title: Do spiroarsoranes exhibit polytopal equilibrium in solution?
abstract: The spiroarsoranes 5-phenyl-1,6-dioxa-4,9-diaza-5lambda(5)-arsaspiro[4.4]nonane (6), (3R,8R)-3,8-dimethyl-5-phenyl-1,6-dioxa-4,9-diaza-5lambda(5)-arsaspiro[4.4]nonane (7), (2S,7S)-2,7-dimethyl-5-phenyl-1,6-dioxa-4,9-diaza-5lambda(5)-arsaspiro[4.4]nonane (8), and (3S,8S)-3,8-dimethyl-(2R,7R)-2,5,7-triphenyl-1,6-dioxa-4,9-diaza-5lambda(5)-arsaspiro[4.4]nonane (9) were prepared by reaction of phenylarsonic acid and the correspondig amino alcohol. The presence of polytopal Delta left arrow over right arrow Lambda equilibrium in 6-9 was demonstrated by HPLC and NMR studies. NBO computations at the MP2/6-31+G(2d,2p) level indicate that methyl substitution in C2 or C3 of the oxazarsolane ring determines the predominance of Delta or Lambda stereoisomers. GIAO B3LYP/6-311++G(2d,2p) computations were used to assign experimental (1)H and (13)C NMR spectra.
authors.affiliation: Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Hidalgo, Carretera Pachuca-Tulancingo Km. 4.5, Mineral de la Reforma, 42184 Hidalgo, México.
authors.forename: Antonio R
authors.initials: AR
authors.lastname: Tapia-Benavides
authors.forename: Luis H
authors.initials: LH
authors.lastname: Mendoza-Huizar
authors.forename: Francisco
authors.initials: F
authors.lastname: Pérez-García
authors.forename: Hugo
authors.initials: H
authors.lastname: Tlahuext
authors.forename: Alejandro
authors.initials: A
authors.lastname: Alvarez
authors.forename: Margarita
authors.initials: M
authors.lastname: Tlahuextl