A convenient entry into the rhoeadan skeleton. Total synthesis of (±) cis-alpinigenine

1982 ◽  
Vol 60 (21) ◽  
pp. 2678-2686 ◽  
Author(s):  
Ijaz Ahmad ◽  
Victor Snieckus
Keyword(s):  
Total Synthesis ◽  
Polyphosphoric Acid ◽  
Chromium Trioxide ◽  
Total Syntheses ◽  
Diisobutylaluminum Hydride ◽  
Hydride Reduction ◽  
Villiger Oxidation ◽  
Parallel Series

Condensation of 4-bromoisochroman-3-one (8a) with N-methyl-3,4-dimethoxy-β-phenethylamine (7) provides the aminolactone 9a which by diisobutylaluminum hydride reduction followed by polyphosphoric acid mediated cyclization gives the tetracyclic product 10a, thus constituting a convergent, short entry into the rhoeadan alkaloid skeleton. Chromium trioxide oxidation of 10a affords a low yield of the corresponding lactone 11a. A parallel series of reactions starting from 7,8-dimethoxy-4-bromoisochroman-3-one (8b), prepared either via Baeyer–Villiger oxidation of 4,5-dimethoxy-2-indanone (14) or, more conveniently, via benzeneboronic acid assisted condensation of 3-hydroxy-4-methoxyphenylacetic acid (18) with formaldehyde, yields 7,8,12,13-tetramethoxy-3-methylrhoeadan (10b). Oxidation of compound 10b with chromium trioxide gives the corresponding lactone 11b also in low yield. Since 11b has been previously converted into (±)-cis-alpinigenine (11c) and (±)-cis-alpinine(11d), this work constitutes total syntheses of these alkaloids.

Total synthesis of ylango sesquiterpenoids: (+)-cis- and (+)-trans-sativenediol, (+)-helminthosporal, (+)-helminthosporol, prehelminthosporal, prehelminthosporal diethyl acetal, (+)-victoxinine, (+)-isosativenediol

1977 ◽  
Vol 55 (6) ◽  
pp. 1039-1044 ◽  
Author(s):  
Edward Piers ◽  
Hans-Peter Isenring
Keyword(s):  
Total Synthesis ◽  
Trifluoroacetic Acid ◽  
Chromium Trioxide ◽  
Major Product ◽  
Hydroxy Ketone ◽  
Diethyl Acetal ◽  
Total Syntheses ◽  
Tricyclic Ketone ◽  
Cis And Trans ◽  
Synthetic Transformations

Oxidation of the previously prepared olefinic alcohol 26 with chromium trioxide – pyridine in dichloromethane containing trifluoroacetic acid gave the tricyclic ketone 29 as the major product. Hydroxylation of the latter, followed by reduction of the resulting α-hydroxy ketone 31, afforded a 1:1 mixture of (+)-cis- (22) and (+)-trans-sativenediol (23). In view of earlier synthetic transformations reported by a number of different researchers, the present work also constitutes formal total syntheses of the enantiomers of the following sesquiterpenoids: (−)-helminthosporal (1), (−)-helminthosporol (2), prehelminthosporal (3), prehelminthosporal diethyl acetal (4), (−)-victoxinine (8), and (−)-isosativenediol (19).

Chemistry of the Podocarpaceae. XXXVII. Oxidative degradations of phyllocladene and isophyllocladene : conversion of isophyllocladene into (+)-Podocarp-8(14)-en-13-one

1972 ◽  
Vol 25 (5) ◽  
pp. 959 ◽  
Author(s):  
RC Cambie ◽  
RC Hayward
Keyword(s):  
Chromium Trioxide ◽  
Optically Active ◽  
Oxidative Decarboxylation ◽  
Lithium Aluminium Hydride ◽  
Keto Acid ◽  
Hydride Reduction ◽  
Lithium Aluminium ◽  
Villiger Oxidation

The ozonolysis of phyllocladene (2) and isophyllocladene (12) has been carried out under a number of different conditions and the ozonide (34) of isophyllocladene has been isolated and characterized. Conversion of phyllocladene (2) into the diacid (20) has been accomplished by several routes from the norketone (3). Isophyllocladene (12) has been converted into (+)-podocarp-8(14)-en-13-one (1), an optically active relay which is useful in synthesis. The route involves ozonolysis of isophyllocladene, Baeyer-Villiger oxidation of the keto aldehyde (25), lithium aluminium hydride reduction of the ester (27), and chromium trioxide-pyridine oxidation of the resulting keto aldehyde (32) which gives the keto acid (30) in 26% overall yield. Oxidative decarboxylation then affords the enone (1) in 14% yield.

scholarly journals Xylochemical Synthesis and Biological Evaluation of Shancigusin C and Bletistrin G

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3224
Author(s):  
Leander Geske ◽  
Ulrich Kauhl ◽  
Mohamed E. M. Saeed ◽  
Anja Schüffler ◽  
Eckhard Thines ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Biological Activities ◽  
Biological Evaluation ◽  
Aromatic Substitution ◽  
Substitution Reactions ◽  
Total Syntheses ◽  
Wittig Olefination ◽  
Starting Point ◽  
Perkin Reaction ◽  
Synthesis And Biological Evaluation

The biological activities of shancigusin C (1) and bletistrin G (2), natural products isolated from orchids, are reported along with their first total syntheses. The total synthesis of shancigusin C (1) was conducted by employing the Perkin reaction to forge the central stilbene core, whereas the synthesis of bletistrin G (2) was achieved by the Wittig olefination followed by several regioselective aromatic substitution reactions. Both syntheses were completed by applying only renewable starting materials according to the principles of xylochemistry. The cytotoxic properties of shancigusin C (1) and bletistrin G (2) against tumor cells suggest suitability as a starting point for further structural variation.

Total syntheses and antiproliferative activities of prenostodione and its analogues

2021 ◽  
Author(s):  
Aldahir Ramos Orea ◽  
María Teresa Ramírez-Apan ◽  
Rosa M. Chávez-Santos ◽  
Rodrigo Aguayo-Ortiz ◽  
Clara I Espitia ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Total Synthesis ◽  
Indole Alkaloid ◽  
Total Syntheses ◽  
Antiproliferative Activities

A high-yielding total synthesis of the indole alkaloid prenostodione was completed in 4 steps and 44% overall yield from 1H-indole-3-carboxylic acid. The expedient syntheses of prenostodiones containing distinct substituents at...

scholarly journals Stereoselective total syntheses of (±)-sinularene and (±)-5-epi-sinularene: a general intramolecular Diels–Alder approach to tricyclic sesquiterpenes

1985 ◽  
Vol 63 (4) ◽  
pp. 993-995 ◽  
Author(s):  
Kazimierz Antczak ◽  
John F. Kingston ◽  
Alex G. Fallis
Keyword(s):  
Double Bond ◽  
Methyl Ester ◽  
Total Synthesis ◽  
Ring System ◽  
Diels Alder ◽  
Exocyclic Double Bond ◽  
Total Syntheses ◽  
Methyl Group ◽  
Secondary Hydroxyl ◽  
Selective Hydrogenolysis

Stereoselective total synthesis of (±)-sinularene and (±)-5-epi-sinularene are described. The sequence employs a "blocked" cyclopentadiene in which the cyclopropane unit also serves as a latent methyl group. Thus intramolecular [4 + 2] cycloaddition of the substituted methyl spiro[2.4]hepta-4,6-dien-1-yl)-2-pentenoate 11 affords 5-benzyloxy-6-isopropyl-8-carbomethoxytetracyclo[5.4.01,7.02,4.02,9]undec-10-ene (12) which after selective hydrogenolysis generates the tricyclo[4.4.01,6.02,8]decane (sinularene) ring system. Removal of the secondary hydroxyl function (Ph3P/CCl4/CH3CN; H2/Pd/C), reduction of the methyl ester (LiAlH4), and introduction of the exocyclic double bond (acetate pyrolysis, 550 °C) completes the synthesis of (±)-sinularene in 14 steps from cyclopentadiene. A parallel series of reactions employing the isopropyl epimer of 12 affords (±)-5-epi-sinularene.

Recent Advances in the Total Synthesis of Clavaminols

Synthesis ◽  
2018 ◽  
Vol 50 (23) ◽  
pp. 4569-4576
Author(s):  
Tian Jin ◽  
Lu Zhao ◽  
Zhe-Bin Zheng ◽  
Xiao Liu ◽  
Liang Sun ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Research Groups ◽  
Total Syntheses ◽  
New Class ◽  
Recent Advances ◽  
Molecular Architectures ◽  
Synthetic Approaches ◽  
Long Chain

Clavaminols are a new class of long-chain 2-amino-3-­alkanols that mostly contain 2R,3S-configurations. Owing to their interesting molecular architectures and promising activities, they have ­become popular targets for synthetic organic chemists. In this review, we highlight 12 total syntheses of clavaminols from different research groups during the period 2009 to 2018.1 Introduction2 Synthetic Approaches toward Clavaminols2.1 Total Synthesis by Chemla and Colleagues (2009)2.2 Total Synthesis by Greck and Colleagues (2010)2.3 Total Synthesis by Sutherland and Zaed (2011)2.4 Total Synthesis by Huang and Colleagues (2011)2.5 Total Synthesis by Kotora and Colleagues (2012)2.6 Total Synthesis by Kumar and Colleagues (2013)2.7 Total Synthesis by Prabhavathi Devi and Colleagues (2013 and 2016)2.8 Total Synthesis by Sarabia and Colleagues (2014)2.9 Total Synthesis by Mohapatra and Colleagues (2016)2.10 Total Synthesis by Lu and Colleagues (2016)2.11 Total Synthesis by Jin and Colleagues (2017)2.12 Total Synthesis by Kumar Pandey and Colleagues (2018)3 Conclusion

scholarly journals Total syntheses of all tri-oxygenated 16-phytoprostane classes via a common precursor constructed by oxidative cyclization and alkyl–alkyl coupling reactions as the key steps

2017 ◽  
Vol 15 (44) ◽  
pp. 9408-9414 ◽  
Author(s):  
Jakub Smrček ◽  
Radek Pohl ◽  
Ullrich Jahn
Keyword(s):  
Total Synthesis ◽  
Oxidative Cyclization ◽  
Coupling Reactions ◽  
Total Syntheses ◽  
Common Precursor ◽  
Key Steps

A parallel total synthesis of 16-F1t-, 16-E1-phytoprostanes and a first synthesis of 16-D1t-phytoprostanes based on a common precursor are described.

scholarly journals Oxazolidinones as Chiral Auxiliaries in the Asymmetric 1,4-Conjugate Addition Reaction Applied to the Total Synthesis of Natural Products: A Supplemental Mini-Review

2018 ◽  
Vol 15 (1) ◽  
pp. 3-20 ◽  
Author(s):  
Vahideh Zadsirjan ◽  
Majid M. Heravi
Keyword(s):  
Total Synthesis ◽  
Biological Activities ◽  
Conjugate Addition ◽  
Chiral Auxiliary ◽  
Addition Reactions ◽  
Chiral Auxiliaries ◽  
Complex Molecules ◽  
Total Syntheses ◽  
Naturally Occurring ◽  
Wide Range

Background: The most frequently used chiral auxiliaries, oxazolidinones (Evans' oxazolidinones) have been employed in 1,4-congugate addition reactions to α,β-unsaturated carbonyl compounds. Supplementary to our previous reports in this mini-review, we attempted to underscore the applications of this strategy in a step (steps) in the total synthesis of some naturally occurring compounds exhibiting diverse biological activities. Objective: In this mini-review, we try to underscore the applications of oxazolidinones (Evans’ oxazolidinones) in 1,4-congugate addition reactions to α,β-unsaturated carbonyl in the total synthesis of some naturally occurring compounds exhibiting diverse biological activities. Conclusion: In spite of well-known superiority of asymmetric catalyzed reactions, the use of auxiliarycontrolled reactions are still considered as commanding, vital and sometimes as only tools in the generation of stereogenic centers during the construction of complex molecules and total synthesis of naturally occurring compounds. The commercial availability, or readily accessibility of a wide variety of chiral amino alcohols as starting materials to synthesize a wide range of oxazolidinones is the merits of them. In addition, the ease of removal and subjection to various and diverse stereoselective reactions make oxazolidinones as the ideal and superior chiral auxiliaries. In this regard, they were successfully used in asymmetric 1,4-conjugate addition reactions with high stereoselectivities. The high degree of asymmetric induction can be attributed to the rigid chelation of N-acyloxazolidinones with metal ions, as well as the covering of one face of the system by the bulkiness of 4-substituent. In summary, in this report, the importance of the applications of chiral oxazolidinones as suitable chiral auxiliaries in the stereoselective, 1,4-conjugate addition reactions in asymmetric synthesis and in particular, the total synthesis of naturally occurring compounds and some complex molecules were underscored. Noticeably, in these total syntheses, this chiral auxiliary is controlling the stereochemistry of a newly created stereogenic center as well as preserving the configuration of other chiral centers, which already have been presented in the precursor. General methods have been established for the attachment of the chiral auxiliary as a moiety to the substrate molecule in high to excellent yields. At the end of these reactions, this auxiliary can be easily removed leaving various desired reactive motifs for the next step in multi-step synthesis.

Total synthesis of the potent antifungal agents bengazole C and E

2009 ◽  
Vol 74 (6) ◽  
pp. 887-900 ◽  
Author(s):  
Álvaro Enríquez-García ◽  
Steven V. Ley
Keyword(s):  
Natural Products ◽  
Antifungal Activity ◽  
Total Synthesis ◽  
Marine Natural Products ◽  
Antifungal Agents ◽  
Nitrile Oxide ◽  
Total Syntheses ◽  
Unique Structure

The bengazoles are marine natural products with unique structure, containing two oxazole rings flanking a single carbon. They show very potent antifungal activity. The total syntheses of bengazole C and E are described following a convergent route which involves diastereoselective cycloaddition of an appropriately substituted nitrile oxide with a butane-1,2-diacetal-protected alkenediol as the key step.

scholarly journals Bioinspired Oxidative Cyclization of the Geissoschizine Skeleton for the Enantioselective Total Synthesis of Mavacuran Alkaloids

2019 ◽  
Author(s):  
Maxime Jarret ◽  
Victor Turpin ◽  
Aurélien Tap ◽  
Jean-Francois Gallard ◽  
Cyrille Kouklovsky ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Oxidative Coupling ◽  
Indole Alkaloids ◽  
Oxidative Cyclization ◽  
Total Syntheses ◽  
Enantioselective Total Synthesis ◽  
Biosynthetic Precursor ◽  
Monoterpene Indole Alkaloids ◽  
Coupling Approach

We report the enantioselective total syntheses of mavacurans alkaloids, (+)-taberdivarine H, (+)-16-hydoxymethyl-pleiocarpamine, (+)-16-epi-pleiocarpamine, and their postulated biosynthetic precursor 16-formyl-pleiocarpamine. This family of monoterpene indole alkaloids is a target of choice since some of its members are subunits of intricate bisindole alkaloids such as bipleiophylline. Inspired by the biosynthetic hypothesis, we explored an oxidative coupling approach from the geissoschizine framework to form the N1-C16 bond. Quaternization of the aliphatic nitrogen was key to achieve the oxidative coupling induced by KHMDS/I<sub>2 </sub>since<sub> </sub>it hides the nucleophilicity of the aliphatic nitrogen and locks the required cis conformation.

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