Pathway structural correlations

Correlations between the Jc,c couplings and the aldopyranosyl ring configuration and conformation have also been deduced.4 Previous correlations involving Cl and C6 were confirmed, extended and/or modified, and new structural correlations involving C1-C5, through single and dual pathways, specifically for 3/c3,cs, 3 + 3 ci,c4, 3./< 2.< s were proposed. 

In contrast, trans-2 + has a C2h symmetry and a 2Bg ground state, therefore in principle allowing a symmetry preserving pathway to correlate it with the ground state of 1 +. The corresponding C2-symmetric transition structure has, at the QCISD(T)//QCISD level of theory and using a 6-31G basis set, an activation energy of 23.4 kcal/mol. However, a frequency analysis of this transition structure... 

Scheme 18 Proposed geometrical changes that occur at the zinc center during a Zn-OH-promoted substrate hydrolysis reaction. This proposed pathway is based on a Btirgi-Dunitz-type structural correlation for TpR,R -ligated zinc complexes.

This section deals with the application of moments of inertia for defining the geometries of coordination compounds and the structural correlations used to map the minimum energy paths of polytopal rearrangement processes in coordination compounds. The fluxionality of coordination compounds has long been recognised, and the pathways for rearrangement have been the subject of much debate. 

Structure correlation to map reaction pathways might become important in the field of the monoclonal catalytic antibodies [145, 146]. These proteins are produced by the immune system to bind molecules which resemble the transition state of a chemical reaction. They show catalytic properties with high substrate specificity. Reactions can be imagined for which a biochemical catalyst is not yet known (e.g. the Diels-Alder reaction). The rational design of catalysts for these reactions requires detailed information about possible transition-state structures, geometrical and energetic aspects of the ligand/receptor interface and results from structure/reactivity relationships which are available from structure correlation. 

Figure 14 Structure correlation study modeling the pathway for protonation of the Co(CO)3L anion at the metal center. Reproduced from Brammer, L Mareque Rivas, J. C. Spilling, C. D. J. Organomet. Chem. 2000,609,36-43 with permission of Elsevier Science S. A.

Structure correlation and reaction pathways. Conformational analysis. ... 

Although it may be too early to feel absolutely secure about the functional structural correlations, these studies establish that steroids, depending upon their structure, can guide the NADPH hydrogen generated by the hexose monophosphate shunt into either the hydroxylation pathway through the cytochrome P450 electron transport chain or into biosynthetic pathways. 

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