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1.
Kan-Lei Ji Shu-Fan He Dong-Dong Xu Wen-Xin He Dr. Jian-Feng Zheng Prof. Dr. Pei-Qiang Huang 《Angewandte Chemie (International ed. in English)》2023,62(25):e202302832
A concise asymmetric total synthesis of (−)-quinocarcin has been accomplished with high step economy from commercially available starting materials. A catalytic enantioselective reductive 1,3-dipolar cycloaddition reaction of N-heteroaryl secondary amides with reactive dipolarophiles using iridium/copper relay catalysis was developed to prepare the key chiral pyrrolidine intermediate with three stereocenters. This protocol features excellent regio-, exo- and enantioselectivities, broad substrate scope, and good functional group tolerance. The high efficiency was also ensured by a RhIII-catalyzed C−H activation/cyclization and a tandem diastereoselective hydrogenation/cyclization to construct the tetrahydroisoquinoline-pyrrolidine tetracyclic core unit of quinocarcin. 相似文献
2.
Zezhong Sun Shuang Jin Jianing Song Lihua Niu Fan Zhang Han Gong Xin Shu Prof. Dr. Yunxia Wang Prof. Dr. Xiangdong Hu 《Angewandte Chemie (International ed. in English)》2023,62(47):e202312599
Cephalotaxus diterpenoids are attractive natural products with intriguing molecular frameworks and promising biological features. As a structurally unusual member, (−)-cephalotanin B possesses an extraordinarily congested heptacyclic skeleton, three lactone units, and nine consecutive stereocenters. Herein, we report an enantioselective total synthesis of (−)-cephalotanin B based on a divergent asymmetric Michael addition reaction, a novel Pauson–Khand/deacyloxylation process discovered in the development of a second-generation stereoselective Pauson–Khand reaction protocol, and an epoxide-opening/elimination/dual-lactonization cascade to construct the challenging propeller-shaped A–B–C ring system as key transformations. 相似文献
3.
Giulio Volpin Nynke A. Vepřek Andreas B. Bellan Prof. Dr. Dirk Trauner 《Angewandte Chemie (International ed. in English)》2017,56(3):897-901
Sinoracutine is a recently isolated alkaloid with unusual stereochemical and biological properties. It features an unprecedented tetracyclic 6/6/5/5 skeleton that bears an N-methylpyrrolidine ring fused to a cyclopentenone. Interestingly, both enantiomers of sinoracutine have been independently isolated from the same plant, yet the molecule does not appear to occur as a racemate. Here, we present a short synthesis of (−)-sinoracutine that relies on a highly diastereoselective Pauson–Khand reaction and a Mandai–Claisen reaction to install the quaternary stereocenter. Our work establishes the absolute configuration of the levorotatory isomer and suggests that the optical purity of sinoracutine varies in nature due to its gradual racemization. Experimental evidence supports this proposal, and a plausible mechanism for the racemization is provided. 相似文献
4.
Dr. Kei Yoshida Kosuke Okada Dr. Hirofumi Ueda Prof. Dr. Hidetoshi Tokuyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(51):23289-23293
We have established a highly convergent 10-step route for the total synthesis of (−)-deoxoapodine, which is a hexacyclic aspidosperma alkaloid. The quaternary C5 center of the characteristic tetrahydrofuran ring was constructed by a chiral-phosphoric-acid-catalyzed enantioselective bromocycloetherification in a 5-endo fashion and subsequent allylation by using the Keck protocol. Construction of the aspidosperma skeleton features the formation of a nine-membered lactam by a catalytic C−H palladation/alkylation cascade at the indole 2-position and an iron-catalyzed oxidative transannular reaction at a late-stage of the synthesis. 相似文献
5.
Friederike Ratsch Dr. Waldemar Schlundt Dominik Albat Anne Zimmer Dr. Jörg-Martin Neudörfl Dr. Thomas Netscher Prof. Dr. Hans-Günther Schmalz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(19):4941-4945
A conceptionally new strategy for the asymmetric (2R-selective) synthesis of α-tocopherol (vitamin E) was developed. In the stereocontrolled key step, a prochiral spiro[chromane-2,3′-cyclobutanol] unit is effectively desymmetrized under C−C bond activation in an unprecedented iridium-catalyzed transformation using (S)-DTBM-SegPhos as a chiral ligand (e.r. 97:3). To complete the synthesis, the side chain was attached through Ru-catalyzed cross-metathesis employing an alkene derived from (R,R)-hexahydrofarnesol. To suppress epimerization during the final hydrogenation, PtO2 had to be used as a catalyst instead of Pd/C. In an alternative approach (employing a propargyl-substituted spiro-cyclobutanol), the side chain was constructed prior to the Ir-catalyzed ring fragmentation (>99:1 d.r.) through enyne cross-metathesis (using an alkene derived from (R)-dihydrocitronellal) followed by Cr-catalyzed 1,4-hydrogenation and (diastereoselective) Pfaltz hydrogenation of the resulting triple-substituted olefin. The work demonstrates the potential of iridium catalysis for enantioselective C−C bond activation. 相似文献
6.
Duringthelastdecade,1,3-dioltypechiralbuildingbIocksofvariousconfigurationshavebeensynthesizedandappliedwidelyinthetotalsynthesisofnaturalpolyenemacrolideantibiotics1'2andla,25-dihydroxyvitaminD3analogues'.RecentlyWeigandandBrucker4synthesizedachiralbuildingblock(4R,6R)-2,2-dimethyl-5-tert-butyldip4-hydroxymethyl-l,3-dioxane1inlOsteps.Herein,wereportasyntheticrouteofnewbuildingblock(4S,6S)-2,2-dimethyl-5-tert-butyldip2,anenantiomerofl,startingfromreadilyavailableandinexpensiveD( )-xylose3i… 相似文献
7.
Kathryn Trentadue Dr. Chia-Fu Chang Dr. Ansel Nalin Prof. Richard E. Taylor 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(43):11126-11131
The family of anti-fungal natural products known as the ambruticins are structurally distinguished by a pair of pyran rings adorning a divinylcyclopropane core. Previous characterization of their biosynthesis, including the expression of a genetically modified producing organism, revealed that the polyketide synthase pathway proceeds via a diol intermediate, known as ambruticin J. Herein, we report the first enantioselective total synthesis of the putative PKS product, ambruticin J, according to a triply convergent synthetic route featuring a Suzuki-Miyaura cross-coupling and a Julia-Kocienski olefination for fragment assembly. This synthesis takes advantage of synthetic methodology previously developed by our laboratory for the stereoselective generation of the trisubstituted cyclopropyl linchpin. 相似文献
8.
Dr. Andreas Lerchen Dr. Narasimhulu Gandhamsetty Elliot H. E. Farrar Dr. Nils Winter Dr. Johannes Platzek Dr. Matthew N. Grayson Prof. Dr. Varinder K. Aggarwal 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(51):23307-23311
(−)-Finerenone is a nonsteroidal mineralocorticoid receptor antagonist currently in phase III clinical trials for the treatment of chronic kidney disease in type 2 diabetes. It contains an unusual dihydronaphthyridine core. We report a 6-step synthesis of (−)-finerenone, which features an enantioselective partial transfer hydrogenation of a naphthyridine using a chiral phosphoric acid catalyst with a Hantzsch ester. The process is complicated by the fact that the naphthyridine exists as a mixture of two atropisomers that react at different rates and with different selectivities. The intrinsic kinetic resolution was converted into a kinetic dynamic resolution at elevated temperature, which enabled us to obtain (−)-finerenone in both high yield and high enantioselectivity. DFT calculations have revealed the origin of selectivity. 相似文献
9.
Dr. Qiang-Shuai Gu Prof. Dan Yang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(21):5980-5983
The mitomycins, a family of bioactive natural products, feature a compact 6/5/5-fused polycyclic ring structure densely decorated with highly reactive and/or fragile quinone, amino ketal, and aziridine as well as carbamate moieties. It is this striking feature that has defeated numerous synthetic attempts towards these apparently small molecules, rendering them one of the most formidable targets for total synthesis. We herein report the first enantioselective synthesis of (+)-mitomycin K, a representative of G series mitomycins. The key step of this synthesis is an enantioselective oxidative cyclization catalyzed by a palladium/(+)-sparteine system that had previously been developed by our group. The robustness of this method bodes well for further applications in the asymmetric total synthesis of natural products, particularly those with characteristic 6/5/5-fused pyrroloindole skeletons. 相似文献
10.
Itsara Khantikaew Masato Takahashi Takuya Kumamoto Noriyuki Suzuki Tsutomu Ishikawa 《Tetrahedron》2012,68(3):878-882
(?)-Benzolactam-V8, an artificially-designed cyclic dipeptide with strong tumor-promoter activity, was synthesized from benzyl (S)-N-(2-formylphenyl)-N-methylvalinate by application of guanidinium ylide-participated asymmetric aziridination followed by the reductive ring-opening reaction of 3-arylaziridine-2-carboxylate formed. 相似文献
11.
Rajiv T. Sawant 《合成通讯》2013,43(15):2269-2277
An efficient organocatalytic route for the preparation of enantioselective synthesis of (S)-1-arylpropan-2-ols derivatives, including the key intermediate of antiepileptic agent (?)-talampanel is described. The key steps involved are L-proline-catalyzed asymmetric α-aminooxylation of aldehydes and regioselective tosylation of diols followed by reduction. 相似文献
12.
《Tetrahedron: Asymmetry》2000,11(22):4609-4615
The title compound was prepared in seven steps starting from the commercially available 4-ketopimelic acid. The key step features an enantioselective lactonization promoted by PPL. 相似文献
13.
Zsuzsa M. Jászay Imre Petneházy Árpád Szabó Péter Bakó György Clementis László Töke 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1)
Abstract Enantioselective PTC phosphorylation of aldehydes performed in a two phase (aq. NaOH/toluene) system mediated by chiral crown ether incorporating one or two sugar units. To avoid the rearrangement of hydroxy phosphonate 3 to nonchiral mixed phosphate ester 4 the hydroxy phosphonate was trapped by alkylation to give 5. 相似文献
14.
First Enantioselective Synthesis of Daphneticin 总被引:2,自引:0,他引:2
XinFengREN KunPENG XiaoChuanCHEN XinGangXIE YaMuXIA XinFuPAN 《中国化学快报》2003,14(6):551-554
An enantioselective total synthesis of chiral daphneticin is reported firstly. 相似文献
15.
Vijay K. Chatare Prof. Dr. Rodrigo B. Andrade 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(21):6003-6005
The macrolactone natural product (−)-albocycline is a promising antibiotic candidate for the treatment of both methicillin resistant Staphylococcus aureus (MRSA) and vancomycin-resistant strains. Herein we report a concise total synthesis of (−)-albocycline in 14 steps from commercially available methyl (R)-3-hydroxybutyrate. Novel key steps include the highly regio- and stereoselective reactions of chiral N-sulfinyl metallodienamines (NSMDs) with aldehydes and the Davis oxaziridine, in addition to the Horner–Wadsworth–Emmons olefination of N-sulfinyl imines. 相似文献
16.
Abstract 1,3‐Dipolar cycloaddition of N‐benzyl nitrone 2 to D‐threo δ‐lactone 15 proceeded with excellent stereoselectivity to provide only one adduct 16. Cycloadduct 16 was subsequently subjected to a sequence of reactions involving rearrangement to γ‐lactone, glycolic cleavage/reduction, protection of the terminal hydroxymethyl group, reduction of the lactone, desilylation/mesylation, and hydrogenolysis of the N‐O bond providing (?)‐isofagomine and its N‐substituted derivatives. The biologic activity of N‐substituted (?)‐isofagomines toward commercially available α‐ and β‐glucosidases, α‐D‐mannosidase, α‐L‐fucosidase, β‐D‐glucuronidase, and β‐D‐galactosidase was tested. 相似文献
17.
《Tetrahedron: Asymmetry》2014,25(18-19):1270-1274
Two enantiomers of brazilin were prepared in 9 steps from 7-hydroxychroman-4-one using the AD-mix-α and AD-mix-β-directed enantioselective dihydroxylation of 3-(4-hydroxy-3-methoxyphenyl)-2H-chromen-7-ol as a key step. 相似文献
18.
《Tetrahedron: Asymmetry》2003,14(19):3033-3041
Treatment of radical precursor 15a having a vinyl sulfide moiety with Bu3SnH in the presence of AIBN in boiling benzene afforded exclusively the 6-exo cyclization product 16a, whereas similar treatment of the exo-methylene compound 15b gave a mixture of the 6-exo cyclization product 16b and the endo-olefin product 17 formed by a 1,5-hydrogen shift. Based on these findings, the synthesis of (−)-aphanorphine was achieved using a sulfur-directed 6-exo-selective aryl radical cyclization of 22. 相似文献
19.
Lima Rodrigues Mahesh S. Majik Santosh G. Tilve Solimabi Wahidulla 《Tetrahedron letters》2018,59(37):3413-3415
(?)-Elemoxide, a fragrant compound was synthesised using commercially available elemol in four steps with overall yield of 32%. The cyclic ether skeleton was constructed via intramolecular hydroalkoxylation using I2 and PhSiH3 catalytic system. Also, intramolecular oxymercuration-demercuration was employed as an alternate approach for cyclization. The various regioselective strategies involving epoxidation of alkene, reduction of epoxide and intramolecular cyclization were the highlights of the work. The key intermediate diol serves as a versatile intermediate for the synthesis of elemoxide and elemene. 相似文献
20.
《Tetrahedron: Asymmetry》1998,9(16):2857-2864
The key intermediate 18 for the synthesis of (−)-ovalicin was synthesized using (−)-quinic acid as the chiral source, through a series of stereocontrolled and efficient chemical reactions, thus establishing a new, formal synthesis of the natural target. The featuring spirocyclic epoxide function has been installed by internal Williamson ether synthesis using the functionalities originally present at C-1 of (−)-quinic acid after the appropriate adjustments required to introduce the necessary functionality at C-2. 相似文献