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1.
Dokuburra Chanti Babu Kankati Ashalatha Chitturi Bhujanga Rao Jon Paul Selvam Jondoss Yenamandra Venkateswarlu 《Helvetica chimica acta》2011,94(12):2215-2220
An efficient and short total synthesis of (?)‐cleistenolide ( 1 ) from D ‐mannitol with an overall yield of 23.6% is described. The chiron approach for the synthesis of (?)‐cleistenolide involves a one‐C‐atom Wittig olefination, a selective allylic triethylsilyl protection, and a Grubbs‐catalyzed ring‐closure‐metathesis (RCM) reaction as the key steps. 相似文献
2.
Xinkan Yang Houqiang Lv Xiaoru Shao Cheng Tao Dr. Huifei Wang Dr. Bin Cheng Dr. Yun Li Jingjing Guo Jing Zhang Prof. Dr. Hongbin Zhai 《Angewandte Chemie (International ed. in English)》2018,57(4):947-951
(?)‐Daphnilongeranin B and (?)‐daphenylline are two hexacyclic Daphniphyllum alkaloids, each containing a complex cagelike backbone. Described herein are the first asymmetric total synthesis of (?)‐daphnilongeranin B and a bioinspired synthesis of (?)‐daphenylline with an unusual E ring embedded in a cagelike framework. The key features include an intermolecular [3+2] cycloaddition, a late‐stage aldol cyclization to install the F ring of daphnilongeranin B, and a bioinspired cationic rearrangement leading to the tetrasubstituted benzene ring of daphenylline. 相似文献
3.
The total synthesis of the naturally occurring noncyanogenic cyanoglucoside (?)‐lithospermoside ( 1 ) was achieved starting from optically pure oxatrinorbornenone (+)‐ 2 in 12 steps and 10% overall yield. The key step of the synthesis, the glycosidation, turned out to be very sensitive to steric hindrance, and we had, therefore, to optimize the choice of the protection used for the two other OH functions of the aglycone. Finally, the desired β‐D ‐glucoside 15 was obtained in a very good yield (72%) under Koenigs–Knorr‐glycosidation conditions, closely related to those used for the total synthesis of (?)‐bauhinin. 相似文献
4.
Koichiro Ota Naoto Sugata Yoshihiko Ohshiro Dr. Etsuko Kawashima Dr. Hiroaki Miyaoka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(42):13531-13537
(?)‐Hybridalactone ( 1 ) is a marine eicosanoid isolated from the red alga Laurencia hybrida. This natural product contains cyclopropane, cyclopentane, 13‐membered macrolactone and epoxide ring systems incorporating seven stereogenic centers. Moreover, this compound has an acid‐labile skipped Z,Z‐diene motif. In this paper, we report on the total synthesis of (?)‐hybridalactone ( 1 ). The unique eicosanoid (?)‐hybridalactone ( 1 ) was synthesized starting from optically active γ‐butyrolactone 2 in a linear sequence comprising 21 steps with an overall yield of 21.9 %. A key step in the synthesis of (?)‐hybridalactone ( 1 ) is the methyl phenylsulfonylacetate‐mediated one‐pot synthesis of the cis‐cyclopropane‐γ‐lactone derivative. This reaction provided an efficient and stereoselective access to cis‐cyclopropane‐γ‐lactone 12 . Further elaboration of the latter compounds through desulfonylation, epoxidation, oxidation, Wittig olefination and Shiina macrolactonization afforded (?)‐hybridalactone. 相似文献
5.
Organocatalytic Asymmetric Mannich Cyclization of Hydroxylactams with Acetals: Total Syntheses of (−)‐Epilupinine, (−)‐Tashiromine,and (−)‐Trachelanthamidine
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Dr. Dipankar Koley Yarkali Krishna Kyatham Srinivas Afsar Ali Khan Ruchir Kant 《Angewandte Chemie (International ed. in English)》2014,53(48):13196-13200
An asymmetric, organocatalytic, one‐pot Mannich cyclization between a hydroxylactam and acetal is described to provide fused, bicyclic alkaloids bearing a bridgehead N atom. Both aliphatic and aromatic substrates were used in this transformation to furnish chiral pyrrolizidinone, indolizidinone, and quinolizidinone derivatives in up to 89 % yield and 97 % ee. The total syntheses of (?)‐epilupinine, (?)‐tashiromine, and (?)‐trachelanthamidine also achieved to demonstrate the generality of the process. 相似文献
6.
Concise Syntheses of bis‐Strychnos Alkaloids (−)‐Sungucine, (−)‐Isosungucine,and (−)‐Strychnogucine B from (−)‐Strychnine
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Dr. Senzhi Zhao Christiana N. Teijaro Heng Chen Dr. Gopal Sirasani Dr. Shivaiah Vaddypally Prof. Dr. Michael J. Zdilla Prof. Dr. Graham E. Dobereiner Prof. Dr. Rodrigo B. Andrade 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(33):11593-11596
The first chemical syntheses of complex, bis‐Strychnos alkaloids (?)‐sungucine ( 1 ), (?)‐isosungucine ( 2 ), and (?)‐strychnogucine B ( 3 ) from (?)‐strychnine ( 4 ) is reported. Key steps included (1) the Polonovski–Potier activation of strychnine N‐oxide; (2) a biomimetic Mannich coupling to forge the signature C23?C5′ bond that joins two monoterpene indole monomers; and (3) a sequential HBr/NaBH3CN‐mediated reduction to fashion the ethylidene moieties in 1 – 3 . DFT calculations were employed to rationalize the regiochemical course of reactions involving strychnine congeners. 相似文献
7.
Lei Li Qiao Yang Dr. Yuan Wang Prof. Yanxing Jia 《Angewandte Chemie (International ed. in English)》2015,54(21):6255-6259
The catalytic asymmetric total syntheses of (?)‐galanthamine ( 1 ) and (?)‐lycoramine ( 2 ) have been achieved by using a conceptually new strategy featuring two metal‐catalyzed reactions as the key steps. A new method for the construction of 3,4‐fused benzofurans has been developed through a palladium‐catalyzed intramolecular Larock annulation reaction, which was successfully applied to the construction of the ABD tricyclic skeleton of 1 and 2 . To achieve the asymmetric synthesis of 1 and 2 , a ScIII/N,N′‐dioxide complex was used to catalyze the enantioselective conjugate addition of 3‐alkyl‐substituted benzofuranone to methyl vinyl ketone for the construction of a chiral quaternary carbon center. 相似文献
8.
Concise and Enantioselective Total Synthesis of (−)‐Mehranine, (−)‐Methylenebismehranine,and Related Aspidosperma Alkaloids
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Dr. Marius Mewald Dr. Jonathan William Medley Prof. Dr. Mohammad Movassaghi 《Angewandte Chemie (International ed. in English)》2014,53(43):11634-11639
We report an efficient and highly stereoselective strategy for the synthesis of Aspidosperma alkaloids based on the transannular cyclization of a chiral lactam precursor. Three new stereocenters are formed in this key step with excellent diastereoselectivity due to the conformational bias of the cyclization precursor, leading to a versatile pentacyclic intermediate. A subsequent stereoselective epoxidation followed by a mild formamide reduction enabled the first total synthesis of the Aspidosperma alkaloids (?)‐mehranine and (+)‐(6S,7S)‐dihydroxy‐N‐methylaspidospermidine. A late‐stage dimerization of (?)‐mehranine mediated by scandium trifluoromethanesulfonate completed the first total synthesis of (?)‐methylenebismehranine. 相似文献
9.
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
10.
Dr. James D. Firth Dr. Steven J. Canipa Dr. Leigh Ferris Prof. Peter O'Brien 《Angewandte Chemie (International ed. in English)》2018,57(1):223-226
An 8‐step, gram‐scale synthesis of the (?)‐sparteine surrogate (22 % yield, with just 3 chromatographic purifications) and a 10‐step, gram‐scale synthesis of (?)‐sparteine (31 % yield) are reported. Both syntheses proceed with complete diastereocontrol and allow access to either antipode. Since the syntheses do not rely on natural product extraction, our work addresses long‐term supply issues relating to these widely used chiral ligands. 相似文献
11.
Suckchang Hong Myunggi Jung Yohan Park Min Woo Ha Cheonhyoung Park Dr. Myungmo Lee Prof. Dr. Hyeung‐geun Park 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(29):9599-9605
A new efficient and concise enantioselective synthetic method for (?)‐horsfiline is reported. (?)‐Horsfiline could be obtained from diphenylmethyl tert‐butyl malonate in 9 steps (32 %,>99 % ee) by using the enantioselective phase‐transfer catalytic allylation (91 % ee) as the key step. This approach can be applied as a practical route for the large‐scale synthesis of spirooxindole natural products, which enables a systematic investigation of their biological activity to be performed. 相似文献
12.
A simple and efficient enantioselective synthesis of chromene, (?)‐(R)‐cordiachromene ( 1 ), and (?)‐(R)‐dictyochromenol ( 2 ) has been accomplished. This convergent synthesis utilizes intramolecular SNAr reaction for the formation of chroman ring, and Seebach's method of ‘self‐reproduction of chirality’ should establish the (R)‐configuration of the C(2) side chain as key steps. 相似文献
13.
Huan Luo Yanfei Liu Dong Liang Zhiyou Hao Yan Wang Chunlei Zhang Qingjian Zhang Dequan Yu 《Helvetica chimica acta》2013,96(10):1936-1942
The first asymmetric total synthesis of (?)‐ligustiphenol is reported. The key step was conducted by exploiting a steric hindrance effect to control the formation of the adduct in a nucleophilic α‐Li‐phenolate addition reaction to the intermediate α‐oxo (?)‐menthyl ester. The synthesis is concise and feasible for the construction of analogous compounds and investigation of their biological activity. 相似文献
14.
Mujahid Mohammad Venkaiah Chintalapudi Jeffrey M. Carney Steven J. Mansfield Pollyanna Sanderson Kirsten E. Christensen Edward A. Anderson 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(50):18345-18349
A highly convergent strategy for the synthesis of the natural product (?)‐rubriflordilactone B, and the proposed structure of (?)‐pseudo‐rubriflordilactone B, is described. Late stage coupling of diynes containing the respective natural product FG rings with a common AB ring aldehyde precedes rhodium‐catalyzed [2+2+2] alkyne cyclotrimerization to form the natural product skeleton, with the syntheses completed in just one further operation. This work resolves the uncertainty surrounding the identity of pseudo‐rubriflordilactone B and provides a robust platform for further synthetic and biological investigations. 相似文献
15.
Prof. Dr. Lutz F. Tietze Stefan Jackenkroll Dr. Christian Raith Dr. Dirk A. Spiegl Johannes R. Reiner Maria Claudia Ochoa Campos 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(15):4876-4882
For the synthesis of (?)‐diversonol (ent‐ 1 ), an enantioselective domino‐Wacker/carbonylation/methoxylation reaction and an enantioselective Wacker oxidation were used to give the chroman in high yield and 96 % and 93 % ee, respectively. Dihydroxylation at the vinyl moiety using the Sharpless procedure and a Wittig–Horner reaction followed by hydrogenation, benzylic oxidation, and an intramolecular acylation provided the tetrahydroxanthenone, from which ent‐ 1 is accessible in a few steps. Furthermore, the synthesis of the diastereomeric diversonol rac‐1,9 a‐epi‐diversonol (rac‐ 41 ) is also described. 相似文献
16.
Bo Xu Wen Xun Shaobin Su Hongbin Zhai 《Angewandte Chemie (International ed. in English)》2020,59(38):16475-16479
Cyclopianes are novel diterpenes featuring a highly strained 6/5/5/5 tetracyclic core embedded with 6–8 consecutive stereocenters. The concise total syntheses of (?)‐conidiogenone B, (?)‐conidiogenone, and (?)‐conidiogenol have been accomplished in 14–17 steps. The present work features a HAT‐mediated alkene–nitrile cyclization to access the cis‐biquinane, a Nicholas/Pauson–Khand reaction to construct the linear triquinane, and a Danheiser annulation to afford the congested angular triquinane skeleton. 相似文献
17.
An efficient, stereocontrolled total synthesis of the complex indole‐diterpene alkaloid (?)‐21‐isopentenylpaxilline ( 1 ) has been achieved. Key elements of the synthesis include the stereocontrolled construction of the advanced eastern hemisphere (?)‐ 68 , involving a highly efficient union of the eastern and western fragments (?)‐ 68 and 5 exploiting our 2‐substituted indole synthesis, application of the Negishi π cycloalkylation tactic as a new, potentially general protocol for the construction of ring C, and the fragmentation of a β,γ‐epoxy ketone to introduce the tertiary OH group at C(13) in the indole diterpene skeleton. 相似文献
18.
Xiaobei Wang Dongliang Xia Ling Tan Huan Chen Hongxiu Huang Dr. Hao Song Prof. Dr. Yong Qin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(41):14602-14607
Total syntheses of (?)‐isoschizogamine and (?)‐2‐hydroxyisoschizogamine are described. The synthesis employs two asymmetric Michael additions to establish chiral centers at C7 and the quaternary carbon C20. Regioselective reduction of the methylthioiminium cation rather than the enamine generates an isoschizogamine‐type pentacyclic skeleton. Acidic hydrolysis of the isoschizogamine‐type intermediate in the absence of oxygen provides natural (?)‐isoschizogamine. Conducting the reaction in the presence of oxygen leads to a multistep oxidative hydrolysis cascade that affords unnatural (?)‐2‐hydroxyisoschizogamine. 相似文献
19.
A highly stereoselective route to the polysubstituted chiral octahydrobenzofuran 12 , a potential synthon for the E‐ring core in the (?)‐reserpine synthesis, is described. The α‐bromo acetal 11 was obtained from inexpensive (?)‐shikimic acid ( 3 ) through a series of highly stereoselective chemical reactions (Scheme). Et3B/Bu3SnH‐Mediated intramolecular radical cyclization of 11 led to compound 12 with the required configuration. 相似文献
20.
Wen‐Kuan WANG Ji‐Yong ZHANG Jin‐Mei HE Shi‐Bing TANG Xiao‐Lei WANG Xue‐Gong SHE Xin‐Fu PAN 《中国化学》2008,26(6):1109-1113
An enantioselective total synthesis of (?)‐cladospolide B was described. The key steps in this synthesis include(a) a Sharpless asymmetric dihydroxylation to elaborate syn diol at C‐4 and C‐5 positions; (b) a Mitsunobu esterification to reverse the configuration at C‐11 from (S) to (R); and (c) a ring‐closing metathesis to access the 12‐membered macrocyclic ring. 相似文献