Molecular Model of Tubocurarine

Curare, the Karib name for the plant from which this molecule is derived, is used in traditional South American medicine and hunting because it is a muscle relaxant. The three papers by Brunsvold and Ostercamp (1, 2, 3) provide us with an abundance of candidates for Featured Molecules this month. All of the major compounds highlighted in the papers, and many of the intermediates in the synthetic schemes, have been added to our collection. Students should note the structural similarities of the various barbiturate species and of the steroid-based compounds, as well as the interesting proto-cage structure of curare. Careful examination of the conformation of the alkyl groups in various of the molecules, when looked at as Newman projections, should convince students that their expectations about staggering substituents on adjacent tetrahedral-like carbon atoms are met in the computations. However, they should also be aware that recent work casts some doubt on the traditional explanation for that staggering (1). Charged species are presented in the collection in ionic form, without counterions (those are given in the papers), and all species except curare and atricurium besylate (molecule 40 in the third paper) were optimized at either HF/631-G(d) or B3LYP/631-G(d). The latter two molecules were optimized using HF/STO-3.
Molecular Model of Tubocurarine   
(Interactive Simulation (1))