281661-31-2Relevant academic research and scientific papers
Total Syntheses of C60- And C100-Dolichols
Hirao, Kohtaro,Ono, Risako,Manabe, Yoshiyuki,Masui, Seiji,Atomi, Haruyuki,Fukase, Koichi
, p. 11549 - 11559 (2020/10/12)
C60- and C100-dolichols were synthesized. A Z-selective Wittig reaction was achieved with high selectivity in a microflow system to realize the scalable supply of the Z-isoprene unit. An isoprene chain was efficiently elongated by an SN2-type coupling between allyl sulfone and allyl chloride using t-BuOK. These key reactions enabled the efficient syntheses of dolichols. This study will pave the way for the functional studies of dolichols.
Characterization of the single-subunit oligosaccharyltransferase STT3A from Trypanosoma brucei using synthetic peptides and lipid-linked oligosaccharide analogs
Ramírez, Ana S.,Boilevin, Jérémy,Biswas, Rasomoy,Gan, Bee Ha,Janser, Daniel,Aebi, Markus,Darbre, Tamis,Reymond, Jean-Louis,Locher, Kaspar P.
, p. 525 - 535 (2017/06/09)
The initial transfer of a complex glycan in protein N-glycosylation is catalyzed by oligosaccharyltransferase (OST), which is generally a multisubunit membrane protein complex in the endoplasmic reticulum but a single-subunit enzyme (ssOST) in some protists. To investigate the reaction mechanism of ssOST, we recombinantly expressed, purified and characterized the STT3A protein from Trypanosoma brucei (TbSTT3A). We analyzed the in vitro activity of TbSTT3A by synthesizing fluorescently labeled acceptor peptides as well as lipid-linked oligosaccharide (LLO) analogs containing a chitobiose moiety coupled to oligoprenyl carriers of distinct lengths (C10, C15, C20 and C25) and with different double bond stereochemistry. We found that in addition to proline, charged residues at the +1 position of the sequon inhibited glycan transfer. An acidic residue at the -2 position significantly increased catalytic turnover but was not essential, in contrast to the bacterial OST. While all synthetic LLO analogs were processed by TbSTT3A, the length of the polyprenyl tail, but not the stereochemistry of the double bonds, determined their apparent affinity. We also synthesized phosphonate analogs of the LLOs, which were found to be competitive inhibitors of the reaction, although with lower apparent affinity to TbSTT3A than the active pyrophosphate analogs.
Formal total synthesis of (-)-spongidepsin
Chandrasekhar,Yaragorla,Sreelakshmi,Reddy, Ch. Raji
, p. 5174 - 5183 (2008/12/20)
The formal total synthesis of (-)-spongidepsin is described. Three fragments I, II, and III were first prepared from readily available starting materials and then assembled to the target compound. The key steps involved in the synthesis are asymmetric α-hydroxylation, Ender's alkylation, and ring-closing metathesis reactions. An alternative route for the fragment II is also achieved involving Sharpless asymmetric epoxidation and Gilman's alkylation as key reactions.
Stereoselective formal total synthesis of the cyclodepsipeptide (-)-spongidepsin
Chandrasekhar, Srivari,Yaragorla, Srinivasa Rao,Sreelakshmi, Lella
, p. 7339 - 7342 (2008/03/14)
The formal total synthesis of (-)-spongidepsin is achieved starting from easily available raw materials involving asymmetric α-hydroxylation, Enders alkylation, and RCM as key reactions.
Synthesis of marine sponge alkaloid hachijodine B and a comment on the structure of ikimine B and on the absolute configuration of niphatesine D
Romeril, Stuart P.,Lee, Victor,Baldwin, Jack E.
, p. 3273 - 3277 (2007/10/03)
The syntheses of the proposed structures of hachijodine B 1, ikimine B 2 and niphatesine D 3 from S-citronellol are described. Our results suggest that the gross structures of hachijodine B and niphatesine D are correct, but that ikimine B was incorrectly
Synthesis and anti-tumor activity of new steroidal nuclear analogues of aragusterol A
Mitome, Hidemichi,Shinohara, Masakazu,Miyaoka, Hiroaki,Yamada, Yasuji
, p. 640 - 645 (2007/10/03)
3α,7α-Dihydroxy-5-epiaragusterol A (3) was synthesized from bile acid (cholic acid) as a new steroidal nuclear analogue of antitumor marine steroid aragusterol A. 7α-Hydroxyaragusterol A (4) was also derived from xestokerol B. The in vitro anti-proliferat
Cyclization into Hydrindanones Using Samarium Diiodide
Sono, Masakazu,Nakashiba, Yasuyo,Nakashima, Katsuyuki,Tori, Motoo
, p. 3099 - 3106 (2007/10/03)
Samarium(II) iodide has been employed to promote vinylogous pinacol coupling reaction of aldehyde onto α,β-unsaturated ketones. The diastereoselectivity of 6-endo products was changed by addition of a proton source and/or HMPA and by the reaction temperature. The cyclization reactions described herein provide a general approach to the syntheses of 3,3-dimethylhydrindanes with a cis-relationship between the OH at C-4 and the proton at C-3a with good diastereoselectivity and under mild reaction conditions.
Complete relative stereochemistry of maitotoxin
Zheng,DeMattei,Wu,Duan,Cook,Oinuma,Kishi
, p. 7946 - 7968 (2007/10/03)
By addressing the relative stereochemistry of the four acyclic portions via organic synthesis, the complete relative stereochemistry of maitotoxin (MTX) has been established as 1B. The relative stereochemistry of the C.1-C.15 portion was elucidated via a two-phase approach: (1) the synthesis of the eight diastereomers possible for model C, representing the C.1-C.11 portion, and the eight diastereomers possible for model D, representing the C.11-C.15 portion, and the comparison of their proton and carbon NMR characteristics with those of MTX, concluding that 9 and 35 represent the relative stereochemistry of the corresponding portions of MTX; (2) the synthesis of the two remote diastereomers 51 and 52, and comparison of their proton and carbon NMR characteristics with those of MTX, concluding that 51 represents the relative stereochemistry of the C.1-C.15 portion of MTX. The relative stereochemistry of the C.35-C.39, C.63-C.68, and C.134-C.142 acyclic portions was established via (1) the synthesis of the 8, 8, and 16 diastereomers possible for models E, F, and G, respectively, and (2) the comparison of their proton and carbon NMR characteristics with those of MTX, concluding that 81, 117, and 187, respectively, represent the relative stereochemistry of the corresponding portions of MTX. Some biogenetic considerations have been given to speculate on the absolute configuration of MTX. The vicinal proton coupling constants observed for models 51, 81, 117, and 187 were used to elucidate their preferred solution conformation. Assembling the preferred solution conformations found for the four acyclic portions allows one to suggest that the approximate global conformation of MTX is represented by the shape of a hook, with the C.35-C.39 portion being its curvature. MTX appears to be conformationally relatively rigid, except for conformational flexibility around the C.7-C.9 and C.12-C.14 portions. On the basis of the experimental results gained in the current work, coupled with those in the AAL-toxin/fumonisin area, it has been pointed out that the structural properties of 51, 81, 117, 187 and their diastereomers are inherent to the specific stereochemical arrangement of the small substituents on the carbon backbone and are independent from the rest of the molecule. Thus, it has been suggested that each of these diastereomers has the capacity to install a unique structural characteristic through a specific stereochemical arrangement of substituents on the carbon backbone, and that fatty acids and related classes of compounds may be able to carry specific information and serve as functional materials in addition to structural materials.
