the two reactions indicate that the effective catalysis by 1 is accompanied by selection for an altered transition state, presumably arising from the preferential stabilization by the catalyst of charge away from the nucleophile and toward the leaving group. These results demonstrate the potential fora catalyst using biologically relevant metal ions to select for an alte red transition state for phosphoryl transfer.
- Morrow, Janet R.,Richard, John P.,et al.,Humphry, Tim,Iyer, Subashree,Iranzo, Olga
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experimental part
p. 17858 - 17866
(2009/08/08)
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- MACROCYCLIC COMPOUNDS USEFUL AS PHARMACEUTICALS
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The present invention provides compounds having formula (I), and additionally provides methods for the synthesis thereof and methods for the use thereof in the treatment of various disorders including inflammatory or autoimmune disorders, and disorders involving malignancy or increased angiogenesis, wherein R1 -R11, t, X, Y, Z, and n are as defined herein.
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Page/Page column 134-135
(2010/02/07)
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- Synthesis of (7S,15S)- and (7R,15S)-dolatrienoic acid
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The stereospecific synthesis of (7S,15S)- and (7R,15S)-dolatrienoic acids (2) was achieved using an approach consisting of 16 linear steps. The C-11-C-16 unit was prepared in seven steps from ethyl (S)lactate and coupled using a trans-selective Wittig - Schlosser reaction to the C-7-C-10 fragment. Chirality at the C-7 position was introduced using an Evan's-type chiral auxiliary in a cobalt-mediated Reformatsky reaction to give the (3S,11S)-aldehyde 24. Subsequent Wittig reaction with a phosphonium salt derived in three steps from tiglic acid gave (7S,15S)-dolatrienoic acid, one of the four possible diastereoisomers of the nonpeptide portion of the strong Cancer cell growth inhibitory cyclodepsipeptide dolastatin 14 (1). A second diastereoisomer, (7R,15S)-dolatrienoic acid, was synthesized employing chiral oxazolidinone 21 by an analogous synthetic route.
- Duffield, Jonathan J.,Pettit, George R.
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p. 472 - 479
(2007/10/03)
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