The structures of chiral and racemate campho[2,3-c]pyrazole: A combined crystallographic, solid-state NMR and computational study

Yap, Glenn P. A.; Claramunt, Rosa M.; López, Concepcíon; García, M. Ángeles; Pérez-Medina, Carlos; Alkorta, Ibón; Elguero, José

doi:10.1016/j.molstruc.2009.11.041

Cited by 12 publications

(9 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Campho[2,3-c]pyrazole, 1 , was synthesized from natural camphor by using the procedure described in ref . The carbon atoms are numbered according to Table 5 of ref ; note that this numbering is different from that in ref .…”

Section: Experimental Methodsmentioning

confidence: 99%

NMR Crystallography of Campho[2,3-c]pyrazole (Z′ = 6): Combining High-Resolution ¹H-¹³C Solid-State MAS NMR Spectroscopy and GIPAW Chemical-Shift Calculations

et al. 2010

Self Cite

View full text Add to dashboard Cite

(1)H-(13)C two-dimensional magic-angle spinning (MAS) solid-state NMR correlation spectra, recorded with the MAS-J-HMQC experiment, are presented for campho[2,3-c]pyrazole. For each (13)C moiety, there are six resonances associated with the six distinct molecules in the asymmetric unit cell (Z' = 6). The one-bond C-H correlations observed in the 2D (1)H-(13)C MAS-J-HMQC spectra allow the experimental determination of the (1)H and (13)C chemical shifts associated with the separate CH, CH(2), and CH(3) groups. (1)H and (13)C chemical shifts calculated by using the GIPAW (Gauge Including Projector Augmented Waves) plane-wave pseudopotential approach are presented. Calculations for the whole unit cell (12 × 29 = 348 atoms, with geometry optimization of all atoms) allow the assignment of the experimental (1)H and (13)C chemical shifts to the six distinct molecules. The calculated chemical shifts for the full crystal structure are compared with those for isolated molecules as extracted from the geometry-optimized crystal structure. In this way, the effect of intermolecular interactions on the observed chemical shifts is quantified. In particular, the calculations are sufficiently precise to differentiate the small (<1 ppm) differences between the (1)H chemical shifts of the six resonances associated with each distinct CH or CH(2) moiety.

show abstract

Section: Experimental Methodsmentioning

confidence: 99%

NMR Crystallography of Campho[2,3-c]pyrazole (Z′ = 6): Combining High-Resolution ¹H-¹³C Solid-State MAS NMR Spectroscopy and GIPAW Chemical-Shift Calculations

et al. 2010

Self Cite

View full text Add to dashboard Cite

show abstract

“…The geometry of the tautomers and hydrogen transfer transition states has been optimized with the hybrid functional B3LYP 25, 26. The 6‐31+G(d,p) basis set27 has been used in combination with the B3LYP functional because it has been shown to provide a good geometrical and electronic description of hydrogen bonded systems 28–33. Frequency calculations have been carried out at the same computational level to verify that the structures obtained correspond to energetic minima or true transition states.…”

Section: Methodsmentioning

confidence: 99%

Thermodynamic and kinetic effects of Lewis acid complexation on a Schiff base present in two tautomeric forms

Alkorta

Elguero

Popelier³

2010

J of Physical Organic Chem

Self Cite

View full text Add to dashboard Cite

The effect of complexation with Lewis acids on the tautomeric equilibrium of a derivative of pyridoxal has been explored using density functional theory. Three complexation sites (pyridine nitrogen, aromatic ring, and carbonyl group) have been considered. The tautomeric equilibrium can be modulated with the formation of complexes at the different sites. The changes observed in the geometric, energetic and electronic properties of the tautomers and transition states have been analyzed. Relationships have been found between those parameters, including a relationship between energetic and geometric parameters in agreement with the Hammond postulate. Copyright © 2010 John Wiley & Sons, Ltd.

show abstract

“…The compounds we have prepared ( Scheme 1 ) and studied, 13 and 14 , are derivatives of (4 S ,7 R )-7,8,8-trimethyl-4,5,6,7-tetrahydro-4,7-methano-2 H -indazole also known as (4 S ,7 R )-campho[2,3- c ]pyrazole, a compound we have previously investigated [ 41 , 42 , 43 , 44 ].…”

Section: Introductionmentioning

confidence: 99%

19F‐NMR Diastereotopic Signals in Two N-CHF2 Derivatives of (4S,7R)-7,8,8-Trimethyl-4,5,6,7-tetrahydro-4,7-methano-2H-indazole

et al. 2017

Self Cite

View full text Add to dashboard Cite

In this paper, we report the anisochrony of the fluorine atoms of a CHF2 group when linked to a pyrazole ring. The pyrazole is part of (4S,7R)-7,8,8-trimethyl-4,5,6,7-tetrahydro-4,7-methano-2H-indazole also known as (4S,7R)-campho[2,3-c]pyrazole, which has two stereogenic centers. Gauge-Independent Atomic Orbital (GIAO)/Becke, 3-parameter, Lee-Yang-Parr (B3LYP)/6-311++G(d,f) calculated 19F chemical shifts of the minimum energy conformations satisfactorily agree with the experimental data. The energy differences between minima need to consider solvent effects (continuum model) to be satisfactorily reproduced.

show abstract

The structures of chiral and racemate campho[2,3-c]pyrazole: A combined crystallographic, solid-state NMR and computational study

Cited by 12 publications

References 37 publications

NMR Crystallography of Campho[2,3-c]pyrazole (Z′ = 6): Combining High-Resolution ¹H-¹³C Solid-State MAS NMR Spectroscopy and GIPAW Chemical-Shift Calculations

NMR Crystallography of Campho[2,3-c]pyrazole (Z′ = 6): Combining High-Resolution ¹H-¹³C Solid-State MAS NMR Spectroscopy and GIPAW Chemical-Shift Calculations

Thermodynamic and kinetic effects of Lewis acid complexation on a Schiff base present in two tautomeric forms

19F‐NMR Diastereotopic Signals in Two N-CHF2 Derivatives of (4S,7R)-7,8,8-Trimethyl-4,5,6,7-tetrahydro-4,7-methano-2H-indazole

Contact Info

Product

Resources

About

The structures of chiral and racemate campho[2,3-c]pyrazole: A combined crystallographic, solid-state NMR and computational study

Cited by 12 publications

References 37 publications

NMR Crystallography of Campho[2,3-c]pyrazole (Z′ = 6): Combining High-Resolution 1H-13C Solid-State MAS NMR Spectroscopy and GIPAW Chemical-Shift Calculations

NMR Crystallography of Campho[2,3-c]pyrazole (Z′ = 6): Combining High-Resolution 1H-13C Solid-State MAS NMR Spectroscopy and GIPAW Chemical-Shift Calculations

Thermodynamic and kinetic effects of Lewis acid complexation on a Schiff base present in two tautomeric forms

19F‐NMR Diastereotopic Signals in Two N-CHF2 Derivatives of (4S,7R)-7,8,8-Trimethyl-4,5,6,7-tetrahydro-4,7-methano-2H-indazole

Contact Info

Product

Resources

About

NMR Crystallography of Campho[2,3-c]pyrazole (Z′ = 6): Combining High-Resolution ¹H-¹³C Solid-State MAS NMR Spectroscopy and GIPAW Chemical-Shift Calculations

NMR Crystallography of Campho[2,3-c]pyrazole (Z′ = 6): Combining High-Resolution ¹H-¹³C Solid-State MAS NMR Spectroscopy and GIPAW Chemical-Shift Calculations