Restricted rotation in substituted acetophenones and benzaldehydes: an interesting solvent effect

Klinck, R. E.; Marr, David H.; Stothers, J. B.

doi:10.1039/c19670000409

Cited by 10 publications

(6 citation statements)

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“…with potassium permanganate under mild conditions opened the ring of thujane to form 32, whereas the same treatment of -thujene or thujone led to 20 or 33 in which oxidation took place at the double bond or carbonyl group.4 In contrast, treatment of sabinol with selenium dioxide did not cleave either ring but yielded a ketone which rapidly dimerized. Similar reactions with manganese dioxide gave sabinone (34) which formed 35 on heating 54. This study corrected an erroneous structure that had been proposed66…”

supporting

confidence: 55%

Chemistry of thujane derivatives

Whittaker¹,

Banthorpe²

1972

Chem. Rev.

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supporting

confidence: 55%

Chemistry of thujane derivatives

Whittaker¹,

Banthorpe²

1972

Chem. Rev.

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“…The latter are not always in number of their derivatives by a variety of tech-agreement with those found at room temperature, a niques (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). In solution at least (1,14), the fact perhaps attributable to varying solvent effects twofold barrier to rotation about the exocyclic car- (20) in the experiments; particularly if the conforbon-carbon bond is 31.4 kJImol for benzaldehyde mational isomers have rather different dipole m0-and 29.3 kJImol for benzoyl fluoride, so that at am-merits (1 1).…”

supporting

confidence: 61%

Theoretical and experimental conformational preferences of the aldehyde and fluoroaldehyde groups in 2-methylbenzaldehyde, 2-trifluoromethylbenzaldehyde, and 4-chloro-2-methylbenzoyl fluoride. Proximate couplings

Schaefer¹,

Salman²,

Wildman³

1980

Can. J. Chem.

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Can. J. Chem. 58,2364(1980. On the basis of long-range spin-spin coupling constants, the 0-syn conformation of 2-methylbenzaldehyde in CCI, solution at 305 K is favored over the 0-anti form by a free energy of 0.5, kJ/mol. This number is compatible with other experiments, as well as with STO-3G MO calculations in which the geometry of the substituents is optimized. The latter yield 0.52 kJ/mol in the internal energy difference. In benzene solution, 2-trifluoromethylbenzaldehyde exists in the 0-anti form to the extent of at least 95% at 305 K. InCCI, solution at this temperature, the population of the 0-syn conformer of 4-chloro-2-methylbenzoylfluoride is likely 75% or more of the total, in semiquantitative agreement with STO-3G optimization procedures. Substantial proximate couplings exist between 'H and 19F nuclei in the sidechains of the latter two compounds and are compared with INDO MO FPT computations. These yield negative values for S J 0 L H v~L F 3 in 2-trifluoromethylbenzaldehyde, whereas the experimental value is 2.23 Hz.TED SCHAEFER, SALMAN R. SALMAN et TIMOTHY A. WILDMAN. Can. J. Chem. 58,2364(1980.En se basant sur les constantes de couplage spin-spin a longue distance on peut conclure que la conformation 0-syn du methyl-2 benzaldehyde en solution dans le CCI, 305 K est favorisee par rapport a la forme 0-anti par une difference d'energie libre de 0,53 kJ/mol. Cette valeurest compatible avec d'autres experiences ainsi qu'avec des calculs OM STO-3G dans lesquels on maximise la geometrie des substituants. Ces derniers donnent une difference d'energie interne de 0,52 kJ/mol. En solution dans le benzine, au moins 95% du trifluoromCthy1-2 benzaldehyde existe sous la forme 0-anti a 305 K. En solution dans le CCI, a cette temperature, probablement 75% ou plus du fluorure de chloro-4 methyl-2 benzyle existe dans la conformation 0-syn; cette conclusion est en accord semi-quantitatifavec les methodes de maximisation du STO-3G. Des couplages approximatifs substantiels existent entre les noyaux de 'H et de 19F des chaines laterales des deux derniers composes et on les compare aux valeurs obtenues par calculs OM INDO FPT. Ces derniers conduisent a des valeurs negatives de sJ0cHv~'F3 pour le trifluoromCthy1-2 benzaldehyde alors que la valeur experimentale est de 2,23 Hz.[Traduit par le journal]

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“…1 The biogenesis of 1 involving the key intermediate 3 (Scheme 1) looked more attractive than the earlier proposal 1 especially in view of the fact that a large number of natural dimers, including 3, have been reported to be formed by heteroatom Diels-Alder self-dimerization. [2][3][4][5][6][7][8][9][10][11] We have now achieved biogenetic-type synthesis of (+)cymbodiacetal (1) starting with (+)-limonene oxide (4) via the key intermediate 3. This is the first report of the synthesis of 1.…”

mentioning

confidence: 99%