A New Rearrangement of Sulfonium Ylides

Ratts, K. W.; Yao, A. N.

doi:10.1021/jo01265a014

Cited by 38 publications

(14 citation statements)

References 23 publications

(17 reference statements)

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“…The same strategy was applied to the synthesis of syn and anti sulfides 13a and 13b using an aldol reaction with amide 12 13 (Scheme 8). In the aldol process involving the amide we found that LiCl was essential to obtain reasonable yields of the aldol adducts.…”

Section: Synthesis Of Sulfides and Sulfonium Saltsmentioning

confidence: 99%

“…All commercially available reagents and solvents were purified and dried according to standard procedures and all experiments were carried out under an inert nitrogen atmosphere. Literature procedures were used to prepare the following compounds: N-benzylidenetoluene-p-sulfonamide, 2b trans-N-( p-tolylsulfonyl)-2,3-diphenylaziridine, 3 cis-N-( p-tolylsulfonyl)-2,3-diphenylaziridine, 3 N,N-diethyl-2-methylsulfanylacetamide, 13 and trimethyloxonium tetrafluoroborate. 20…”

Section: Experimental Generalmentioning

confidence: 99%

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Additions of stabilised and semi-stabilised sulfur ylides to tosyl protected imines: are they under kinetic or thermodynamic control?

Aggarwal

Charmant

Ciampi

et al. 2001

J. Chem. Soc., Perkin Trans. 1

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Sulfur ylides react with imines, via betaines, to give aziridines. We sought to determine whether betaine formation was reversible in reactions of benzyl-, amide-and ester-stabilised ylides by carrying out cross-over experiments. Thus, the intermediate betaines were generated independently from the corresponding sulfonium salt in the presence of a more reactive imine ( p-nitrobenzaldimine). It was found that no incorporation of the more reactive imine was observed in reactions with the benzyl-stabilised ylide, whilst >80% incorporation of the p-nitrobenzaldimine was observed from the ester-and amide-stabilised ylides. These results indicate that benzyl-stabilised ylides react irreversibly with imines but ester-and amide-stabilised react reversibly. Thus, the stereocontrolling step of the process is dependent on the type of ylide employed and the results are used to account for the different diastereoselectivities observed with the different ylides.Scheme 2 Catalytic asymmetric aziridination of imines with in situ generation of diazo compounds.

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Section: Synthesis Of Sulfides and Sulfonium Saltsmentioning

confidence: 99%

Section: Experimental Generalmentioning

confidence: 99%

Additions of stabilised and semi-stabilised sulfur ylides to tosyl protected imines: are they under kinetic or thermodynamic control?

Aggarwal

Charmant

Ciampi

et al. 2001

J. Chem. Soc., Perkin Trans. 1

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“…The configuration at selenium and the long Se-C(13) bond are indicative of a large contribution from the ylide resonance structure lb. X-Ray data on a sulfur ylide 3 revealed that the sulfur atom lay CN \ _^CN +Z > ch3 3 0.74 A out of the plane of its three neighbors,19 while the selenium-containing compound 4 had an effectively planar arrangement at selenium and an Se-C distance of 1.802 (11) Á, a value which implied considerable double bond character in the Se-C bond in 4. 20 In 2, the two Se-C bonds in the five-membered ring were much longer (1.99 and 2.01 A) than in 1 and the selenium lay even further (0.91 A) out of the plane of its three bonded neighbors.…”

Section: Resultsmentioning

confidence: 99%

Preparation and structural features of a selenium ylide, diacetylmethylenediphenylselenurane

Wei¹,

Paul²,

Chang³

et al. 1974

J. Am. Chem. Soc.

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Diacetylmethylenediphenylselenurane, 1, a selenium ylide, was prepared by the reaction of diphenylselenium dichloride with sodium acetylacetonate in methanol solution. The nmr spectrum showed a methyl singlet at 2.43 ppm. X-Ray analysis confirmed the structure as an ylide and showed that the configuration at selenium was pyramidal with Se lying 0.78 A out of the plane of its three bonded atoms. Low-temperature nmr studies show that the equilibration of the two methyl groups proceeds via an energy barrier of <10 kcal/mol. The crystals of 1 are monoclinic with a = 13.297 ( 7), b = 13.418 (6), c = 9.112 (5) Á, and ß = 111.7 (1)°; the space group is P2Jc and there are four molecules of Ci7Hie02Se in the unit cell.

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“…Formation of 12 is closely analogous to the rearrangement leading to 8 and also has precedent in reactions of other keto ylides. 15 Of particular concern in our laboratory is the possibility of converting Diels-Alder adducts 2 into large ring sulfides by 2.3sigmatropic ring expansion.16 This reaction can be surprisingly facile. For example, treatment of 7 with (CH3)30+BF4" followed by KO-r-Bu (instead of DBU as in preparation of 8) produces the thiacyclononene 14 as the major product (32%) via the kinetically favored methylide and 8 (11%) derived from the carbonyl-stabilized ylide.…”

Section: C02ch3amentioning

confidence: 99%