peri-Interaction, ortho-interaction, and barriers to internal rotation. A dynamic nuclear magnetic resonance and molecular mechanics investigation of 1,2-dineopentylbenzene and 1,8-dineopentylnaphthalene

Anderson, J. Edgar; Barkel, D. J. D.; Jørgensen, Flemming Steen

doi:10.1039/p29880000199

Cited by 6 publications

(10 citation statements)

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“…La condensation de ces phtalonitriles avec du chlorure de nickel dans du N,N-dim6thylaminodthanol conduit d la formation des 1,4,8,11,15,18,22,25-octan6opentoxyphtalocyaninato nickel(il) (3) et 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25Jrexa-ddcandopentoxyphtalocyaninato nickel(Il) (7). Les spectres RMN (1,2).…”

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“…The rH NMR spectra of these phthalocyanines and the related 2,3,9,10,16,17,23,24-octaneopentoxyphthalocyaninato R6sum6 : On ddcrit les synthdses des 3,6-din6opentoxy-et 3,4,5,6-tdtrandopentoxyphtalonitriles. La condensation de ces phtalonitriles avec du chlorure de nickel dans du N,N-dim6thylaminodthanol conduit d la formation des 1,4,8,11,15,18,22,25-octan6opentoxyphtalocyaninato nickel(il) (3) et 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24, (3,8), and nonlinear optics (9-l l). Applications of peripherally unsubstituted phthalocyanines are limited due their insolubility in common organic solvents and water (10, 1 l).…”

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The syntheses and NMR studies of hexadeca- and octaneopentoxyphthalocyanines

Bhardwaj¹,

Andraos²,

Leznoff³

2002

Can. J. Chem.

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Atrstract: The syntheses of 3,6-dineopentoxyphthalonitrile and 3,4,5,6tetraneopentoxyphthalonitrile are described. Condensation of these phthalonitriles with nickel chloride in lr'.N-dimethylarninoethanol yielded 1,4,8,11,15,18,22,25-octaneopentoxyphthalocyaninato nickel(Il) (3) and 1,2,3,4.8.9,10,11,15,16,17,18.22,23,24.25-hexadecaneopentoxyphtlralocyaninato nickel(Il) (7). The rH NMR spectra of these phthalocyanines and the related 2,3,9,10,16,17,23,24-octaneopentoxyphthalocyaninato R6sum6 : On ddcrit les synthdses des 3,6-din6opentoxy-et 3,4,5,6-tdtrandopentoxyphtalonitriles. La condensation de ces phtalonitriles avec du chlorure de nickel dans du N,N-dim6thylaminodthanol conduit d la formation des 1,4,8,11,15,18,22,25-octan6opentoxyphtalocyaninato nickel(il) (3) et 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24, (3,8), and nonlinear optics (9-l l). Applications of peripherally unsubstituted phthalocyanines are limited due their insolubility in common organic solvents and water (10, 1 l). Phthalocyanines possess an extended aconjugated electron system which pennits n stacking (aggregation) betu'een planar macrocycles, provided the distance between the macrocycles is small (10). Adding substituents to the periphery of the macrocycles increases their solubility since these substituents increase the distance between the stacked phthalocyanines and enable their solvation (10,12

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The syntheses and NMR studies of hexadeca- and octaneopentoxyphthalocyanines

Bhardwaj¹,

Andraos²,

Leznoff³

2002

Can. J. Chem.

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“…3,4-Dineopentylthiophene (4c). Neopentyl is another bulky group, and synthesis and structural chemistry of benzene derivatives carrying two neopentyl groups on adjacent positions have attracted considerable attention . Application of our thiophene synthesis to 3,4-dineopentylthiophene ( 4c ) is also successful 4c.…”

Section: Preparation Of Congested Thiophenesmentioning

confidence: 99%

“…The Diels−Alder reaction of thiophene 1,1-dioxides 13c and 14c provides a convenient synthesis of congested molecules that carry two neopentyl groups on adjacent positions of the six-membered aromatic compounds. 3,4,5,6-Tetramethyl-1,2-dineopentylbenzene, the first compound of this class, was synthesized in 1964 18a18b.…”

Section: Conversion Of Thiophenes To Congested Benzene and Pyridazine...mentioning

confidence: 99%

“…3,4,5,6-Tetramethyl-1,2-dineopentylbenzene, the first compound of this class, was synthesized in 1964 18a18b. Heating the thiophene 1,1-dioxide 13c and phenyl vinyl sulfone in refluxing chlorobenzene for 15 h gave 17c directly in 83% yield with elimination of benzenesulfinic acid and sulfur dioxide.…”

Section: Conversion Of Thiophenes To Congested Benzene and Pyridazine...mentioning

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Preparation of Congested Thiophenes Carrying Bulky Substituents on the 3- and 4-Positions and Their Conversion to the Benzene Derivatives

et al. 1998

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Highly congested thiophenes, 3,4-di-tert-butyl-, 3,4-di(1-adamantyl)-, 3,4-dineopentyl-, and 3-(1-adamantyl)-4-tert-butylthiophenes (4a−d), were prepared in satisfactory overall yields by intramolecular reductive coupling of 3-thiapentane-1,5-diones (1a−d) followed by acid-catalyzed dehydration of the resulting thiolane-3,4-diols (2a−d). Experimental procedures of this thiophene synthesis are fully described. Oxidation of the thiophenes 4a−d with m-CPBA gave the corresponding thiophene 1,1-dioxides 13a−d in good yields. The Diels−Alder reactions of 13a−d with phenyl vinyl sulfone gave o-di-tert-butyl-, o-di(1-adamantyl)-, o-dineopentyl-, and o-(1-adamantyl)-tert-butylbenzenes (17a−d) directly in high yields with loss of benzenesulfinic acid and sulfur dioxide. The dioxides 13a−d also underwent Diels−Alder reactions with alkynic dienophiles to give the corresponding benzene derivatives carrying two bulky substituents on adjacent positions. Pyridazines 25b,c, carrying bulky substituents on the 4- and 5-positions, were also synthesized through Diels−Alder reaction of 13b,c with PTAD. Dimethylation of the 2- and 5-positions of 13a−d was attained by treatment with strong bases followed by reactions with methyl iodide. The resulting tetrasubstituted thiophene 1,1-dioxides 14a−d reacted with DMAD to give highly congested hexasubstituted benzene derivatives 15a−d in good yields. Finally, structural features of the congested molecules are discussed on the basis of NMR analyses. Typically, the barriers to rotation (ΔH ⧧) about the benzene to the bulky substituents of 15a,c,d were determined to be 8.59, 15.3, and 7.40 kcal/mol, respectively, by NMR total line-shape analysis.

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