Botational babbiers in the ester function of some carbamates. The use of an iterative computer program in a nmr study

Werf, Siebren van der; Olijnsma, T.; Engberts, Jan B. F. N.

doi:10.1016/s0040-4039(00)90574-4

Cited by 15 publications

(3 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The calculation results showed that there are two conformers of hydrogen‐bonding O ‐monoprotonated carbamate, SM‐1 and SM‐2 . The calculated rotational barrier with respect to the OC(O) bond of the carbamate functionality amounts to 15 kcal mol −1 (not shown in Figure 4A), which is comparable to experimental values of typical carbamates 23. While the reactive conformer SM‐2 ( SM‐2 a and SM‐2 b ) is unstable than the conformer SM‐1 ( SM‐1 a and SM‐1 b ) and SM‐1 is a predominant conformer, the conformers are in equilibrium and SM‐2 may exist in a small fraction.…”

Section: Resultssupporting

confidence: 75%

Acid‐Promoted Chemoselective Introduction of Amide Functionality onto Aromatic Compounds Mediated by an Isocyanate Cation Generated from Carbamate

Sumita

Kurouchi

Otani

et al. 2014

Chemistry An Asian Journal

View full text Add to dashboard Cite

Carbamates have been used as precursors of isocyanates, but heating in the presence of strong acids is required because cleavage of the C-O bond in carbamates is energy-demanding even in acid media. Direct amidation of aromatic compounds by isocyanate cations generated at room temperature from carbamoyl salicylates in trifluoromethanesulfonic acid (TfOH) was examined. Carbamates with ortho-salicylate as an ether group (carbamoyl salicylates) showed dramatically accelerated O-C bond dissociation in TfOH, which resulted in facile generation of the isocyanate cation. These chemoselective intermolecular aromatic amidation reactions proceeded even at room temperature and showed good compatibility with other electrophilic functionalities and high discrimination between N-monosubstituted carbamate and N,N-disubstituted carbamate. The reaction rates of secondary and tertiary amide formation were markedly different, and this difference was utilized to achieve successive (tandem) amidation reactions of molecules with an N-monosubstituted carbamate and an N,N-disubstituted carbamate with two kinds of aromatic compounds.

show abstract

Section: Resultssupporting

confidence: 75%

Acid‐Promoted Chemoselective Introduction of Amide Functionality onto Aromatic Compounds Mediated by an Isocyanate Cation Generated from Carbamate

Sumita

Kurouchi

Otani

et al. 2014

Chemistry An Asian Journal

View full text Add to dashboard Cite

show abstract

“…The barriers of rotation around the N- -CO of amides 45 are about 17−18 kcal/mol, increasing up to 20 kcal/mol as the dielectric constant and hydrogen-bond donating ability of the solvent increase, and decrease to 15−17 kcal/mol in carbamates becoming insensitive to solvent polarity. Rotational barriers around the O- -CO bond of carbamates are about 16 kcal/mol, decreasing to 10 kcal/mol in methyl esters. Rotational barriers of around 6 kcal/mol have been calculated for the rotation of a carboxylate out of the plane of a phenyl ring …”

Section: Resultsmentioning

confidence: 94%

Experimental Determination of the Absolute Enantioselectivity of an Antibody-Catalyzed Diels−Alder Reaction and Theoretical Explorations of the Origins of Stereoselectivity

Cannizzaro

Ashley

et al. 2003

J. Am. Chem. Soc.

View full text Add to dashboard Cite

The exo and endo Diels-Alder adducts of p-methoxycarbonylbenzyl trans-1,3-butadiene-1-carbamate and N,N-dimethylacrylamide have been synthesized, and the absolute configurations of resolved enantiomers have been determined. On the basis of this information, the absolute enantioselectivities of the Diels-Alder reaction catalyzed by antibodies 13G5 and 4D5 as well as other catalytic antibodies elicited in the same immunizations have been established. The effects of different arrangements of catalytic residues on the structure and energetics of the possible Diels-Alder transition states were modeled quantum mechanically at the B3LYP/6-311++G**//B3LYP/6-31+G** level of theory. Flexible docking of these enantiomeric transition states in the antibody active site followed by molecular dynamics on the resulting complexes provided a prediction of the transition-state binding modes and an explanation of the origin of the observed enantioselectivity of antibody 13G5.

show abstract

“…Studies on other carbamates point to partial double bond character occurring along the ethereal oxygen-carbon bond, rather than tautomerization. 13 It is difficult, therefore, to reconcile the previously reported results for 17. However, the anilide proton from salicylanilide, a possible hydrolysis product from 17, does resonate at 10.5.…”

Section: ^Conhph Oconhch3 16mentioning

confidence: 92%

Question of amide group participation in carbamate hydrolysis

Hegarty¹,

Frost²,

Coy³

1974

J. Org. Chem.

View full text Add to dashboard Cite

Botational babbiers in the ester function of some carbamates. The use of an iterative computer program in a nmr study

Cited by 15 publications

References 10 publications

Acid‐Promoted Chemoselective Introduction of Amide Functionality onto Aromatic Compounds Mediated by an Isocyanate Cation Generated from Carbamate

Acid‐Promoted Chemoselective Introduction of Amide Functionality onto Aromatic Compounds Mediated by an Isocyanate Cation Generated from Carbamate

Experimental Determination of the Absolute Enantioselectivity of an Antibody-Catalyzed Diels−Alder Reaction and Theoretical Explorations of the Origins of Stereoselectivity

Question of amide group participation in carbamate hydrolysis

Contact Info

Product

Resources

About