MM3(96) CONFORMATIONAL ANALYSIS OF d-GLUCARAMIDE AND X-RAY CRYSTAL STRUCTURES OF THREE d-GLUCARIC ACID DERIVATIVES—MODELS FOR SYNTHETIC POLY(ALKYLENE d-GLUCARAMIDES)

Abstract

An exhaustive conformational analysis of d-glucaramide was carried out using MM3(96) [MM3(96). Molecular Mechanics Software used with permission from N.L. Allinger; University of Georgia]. Nine torsion angles were each driven in increments of 120°, generating 19,683 starting conformations. Each conformation was then fully energy-minimized using MM3's block diagonal/full matrix optimization option at dielectric constants of both 3.5 and 6.5. Conformer populations were calculated based on the modeling results and calculated theoretical average ¹H vicinal coupling constants were compared to experimental values obtained in D ₂O solution. Crystal structures of three acyclic d-glucaric acid derivatives (N, N′-dimethyl- d-glucaramide, dipotassium d-glucarate, and sodium potassium d-glucarate) are reported. These structures and that of previously reported monopotassium glucarate correspond closely with model conformations that were within one kcal/mol of the global minimum.

ACKNOWLEDGMENT

Financial support for this work was provided in part by a Graduate Assistance in Areas of National Need (GAANN) fellowship to S. Styron.