Über den mechanismus der sulfilimin-bildung—II

“…. +--To; To1II for the reaction between (+)-(R)-methyl ptolyl sulfoxide (8) 911 reagent, giving a six-membered ring sulfurane intermediate. If, as shown in Scheme 11, both incoming and leaving groups occupy equatorial positions, the decomposition of the sulfurane will give…”

mentioning

confidence: 99%

The chemistry of sulfilimines

Gilchrist¹,

Moody²

1977

Chem. Rev.

226

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“…16 The (±)-2-cyanothiane (3) and (±)-2-cyanoselenane (4) were prepared, as outlined in the Scheme 1, by the cyclization of (±)-2,5-dibromohexanoic acid (5) 17,18 with sodium sulfide 17,18 or selenide, followed by purification of the heterocyclic carboxylic acids (6, 7) as their methyl esters (8,9), 17,18 and ammonolysis of these afforded the corresponding amides (10,11), which were then dehydrated to yield the target nitriles (3,4) .…”

Section: Resultsmentioning

confidence: 99%

“…This acid was prepared according to a literature procedure 17,18 and obtained as an oil, bp 125-130 8C/0.05 mm Hg, which crystallized on storage, mp 45-47 8C. 1 H NMR d H (ppm): 11.11 (1H, br s), 4.23 (1H, dd, J = 6.6 and 7.9 Hz) 3.37 (2H, t, J = 6.6 Hz), 2.05 (2H, m), 1.87 (2H, m), 1.85 (1H, m), 1.64 (1H, m).…”

Section: Methodsmentioning

confidence: 99%

Concerning the conformational preferences of the 2-cyano derivatives of oxane, thiane, and selenane

et al. 2010

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This paper investigates the origin of the anomalous anomeric effect in merosinigrin, a 2-cyanothiane in which the cyano group is axial as expected for the anomeric effect, but in which bond distances are opposite to that expected from the n S ?s Ã CÀCN orbital interaction, which underlies the classical anomeric effect. The model compounds, 2-cyanooxane, 2-cyanothiane, and 2-cyanoselenane, were synthesized and studied both experimentally and computationally. Both the thia and selena systems displayed an even higher preference for the axial conformation than the oxa system but also exhibited the bond length anomalies found previously in merosinigren. Natural bond order (NBO) analysis of the B3LYP/6-311+G(3df,2p) wave functions of the axial and equatorial forms of the three systems confirmed a weakening of the n?s* orbital interaction in the O, S, and Se series, and a strengthening of a s-p*(CN) interaction that explains the bond length reversals observed in the S and Se systems. It also revealed a new mechanism, n?p*, namely, a through-space interaction between the nonbonded lone pair electrons of the heteroatom and the p* orbital of the cyano group, which selects for the axial conformation.Résumé : Dans ce travail, on recherche l'origine de l'effet anomère anormal dans la mérosinigrine, un 2-cyanothiane dans lequel le groupe cyano est axial, tel qu'on pourrait s'y attendre en raison de l'effet anomère, mais dans lequel les longueurs des liaisons sont à l'inverse de celles attendues sur la base d'une interaction orbitalaire n S ?s Ã CÀCN qu'on retrouve dans l'effet anomère classique. On a synthétisé les composés modèles, 2-cyanooxane, 2-cyanothiane et 2-cyanolélénane et on les a étudiés tant d'un point de vue expérimental que théorique. Les systèmes thia et séléna présentent tous les deux une préférence pour la conformation axiale qui est supérieure à celle du système oxa, mais ils présentent aussi les anomalies de longueurs des liaisons qui ont été observées antérieurement dans la mérosinigrène. Une analyse de l'ordre naturel de liaison (ONL) des fonctions d'onde B3LYP/6-311+G(3d,2p) des formes équatoriales et axiales des trois systèmes confirme un affaiblissement de l'interaction de l'orbitale n?s* dans les séries O, S et Se et un affermissement de l'interaction s-p*(CN) qui explique les inversions des longueurs des liaisons observées dans les systèmes S et Se. Elle met aussi en évidence un nouveau mécanisme, n?p*, à savoir une interaction à travers l'espace entre la paire d'électrons non liée de l'hétéroatome et l'orbitale p* du groupe cyano qui choisit la conformation axiale.

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Über den mechanismus der sulfilimin-bildung—II

Cited by 19 publications

References 7 publications

Spiro-λ4-sulfanes with O-ligands of different electronegativity in axial positions. A comparison of CH2O–SIV–OCO and CH2O–S+IV · · · OC bond systems

Spiro-λ4-sulfanes with O-ligands of different electronegativity in axial positions. A comparison of CH2O–SIV–OCO and CH2O–S+IV · · · OC bond systems

The chemistry of sulfilimines

Concerning the conformational preferences of the 2-cyano derivatives of oxane, thiane, and selenane

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