Unusual steric effects in sulfonyl transfer reactions

Hinchliffe, Paul S.; Wood, J. Matthew; Davis, Andrew M.; Austin, Rupert P.; Beckett, R.Paul; Page, Michael I.

doi:10.1039/b104923m

Cited by 9 publications

(15 citation statements)

References 12 publications

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“…11, 15 A large SKIE k (H 2 O)/k (D 2 O) of 4.4 is observed for the pH independent hydrolytic reaction, k 0 . This is not consistent with water acting solely as a nucleophile with rate limiting attack at the sulfonyl centre but is indicative of rate limiting proton transfer perhaps involving general acid catalysis by water (12). Another alternative mechanism to account for the large SKIE is the general base catalysed addition of water.…”

Section: (Iv) Reactions Of N-benzoyl -Sultam With Nucleophilesmentioning

confidence: 81%

Reactivity and the mechanisms of reactions of β-sultams with nucleophiles

Wood

Hinchliffe

Laws

et al. 2002

J. Chem. Soc., Perkin Trans. 2

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Section: (Iv) Reactions Of N-benzoyl -Sultam With Nucleophilesmentioning

confidence: 81%

Reactivity and the mechanisms of reactions of β-sultams with nucleophiles

Wood

Hinchliffe

Laws

et al. 2002

J. Chem. Soc., Perkin Trans. 2

Self Cite

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“…In contrast to carboxamides, the hydrogen bond acceptor in sulfonamides is the sulfonyl oxygen, whereas their protonation occurs at the nitrogen atom. Therefore, we have calculated, using the B3LYP/6–311G** method, the H‐bonded complexes of carboxamides and sulfonamides with phenol having the OH … O=S or OH … N hydrogen bond.…”

Section: Resultsmentioning

confidence: 99%

“…Note that the conclusion that the conjugation of the type present in carboxamides is lacking in sulfonamides was made in an earlier computational study . However, irrespective of the mechanism of the charge transfer, sulfonamides are more acidic than carboxamides by ~5 p K units . Sulfonamides are good hydrogen bond donors and as such can be used as anion receptors .…”

Section: Introductionmentioning

confidence: 94%

The basicity of sulfonamides and carboxamides. Theoretical and experimental analysis and effect of fluorinated substituent

Shainyan

Chípanina

Oznobikhina

2012

J of Physical Organic Chem

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The basicity of a series of sulfonamides and carboxamides with respect to protonation and hydrogen-bonded complex formation with phenol was investigated by calculations using the Becke three-parameter hybrid functional combined with Lee-Yang-Parr correlation functional with the 6-311G** and 6-311++G** basis sets and by infrared spectroscopy. The effect of fluorinated substituent was studied for the two series. The proton affinity of nitrogen in sulfonamides is higher than oxygen, in contrast to carboxamides, which are protonated at oxygen. The phenyl group in benzenesulfonamide increases the basicity of both heteroatoms, but more strongly of the nitrogen, whereas in benzamide the effect on the two heteroatoms is about the same. The CF 3 group equally decreases the basicity of nitrogen and oxygen atoms in sulfonamides and carboxamides. The second fluorinated substituent decreases the basicity of oxygen in (CF 3 CO) 2 NH more strongly than of nitrogen. For sulfonamides, the same effect results in the reverse of the center of basicity from nitrogen in (MeSO 2 ) 2 NH to oxygen in (CF 3 SO 2 ) 2 NH. All studied carboxamides give H-complexes via the carbonyl oxygen, whereas for sulfonamides two types of H-complexes, with the OHÁÁÁN and OHÁÁÁO=S, were found theoretically, the latter being more stable. The exception is bisimide (CF 3 SO 2 ) 2 NH, for which only the OHÁÁÁO=S complex is stable. Experimentally, only the oxygen-bound complexes are observed. Analysis of the natural charges revealed an 'abnormal' increase of the electron density on the NH group by electron-acceptor substituents in CF 3 SO 2 NHR, which was explained using the natural bond orbital analysis by loosening of the S-N bond because of orbital interactions with the s* SÀN orbital.

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“…Hinchliffe et al described some unexpected α-alkyl substituent effects upon ringopening reactions accompanying the alkaline hydrolysis of N-acyl-β-sultams. 53 The hydrolysis of N-acyl-β-sultams generally occurs with ring opening and S-N fission in contrast to the C-N fission observed in analogous acyclic N-acyl sulfonamides. N-acyl derivatives are at least 10 6 -fold more reactive than their acyclic N-acylsulfonamide counterparts.…”

Section: Acyl Transfer: Sulfurmentioning

confidence: 99%

6 Reaction mechanisms : Part (i) Polar reactions

Dalby

2002

Annu. Rep. Prog. Chem., Sect. B: Org. Chem.

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Unusual steric effects in sulfonyl transfer reactions

Cited by 9 publications

References 12 publications

Reactivity and the mechanisms of reactions of β-sultams with nucleophiles

Reactivity and the mechanisms of reactions of β-sultams with nucleophiles

The basicity of sulfonamides and carboxamides. Theoretical and experimental analysis and effect of fluorinated substituent

6 Reaction mechanisms : Part (i) Polar reactions

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