123731-68-0Relevant articles and documents
Long-range stereo-relay: Relative and absolute configuration of 1,n-glycols from circular dichroism of liposomal porphyrin esters
MacMillan, John B.,Molinski, Tadeusz F.
, p. 9944 - 9945 (2004)
The relative and absolute configurations of long-chain syn- and anti-1,5-, 1,7- and 1,9-glycols were determined from exciton-coupled circular dichroism (ECCD) of the corresponding bis-5-(4′-carboxyl)-5,10,15,20-tetraphenylporphyrin esters measured in uniform (φ = 26 nm), unilamellar liposomes. Long-range transmission of configuration by ECCD is made possible through partial ordering of glycol ester-lipid molecules by liposomal bilayers. Copyright
Identification of a Grain Beetle Macrolide Pheromone and Its Synthesis by Ring-Closing Metathesis Using a Terminal Alkyne
H?tling, Susann,Bittner, Celine,Tamm, Matthias,D?hn, Sonja,Collatz, Jana,Steidle, Johannes L. M.,Schulz, Stefan
, p. 5004 - 5007 (2015)
A major C18-macrolide was found during analysis of the frass of the storage beetle Oryzaephilus surinamensis to be (9Z,12Z,15R)-octadeca-9,12-dien-15-olide (10, cucujolide XI). The synthesis used ring-closing alkyne metathesis as a key step. The highly active 2,4,6-trimethylbenzylidyne molybdenum complex [MesCMo{OC(CF3)2Me}3] (12) allowed the use of a terminal alkyne and afforded the product in excellent yield. Bioassays proved the activity of the R-enantiomer 10 in the aggregation of the beetle. Cucujolide XI is the first macrolide pheromone oxidized at the ω-4 position.
A formal synthesis of porantheridine and an epimer
Bates, Roderick W.,Lu, Yongna
, p. 9460 - 9465 (2009)
(Chemical Equation Presented) A formal synthesis of porantheridine and a synthesis of its C6-epimer have been completed, employing silver-catalyzed allene cyclization to form a common cis-isoxazolidine intermediate and related N-acyl iminium ion intermediates for side-chain introduction. The stereochemistry of this step can be controlled by choice of the N-protection method.
Comparative molecular field analysis of fenoterol derivatives interacting with an agonist-stabilized form of the β2-adrenergic receptor
Plazinska, Anita,Pajak, Karolina,Rutkowska, Ewelina,Jimenez, Lucita,Kozocas, Joseph,Koolpe, Gary,Tanga, Mary,Toll, Lawrence,Wainer, Irving W.,Jozwiak, Krzysztof
, p. 234 - 246 (2014/01/17)
The β2-adrenergic receptor (β2-AR) agonist [3H]-(R,R′)-methoxyfenoterol was employed as the marker ligand in displacement studies measuring the binding affinities (Ki values) of the stereoisomers of a series of 4′-methoxyfenoterol analogs in which the length of the alkyl substituent at α′ position was varied from 0 to 3 carbon atoms. The binding affinities of the compounds were additionally determined using the inverse agonist [3H]-CGP-12177 as the marker ligand and the ability of the compounds to stimulate cAMP accumulation, measured as EC50 values, were determined in HEK293 cells expressing the β2-AR. The data indicate that the highest binding affinities and functional activities were produced by methyl and ethyl substituents at the α′ position. The results also indicate that the Ki values obtained using [3H]-(R,R′)-methoxyfenoterol as the marker ligand modeled the EC50 values obtained from cAMP stimulation better than the data obtained using [3H]-CGP-12177 as the marker ligand. The data from this study was combined with data from previous studies and processed using the Comparative Molecular Field Analysis approach to produce a CoMFA model reflecting the binding to the β2-AR conformation probed by [3H]-(R,R′)-4′-methoxyfenoterol. The CoMFA model of the agonist-stabilized β2-AR suggests that the binding of the fenoterol analogs to an agonist-stabilized conformation of the β2-AR is governed to a greater extend by steric effects than binding to the [3H]-CGP-12177-stabilized conformation(s) in which electrostatic interactions play a more predominate role.
Bioproduction of chiral epoxyalkanes using styrene monooxygenase from rhodococcus sp. ST-10 (RhSMO)
Toda, Hiroshi,Imae, Ryouta,Itoh, Nobuya
, p. 3443 - 3450 (2015/02/05)
We describe the enantioselective epoxidation of straight-chain aliphatic alkenes using a biocatalytic system containing styrene monooxygenase from Rhodococcus sp. ST-10 and alcohol dehydrogenase from Leifsonia sp. S749. The biocatalyzed enantiomeric epoxidation of 1-hexene to (S)-1,2-epoxyhexane (44.6 mM) using 2-propanol as the hydrogen donor was achieved under optimized conditions. The biocatalyst had broad substrate specificity for various aliphatic alkenes, including terminal, internal, unfunctionalized, and di- and tri-substituted alkenes. Here, we demonstrate that this biocatalytic system is suitable for the efficient production of enantioenriched (S)-epoxyalkanes.
Studies towards the synthesis of neopeltolide: Synthesis of a ring-closing metathesis macrocyclization precursor
Florence, Gordon J.,Cadou, Romain F.
scheme or table, p. 5761 - 5763 (2010/12/18)
An advanced ring-closing metathesis precursor for the synthesis of the marine macrolide neopeltolide is prepared in a stereocontrolled manner by the coupling of the C2-C10 and C11-C16 subunits. The metathesis reaction of 4 with Grubbs' II or Nolan's indenylidene catalyst led to the unexpected formation of cycloheptene 18.
Total synthesis of neopeltolide and analogs
Cui, Yubo,Tu, Wangyang,Floreancig, Paul E.
scheme or table, p. 4867 - 4873 (2010/08/06)
Neopeltolide, a potent cytotoxin from a Carribean sponge, was synthesized through a brief sequence that highlights the use of ethers as oxocarbenium ion precursors. Other key steps include an acid-mediated etherification and sequence that features a Sonogashira reaction, an intramolecular alkyne hydrosilylation reaction, and a Tamao oxidation. The alkene that is required for the oxidative cyclization can be hydrogenated to provide access to the natural product or an epimer, or can be epoxidized or dihydroxylated to form polar analogs.
Total synthesis and biological evaluation of the cytotoxic resin glycosides ipomoeassin A-F and analogues
Nagano, Takashi,Pospisil, Jiri,Chollet, Guillaume,Schulthoff, Saskia,Hickmann, Volker,Moulin, Emilie,Herrmann, Jennifer,Mueller, Rolf,Fuerstner, Alois
supporting information; experimental part, p. 9697 - 9706 (2010/04/29)
A multitasking C-silylation strategy using the readily available compound 26 as a surrogate for cinnamic acid represents the key design element of a total synthesis of all known members of the ipomoeassin family of resin glyosides. This protecting group maneuver allows the unsaturated acids decorating the glucose subunit of the targets to be attached at an early phase of the synthesis, prevents their participation in the ruthenium-catalyzed ring-closing metathesis (RCM) used to form the macrocyclic ring, and protects them against reduc tion during the hydrogenation of the resulting cycloalkene over Wilkinson's catalyst. As the C-silyl group can be concomitantly removed with the O-TBS substituent using tris(dimethylamino)sulfonium difluorotrimethylsilicate (TASF) in acetonitrile, no separate protecting group manipulations were necessary in the final stages, thus contributing to a favorable overall "economy of steps". In addition to the naturally occurring ipomoeassins, a small set of synthetic analogues has also been prepared by "diverted total synthesis". The cytotoxicity of these compounds was assayed with two different cancer cell lines. The recorded data confirm previous findings that the acylation- and oxygenation pattern of these amphiphilic glycoconjugates is highly correlated with their biological activity profile. Ipomoeassin F turned out to be the most promising member of the series, showing IC50 values in the low nanomolar range.
Total syntheses of ipomoeassin B and E
Fuerstner, Alois,Nagano, Takashi
, p. 1906 - 1907 (2007/10/03)
A concise, flexible, and efficient total synthesis of the cytotoxic resin glycosides ipomoeassin B (1) and ipomoeassin E (2) is reported which features the advantages of a novel protecting group strategy employing (Z)-3-dimethyl(phenyl)silyl-2-propenoic acid as cinnamic acid surrogate. The use of this readily available compound allowed the macrocycle of the glycolipids to be formed by ring closing olefin metathesis (RCM) with the aid of the second generation Grubbs carbene complex 12. The resulting E/Z mixture could be selectively hydrogenated using Wilkinson's catalyst [RhCl(PPh3)3] without affecting the unsaturated esters in the periphery of the compound, before the C-silyl group was cleaved off with TASF [tris(dimethylamino)sulfonium difluorotrimethylsilicate] under notably mild conditions to release the required cinnamate moiety. Other key steps of the synthesis route comprise the formation of the disaccharide linkage by the trichloroacetimidate method, the formation of the chiral acid segment 19 via a VO(acac)2-catalyzed, tert-BuOOH-induced oxidative rearrangement of the optically pure furyl alcohol (-)-15 (Achmatowicz-type reaction), and a reductive cleavage of the 4,6-O-p-methoxybenzylidene acetal in 5 with NaBH3CN and Me3SiCl (TMSCl), the regiochemical course of which was found to be opposite to that previously reported in the literature for sterically less encumbered substrates. Copyright
Asymmetric epoxidation of terminal alkenes with hydrogen peroxide catalyzed by pentafluorophenyl PtII complexes
Colladon, Marco,Scarso, Alessandro,Sgarbossa, Paolo,Michelin, Rino A.,Strukul, Giorgio
, p. 14006 - 14007 (2007/10/03)
Easily accessible chiral PtII complexes 1 allow highly enantioselective and completely regioselective asymmetric epoxidation of terminal alkenes with hydrogen peroxide. Copyright
