The barrier to rotation in α,β-substituted styrenes. A DNMR investigation

Anderson, J. Edgar; Barkel, D. J. D.; Cooksey, Christopher J.

doi:10.1016/s0040-4039(00)81609-3

Cited by 13 publications

(11 citation statements)

References 7 publications

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“…(8Z)-8-Chloro-6,7-dihydro-9-(1,2-dihydronaphthalen-4-yl)-7-methoxy-5H-benzo [7]annulene (1a 31.08, 40.80, 58.52, 80.32, 124.61, 126.92, 127.00, 127.46, 128.47, 129.31, 129.68, 131.32, 134.13, 134.69, 136.40, 136.86, 137.81, 137.93, 138.68, 140.78. (8Z)-8-Chloro-7-ethoxy-6,7-dihydro-9-(1,2-dihydronaphthalen-4-yl)-5H-benzo [7]annulene (1b).…”

Section: General Methods For the Preparation Of 1a-1hmentioning

confidence: 99%

“…(8Z)-8-Chloro-7-ethoxy-6,7-dihydro-9-(1,2-dihydronaphthalen-4-yl)-5H-benzo [7]annulene (1b). Colorless oil.…”

Section: General Methods For the Preparation Of 1a-1hmentioning

confidence: 99%

“…23.85, 28.46, 30.94, 41.10, 66.25, 78.21, 124.44, 127.04,127.14, 127.57, 128.25(2C), 128.68, 129.18, 130.83, 134.62, 135.07, 136.44, 136.88, 137.69, 139.77, 140.93 23.95, 28.55, 31.17, 41.02, 66.34, 78.23, 124.64, 126.94, 126.98, 127.47, 128.03, 128.10, 128.46, 129.78, 131.37, 134.15, 135.54, 135.85, 137.57, 138.64, 140.88. (8Z)-8-Chloro-6,7-dihydro-9-(1,2-dihydronaphthalen-4-yl)-7-propoxy-5H-benzo [7] 23.40, 23.84, 28.44, 30.99, 41.07, 72.55, 78.66, 124.48, 126.92, 126.97, 127.08, 128.18, 128.19, 128.62, 129.14, 130.69, 134.33, 135.17, 135.98, 136.45, 139.71, 140.80, 140.96 23.45, 23.93, 28.53, 31.16, 41.00, 72.68, 78.66, 124.64, 127.43, 128.05, 128.07, 128.37, 127.53(2C), 129.68, 131.27, 134.17, 135.55, 136.86, 137.53, 136.85, 138.79, 140.89. (8Z)-7-Butoxy-8-chloro-6,7-dihydro-9-(1,2-dihydronaphthalen-4-yl) 19.77, 23.83, 28.42, 30.98, 32.25, 41.05, 70.69, 78.67, 124.47, 126.89, 127.05, 127.51, 128.16(2C), 128.63, 129.13, 130.70, 134.56, 135.20, 135.93, 136.44, 139.70, 140.80, 140.96 19.89, 23.92, 28.52, 31.15, 32.34, 40.10, 70.48, 78.67, 124.63, 126.94(2C), 127.41, 128.05(2C), 128.34, 129.66, 131.27, 134.17, 135.54, 136.85, 137.49, 137.84, 138.78, 140.89.…”

Section: Majormentioning

confidence: 99%

“…

AbstractConformational diastereomers of 7-substituted-(8Z)-8-chloro-6,7-dihydro-9-(1,2-dihydronaphthalen-4-yl)-5H-benzo [7]annulene 1 are observed at room temperature in solution. Two conformational processes are possible in 1, i.e.

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mentioning

confidence: 99%

“…22 The barrier to ring inversion in 5-(2-chlorophenyl)-1H-benzo[e][1,4]diazepin-2(3H)-one 2 (Scheme 1) is reported to be 43.6 kJ/mol. 22d In this paper, conformational analysis of the 7-substituted-(8Z)-8-chloro-6,7-dihydro-9-(1,2-dihydro-naphthalen-4-yl)5H-benzo [7] annulene 1 (Scheme 1) is discussed. …”

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confidence: 99%

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The conformational diastereomers of 7-substituted-(8Z)-8-chloro-6,7-dihydro-9-(1,2-dihydro-6-R-naphthalen-4-yl)-2-R-5H-benzo[7]annulene, the question of atropisomerism versus ring inversion

Ranjbar¹,

Roshan²

2010

Arkivoc

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Conformational diastereomers of 7-substituted-(8Z)-8-chloro-6,7-dihydro-9-(1,2-dihydronaphthalen-4-yl)-5H-benzo [7]annulene 1 are observed at room temperature in solution. Two conformational processes are possible in 1, i.e. atropisomerism around the sp 2 -sp 2 pivot bond and ring inversion of cycloheptadiene moiety which together provide four minima structures. The 3 J calculation by Haasnoot equation on optimized structures is accordance with the 7-substituents in pseudo equatorial (exo) position in both forms. The barrier to conformational process is determined by dynamic 1 H-NMR spectroscopy to be ∆G ≠ (365K) =74.5±0.5 kJ/mol. Solvent dependent populations of the two forms are studied in DMSO-d 6 and CDCl 3 , the population ratio is not sensitive to solvent polarity.

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Section: General Methods For the Preparation Of 1a-1hmentioning

confidence: 99%

“…(8Z)-8-Chloro-7-ethoxy-6,7-dihydro-9-(1,2-dihydronaphthalen-4-yl)-5H-benzo [7]annulene (1b). Colorless oil.…”

Section: General Methods For the Preparation Of 1a-1hmentioning

confidence: 99%

Section: Majormentioning

confidence: 99%

“…

…”

mentioning

confidence: 99%

mentioning

confidence: 99%

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The conformational diastereomers of 7-substituted-(8Z)-8-chloro-6,7-dihydro-9-(1,2-dihydro-6-R-naphthalen-4-yl)-2-R-5H-benzo[7]annulene, the question of atropisomerism versus ring inversion

Ranjbar¹,

Roshan²

2010

Arkivoc

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Enantioselective Synthesis of the Chromane Moiety of Vitamin E

Tietze¹,

Görlitzer²,

Schuffenhauer³

et al. 1999

Eur. J. Org. Chem.

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Several new approaches for the enantioselective synthesis of the chromane moiety of vitamin E are described. Sonogashira coupling of 3a with the alkyne 4 and subsequent elimination gave 6, which was bis(hydroxylated) in 93% yield and with 85% ee. Recrystallization gave enantiopure 7a, which was hydrogenated and transformed into the vitamin E precursor 11. The bis(hydroxylation) of 18 and 21 to give 9 and 22, respectively, was less than satisfactory, proceeding with ee values of 28% and 18%. In contrast, stereoselective allylation of ketone 15 followed by removal of the protecting group or ozonolysis of the allyl moiety furnished the allyl alcohol 26 and the aldehyde 27, respectively, in almost enantiopure form, which again could be used as precursors for vitamin E. Partial hydrogenation of 5a gave the alkene 32a and that of 28 the alkene 30b, both of which show interesting atropisomerism.

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NMR Study of Conformational Preferences of Inhibitors of Monoamine Uptake

Appell

Krunić

Choi

et al. 2002

Quant. Struct.-Act.Relat.

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We have used the recently developed tensor decomposition 3D-QSAR method to predict the conformation and alignment of cocaine derivatives bound to the monoamine transporters, NET, DAT and SERT. The analysis revealed that the ligands bind to the receptors in a conformation with the 3b-aryl group orthogonal or approximately orthogonal to the tropane ring. Semi rigid ligands have been prepared with a 3b-aryl group having strong conformational preferences for this orientation. Two compounds had affinities for the DAT and SERT in the low nanomolar range. The solution conformation of one compound has been determined and the results support the results of the 3D-QSAR analysis. Comparisons of affinities and selectivities of these ligands are discussed.We have recently published a methodology for exploring the effects of conformation and alignment on biological activity using descriptor data developed from molecular field analysis of the structures. The structure-activity data are analyzed by 3-way PLS [1]. The application of this method to published binding data of ligands to the monoamine transporters suggests that selectivity and/or affinity may be determined in large part by ligand conformation.We have designed, synthesized and evaluated a number of rigid and semi-rigid tropane derivatives and evaluated their binding to the transporter proteins [2] and the data for two analogs, ( / À )1a and ( / À )1b shown in Figure 1, are reported here.The compounds, 2a and 2b, are a-and b-disubstituted naphthylethylenes which are known to have strong conformational preferences [4,5]. For example, 2a with R 1 CH 3 , has been shown with temperature-dependent nmr to have a barrier to rotation through a transition state in which the naphthyl group is planar to the ethylene group of ) 26 kcal/mole. Similarly, 2b with R 1 CH 3 , has a barrier to rotation through a planar transition state of about 6.5 kcal/ mole. By building this system into the tropane ring, as in 1a and 1b, it is possible to have ligands with fewer degrees of internal rotational degrees of freedom. In addition, this would overcome unfavorable entropic effects on binding [6].To explore the conformational properties of 1a and 1b, their structures were built using the Cerius2 program [7] and the Universal Open Force Field [8]. The molecules were modeled in the neutral form and partial charges were applied using the Charge-Equilibration [9] method. Structures were minimized to convergence. The global minima and higher energy wells were found by performing a systematic energy search where each torsion angle was rotated in 308 increments. This analysis of 1a shows that its lowest energy conformation has the naphthyl group with a 38 Quant. Struct.-Act. Relat., 21 (

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The barrier to rotation in α,β-substituted styrenes. A DNMR investigation

Cited by 13 publications

References 7 publications

The conformational diastereomers of 7-substituted-(8Z)-8-chloro-6,7-dihydro-9-(1,2-dihydro-6-R-naphthalen-4-yl)-2-R-5H-benzo[7]annulene, the question of atropisomerism versus ring inversion

The conformational diastereomers of 7-substituted-(8Z)-8-chloro-6,7-dihydro-9-(1,2-dihydro-6-R-naphthalen-4-yl)-2-R-5H-benzo[7]annulene, the question of atropisomerism versus ring inversion

Enantioselective Synthesis of the Chromane Moiety of Vitamin E

NMR Study of Conformational Preferences of Inhibitors of Monoamine Uptake

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