A Total Synthesis of the Styryllactone (+)-Goniodiol from Naphthalene

2003 ◽  
Vol 56 (6) ◽  
pp. 585 ◽  
Author(s):  
Martin G. Banwell ◽  
Mark J. Coster ◽  
Alison J. Edwards ◽  
Ochitha P. Karunaratne ◽  
Jason A. Smith ◽  
...  
Keyword(s):  
Total Synthesis ◽  
First Generation ◽  
Lithium Perchlorate ◽  
Protecting Group ◽  
Microbial Oxidation ◽  
Ring Closing Metathesis ◽  
Enantiomerically Pure ◽  
Benzylic Alcohol ◽  
Acid Catalyzed ◽  
Metal Catalyzed

The cytotoxic natural product (+)-goniodiol (1) has been prepared in twelve steps from the enantiomerically pure cis-dihydrocatechol (2), which is readily obtained by microbial oxidation of naphthalene. Elaboration of compound (2) involves an initial oxidative cleavage to dialdehyde (7) followed by reduction to give diol (12). Conversion of compound (12) into acetal (17) required, inter alia, selective oxidation of the benzylic alcohol moiety followed by a metal-catalyzed decarbonylation of the resulting aldehyde. Allylation of compound (17) with allyltributylstannane in the presence of lithium perchlorate gave a ca. 2.7 : 1 mixture of alcohols (18) and (19), each of which was converted into the corresponding acrylate under standard conditions. Subjection of these ester derivatives to a ring-closing metathesis (RCM) reaction with Grubbs' first-generation catalyst gave the anticipated lactones (22) and (23). Acid-catalyzed removal of the acetonide protecting group within compound (22) then afforded (+)-goniodiol (1), while analogous deprotection of congener (23) afforded 6-epi-(+)-goniodiol (24).

scholarly journals Diastereoselective Total Synthesis of (+)-Raputindole A: An Iridium- Catalyzed Cyclization Approach

2020 ◽  
Author(s):  
Ronaldo Pilli ◽  
Juliana Lira Luna Freire Regueira ◽  
Luiz Fernando Silva Jr.
Keyword(s):  
Total Synthesis ◽  
Heck Reaction ◽  
Enzymatic Resolution ◽  
Enantiomerically Pure ◽  
Tricyclic Core ◽  
Benzylic Alcohol ◽  
Convergent Approach

This work describes the total synthesis of Raputindole A <b>(1)</b> through a convergent approach which features: 1) an iridium-catalyzed cyclization to assembly the tricyclic core of the northern part, 2) enzymatic resolution to secure the preparation of enantiomerically pure benzylic alcohol, 3) installation of the butenyl substituent via methallylation of the corresponding benzylic carbocation and coupling of the northern and southern parts via Heck reaction. (+)-Raputindole A <b>(1)</b> was prepared in 10 steps (LLS) and 10% overall yield.

The Evans Synthesis of (–)-Nakadomarin A

2015 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Organic Synthesis ◽  
Allyl Alcohol ◽  
First Generation ◽  
Direct Conversion ◽  
Heck Coupling ◽  
Ring Closing Metathesis ◽  
Selective Activation ◽  
Enantiomerically Pure ◽  
Ru Catalyst ◽  
Nakadomarin A

(–)-Nakadomarin A (4), isolated from the marine sponge Amphimedon sp. off the coast of Okinawa, shows interesting cytotoxic and antibacterial activity. David A. Evans of Harvard University prepared (J. Am. Chem. Soc. 2013, 135, 9338) 4 by coupling the enantiomerically pure lactam 2 with the prochiral lactam 1. The preparation of 1 began with the aldehyde 5. Following the Comins protocol, addition of lithio morpholine to the carbonyl gave an intermediate that could be metalated and iodinated. Protection of the aldehyde followed by Heck coupling with allyl alcohol gave the aldehyde 7. Addition of the phosphorane derived from 8 followed by deprotection gave 9 with the expected Z selectivity. Addition of the phosphonate 10 was also Z selective, leading to the lactam 1. The preparation of 2 began with the enantiomerically pure imine 12. The addition of 13 was highly diastereoselective, setting the absolute configuration of 15. Alkylation with the iodide 16 delivered 17, which was closed to 2 under conditions of kinetic ring-closing metathesis, using the Grubbs first generation Ru catalyst. The condensation of 1 with 2 gave both of the diastereomeric products, with a 9:1 preference for the desired 3. Experimentally, acid catalysis alone did not effect cyclization, suggesting that the cyclization is proceeding via silylated intermediates. The diastereoselectivity can be rationalized by a preferred extended transition state for the intramolecular Michael addition. Selective activation of 3 followed by reduction gave 18, which underwent Bischler-Napieralski cyclization to give an intermediate that could be reduced to (–)-nakadomarin A (4). It was later found that exposure of 3 to Tf2O and 19 followed by the addition of Redal gave direct conversion to 4. It is instructive to compare this work to the two previous syntheses of 4 that we have highlighted, by Dixon (OHL May 3, 2010) and by Funk (OHL July 4, 2011). Together, these three independent approaches to 4 showcase the variety and dexterity of current organic synthesis.

De novo protecting-group-free total synthesis of (+)-muricadienin, (+)-ancepsenolide and (+)-3-hexadecyl-5-methylfuran-2(5H)-one

2016 ◽  
Vol 14 (38) ◽  
pp. 9072-9079 ◽  
Author(s):  
Rupesh A. Kunkalkar ◽  
Debasish Laha ◽  
Rodney A. Fernandes
Keyword(s):  
Total Synthesis ◽  
De Novo ◽  
Protecting Group ◽  
Ring Closing Metathesis ◽  
Type Coupling

A de novo protecting-group-free total synthesis of (+)-muricadienin, (+)-ancepsenolide and (+)-3-hexadecyl-5-methylfuran-2(5H)-one has been achieved by ring-closing-metathesis and sp–sp3 Sonogashira type coupling.

Protecting-Group-Free Total Synthesis of Anticancer (±)-Melotenine A

Synthesis ◽  
2021 ◽  
Author(s):  
Adisak Thanetchaiyakup ◽  
Hassayaporn Rattanarat ◽  
Sudaporn Aree ◽  
Tanwawan Duangthongyou ◽  
Tanin Nanok ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Human Cancer ◽  
Alder Reaction ◽  
Diels Alder ◽  
Protecting Groups ◽  
Protecting Group ◽  
Ring Closing Metathesis ◽  
Human Cancer Cell Lines ◽  
Diels Alder Reaction ◽  
Key Steps

Melotenine A, isolated from Melodinus tenuicaudatus, possesses significant anticancer activity against several human cancer cell lines. The synthesis of (±)-melotenine A was achieved without the use of any protecting groups in 11 steps with an overall yield of 7%. The key steps of our strategy were the Diels–Alder reaction to construct the tetracyclic framework and ring-closing metathesis to form the seven-membered ring of (±)-melotenine A.

scholarly journals The Pictet-Spengler Reaction Updates Its Habits

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 414 ◽  
Author(s):  
Andrea Calcaterra ◽  
Laura Mangiardi ◽  
Giuliano Delle Monache ◽  
Deborah Quaglio ◽  
Silvia Balducci ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Multicomponent Reaction ◽  
Michael Addition ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
Synthetic Method ◽  
Ring Closing Metathesis ◽  
Phase Synthesis ◽  
Acid Catalyzed ◽  
High Yields

The Pictet-Spengler reaction (P-S) is one of the most direct, efficient, and variable synthetic method for the construction of privileged pharmacophores such as tetrahydro-isoquinolines (THIQs), tetrahydro-β-carbolines (THBCs), and polyheterocyclic frameworks. In the lustro (five-year period) following its centenary birthday, the P-S reaction did not exit the stage but it came up again on limelight with new features. This review focuses on the interesting results achieved in this period (2011–2015), analyzing the versatility of this reaction. Classic P-S was reported in the total synthesis of complex alkaloids, in combination with chiral catalysts as well as for the generation of libraries of compounds in medicinal chemistry. The P-S has been used also in tandem reactions, with the sequences including ring closing metathesis, isomerization, Michael addition, and Gold- or Brønsted acid-catalyzed N-acyliminium cyclization. Moreover, the combination of P-S reaction with Ugi multicomponent reaction has been exploited for the construction of highly complex polycyclic architectures in few steps and high yields. The P-S reaction has also been successfully employed in solid-phase synthesis, affording products with different structures, including peptidomimetics, synthetic heterocycles, and natural compounds. Finally, the enzymatic version of P-S has been reported for biosynthesis, biotransformations, and bioconjugations.

A First Generation Chemoenzymatic Synthesis of (+)-Galanthamine

2010 ◽  
Vol 63 (10) ◽  
pp. 1437 ◽  
Author(s):  
Martin G. Banwell ◽  
Xinghua Ma ◽  
Ochitha P. Karunaratne ◽  
Anthony C. Willis
Keyword(s):  
Total Synthesis ◽  
First Generation ◽  
Claisen Rearrangement ◽  
Starting Material ◽  
Chemoenzymatic Synthesis ◽  
Quaternary Carbon ◽  
Enantiomerically Pure ◽  
Rearrangement Reaction

A total synthesis of (+)-galanthamine [(+)-1] has been achieved using the readily available and enantiomerically pure metabolite 2 as starting material. The quaternary carbon centre (C8a) associated with target 1 was constructed using the Eschenmoser–Claisen rearrangement reaction.

Total Synthesis by Alkene Metathesis: Amphidinolide X (Urpí/Vilarrasa), Dactylolide (Jennings), Cytotrienin A (Hayashi), Lepadin B (Charette), Blumiolide C (Altmann)

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
First Generation ◽  
Allylic Alcohols ◽  
Silyl Ether ◽  
Ring Closing Metathesis ◽  
Enantiomerically Pure ◽  
Ru Catalyst ◽  
Mo Catalyst ◽  
Metathesis Catalysts ◽  
The University ◽  
Medium Rings

To assemble the framework of the cytotoxic macrolide Amphidinolide X 3, Fèlix Urpí and Jaume Vilarrasa of the Universitat de Barcelona devised (Organic Lett. 2008, 10, 5191) the ring-closing metathesis of the alkenyl silane 1. No Ru catalyst was effective, but the Schrock Mo catalyst worked well. In the course of a synthesis of (-)-Dactylolide 6, Michael P. Jennings of the University of Alabama offered (J. Org. Chem. 2008, 73, 5965) a timely reminder of the particular reactivity of allylic alcohols in ring-closing metathesis. The cyclization of 4 to 5 proceeded smoothly, but attempted ring closing of the corresponding bis silyl ether failed. Polyenes such as ( + )-Cytotrienin A 8 are notoriously unstable. It is remarkable that Yujiro Hayashi of the Tokyo University of Science could (Angew. Chem. Int. Ed. 2008, 47, 6657) assemble the triene of 8 by the ring-closing metathesis of the highly functionalized precursor 7. Bicyclo [2.2.2] structures such as 9 are readily available by the addition of, in this case, methyl acrylate to an enantiomerically-pure 2-methylated dihydropyridine. André B. Charette of the Université de Montréal found (J. Am. Chem. Soc. 2008, 130, 13873) that 9 responded well to ring-opening/ring-closing metathesis, to give the octahydroquinoline 10. Functional group manipulation converted 10 into the Clavelina alkaloid ( + )-Lepadin B 11. The construction of trisubstituted alkenes by ring-closing metathesis can be difficult, and medium rings with their transannular strain are notoriously challenging to form. Nevertheless, Karl-Heinz Altmann of the ETH Zürich was able (Angew. Chem. Int. Ed. 2008, 47, 10081), using the H2 catalyst, to cyclize 12 to cyclononene 13, the precursor to the Xenia lactone ( + )-Blumiolide C 14. It is noteworthy that these fi ve syntheses used four different metathesis catalysts in the key alkene forming step. For the cyclization of 7, the use of the Grubbs first generation catalyst G1, that couples terminal alkenes but tends not to interact with internal alkenes, was probably critical to success.

scholarly journals Rapid, two-pot procedure for the synthesis of dihydropyridinones; total synthesis of aza-goniothalamin

2020 ◽  
Vol 16 ◽  
pp. 135-139
Author(s):  
Thomas J Cogswell ◽  
Craig S Donald ◽  
Rodolfo Marquez
Keyword(s):  
Total Synthesis ◽  
Protecting Group ◽  
Ring Closing Metathesis ◽  
One Pot ◽  
High Yields

A fast, protecting-group-free synthesis of dihydropyridinones has been developed. Starting from commercially available aldehydes, a novel one-pot amidoallylation gave access to diene compounds in good yields. Ring-closing metathesis conditions were then employed to produce the target dihydropyridinones efficiently and in high yields.

The total synthesis of (+)-aspicilin using 2,3-butane diacetal protected butane tetrols via a chiral memory protocol

2001 ◽  
Vol 79 (11) ◽  
pp. 1668-1680 ◽  
Author(s):  
Darren J Dixon ◽  
Alison C Foster ◽  
Steven V Ley
Keyword(s):  
Total Synthesis ◽  
Lewis Acid ◽  
Selective Hydrogenation ◽  
Protecting Group ◽  
Ring Closing Metathesis ◽  
Total Syntheses ◽  
Key Steps

The total syntheses of the polyhydroxylated macrolactone (+)-aspicilin and a diastereoisomer have been achieved via a concise route, starting from the spatially desymmetrized (R',R',R,S)-2,3-butanediacetal-protected butane tetrol 13. The key steps include a regioselective silyl protection of 13 and a stereoselective Lewis acid mediated addition of allyltributylstannane to the equatorially disposed aldehyde of 4. Macrocyclization is achieved using ring closing metathesis, after which selective hydrogenation and protecting group removal yields the natural product.Key words: aspicilin, butanediacetal, desymmetrization, macrolactone, metathesis.

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