Etude structurale de deux oxazabicyclo [3.3.1.] nonanone: Mise en évidence des différences de conformation du système bicyclique

Abstract

The two varieties of the title compound, A = C 28 H33N0 6 , and B = C 3 iH3 9 N0 6 , crystallize in the triclinic system space group P\ with α = 10.605(9)Â, è = 11.85(l)A, c = 12.19(l)Â, oc = 109.2(9)°, /?=113.7(1)°, 7 = 89.35(9)° for the former and a = 10.273(l)Â, b = 11.561(8)Â, c = 12.605(8) À, <* = 101.65(8)°, β = 96.09(7)°, 7 = 92.82(7)°. Both structures have been determined using direct methods and refined to conventional R factors of 0.050 (A) and 0.054 (B) for 4712 and 5102 reflections, respectively. Both chair-chair and boat-chair conformations can exist. The drastic sterical effects of the substituent brought by the nitrogen atom have been emphasized.

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

“…Although the phenyl groups and the carboxylic groups are regarded as largely free to rotate around their bonds to the nonanone skeleton, certain rules of preferred orientation of the substituents -dependent on the configuration -can be observed. In Table V angles between mean planes through the benzene rings, the carboxylic groups and certain mean planes of the nonanone skeleton are listed for the three molecules investigated in this paper and the chairchair molecule A determined by Caujolle [6]. The chair-boat molecule B reported by Caujolle is not comparable with the former molecules.…”

“…X-ray crystal structure analyses were done. Crystal structure analyses of J. Caujolle et al [6] of two similarly substituted oxaazabicyclo[3.3.1]-nonanones have shown that they have chair-chair (A) and chair-boat (B) conformations. The piperidone ring shows a chair conformation, if the nitrogen possesses an N-methyl substituent, and it shows a boat conformation, if the nitrogen has an N-r-butyl group.…”

“…These two conformations (A and B) are possible structures for the two isomers la and lb, both with N-methyl substituents. According to the results of Caujolle [6], the bulky N-r-butyl groups should be the determining factor for the stabilization of a boat conformation. Therefore, a boat conformation of the N-heterocyclic ring in la or lb seems improbable.…”

Kappa-receptor selective binding of opioid ligands with a heterocyclic bicyclo[3.3.1]nonan-9-one structure

“…Previous studies of the structure of 2,6-diarylsubstituted 3-oxa-7-aza-and 3,7diaza-bicyclo[3.3.1]nonan-9-ones revealed a chair-chair conformation [2,17] in the case of the oxygen in 3-position as well as in the case of the nitrogen at that position [8,10] from both crystals and semiempirical calculations. Thus, we built up the geometry of the diazabicyclo[3.3.1]nonan-9-one from the X-ray analysis data [8] and calculated the energetically favorable conformations by means of AM1. The calculated chair-chair conformation is similar to the geometry found by X-ray analysis [8].…”

Stereochemical behaviour of κ-agonistic 2,4-dipyridin-2-yl-3,7-diazabicyclo[3.3.1]nonanones—influence of the substituent in position N3

“…14 In addition to the conformational and configurational isomers discussed above, a chair-boat conformation was found when N7 carries large substituents such as tert-butyl or adamantyl residues. 14, 15 The 3,7-diazabicyclo[3.3.1]nonanone-1,5-dicarboxylates can be synthezised by a double Mannich reaction starting off with the condensation of 1 mole of a corresponding primary amine, and 2 moles of an arylaldehyde and dialkyl oxoglutarate. The thus obtained piperidones can be converted with formaldehyde and a corresponding primary amine to give diazabicyclononanones of a varying substitution pattern (see Fig.…”