ChemInform Abstract: Catalytic Ring-Closing Metathesis: A New, Powerful Technique for Carbon-Carbon Coupling in Organic Synthesis

ChemInform ◽  
2010 ◽  
Vol 26 (51) ◽  
pp. no-no
Author(s):  
H.-G. SCHMALZ
Keyword(s):  
Organic Synthesis ◽  
Ring Closing Metathesis ◽  
Powerful Technique

Alkene and Alkyne Metathesis: Phaseolinic Acid (Selvakumar), Methyl 7-Dihydro-trioxacarcinoside B (Koert), Arglabin (Reiser) and Amphidinolide V (Fürstner)

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Organic Synthesis ◽  
Second Generation ◽  
Secondary Alcohol ◽  
Allylic Alcohol ◽  
Alkyne Metathesis ◽  
Max Planck ◽  
Ring Closing Metathesis ◽  
Relative Configuration ◽  
Stereogenic Centers ◽  
Ru Complexes

As N. Selvakumar of Dr. Reddy’s Laboratories, Ltd., Hyderabad approached (Tetrahedron Lett. 2007, 48, 2021) the synthesis of phaseolinic acid 6, there was some concern about the projected cyclization of 2 to 3, as this would involve the coupling of two electron-deficient alkenes. In fact, the Ru-mediated ring-closing metathesis proceeded efficiently. The product unsaturated lactone 3 could be reduced selectively to either the trans product 4 or the cis product 5. There has been relatively little work on the synthesis of the higher branched sugars, such as the octalose 13, a component of several natural products. The synthesis of 13 (Organic Lett. 2007, 9, 4777) by Ulrich Koert of the Philipps-University Marburg also began with a Baylis-Hillman product, the easily-resolved secondary alcohol 8. As had been observed in other contexts, cyclization of the protected allylic alcohol 9a failed, but cyclization of the free alcohol 9b proceeded smoothly. V-directed epoxidation then set the relative configuration of the stereogenic centers on the ring. Ring-closing metathesis to construct tetrasubstituted alkenes has been a challenge, and specially-designed Ru complexes have been put forward specifically for this transformation. Oliver Reiser of the Universität Regensburg was pleased to observe (Angew. Chem. Int. Ed. 2007, 46, 6361) that the second-generation Grubbs catalyst itself worked well for the cyclization of 17 to 18. Again in this synthesis, catalytic V was used to direct the relative configuration of the epoxide. Intramolecular alkyne metathesis is now well-established as a robust and useful method for organic synthesis. It was also known that Ru-mediated metathesis of an alkyne with ethylene could lead to the diene. The question facing (Angew. Chem. Int. Ed . 2007, 46, 5545) Alois Fürstner of the Max-Planck-Institut, Mülheim was whether these transformations could be carried out on the very delicate epoxy alkene 21. In fact, the transformations of 21 to 22 and of 22 to 23 proceeded well, setting the stage for the total synthesis of Amphidinolide V 25.

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.

Ring-Closing Metathesis and Related Processes in Organic Synthesis

1995 ◽  
Vol 28 (11) ◽  
pp. 446-452 ◽  
Author(s):  
Robert H. Grubbs ◽  
Scott J. Miller ◽  
Gregory C. Fu
Keyword(s):  
Organic Synthesis ◽  
Ring Closing Metathesis

scholarly journals Metal-catalyzed organic reactions by Resonant Acoustic Mixing

2021 ◽  
Author(s):  
Lori Gonnet ◽  
Cameron Lennox ◽  
Jean-Louis Do ◽  
Ivani Malvestiti ◽  
Stefan Koenig ◽  
...  
Keyword(s):  
Ball Milling ◽  
Organic Synthesis ◽  
Mechanochemical Synthesis ◽  
Catalytic Synthesis ◽  
Antidiabetic Drug ◽  
Ring Closing Metathesis ◽  
Reaction Conditions ◽  
Metal Catalyzed ◽  
Resonant Acoustic Mixing ◽  
Model Reactions

We introduce catalytic organic synthesis by Resonant Acoustic Mixing (RAM): a mechanochemical methodology that does not require bulk solvent or milling media. Using as model reactions ruthenium-catalyzed ring-closing metathesis, ene-yne metathesis and copper-catalyzed sulfonamide-isocyanate coupling, we demonstrate RAM-based mechanochemical synthesis that is faster and operationally simpler than conventional ball milling. Moreover, the method can be readily scaled-up, as demonstrated by straightforward catalytic synthesis of the antidiabetic drug Tolbutamide from hundreds of milligrams to at least 10 grams, without any significant changes in reaction conditions.

ChemInform Abstract: Ring-Closing Metathesis and Related Processes in Organic Synthesis

ChemInform ◽  
2010 ◽  
Vol 27 (12) ◽  
pp. no-no
Author(s):  
R. H. GRUBBS ◽  
S. J. MILLER ◽  
G. C. FU
Keyword(s):  
Organic Synthesis ◽  
Ring Closing Metathesis

scholarly journals The issue of ‘molecular radiators’ in microwave-assisted reactions. Computational calculations on ring closing metathesis (RCM)

2014 ◽  
Vol 12 (15) ◽  
pp. 2436-2445 ◽  
Author(s):  
A. M. Rodríguez ◽  
P. Prieto ◽  
A. de la Hoz ◽  
A. Díaz-Ortiz ◽  
J. I. García
Keyword(s):  
Organic Synthesis ◽  
Ring Closing Metathesis ◽  
Microwave Assisted ◽  
Computational Calculations

Computational calculations on ring closing metathesis clarify the influence of molecular radiators in Microwave Assisted Organic Synthesis (MAOS).

Ring Closing Metathesis Approach for the Construction of Carbazoles and Indole-Fused Ring Systems

2021 ◽  
Author(s):  
Tirtha Mandal ◽  
Jyotirmayee Dash
Keyword(s):  
Organic Synthesis ◽  
Biologically Active Compounds ◽  
Biologically Active ◽  
Ring Closing Metathesis ◽  
Active Compounds ◽  
Widespread Occurrence ◽  
Ring Systems ◽  
Fused Ring

The synthesis and functionalization of carbazole ring systems have received considerable attention in organic synthesis due to their widespread occurrence in biologically active compounds . One of the classical methods...

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