Application of a Model Building Approach to Molecular Mechanics (MM3) for Calculating Low‐Energy Conformations of Tetra‐O‐Acyl‐N,N′‐Dialkyl‐D‐Glucaramides

Abstract

A model building approach was used in conjunction with the MM3 molecular mechanics program to find the low‐energy conformations of three tetra‐O‐acyl‐N,N′‐dimethyl‐d‐glucaramide molecules: tetra‐O‐propanoyl‐(2), 2‐methylpropanoyl‐(3) and 2,2‐dimethylpropanoyl‐N,N′‐dimethyl‐d‐glucaramide (4), and tetra‐O‐acetyl‐N,N′‐dihexyl‐d‐glucaramide (5). A set of models was chosen for calculation of the low‐energy conformations of parent tetra‐O‐acetyl‐N,N′‐dimethyl‐d‐glucaramide (1), with additional models required to simulate conformationally more complex diamides 2–5. The dominant low‐energy conformations of 2 and 3 were very similar to that from 1, whereas very sterically constrained 4, with four bulky pendant O‐2,2‐dimethylpropanoyl groups, and 5, with terminal n‐hexyl groups, adopted different conformations. Stereoregular alternating head tail–tail head and repeating head tail–poly(hexamethylene 2,3,4,5‐tetra‐O‐acetyl‐D‐glucaramide) oligomers were graphically generated to provide some insight into the possible conformations of the actual acylated polyamides in nonpolar solution.