title: Crystal structures of two chiral piperidine derivatives: 1-[(1R)-2-hy-droxy-1-phenyl-eth-yl]piperidin-4-one and 8-[(1S)-1-phenyl-eth-yl]-1,4-dioxa-8-aza-spiro-[4.5]decane-7-thione.
abstract: The crystal structures of the two title piperidine derivatives show different conformations for the six-membered heterocycle. The N-substituted 4-piperidinone 1-[(1R)-2-hy-droxy-1-phenyl-eth-yl]piperidin-4-one, C13H17NO2, (I), has a chair conformation, while the piperidine substituted in position 2 with a thio-carbonyl group, 8-[(1S)-1-phenyl-eth-yl]-1,4-dioxa-8-aza-spiro-[4.5]decane-7-thione, C15H19NO2S, (II), features a half-chair conformation. Comparison of the two structures, and data retrieved from the literature, suggests that the conformational flexibility is mainly related to the hybridization state of the C atom α to the piperidinic N atom: a Csp (3) atom favours the chair conformer, while a Csp (2) atom distorts the ring towards a half-chair conformer. In the crystal structure of (I), weak C-H⋯O hydrogen bonds link the mol-ecules into supra-molecular chains propagating along the b-axis direction. In the crystal of (II), the mol-ecules are linked by weak C-H⋯S contacts into supra-molecular chains propagating along the b-axis direction.
authors.affiliation: Universidad Juárez Autónoma de Tabasco, División Académica de Ciencias Básicas, Km. 1 carretera Cunduacán, Jalpa de Méndez AP 24, Cunduacán, Tabasco, Mexico.
authors.forename: Nancy
authors.initials: N
authors.lastname: Romero
authors.affiliation: Instituto de Física, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, 72570 Puebla, Pue., Mexico.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Bernès
authors.affiliation: Universidad Juárez Autónoma de Tabasco, División Académica de Ciencias Básicas, Km. 1 carretera Cunduacán, Jalpa de Méndez AP 24, Cunduacán, Tabasco, Mexico.
authors.forename: Luis F
authors.initials: LF
authors.lastname: Roa
authors.affiliation: Centro de Química, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, 72570 Puebla, Pue., Mexico.
authors.forename: Joel L
authors.initials: JL
authors.lastname: Terán
authors.affiliation: Centro de Química, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, 72570 Puebla, Pue., Mexico.
authors.forename: Dino
authors.initials: D
authors.lastname: Gnecco
keywords: crystal structure; piperidine; piperidone; ring conformation; thione