Control of the conformational equilibria in aza-cis-decalins: structural modification, solvation, and metal chelation.
A series of amino alcohol- and diamino-cis-decalins were synthesized and their conformational properties investigated. The equilibrium distributions of the conformational isomers were measured via NMR spectroscopy. The equilibrium ratios depend on the position of the substituents on the decalin ring system and the solvent. The 7-substituted 1-aza-cis-decalins are more likely to adopt the N-in form than the 5-substituted analogues. The N-in form is generally favored in nonpolar solvents, while the N-out form is favored in polar solvents. Complexation with LiClO4 and Et2Zn alters the equilibrium to favor the N-in decalin conformer. Both conformers coordinate lithium ions such that "on/off" conformational switching is not observed for these decalins. Comparison of the results with complexation studies of (-)-sparteine allows the criteria for an ideal "on/off" conformational switch to be defined.
Phuan
Puay-Wah
PW
Department of Chemistry, Roy and Diana Vagelos Laboratories, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Kozlowski
Marisa C
MC
D000438:Alcohols / Q000737:chemistry; D000588:Amines / Q000737:chemistry; D001372:Aza Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D002384:Catalysis; D002614:Chelating Agents / Q000737:chemistry; D008024:Ligands; D008094:Lithium / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008968:Molecular Conformation; D015394:Molecular Structure; D009281:Naphthalenes / Q000138:chemical synthesis* / Q000737:chemistry*; D013034:Sparteine / Q000737:chemistry; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D015032:Zinc / Q000737:chemistry
D000438:Alcohols; D000588:Amines; D001372:Aza Compounds; D002614:Chelating Agents; D008024:Ligands; D009281:Naphthalenes; D013034:Sparteine; C007229:decalin; D008094:Lithium; D015032:Zinc