Theoretical insights into on-water catalytic effect in the biogenesis of triterpene dimers: from one-step to two-step hetero Diels-Alder reaction

2021 ◽  
Author(s):  
Mariana Quesadas-Rojas ◽  
Gonzalo J. Mena-Rejon ◽  
Carolina S. Castro-Segura ◽  
David Caceres-Castillo ◽  
Ramiro F. Quijano-Quiñones
Keyword(s):  
Aqueous Medium ◽  
Catalytic Effect ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
One Step

The reaction for the formation of the Xuxuarine Atriterpene dimer in an aqueous medium was studied using ONIOM/CPCM-X scheme at ONIOM(M06-2X/6-31G(d,p):PM6) level of theory, along with the inclusion of one...

The Roush Synthesis of ( + )-Superstolide A

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Malignant Cell ◽  
Alder Reaction ◽  
Diels Alder ◽  
Protecting Group ◽  
The Third ◽  
Diels Alder Reaction ◽  
Single Diastereomer ◽  
Superstolide A ◽  
One Step ◽  
Fourth Component

( + )-Superstolide A 3, isolated from the New Caledonian sponge Neosiphonia superstes, shows interesting cytotoxicity against malignant cell lines at ~ 4 ng/mL concentration. The key transformation in the synthesis of 3 described (J. Am. Chem. Soc. 2008, 130, 2722) by William R. Roush of Scripps Florida was the transannular Diels-Alder cyclization of 2, which established, in one step with high diastereocontrol, both the cis decalin and the macrolactone of 3. The octaene 1 was assembled from four stereodefined fragments. The first, the linchpin 6, was prepared from the stannyl aldehyde 4. Homologation gave the enyne 5, which on hydroboration and oxidation gave 6. Earlier, Professor Roush had optimized the crotylation of the protected alaninal 7. In this case, the Brown reagent 8 delivered the desired Felkin product 9. Protection followed by ozonolysis gave the aldehyde 10. Crotylation with the Roush-developed tartrate 11 then gave the alkene 12, setting the stage for conversion to the iodide 13. Coupling of 13 with 6 completed the preparation of 14. The third component of (+)-superstolide A 3, the phosphonium salt 21, was assembled by Brown allylation of the aldehyde 15, to give 17. Protecting group interchange followed by ozonolysis delivered 18, which via Still-Gennari homologation was carried on to 21. Condensation with the fourth component, the aldehyde 22 , and esterification with 14 then gave 1. Under high dilution Suzuki conditions 1 was converted to 2. Storage in CDCl3 for five days, or brief warming, cyclized 2 to a single diastereomer of the transannular Diels-Alder product, that was carried on to (+)-superstolide A 3. While acyclic trienes comparable to 2 could be induced to cyclize, the transannular Diels-Alder reaction proceeded with much higher diastereocontrol.

scholarly journals On the Catalytic Effect of Water in the Intramolecular Diels–Alder Reaction of Quinone Systems: A Theoretical Study

Molecules ◽  
2012 ◽  
Vol 17 (11) ◽  
pp. 13687-13703 ◽  
Author(s):  
Jorge Soto-Delgado ◽  
Arie Aizman ◽  
Renato Contreras ◽  
Luis Domingo
Keyword(s):  
Catalytic Effect ◽  
Theoretical Study ◽  
Alder Reaction ◽  
Diels Alder ◽  
Effect Of Water ◽  
Diels Alder Reaction

One step synthesis of 2-alkenylchromanes via inverse electron-demand Hetero-Diels–Alder reaction of o -quinone methide with unactivated dienes

Tetrahedron ◽  
2016 ◽  
Vol 72 (47) ◽  
pp. 7642-7649 ◽  
Author(s):  
Jian Liu ◽  
Xiaoxiao Wang ◽  
Lubin Xu ◽  
Zhihui Hao ◽  
Liang Wang ◽  
...  
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Quinone Methide ◽  
Inverse Electron Demand ◽  
Diels Alder Reaction ◽  
One Step ◽  
Electron Demand
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