Conformation in solution of tetraaryl‐3,7‐diazabicyclo[3.3.1]‐nonanes and tetra‐ and pentaaryl‐1,3‐diazaadamantanes. A nuclear magnetic resonance study

Abstract

The proton NMR spectra of a series of tetraaryl‐3,7‐diazabicyclo[3.3.1]nonanes, 5–12, have been assigned with the aid of nuclear Overhauser difference spectroscopy. The NOE's together with spin lattice relaxation times have been used to show that these molecules adopt the chair‐boat conformation with all aryl groups being equatorial. This conformation and the torsional angles of the aryl groups are similar to those found in the solid state. Analogous studies have been carried out with tetra‐ and pentaaryl‐1,3‐diazaadamantanes, 3, 4, 13, and 14. A surprisingly low barrier of rotation (4b: δG 298≠ = 42 kJ. mol−1) has been found for the two 1,3‐diaxially oriented aryl groups in these systems. Carbon‐13 chemical shift data are reported for the above compounds. Those of the 3,7‐diazabicyclononanes 5–12 are found to be consistent with the proposed chair‐boat conformation. Nitrogen‐15 chemical shift data and 13C‐15N coupling constants are also in accord with this conformation. A stereoselective reduction of 4,8,9,10‐tetrakis(3,5‐dimethylphenyl)‐1,3‐diaza‐6‐adamantanone (4b) to the corresponding alcohol 15 and the ready acidcatalyzed rearrangement of this alcohol to 16, the first example of the 9‐oxa‐1,5‐diazatricyclo‐[5.3.1.03,8]undecane ring system, is described.

Bispidine Coordination Chemistry

“…Here, the structure is the result of a minimization of close contacts of all substituents. In analogy to the systems reported above, all aryl substituents prefer equatorial positions, and Scheme 12 this is possible in a cb conformation with two exo-and two endo-phenyl groups (60,162,163). For the most stable double-chair conformation, which is the geometry that coordinates to metal ions, substituents in the C2,C4-positions can have exo-exo, exo-endo, or endo-endo orientation (Chart 17).…”

Synthesis of diversely substituted adamantanes as a new class of antimicrobial agent

“…The compounds 5a-m were characterized by IR, 1 H-NMR, and 13 C-NMR. Among these, the synthesis and their unambiguous chemical shift assignments of and 5a-m (except 5c, 5e, 5f, 5h, 5l) were already reported, and their spectral values were found to be in accord with the literature [16][17][18][19][20][21]; and hence the characterizations of remaining compounds 5c, 5e, 5f, 5h, 5l were included in the experimental section. However, the microbial screening of all these compounds was not reported in the literature and hence all of these compounds were synthesized.…”

“…Though the synthesis of 4,8,9,10-tetraaryl-1,3-diazatricyclo[3.3.1.1]decan-6-ones and its corresponding alcohols have been reported [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] for a limited number of derivatives, their biological significance is not yet explored and hence in the present work 4,8,9,10-tetraaryl-1,3-diazatricyclo[3.3.1.1]decan-6-ones were synthesized using the reports available in the literature [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30], which in turn reduced into 4,8,9,10-tetraaryl-1,3-diazatricyclo[3.3.1.1]decan-6-ols using NaBH 4 ; characterized using IR, 1 H NMR, 13 C NMR, and mass spectral data and then subjected to antimicrobial evaluation against various microbial strains and the results were discussed.…”

“…The products 6a-m were characterized by IR, 1 H-NMR, and 13 C-NMR. Though some of these derivatives were already reported [16][17][18][19][20][21]; their complete chemical shift assignments were not available and hence the characterizations of 6a-m were included in the experimental section.…”

Synthese und Struktur diastereomerer 2,4,6,8‐Tetraaryl‐3‐azabicyclo[3.3.1]nonane und ihre Konformation im Kristall und in Lösung. Stereochemie der Mannich‐Reaktion von cis ‐3,5‐Diphenylcyclohexanon und ‐4‐heteracyclohexanonen

“…The dichotomy in the steric course of the Mannich reaction of the cis-diphenyl six-membered ring ketones 3a -d is discussed. Unser grol3tes Interesse galt den 2,4,6, llnonanen als Modellsubstanzen fur Versuche zur Dehydrierung von 1 zu den entsprechenden cyclischen Iminen. (6) 0.0260 ( ren, von 4a abgeleiteten Alkohole legt zwar nahe, dal3 Baliah und Usha 3-Azabicyclononane dieser Konfiguration, z.B.…”