<b>Long-Range Nuclear Spin-Spin Coupling. Allenic and Polyacetylenic Systems</b>

Snyder, Eugene I.; Roberts, John D.

doi:10.1021/ja00868a013

Cited by 62 publications

(17 citation statements)

References 1 publication

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“…The signs of the coupling constants between the ring and y protons (see 1) were determined by partial decoupling (14) experiments in which the transitions of the a protons were irradiated for given spin states of the y protons, while detecting those of the ring protons. The signs of the coupling constants in Table 1 follow on the basis that 4~a , is negative, as it is if ,J(H, CH,) in 1-chloro-l,2-butadiene is positive (15)(16)(17). The sign of the dipolar coupling between the y protons in 1 is consistent with the absolute signs in Table 1 (see below).…”

Section: Methodssupporting

confidence: 59%

¹H and¹³C nuclear magnetic resonance and molecular orbital studies of the internal rotational potential and of spin–spin coupling transmission in phenylallene

Schaefer¹,

Kroeker²,

McKinnon³

1995

Can. J. Chem.

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The 'H nuclear magnetic resonance spectra of phenylallene, diluted in acetone-d6 and benzene-d6, yield long-range coupling constants over as many as eight formal bonds between the ring and side-chain protons. These are discussed in terms of o-and IT-electron spin-spin coupling mechanisms, which are sensitive to the torsion angle between the allenyl and phenyl fragments. The torsion angle is assessed by means of molecular orbital computations of the internal rotational potential, whose height is calculated as 16.0 kJ1mol at the MP216-31G* level of correlation-gradient theory. Comparison with experimental and theoretical internal rotational potentials for styrene suggests that steric repulsions in the planar form of styrene amount to about 4 Idlmol. In a field of 7.0 T, phenylallene is partially aligned, entailing a positive dipolar coupling constant between the methylene protons, from which absolute signs of the spin-spin coupling constants involving these protons can be inferred. Such coupling constants over seven and eight bonds, to the mefa and para protons, are taken as being mediated by the extended a-electron system, providing a measure of IT-electron contributions to coupling constants between mefa protons and those in side chains (spin correlation). Some coupling constants between protons and I3c nuclei in the side chain, as well as between ring protons and these I3c nuclei, are also discussed in terms of spin coupling mechanisms. Solvent perturbations of one-bond proton~arbon coupling constants in the allenyl group do not follow the usual pattern in which an increase in polarity of the solvent is associated with an increase in the magnitude of the coupling constant.

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Section: Methodssupporting

confidence: 59%

¹H and¹³C nuclear magnetic resonance and molecular orbital studies of the internal rotational potential and of spin–spin coupling transmission in phenylallene

Schaefer¹,

Kroeker²,

McKinnon³

1995

Can. J. Chem.

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“…When Pd(PPh 3 ) 4 or PdCl 2 (PPh 3 ) 2 was used as the catalyst, a satisfactory yield could be also obtained (Entries 13, 14). If the catalyst was replaced by Pd/C or PdCl 2 or Pd(OAc) 2 , the coupling reaction afforded the corresponding product in low to moderate yields (Entries [15][16][17]. This observation suggested that the presence of PPh 3 , a phosphine ligand, would promote the reaction.…”

Section: Resultsmentioning

confidence: 99%

An Efficient and Practical Process for Pd/Cu CocatalyzedHomocoupling Reaction of Terminal Alkynes Using Sodium Percarbonate as a Dual Reagent in Aqueous Media

Zhou¹,

Zhan²,

Liu³

et al. 2007

Chin. J. Chem.

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A new process for the Pd/Cu co-catalyzed homocoupling reaction of terminal alkynes was developed. The reaction was carried out in aqueous media with sodium percarbonate as both a clean oxidant and a base. Meanwhile, a palladium complex immobilized on a synthetic PS-PEG 400 -PPh 2 resin was used as the catalyst, which may be recovered by simple filtration and reused for several times with high activity.

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“…The products were purified by gc (SP 1000 column), when the alcohol 5 was separated from the hydrocarbons 6 and 7. Spectra of the title alcohol (19). This compound (7) has a slightly longer retention time on an S P 1000 column than 6.…”

Section: ~~U ~~-P C~i I~~i I ? I C~~i I~i -~~~~~~O -mentioning

confidence: 99%

Synthesis and stereochemistry of hydrogenated 1,1,4,4,7a-pentamethylindenes

Thomas¹,

Ozainne²

1980

Can. J. Chem.

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DPciic; 2 la tne'tnoire de Dr. Lc:o ma riot^ ALAN FRANCIS THOMAS, MICHEL OZAINNE, and RENEE GUNTZ-DUBINI. Can. J. Chem. 58. 1810 (1980). Ease of methylation of hydrogenated 2H-inden-2-ones depends on the presence of a double bond in the cyclohexane ring, and occurs readily with compound 20 but not with 10. Differences of reactivity are also noted in Wittig reactions. Most reactions of the system are highly stereoselective. and the stereochemistry of hydrogenated indenes is discussed. ALAN FRANCIS THOMAS, MICHEL OZAINNE et R E N~F .GUNTZ-DUBINI. Can. J. Chem. 58, 1810 (1980). La facilite avec laquelle les indkne-2H ones-2 hydrogenees sont methylees depend de la presence d'une double liaison dans le cycle a six chainons; ainsi, la methylation du compose 20 est beaucoup plus facile que celle du compose 10. On constate egalement des differences de reactivite lors de la reaction de Wittig. La plupart des reactions de ce systkme sont hautement stCreoselectives. ce qui nous a permis d'ailleurs d'approfondir notre connaissance de la stCrCochimie des indknes hydrogines.

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Long-Range Nuclear Spin-Spin Coupling. Allenic and Polyacetylenic Systems

Cited by 62 publications

References 1 publication

¹H and¹³C nuclear magnetic resonance and molecular orbital studies of the internal rotational potential and of spin–spin coupling transmission in phenylallene

¹H and¹³C nuclear magnetic resonance and molecular orbital studies of the internal rotational potential and of spin–spin coupling transmission in phenylallene

An Efficient and Practical Process for Pd/Cu CocatalyzedHomocoupling Reaction of Terminal Alkynes Using Sodium Percarbonate as a Dual Reagent in Aqueous Media

Synthesis and stereochemistry of hydrogenated 1,1,4,4,7a-pentamethylindenes

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Long-Range Nuclear Spin-Spin Coupling. Allenic and Polyacetylenic Systems

Cited by 62 publications

References 1 publication

1H and13C nuclear magnetic resonance and molecular orbital studies of the internal rotational potential and of spin–spin coupling transmission in phenylallene

1H and13C nuclear magnetic resonance and molecular orbital studies of the internal rotational potential and of spin–spin coupling transmission in phenylallene

An Efficient and Practical Process for Pd/Cu CocatalyzedHomocoupling Reaction of Terminal Alkynes Using Sodium Percarbonate as a Dual Reagent in Aqueous Media

Synthesis and stereochemistry of hydrogenated 1,1,4,4,7a-pentamethylindenes

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¹H and¹³C nuclear magnetic resonance and molecular orbital studies of the internal rotational potential and of spin–spin coupling transmission in phenylallene

¹H and¹³C nuclear magnetic resonance and molecular orbital studies of the internal rotational potential and of spin–spin coupling transmission in phenylallene