Stereochemistry of Substituted Isomeric 3-Oxa-7-aza-bicyclo[3.3.1]nonan-9-ones

Abstract

<jats:title>Abstract</jats:title><jats:p> Two isomers of 7-methyl-9-oxo-2,4-diphenyl-3-oxa-7-aza-bicyclo[3.3.1]nonan-1,5-ethyl dicarboxylate (1a and 1b) were obtained by condensation of 2,6-diphenyl-1-oxa-4-oxo-cyclohexan-3,5-ethyl dicarboxylate with methylamine and formaldehyde. Their crystal structures were determined by X-ray diffraction. They crystallize in the triclinic space group P1̄ with (for 1a) a = 12.907(5), b = 11.223(4), c = 8.993(4) Å, α = 105.82(4), β = 100.14(5), γ = 97.35(4)°, and (for 1b) a = 16.400(7), b = 13.062(4), c = 11.336(2) Å, α = 94.19(3), β = 94.74(3), γ = 102.56(4)°. This investigation has shown that isomer 1a has the boat-chair conformation, and isomer 1b has the chair-chair conformation. The formation of la causes a configurational change of the phenyl substituents. The two species are characterized by NMR spectroscopy. - Another comparable bicyclononanone with a bulky substituent at the nitrogen atom has been synthesized and was investigated spectroscopically. This compound should have chair-boat conformation (with the boat conformation in the N-heterocyclic ring) whereas 1a has the boat conformation in the O-heterocyclic ring.</jats:p>

Structure of diethyl 9-hydroxy-7-methyl-2,4-diphenyl-3-oxa-7-aza-1,5-bicyclo[3.3.1]nonanedicarboxylate

“…H atoms have been omitted for clarity, except for H(10) (with arbitrary diameter) which forms an intramolecular hydrogen bond (dashed). Since the molecules are attracted merely by van der Waals interactions a comparatively small density results (D x = 1.276 g cm-a), which is in accord with the densities of two related bicyclononanones without hydrogen bonding (D x = 1.251, 1.275 g cm-a; K/ippers, Hesse et al, 1987), and which is significantly lower than the density of a related diazaadamantanol (D x = 1.350 g cm-3; K/ippers, Samhammer & Hailer, 1987) where an intermolecular hydrogen bond provides further intermolecular attraction. Fig.…”

Conformational and configurational behaviour of κ-agonistic 3,7-diazabicyclo[3.3.1]nonan-9-ones—synthesis, nuclear magnetic resonance studies and semiempirical PM3 calculations

“…5 In this series of compounds, a bc conformation (b in the higher substituted piperidone) is impossible unless an epimerisation of the aryl substituents has taken place in an initial c conformation. 7 In addition to the various ring conformations, restricted rotations of the aryl substituents at C2 and C4 were observed. Especially in the case of N3-methylation, the rotational barrier was high enough to prevent the rings from rotating.…”

Novel Complexes of 3-[3-(1H-Imidazol-1-yl)propyl]-3,7-diaza-bispidines and β-Cyclodextrin as Coatings to Protect and Stimulate Sprouting Wheat Seeds

“…The initial reagents were obtained from Sigma-Aldrich: 3-(1 H -imidazol-1-yl)propan-1-amine ( 3 ) and 1-Boc-piperidin-4-one ( 4 ), but 1-(3-butoxypropyl)piperid-4-one ( 5 ) was synthesized [ 16 ]. The NMR signals found for the bispidines and bispidinones were close to related but different systems [ 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. Elemental analyses were performed on new compounds by Atlantic Microlabs (Norcross, GA, USA).…”