version date: 1 December 2006 Table 1 Conformational analysis of the acetylcholine molecule(12)visualized through the Newman projection of o-C-C-N bond( Chem 3D and Weblab Viewer). OC(O)CH3 (H3C)3 N OC(O)CH3 兴芋效 Dihedral angle 118 178 238 298 358 Conformations Synclinal Anticlinal Anti- Anticlinal Synclinal Synplanar periplanaR Energy(Kcal/mol) 23 18 15 18 22 37 The energy versus angle graphs corresponding to the different conformations of (12) nay be constructed to interpret and compare their properties, and the steps in the changes are registered and animated. To complete the conformational analysis the students repeat the same task for S-(+)methacholine(13)(Graph 2), a muscarinic cholinergic agonist, to verity the spatial influence of the methyl group by comparing the steric energy versus dihedral angle graphs. In the S-methacholine example, the stable conformation is close to a synclinal with an 80 angle The biologically inactive isomer R-()-methacholine has its stable conformation near the anticlinal form(280%) <www.iupac.org/publications/cd/medicinalchemistry/>11 Table 1 Conformational analysis of the acetylcholine molecule (12) visualized through the Newman projection of O–C–C–N bond (Chem 3D and Weblab Viewer). H H OC(O)CH3 H H N+ (CH3)3 OC(O)CH3 H H H N+(CH3)3 H OC(O)CH3 H H H H N+ (CH3) OC(O)CH3 H H N+ (CH3)3 H H OC(O)CH3 H (H3C)3 H + N H H OC(O)CH3 H H H (H3C)3 +N H OC(O)CH3 H H H N+(CH3)3 H 1 Dihedral angle 58 118 178 238 298 358 Conformations Synclinal (+) Anticlinal (+) Anti￾periplanar Anticlinal (–) Synclinal (–) Synplanar Energy (Kcal/mol) 23 18 15 18 22 37 The energy versus angle graphs corresponding to the different conformations of (12) may be constructed to interpret and compare their properties, and the steps in the changes are registered and animated. To complete the conformational analysis the students repeat the same task for S-(+) methacholine (13) (Graph 2), a muscarinic cholinergic agonist, to verity the spatial influence of the methyl group, by comparing the steric energy versus dihedral angle graphs. In the S-methacholine example, the stable conformation is close to a synclinal with an 80° angle. The biologically inactive isomer R-(–)- methacholine has its stable conformation near the anticlinal form (280°). <www.iupac.org/publications/cd/medicinal_chemistry/> version date: 1 December 2006