Preparative and structural studies on certain sulphur-ylides

Nozaki, Hitosi; Tunemoto, Daiei; Morita, Zenzo; Nakamura, Katsumi; Watanabe, Kentaro; Takaku, M.; Kondo, Kiyoshi

doi:10.1016/s0040-4020(01)88826-8

Cited by 41 publications

(11 citation statements)

References 30 publications

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“…Prior studies have established a pyramidal structure for the sulfur center in acyclic sulfonium ylides, 19,20 and the pyramidal inversion barrier for ethylmethylsulfonium phenacylide(5)has beendetermined to be23.3 kcal/ mo1.20 Our estimate of a lower limit for pyramidal inversion in 2 of 16.8 kcal/mol and in 3 of 22.3 kcal/mol is therefore consistent with the view that thiabenzenes are ylide-like in character. 9, lo…”

Section: Department Of Chemistry Princeton Uizioersity Princeton Nesupporting

confidence: 84%

Thiabenzenes. III. Pyramidal stability at sulfur

Maryanoff¹,

Senkler²,

Stackhouse³

et al. 1974

J. Am. Chem. Soc.

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Section: Department Of Chemistry Princeton Uizioersity Princeton Nesupporting

confidence: 84%

Thiabenzenes. III. Pyramidal stability at sulfur

Maryanoff¹,

Senkler²,

Stackhouse³

et al. 1974

J. Am. Chem. Soc.

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“…We demonstrated that the structure of keto ylide hemihydrate 13a (see Ref. 13) consists of centrosymmetric H bonded dimers formed by two ester molecules, which are linked together by strong C=O...H-O hydrogen bonds between the carbonyl groups and the water molecule (Fig. 4).…”

Section: Table 2 Bond Lengths (D) and Bond Angles (ω) In Molecule 12mentioning

confidence: 84%

“…, H arom ) 13. C NMR, δ: 14.37 (CH 2 CH 3 ); 59.40 (CH 2 CH 3 ); 59.93 (C ylide ); 129.10, 129.23, 130.50, 131.04 (C arom ); 166.12 (C=O).…”

mentioning

confidence: 99%

Reactions of distabilized β-dicarbonyl sulfonium and iodonium ylides with isocyanates

et al. 2006

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The reactions of tosyl isocyanate with diethyl diphenylsulfuranylidenemalonate, 2 di methylsulfuranylidenedimedone, and 2 dimethylsulfuranylideneindane 1,3 dione afforded 1,3 ditosyl 5,5 diethoxycarbonylimidazolidine 2,4 dione and tosylimination products at the keto groups, respectively. Phenyliodonium ylides derived from diethyl malonate and ethyl acetate react with 3,4 dichlorophenyl isocyanate to form substituted oxazolin 2 ones.Key words: distabilized β dicarbonyl sulfonium and iodonium ylides, aryl isocyanates, tosyl isocyanate, tosylimination, 1,3 ditosyl 5,5 dicarbethoxyimidazolidine 2,4 dione, oxazolin 2 one, X ray diffraction study.Distabilized cycloimmonium, sulfonium, and iodo nium ylides derived from β dicarbonyl compounds have attracted considerable attention as functional nucleophilic reagents. 1-3 The electronic structures of these compounds give promise that interesting results will be obtained in comparative studies of the reactions of distabilized ylides with isocyanates.As part of our research on the reactions of carbanions with isocyanates, 4 we qualitatively correlated the reactivi ties of distabilized β dicarbonyl cycloimmonium, iodo nium, and sulfonium ylides with the Mulliken charges on the ylide carbon atoms calculated by the quantum chemi cal DFT B3LYP/LanL2DZ method.As can be seen from the above data, the highest nega tive charge is concentrated on the carbon atom of pyridinium ylide, the ylide carbon atom of the iodine derivative bears a somewhat lower negative charge, and the anionic charges are delocalized to the greatest extent in sulfur ylides. The nucleophilic reactivity of the ylides under consideration can correlate with the negative charges on the ylide carbon atoms. However, the scheme of interactions can also be influenced by the strength of the bond between the ylide carbon atom and the hetero atom. Apparently, this type of compounds have the weak est C-I bond. Therefore, in summary of the above men tioned factors, pyridinium and phenyliodonium ylides would be expected to exhibit the highest reactivity toward isocyanates. However, the schemes of their interactions can be substantially differrent due to the above mentioned structural features.Actually, pyridinium ylide 1 reacts with aryl isocyan ates at room temperature in a solution in CH 2 Cl 2 provid ing the C→N migration of the ethoxycarbonyl group in the second step of the reaction. This rearrangement af fords new pyridinium ylide 3 containing the carbamate function 5 (Scheme 1).The reaction according to Scheme 1 is a special case of the reactions of carbanions derived from esters with alkyl and aryl isocyanates giving rise to new types of carbamates through the insertion of the isocyanate mol ecule at the C-CO 2 Alk bond of the starting carbanion. 6 Taking into account the above mentioned reactivity of nitrogen ylides toward aryl isocyanates and with the aim of comparing the reactivities of different distabilized ylides, we performed the reactions of isocyanates with iodonium and sulfonium derivatives, for which only sc...

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“…The lack of broadening of the methyl peak in the 1 H-NMR spectrum of the selenonium ylide 11 upon cooling to −60 • C indicates that the equilibration of the two methyl groups proceeds via an energy barrier of <10 kcal/mol [27]. This value is lower than that of the sulfonium ylide Me 2 SC(COCMe) 2 for which a barrier of 12 kcal/mol (based on C-methyl signals broadening at −25 • C) was reported [36]. The 1 H-NMR spectra were used for the determination of the diastereoisomeric excesses of selenonium ylides 15a and 15b.…”

Section: Ohmentioning

confidence: 85%

“…This is most probably the reason why there is only one publication, in the available chemical literature, devoted specifically to 77 Se-NMR spectroscopy. The basic topic of this paper, published in Russian as early as 1982, is a brief discussion on the relationship between the structure of selected selenonium ylides and their 77 Se chemical shift [36]. The table prepared based on the original data is placed below (Figure 10).…”

Section: Structural Featuresmentioning

confidence: 99%