Dimethyl sulfonium Methylide

N-Metkylation ofindoles Indoles can be selectively N-methylated by dimethyl-sulfonium methylide in THF at room temperature. 

Methylation Diazomethane-Boron fluoride etherale. Dimethylcopperlithium. Dimethyl-sulfonium methylide. Iodine Methyl iodide. Methyl-(tri-n-butylphosphine) copper complex. Silver perchlorate. Simmons-Smith reagent. Sodium hydride. 

OXIRANES (Dimethylamino)phenyl-oxosulfonium methylide. Dimethyl-sulfonium methylide. (Dimethyl sulfoxide, derived reagent (b)). Methylene bromide-Lithium. Methylphenyl-N-p-tohienesulfonylsulfoximine. 

The synthesis of lettucenin A was achieved by Monde et al. and this is described in Scheme 14. Indanone (146) was treated with dimethyl sulfonium methylide to give an aldehyde and allyl alcohol, which were... 

Eine zu (22) analoge Zwischenstufe (27) konnte den Reaktionsverlauf zwanglos erklaren. Mit dem Dimethyl-sulfonium-methylid (3) wurde da-gegen nur o-Methoxy-benzaldehyd erhalten. 

Ohne Angaben fiber seine Reaktionsfahigkeit wurde das aus Dinitro-methan, Dimethylsulfoxyd und Acetanhydrid in 36 % Ausbeute zugang-liche Dinitro-dimethyl-sulfonium-methylid (101) beschrieben (J7), das sich gegenfiber Dinitromethan... 

Related Reagents. Two similar carbonyl-stabilized dimethyl-sulfonium methylides (1 and 2) have been reported to function as cyclopropanating reagents In a fashion analogous to... 

A new, complementary approach to enyne metathesis has also emerged in the work of Singh and Ghosh (Scheme 1.12) [50, 51]. A stepwise methylenation (using dimethyl sulfonium methylide ylide 78) and Stille-Gennari olefination sequence... 

Dimethyl sulfonium-2-pyridyl carbonyl methylide (Ypy-5) [65] initiated radical polymerization of styrene in dimethyl sulfoxide at 85 0.1°C for 6 h under a nitrogen blanket. (See Table 4.)... 

Table 4 Effect of Ylide Concentration on the Rate of Polymerization of Styrene Initiated by Dimethyl Sulfonium 2-Pyridyl Carbonyl Methylide...

One of the most remarkable recent extensions of the chemistry of aurated ylides was the multiauration of dimethyl(oxo)sulfonium methylide using trimethyl(oxo)sulfonium salts and (Ph3P)Au(acac) in different... 

Synthesis of racemic naproxene Friedel-Crafts acylation (aluminum chloride - nitrobenzene) of p-naphthol methyl ether affords 2-acetyl-6-methoxy naphthalene, which, when treated with either dimethyl sulfonium or dimethylsulfoxonium methylide, gives 2-(6-methoxynaphthalen-2-yl)propylene oxide. Treatment of the latter with boron trifluoride etherate in tetrahydrofuran gives 2-(6-methoxynaphthalen-2-yl)propionaldehyde, which is oxidized using Jones reagent (4 M chromic acid) to yield the racemic 2-(6-methoxynaphthalen-2-yl)propionic acid. 

The reaction of optically active (l-diethoxyphosphoryl)vinyl p-tolyl sulfoxide (20) with sulfur ylides has provided the corresponding cyclopropanes (21) in high yields (g) (Scheme 10).52,53 With fully deuterated dimethyl(oxo)sulfonium methylide, (CD3)2 S(0)CD2, the cyclopropanation reaction occurred in a highly diastereoselective... 

Die leichte Decarboxylierung der Saure (108) bei 56° mit Piperidin zum Dimethyl-dodecyl-sulfoniumsalz erfolgt vermutlich fiber das energe-tisch relativ gttnstige S-Dodecyl-S-methyl-sulfonium-methylid (70). 

Chlorosulfonyl isocyanate reacts similarly with dimethyl sulfoxide. Also, carbonyl isocyanates undergo an exchange reaction with dialkyl sulfoxides to give the corresponding sulfilimines . In contrast, dimethyl-oxo-sulfonium-methylid 170 reacts with isocyanates to give linear adducts 171 °. 

Pyridinium ylide is considered to be the adduct car-bene to the lone pair of nitrogen in pyridine. The validity of this assumption was confirmed by Tozume et al. [12J. They obtained pyridinium bis-(methoxycarbonyl) meth-ylide by the photolysis of dimethyl diazomalonate in pyridine. Matsuyama et al. [13] reported that the pyridinium ylide was produced quantitatively by the transylidalion of sulfonium ylide with pyridine in the presence of some sulfides. However, in their method it was not easy to separate the end products. Kondo and his coworkers [14] noticed that this disadvantage was overcome by the use of carbon disulfide as a catalyst. Therefore, they used this reaction to prepare poly[4-vinylpyridinium bis-(methoxycarbonyl) methylide (Scheme 12) by stirring a solution of poly(4-vinylpyridine), methylphenylsulfo-nium bis-(methoxycarbonyl)methylide, and carbon disulfide in chloroform for 2 days at room temperature. 

This precursor of dimethylsulfonium methylide is prepared in almost quantitative yield by mixing dimethyl sulfide (6 g.) and methyl iodide (14 g.). The sulfonium iodide separates as a solid cake and after 24 hrs. it is collected, crystallized from ethanol, and washed with ether. 

The copper-catalyzed methylene transfer from sulfonium ylidcs to electron-rich olefins proceeds stereospecifically and probably involves a methylene copper complex15. Sulfonium, sulfoxonium, and (dialkylamino)sulfoxonium ylides are nucleophilic species and, in uncatalyzed reactions, only good Michael acceptors are attacked16 (see also Vol. IV/3, p 139 and Vol. E 11 2, p 1422). The cyclopropanation proceeds stepwise via a zwitterion, and therefore the olefin configuration is not necessarily reflected in the cyclopropane stereochemistry. Thus, both dimethyl ( )- or (Z)-2-butenedioate react with dimethylamino(phenyl)sulfoxonium methylide to give the //ww-substituted cyclopropane 4 only1. ... 

Sulfonium, dimethyl-, 2-ethoxy-2-oxoethylide, 8 —, dimethyl-, methylide (Me CH ... 

Another difference in the reactivity of these two ylids is reflected in their reactions with a, 3-unsaturated ketones. The carboethoxy dimethylsulfonium methylid 620 reacted with cyclohexenone to give the usual alkoxy sulfonium salt 621. Intramolecular displacement of dimethyl sulfide led to the expected oxirane (622) analogous to the formation of 614. Dialkylsulfonium ylids react via 1,2-addition with displacement of the... 

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