Macrocycles All Aflutter: Substitution at an Allylic Center Reveals the Conformational Dynamics of [13]‐Macrodilactones

Abstract

The shapes adopted by large-ring macrocyclic compounds play a role in their reactivity and their ability to be bound by biomolecules. We investigated the synthesis, conformational analysis, and properties of a specific family of [13]-macrodilactones as models of natural-product macrocycles. The features of our macrodilactones enabled us to study the relationship between stereogenic centers and planar chirality through the modular synthesis of new members of this family of macrocycles. Here we report on insights gained from a new [13]-macrodilactone that is substituted at a position adjacent to the alkene in the molecule. Analysis of the compound, in comparison to an α-substituted regioisomer, by using X-ray crystallography, NMR coupling constants, and reaction-product characterization in concert with computational chemistry, revealed that the alkene unit is dynamic. That is, the data support a model in which the alkene in our [13]-macrodilactones oscillates between two conformations. A difference in reactivity of one conformation compared to the other leads to manifestation of this dynamic behavior. The results underscore the local conformational dynamics observed in some natural-product macrocycles, which could have implications for biomolecule binding.

autoDIAS: a python tool for an automated distortion/interaction activation strain analysis

“…This analysis can be applied to single geometries or multiple geometries along a scan or reaction coordinate, to provide information on the nature of interaction between the fragments and the potential energy surface. This method has been widely applied for a broad range of chemical systems such as cycloadditions, ene reactions, metal complexes and catalysis, organocatalysis, and addition and substitution reactions …”

autoDIAS: A Python Tool for an Automated Distortion/Interaction Activation Strain Analysis

“…This analysis can be applied to single geometries or multiple geometries along a scan or reaction coordinate, to provide information on the nature of interaction between the fragments and the potential energy surface. This method has been widely applied for a broad range of chemical systems such as cycloadditions, [6][7][8][9][10][11][12][13][14][15][16][17][18] ene reactions, 19 metal complexes and catalysis, [20][21][22][23][24][25][26][27] organocatalysis, [28][29][30][31] and addition 32 and substitution reactions. [33][34][35] The implementation of a DIAS analysis is straight forward and can be performed using any electronic structure software.…”