¹H, ¹³C and ¹⁷O NMR spectroscopic study of four bicyclo [3.1.1]heptenes (derivatives of α‐pinene) and four bicyclo[3.1.1]heptanes (derivatives of β‐pinene)

Abstract

Four derivatives of 2,6,6-trimethylbicyclo [ 3.1.1 1 hept-2-ene (a-pinene) and four derivatives of 2-methylene-6,6-dimethylbicyclo[ 3.1.1 jheptane (p-pinene) were synthesized and their 'H, 13C and "0 NMR spectra were measured, analysed and assigned. The 'H NMR spectral parameters were obtained by computer-aided analyses of the very complex multi-spin, second-order spectra. Some of the "C NMR chemical shift assignments of these compounds reported in the literature should be changed, based on these accurate 'H NMR spectral analyses and carboeproton chemical shift correlated spectra (COSY). The new assignments are supported by the ' J(C,H) values, which show a strong dependence on the bond angle and the steric strain of the ring system concerned.

(+)- and (−)-α-Pinene as chiral recognition probes with natural cyclodextrins and their permethylated derivatives. An aqueous NMR study

“…2) was carried out with COSY, DQS and HETCOR experiments and was in agreement with reported NMR parameters of 1 in other solvents. 9, 10 The very low solubility of the corresponding adducts with βand γ-CD did not allow studies of the guest in the solution, whereas with TMγ-CD complex formation was not detected, as mentioned above.…”

13C NMR chemical shift assignment based on 13C INADEQUATE and heteronuclear 13C, 1H-COSY experiments and absolute configuration of a new chiral pentacyclic pinocarvone dimer

“…A similar tendency to dimerization has also been reported for trimethylt4. 1 .O]bicycloheptane (carane) derivatives containing the corresponding exocyciic enone str~cture.~ The molecular structure and absolute configuration of 1 were determined by X-ray crystallography. The complete I3C NMR chemical shift assignment of 1 was obtained by means of two-dimensional INADEQUATE and C,H-COSY experiments.…”

Dolabella‐3,7,18‐triene, the main constituent of the essential oil of the white lotus flower (Nymphaea lotus, Nymphaeaceae)

“…Chemical shifts were computed on the obtained MMFF94 geometries by means of DFT GIAO computations using the B3LYP functional and the 6‐31G* basis sets, as implemened in the Gaussian09 program . To convert the computed shieldings into shifts, shieldings were computed at the same level for β ‐pinene and a linear relationship (eq ) was established by least‐squares fitting to the β ‐pinene available experimental data …”