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1.
A novel strategy for the synthesis of benzofuran skeleton neolignans: application to ailanthoidol,XH-14, and obovaten 总被引:3,自引:0,他引:3
A convenient and general approach to the synthesis of the benzofuran skeleton compounds ailanthoidol, XH-14, and obovaten was developed. Starting from vanillin, a series of reactions afforded 7 in 71% yield. Treatment of 7 with n-BuLi followed by addition of substituted benzaldehydes resulted in the formation of carbinols 11 and 31. The substituted benzophenones obtained from oxidation of 11 and 31 were treated with trimethylsilyldiazomethane lithium salt to give diphenylacetylenes 15 and 33, respectively. 15 and 33 were then cyclized in the presence of either mercury acetate in acetic acid or bromine in chloroform to give 3-chloromercurio- or 3-bromobenzofuran, respectively. The 3-chloromercurio intermediates could be reduced to proton or derivatized to ester or bromide, leading to the synthesis of ailanthoidol, XH-14, and obovaten, respectively. In addition, necleophilic substitution was used to introduce a formyl or methyl group into the 3-bromobenzofuran derivatives, providing an alternative pathway to XH-14 and obovaten. The final elongation and deprotection reaction furnished the desired ailanthoidol, XH-14, and obovaten in yields of 30, 15, and 11%, respectively. 相似文献
2.
Dr. Naoto Yamasaki Ikumi Iwasaki Kazu Sakumi Dr. Rei Hokari Dr. Aki Ishiyama Dr. Masato Iwatsuki Masataka Nakahara Prof. Dr. Shuhei Higashibayashi Prof. Dr. Takeshi Sugai Prof. Dr. Hiroshi Imagawa Prof. Dr. Miwa Kubo Prof. Dr. Yoshiyasu Fukuyama Prof. Dr. Satoshi Ōmura Prof. Dr. Hirofumi Yamamoto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(17):5555-5563
The total synthesis of dehydroantofine was achieved by employing a novel, regioselective, azahetero Diels–Alder reaction of easily accessible 3,5-dichloro-2H-1,4-oxazin-2-one with 14 a as a key step. Furthermore, it is demonstrated that dehydroantofine is a promising candidate as a new antimalarial agent in a biological assay with chloroquine-resistant Plasmodium falciparum. 相似文献
3.
Haruhiko Fuwa Yuta Okuaki Naoya Yamagata Makoto Sasaki 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(3):882-887
(−)‐Lyngbyaloside B is a 14‐membered macrolide glycoside isolated from the marine cyanobacterium Lyngbya sp. as a cytotoxic substance by Moore and co‐workers. The first total synthesis of (−)‐lyngbyaloside B and the reassignment of its stereostructure is described. The synthesis features an Abiko–Masamune aldol reaction, a vinylogous Mukaiyama aldol reaction, and a macrocyclization involving an acyl ketene intermediate for the construction of the macrocyclic backbone, which contains an acylated tertiary alcohol. The antiproliferative activity of selected compounds against a small panel of human cancer cell lines is also reported. 相似文献
4.
Total Synthesis,Stereochemical Reassignment,and Biological Evaluation of (−)‐Lyngbyaloside B
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Prof. Dr. Haruhiko Fuwa Yuta Okuaki Naoya Yamagata Prof. Dr. Makoto Sasaki 《Angewandte Chemie (International ed. in English)》2015,54(3):868-873
(?)‐Lyngbyaloside B is a 14‐membered macrolide glycoside isolated from the marine cyanobacterium Lyngbya sp. as a cytotoxic substance by Moore and co‐workers. The first total synthesis of (?)‐lyngbyaloside B and the reassignment of its stereostructure is described. The synthesis features an Abiko–Masamune aldol reaction, a vinylogous Mukaiyama aldol reaction, and a macrocyclization involving an acyl ketene intermediate for the construction of the macrocyclic backbone, which contains an acylated tertiary alcohol. The antiproliferative activity of selected compounds against a small panel of human cancer cell lines is also reported. 相似文献
5.
A stereoselective synthesis of 14‐membered macrolide hamigeromycin E ( 6 ) has been studied by employing ortho‐lithiated formylation, Barbier allylation, Julia–Kocienski olefination, Mitsunobu esterification, and ring‐closing metathesis (RCM) reactions. The final RCM reaction did not provide the target molecule. This study has prompted us to synthesize a stereoisomer of zeaenol and accomplish the total synthesis with the above protocols. 相似文献
6.
《Helvetica chimica acta》2018,101(4)
The total syntheses of the neural anti‐inflammatory agents guignarderemophilanes C and D have been accomplished for the first time starting from γ‐hydroxy carvone in 15 and 14 steps, respectively. The presented synthetic route proceeds via a known intermediate, whose synthesis has been elaborated in our group in the course of the total synthesis of the sesquiterpenoid periconianone A. Key for the successful conversion of this intermediate into both targets was finding a suitable strategy to install the 1,2,3‐trihydroxylated A‐ring scaffold. For this purpose, we effectively employed a Mitsunobu inversion, epoxidation, and regioselective epoxide opening sequence, before the bicyclic ring system was constructed by an aldol condensation reaction on a sterically demanding substrate. Our reported synthesis set the stage for SAR studies to prepare even more potent compounds by modification and derivatization of the natural product's scaffold. 相似文献
7.
8.
Shuyu Chu Dr. Stephen Wallace Prof. Dr. Martin D. Smith 《Angewandte Chemie (International ed. in English)》2014,53(50):13826-13829
A concise and efficient synthesis of (?)‐gephyrotoxin from L ‐pyroglutaminol has been realized. The key step in this approach is a diastereoselective intramolecular enamine/Michael cascade reaction that forms two rings and two stereocenters and generates a stable tricyclic iminium cation. A hydroxy‐directed reduction of this intermediate plays a key role in establishing the required cis‐decahydroquinoline ring system, enabling the total synthesis of (?)‐gephyrotoxin in nine steps and 14 % overall yield. The absolute configuration of the synthetic material was confirmed by single‐crystal X‐ray diffraction and is consistent with the structure originally proposed for material isolated from the natural source. 相似文献
9.
A new general concept for the total synthesis of pseurotin A ( 1 ), a secondary metabolite of Pseudeurotium ovalis STOLK , which possesses a highly substituted 1-oxa-7-azaspiro[4.4]nonane skeleton, is presented. A key intermediate of the planned reaction sequence is the functionalized γ-lactone 8 . The corresponding protected compound 52 was prepared using (S)-O,O-isopropylideneglyceraldehyde ( 13 ) and the bromoacetal 14 as starting material. γ-Lactone 52 was obtained in enantiomerically pure state in ten steps. It possesses the desired configuration. 相似文献
10.
Kenta Rakumitsu Jukiya Sakamoto Prof. Dr. Hayato Ishikawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(38):8996-9000
The first enantioselective total syntheses of (−)-secologanin ( 1 ), (−)-5-carboxystrictosidine ( 2 ), and (−)-rubenine ( 3 ) were accomplished in 10, 9, and 14 steps, respectively. The key transformation in the synthesis of 1 was a sequential anti-selective organocatalytic Michael reaction/Fukuyama reduction/spontaneous cyclization to form an optically active dihydropyran ring. In addition, the secologanin tetraacetate ( 16 ), which is a potential key intermediate for the bioinspired divergent syntheses of monoterpenoid indole alkaloids, was prepared in gram-scale in seven steps. The total syntheses of 2 and 3 , which are classified as glycosylated monoterpenoid indole alkaloids, were achieved through bioinspired transformations such as a diastereoselective Pictet–Spengler reaction, a site- and stereoselective epoxidation, and a site-selective epoxide ring-opening followed by a lactonization reaction. 相似文献
11.
Singanaboina Rajaram Udugu Ramulu Dasari Ramesh Peddikotla Prabhakar Yenamandra Venkateswarlu 《Helvetica chimica acta》2013,96(11):2115-2123
An efficient stereoselective total synthesis of the bioactive 14‐membered natural macrocyclic bislactone 4‐ketoclonostachydiol is described. The strategy involves a Jacobsen's hydrolytic kinetic resolution (HKR), epoxide opening, MacMillan α‐hydroxylation, Horner? Wadsworth? Emmons olefination, a Grignard reaction, and Hoveyda? Grubbs‐II‐catalyzed ring‐closing metathesis (RCM) as key steps. 相似文献
12.
Thirty years after its discovery by Gilman and Wittig, the Directed ortho Metalation (DoM) reaction continues to march in synthetically useful paths. To offer evidence for this statement, this lecture review describes a new and general cumyl Directed Metalation Group (DMG) (Schemes 2–6) and a phosphine oxide DMG (Schemes 7 and 8). Aryl-aryl cross-coupling chemistry is highlighted by polymer support Suzuki-Miyaura (Schemes 10 and 11) and an aryl O-carbamate-Grignard of value in the construction of naphthalenes (Scheme 12) and indoles (Scheme 13) and, for the latter class of compounds, in the generation of 4,5-quinodimethane intermediates (Scheme 14) for the synthesis of corresponding annelated derivatives (Scheme 15). The marriage of DoM with the Negishi cross-coupling reaction is demonstrated in general (Scheme 16). The concept of Directed remote Metalation (DreM) (Schemes 17 and 19) is applied to the synthesis of dibenzopyranones (Scheme 18), xanthones (Scheme 21), acridones, dibenzoazepinones, and oxindoles (Scheme 20). In this context, a carbanionic N-to-ortho-C t-Boc migration leading to anthranilate esters is also achieved (Scheme 20). For provision of diaryl ethers, diaryl sulfides, and diaryl amines, a new copper catalyst is introduced into the venerable Ullmann reaction (Scheme 22) and its extension by DoM, and cross-coupling chemistry is indicated (Scheme 23). A recently evolving link to DoM, the Grubbs metathesis process is manifested in the total synthesis of two natural products (Schemes 25 and 26) and has anticipated use more broadly in heterocyclic synthesis. (Scheme 27). 相似文献
13.
Bo Xu Bingyang Wang Wen Xun Fayang G. Qiu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(17):5810-5813
A concise and highly stereoselective total synthesis of the Daphniphyllum alkaloids (?)‐daphenylline has been accomplished. The synthesis was started from (S)‐carvone and proceeded via a stereoselective Mg(ClO4)2‐catalyzed intramolecular amide addition cyclization, an intramolecular Diels–Alder reaction to construct the ABCD tetracyclic core architecture, and a Robinson annulation coupled with an oxidative aromatization sequence. Finally, the DF ring system was installed through an intramolecular Friedel–Crafts cyclization. The total synthesis of (?)‐daphenylline is achieved in 19 steps in the longest reaction sequence and in 7.6 % overall yield. 相似文献
14.
A simple and efficient stereoselective total synthesis of sporiolide B and attempted synthesis of sporiolide A, from epichlorohydrin, using asymmetric synthetic approach is reported. The key reactions involved are Sharpless epoxidation, Jacobsen reaction, syn-allylation, Yamaguchi esterification, and Grubbs ring-closing metatheses reaction to result in the macrocyclic ring system. 相似文献
15.
Hossein Eshghi Mehdi Bakavoli Hassanali Moradi 《中国化学快报》2008,19(12):1423-1426
Fe(HSO4)3 has been used as an efficient and recyclable catalyst for the one-pot synthesis of 14-aryl- or alkyl-14Hdibenzo[aj]xanthene derivatives by the reaction of 2-naphtol and aldehydes. Different types of aromatic and aliphatic aldehydes are used in the reaction and in all cases the products were obtained in good to excellent yields. 相似文献
16.
Yonglei Que Hao Shao Dr. Haibing He Prof. Dr. Shuanhu Gao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(19):7514-7519
The asymmetric total synthesis of farnesin, a rearranged ent-kaurenoid, was achieved through a convergent approach involving photo-Nazarov and intramolecular aldol cyclizations to build the syn-syn-syn hydrofluorenol ABC ring system and bicyclo[3.2.1]octane CD ring system in the first application of a UV-light-induced excited-state Nazarov cyclization of a non-aromatic dicyclic divinyl ketone in a total synthesis. Unlike the conventional acid-promoted ground-state Nazarov reaction, the excited-state Nazarov reaction enables stereospecific formation of the highly strained syn-syn-syn-fused hydrofluorenone scaffold through a disrotatory cyclization. 相似文献
17.
Full details of the asymmetric total synthesis of erythro-8-O-4′-neolignan, machilin C, and its analogue perseal A are reported. The synthesis was involved in the Sharpless dihydroxylation
reaction that occurred with excellent asymmetric induction, and the Mitsunobu reaction which occurred with inversion of the
absolute configuration from the threo to the erythro isomer. The synthesis was achieved from simple vanillin in eight to twelve steps. 相似文献
18.
Dr. Kei Kitamura Yoshihiko Maezawa Dr. Yoshio Ando Prof. Dr. Takenori Kusumi Prof. Dr. Takashi Matsumoto Prof. Dr. Keisuke Suzuki 《Angewandte Chemie (International ed. in English)》2014,53(5):1262-1265
A concise, highly convergent total synthesis of saptomycin B, a member of the pluramycin class of antitumor antibiotics, is reported. The target compound was assembled from four building blocks (a tricyclic platform, two sugars, and an alkynal) in 15% yield through 10 synthetic operations. The key steps included the regioselective installation of two amino sugars (L ‐vancosamine and D ‐angolosamine) on the tricycle and the efficient construction of the tetracyclic skeleton by an aldol reaction followed by formation of the pyranone. The unknown configuration at C14 was assigned as R. 相似文献
19.
An Efficient Stereoselective Total Synthesis of Bioactive (3R,5R)‐1‐(4‐Hydroxyphenyl)‐7‐phenylheptane‐3,5‐diol via Asymmetric Aldol Reaction
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An efficient stereoselective total synthesis of (3R,5R)‐1‐(4‐hydroxyphenyl)‐7‐phenylheptane‐3,5‐diol ( 1 ) is reported based on the Mukaiyama aldol reaction. The total synthesis of compound 1 was accomplished with 30% overall yield in simple eight steps from commercially available trans‐cinnamaldehyde. 相似文献
20.
Dr. Govind Goroba Pawar Dr. Ajit Prabhakar Kale Pooja Sah Prof. Manmohan Kapur 《European journal of organic chemistry》2023,26(3):e202201277
The total synthesis of the 14-membered resorcylic acid lactone neocosmosin A is described. The key step in the synthesis is the palladium-catalyzed α-arylation of TES-enol ethers of enones. The employment of the α-arylation approach to this class of resorcylic acid lactones is a new approach, which has the scope of being generalized into a unified approach for the synthesis of this class of natural products. 相似文献