title: Comparison of the crystal structures of 4,4'-bis-[3-(4-methyl-piperidin-1-yl)prop-1-yn-1-yl]-1,1'-biphenyl and 4,4'-bis-[3-(2,2,6,6-tetra-methyl-piperidin-1-yl)prop-1-yn-1-yl]-1,1'-biphen-yl.
abstract: As part of a comprehensive program to discover α9α10 nicotinic acetyl-choline receptor antagonists, the title compounds C30H36N2, (I), and C36H48N2, (II), were synthesized by coupling 4,4'-bis-(3-bromo-prop-1-yn-1-yl)-1,1'-biphenyl with 4-methyl-piperidine and 2,2,6,6-tetra-methyl-piperidine, respectively, in aceto-nitrile at room temperature. In compound (I), the biphenyl system has a twisted conformation with a dihedral angle of 26.57 (6)° between the two phenyl rings of the biphenyl moiety, while in compound (II), the biphenyl moiety sits on a crystallographic inversion centre so the two phenyl rings are exactly coplanar. The terminal piperidine rings in both compound (I) and compound (II) are in the chair conformation. In compound (I), the dihedral angles about the ethynyl groups between the planes of the phenyl rings and the piperidine ring N atoms are 37.16 (16) and 14.20 (17)°. In compound (II), the corresponding dihedral angles are both 61.48 (17)°. There are no noteworthy inter-molecular inter-actions in (I), but in (II) there is a small π-overlap between inversion-related mol-ecules (1 - x, 1 - y, 1 - z), with an inter-planar spacing of 3.553 (3) Å and centroid-to-centroid separation of 3.859 (4) Å.
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
authors.forename: Anqi
authors.initials: A
authors.lastname: Wan
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
authors.forename: Narsimha Reddy
authors.initials: NR
authors.lastname: Penthala
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
authors.forename: E Kim
authors.initials: EK
authors.lastname: Fifer
authors.affiliation: Department of Chemistry, University of Kentucky, Lexington KY 40506, USA.
authors.forename: Sean
authors.initials: S
authors.lastname: Parkin
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Crooks
keywords: biphenyl ring; bis-tertiary ammonium analog; crystal structure; piperidine ring