1885-07-0Relevant articles and documents
Design, synthesis and antitumor activity evaluation of Chrysamide B derivatives
Zhu, Longqing,Li, Junfang,Fan, Xiaohong,Hu, Xiaoling,Chen, Jinhong,Liu, Yonghong,Hao, Xiangyong,Shi, Tao,Wang, Zhen,Zhao, Quanyi
, (2021/04/29)
Marine natural products derived from special or extreme environment provide an important source for the development of anti-tumor drugs due to their special skeletons and functional groups. In this study, based on our previous work on the total synthesis and structure revision of the novel marine natural product Chrysamide B, a group of its derivatives were designed, synthesized, and subsequently of which the anti-cancer activity, structure-activity relationships and cellular mechanism were explored for the first time. Compared with Chrysamide B, better anti-cancer performance of some derivatives against five human cancer cell lines (SGC-7901, MGC-803, HepG2, HCT-116, MCF-7) was observed, especially for compound b-9 on MGC-803 and SGC-7901 cells with the IC 50 values of 7.88 ± 0.81 and 10.08 ± 1.08 μM, respectively. Subsequently, cellular mechanism study suggested that compound b-9 treatment could inhibit the cellular proliferation, reduce the migration and invasion ability of cells, and induce mitochondrial-dependent apoptosis in gastric cancer MGC-803 and SGC-7901 cells. Furthermore, the mitochondrial-dependent apoptosis induced by compound b-9 is related with the JAK2/STAT3/Bcl-2 signaling pathway. To conclude, our results offer a new structure for the discovery of anti-tumor lead compounds from marine natural products.
Enhanced enantioselectivity in heterogeneous manganese-catalyzed asymmetric epoxidation with nanosheets modified amino acid Schiff bases as ligands by modulating the orientation and the arrangement order
An, Zhe,Han, Hongbo,He, Jing,Jiang, Yitao,Ping, Qi,Shu, Xin,Song, Hongyan,Tang, Yuanzhong,Wang, Wenlong,Xiang, Xu,Zhu, Yanru
, p. 22 - 36 (2021/08/25)
Catalytic enantioselective epoxidation of olefins plays an important role in the production of optically-active epoxy. Transition-metal complexes prove efficient for the catalytic epoxidation of un-functionalized olefins by employing privileged chiral lig
Enantiocomplementary Epoxidation Reactions Catalyzed by an Engineered Cofactor-Independent Non-natural Peroxygenase
Crotti, Michele,Kataja, Kim M.,Poelarends, Gerrit J.,Saravanan, Thangavelu,Xu, Guangcai
, p. 10374 - 10378 (2020/04/23)
Peroxygenases are heme-dependent enzymes that use peroxide-borne oxygen to catalyze a wide range of oxyfunctionalization reactions. Herein, we report the engineering of an unusual cofactor-independent peroxygenase based on a promiscuous tautomerase that accepts different hydroperoxides (t-BuOOH and H2O2) to accomplish enantiocomplementary epoxidations of various α,β-unsaturated aldehydes (citral and substituted cinnamaldehydes), providing access to both enantiomers of the corresponding α,β-epoxy-aldehydes. High conversions (up to 98 %), high enantioselectivity (up to 98 % ee), and good product yields (50–80 %) were achieved. The reactions likely proceed via a reactive enzyme-bound iminium ion intermediate, allowing tweaking of the enzyme's activity and selectivity by protein engineering. Our results underscore the potential of catalytic promiscuity for the engineering of new cofactor-independent oxidative enzymes.
Recoverable polystyrene-supported catalysts for Sharpless allylic alcohols epoxidations
Bartá?ek, Jan,Drabina, Pavel,Váňa, Ji?í,Sedlák, Milo?
, p. 123 - 132 (2019/02/27)
In this work, new heterogeneous catalysts intended for enantioselective Sharpless epoxidation were prepared. The catalysts are based on Ti(IV) complexes of cross-linked swellable spherical copolymer beads of styrene with ethyl-(4-vinylbenzyl)-L-tartrate, or with ethyl-(2R,3R)-2,3-dihydroxy-4-oxo-5-(4-vinylphenyl)pentanoate. These catalysts were tested in epoxidation of cinnamyl alcohols. High conversion (up to 99%) and high enantioselectivity (up to 99% ee) were achieved in the case of catalysts based on copolymers of styrene with ethyl-(4-vinylbenzyl)-L-tartrate (5, 20, 50%). Unfortunately, the copolymers lost their enantioselectivity due to the leaching of L-tartrate, caused by alcoholysis of ester bond. This problem has been overcome by replacing the ester bond by a stable keto bond. The prepared catalyst based on the copolymer of styrene with ethyl-(2R,3R)-2,3-dihydroxy-4-oxo-5-(4-vinylphenyl)pentanoate (20%) achieved a similarly high conversion and enantioselectivity as in the previous case (up to 99%, up to 99% ee) and was successfully recycled.
A highly stereoselective synthesis of glycidic amides based on a new class of chiral sulfonium salts: Applications in asymmetric synthesis
Sarabia, Francisco,Vivar-García, Carlos,García-Castro, Miguel,García-Ruiz, Cristina,Martín-Gálvez, Francisca,Sánchez-Ruiz, Antonio,Chammaa, Samy
supporting information, p. 15190 - 15201 (2013/01/15)
A new type of chiral sulfonium salts that are characterized by a bicyclic system has been designed and synthesized from α-amino acids. Their corresponding ylides, which were prepared by basic treatment of the sulfonium salts, reacted smoothly with a broad array of simple and chiral aldehydes to provide trans-epoxy amides in reasonable to very good yields and excellent stereoselectivities (>98 %). The obtained epoxy amides were found to be useful as synthetic building blocks. Thus, they were reduced into their corresponding epoxy alcohols and subjected to oxirane-ring-opening reactions with different types of nucleophiles.
Asymmetric epoxidation of α,β-unsaturated aldehydes in aqueous media catalyzed by resin-supported peptide-containing unnatural amino acids
Akagawa, Kengo,Kudo, Kazuaki
experimental part, p. 843 - 847 (2011/06/11)
The enantio- and diastereoselective epoxidation of α,β- unsaturated aldehydes in aqueous media was realized using a resin-supported peptide catalyst. Introducing the hydrophobic and bulky unnatural amino acid 3-(1-pyrenyl)alanine into the peptide sequence was effective for enhancing the reaction rate and enantioselectivity.
A highly efficient methodology of asymmetric epoxidation based on a novel chiral sulfur ylide
Sarabia, Francisco,Chammaa, Samy,Garcia-Castro, Miguel,Martin-Galvez, Francisca
supporting information; experimental part, p. 5763 - 5765 (2010/01/31)
A new type of chiral sulfur ylides has been synthesized and their reactivities against carbonyl compounds tested, showing a high degree of stereoselectivity in the formation of trans epoxy amides under very mild reaction conditions.
Organocatalytic asymmetric epoxidation reactions in water-alcohol solutions
Zhuang, Wei,Marigo, Mauro,Jorgensen, Karl Anker
, p. 3883 - 3885 (2007/10/03)
The diastereo- and enantioselective organocatalytic epoxidation of α,β-unsaturated aldehydes in aqueous solutions is presented. By the screening of the reaction conditions for the epoxidation of cinnamic aldehyde applying hydrogen peroxide as the oxidant and 2-[bis-(3,5-bis-trifluoromethyl- phenyl)-trimethylsilanyloxy-methyl]-pyrrolidine as the catalyst, a highly stereoselective reaction has been developed. The scope of the diastereo- and enantioselective organocatalytic epoxidation in aqueous solutions is documented by the asymmetric epoxidation of α,β-unsaturated aldehydes with enantioselectivities up to 96% ee. The Royal Society of Chemistry 2005.
Methods for protection of stratified squamous epithelium against injury by noxious substances and novel agents for use therefor
-
, (2008/06/13)
Novel sulfate ester agents and the use of those agents for treating gastroesophageal reflux disease (GERD) are described, exemplary agents being of the formula: wherein X is —OCH2— or —CH2O—; Y is a group pendant from X comprising at least one —OSO3R4 moiety, wherein R4 is H or a pharmaceutically acceptable cation; n is an integer from 1-3; and R1 and R2 are each independently selected from the group consisting of —H, a halogen with an atomic number from 9 to 53, —SO3R4, —NCS, —NCO, —NH(CO)—OR3, —NH(CS)SR3, —NH(C═NH)OR3, —NHCOCH2Cl, —NHCOCH2Br, —NHCO—CH═CH2, —NHC(O)—CF3, wherein R4 is H or a pharmaceutically acceptable cation.
Catalytic Asymmetric Epoxidation and Kinetic Resolution: Modified Procedures Including in Situ Derivatization
Gao, Yun,Hanson, Robert M.,Klunder, Janice M.,Ko, Soo Y.,Masamune, Hiroko,Sharpless, K. Barry
, p. 5765 - 5780 (2007/10/02)
The use of 3A or 4A molecular sieves ( zeoiltes ) substantially increases the scope of the titanium(IV)-catalyzed asymmetric epoxidation of primary allylic alcohols.Whereas without molecular sieves epoxidations employing only 5 to 10 mol percent Ti(O-i-Pr)4 generally led to low conversion or low enantioselectivity, in the presence of molecular sieves such reactions generally led to high conversion (>95percent) and high enantioselectivity (90-95percent ee).The epoxidations of 20 primary allylic alcohols are described.Especially noteworthy are the epoxidations of cinnamyl alcohol, 2-tetradecyl-2-propen-1-ol, allyl alcohol, and crotyl alcohol-compounds which heretofore had been considered difficult substrates for asymmetric epoxidation.In the case of allylic alcohol, the use of cumene hydroperoxide substantially increases both the reaction rate and the conversion, even in the absence of molecular sieves.In general, enantioselectivities are slightly depressed (by 1-5percent ee) relative to reactions employing 50-100 mol percent Ti(O-i-Pr)4.The epoxidation of low molecular weight allylic alcohols is especially facilitated and, in conjuction with in situ derivatization, provides for the synthesis of many epoxy alcohol synthons which were previously difficult to obtain.The kinetic resolution of four secondary allylic alcohols with 10 mol percent Ti(O-i-Pr)4 is also described.The role of molecular sieves in the reaction and the effects of variation in reaction stoichiometry, oxidant, and tartrate are discussed.
