scholarly journals (2Sp,4R,6R,8Sp)-4,6-Dimethyl-1-phenyl-diferroceno-1-phosphines

Molbank ◽  
10.3390/m1098 ◽  
2019 ◽  
Vol 2019 (4) ◽  
pp. M1098 ◽  
Author(s):  
Philipp Honegger ◽  
Michael Widhalm
Keyword(s):  
Chemical Catalysis ◽  
Single Diastereomer

Ferrocene-based compounds are powerful asymmetric ligands usable for chemical catalysis. We present the synthesis of six new homochiral diferroceno cycles potentially useful as P,O-, P,N- or P,S-ligands. Due to the stereoconservative nature of the SN1 reaction at carbons adjacent to ferrocene units, we obtained a single diastereomer of the 8-membered diferroceno[c,f]heterophosphocines in all cases.

Protein Flexibility Catalyzes a Cell Signaling Reaction of the Ras-GAP Complex

2019 ◽  
Author(s):  
Keiei Kumon ◽  
Masahiro Higashi ◽  
Shinji Saito ◽  
Shigehiko Hayashi
Keyword(s):  
Cell Signaling ◽  
Conformational Changes ◽  
Catalytic Reaction ◽  
Protein Complex ◽  
Enzyme Mechanism ◽  
Activation Free Energy ◽  
Chemical Catalysis ◽  
Simple Chemical ◽  
A Cell ◽  
Enzyme Molecules

Many enzyme molecules exhibit characteristic global and slow dynamics which furnish them with allostery realizing remarkable molecular functionalities more than simple chemical catalysis. However, molecular mechanism of a catalytic reaction associated with the molecular flexibility of enzymes is not well-understood. Here we report a hybrid molecular simulation study on GTPase activity of a Ras-GAP protein complex for cell signaling termination. We unveiled that extensive conformational changes of the protein complex and exclusion of internal water molecules are induced upon the transition state (TS) formation in the catalytic reaction and significantly lower the reaction activation free energy. We also revealed that tumor-related mutations perturb those conformational changes upon the TS formation, leading to reduction of the catalytic activity. The findings of the remarkably dynamic protein conformation directly linking to the catalytic reaction have broad implications for understanding of enzyme mechanism and for developments of allosteric drugs and novel catalysts.

Oxygen defects-stabilized heterogeneous single atom catalysts: preparation, property and catalytic application

2021 ◽  
Author(s):  
Lei Zhang ◽  
Xiu-Fei Zhao ◽  
Zhengqiu Yuan ◽  
Ming Wu ◽  
Hu Zhou
Keyword(s):  
Electronic Structure ◽  
Single Atom ◽  
Metal Species ◽  
Coordination Environment ◽  
Chemical Catalysis ◽  
Catalytic Application ◽  
Oxygen Defects ◽  
Catalysts Preparation

Single atom catalysts (SACs) show outstanding activity and selectivity in chemical catalysis owing to its unique electronic structure and unsaturated coordination environment, in which every dispersed metal species on support...

Cryptic functions of enzymes in chemical catalysis

1983 ◽  
Vol 114 (10) ◽  
pp. 1059-1069 ◽  
Author(s):  
A. Previero ◽  
M-A. Coletti-Previero ◽  
L. Galzigna
Keyword(s):  
Chemical Catalysis

scholarly journals Characterization of the Amino Acids fromNeisseria meningitidisMethionine Sulfoxide Reductase B Involved in the Chemical Catalysis and Substrate Specificity of the Reductase Step

2007 ◽  
Vol 282 (44) ◽  
pp. 32397-32405 ◽  
Author(s):  
Fabrice Neiers ◽  
Sanjiv Sonkaria ◽  
Alexandre Olry ◽  
Sandrine Boschi-Muller ◽  
Guy Branlant
Keyword(s):  
Amino Acids ◽  
Substrate Specificity ◽  
Chemical Catalysis

Combined biological and chemical catalysis in the preparation of oxycodone

Tetrahedron ◽  
2004 ◽  
Vol 60 (3) ◽  
pp. 561-568 ◽  
Author(s):  
Adam J Walker ◽  
Neil C Bruce
Keyword(s):  
Chemical Catalysis

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.

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