Methylthio carbene

Chloro(methylthio)carbene is generated from dichloro(methylthio)methane... 

Generation and reaction of chloro(methylthio)carbene Procedure 7.1.15 is used replacing the PhSCHCl2 with MeSCHCl2 (5.24 g, 40 mmol). 

Phenylthiocarbene, chloro(phenylthio)carbene, their seleno analogues, and the less electrophilic chloro(methylthio)carbene react with a range of alkenes [145-148], as does chloro(phenoxy)carbene [149]. 

Transient carbene (9) is expected to be a reaction intermediate in the transformation of butadiyne-linked triazene (8) to alkyne-linked bis-2//-indazolcs (10).18 Experimental data and DFT calculations support carbene (9) as an intermediate in this stepwise, non-synchronous coarctate reaction. Methoxy(methylthio)carbene (12) has been observed by UV photoelectron spectroscopy after gas-phase decomposition of oxadiazoline (11).19 The oxadiazoline (13) allows the generation of the acetoxy(methoxy)carbene (14) 20 -pjjg reaC jvj y 0f (he latter with isocyanates has been explored. Such reactions generally yield methyl (acetylamino)oxoacetates (15). DFT calculations permitted interpretation of the experimental data. 

Chloro(methylthio)carbene is an electrophilic carbene 0.91) and, generated using... 

Chloro(methylthio)carbene is an electrophilic carbene (/nCicsMe 0.91) and, generated using potassium terf-butoxide, is kinetically free (experiments carried out with crown ether and without this additive).42... 

C2 6H2 el 2I, 7 -Cyclopentadienyliodomethyl(methylthio)carbene(tri-phenylphosphine)iridium(III), 46B, 903 C2 6H2 eOPdS, 3-Thio-1,3-diphenylprop-2-en-1-one-norbornenyl-2-methyl-allylpalladium(II), 39B, 573... 

Because a-alkoxyalkyl iron complexes are thermally unstable [467] they cannot be stored for long periods of time. More suitable carbene precursors are the corresponding a-(dimethylsulfonium)alkyl complexes, which can be stored indefinitely under ambient conditions [468-473], These complexes are prepared by S-alkylation of a-(methylthio)alkyl complexes, which can be prepared by alkylation of metallates with a-halothioethers, by addition of C-nucleophiles to (alkylthio)carbene complexes, or by addition of thiols to carbene complexes. 

Two recent examples belong to this class of reaction for carbene complexes. Pentacarbonyl[methylthio (methyl) carbene3chromium(0) and -tungsten (0) react at low temperatures with hydrogen bromide to give pentacarbonyl[(l-bromoethyl)metliylsulfide] complexes (65) ... 

Cycfoheptan 2,2-Bis-[methylthio]-l-oxo- E19b, 1704 (Carben + cycl. Keton)... 

Benzol 2-(2-Ethoxy-propyl)-l-methylthio- El9b, 878 (Carben + Ether)... 

Carbanions 128, generated from the corresponding Fischer carbene complexes with -butyllithium, reacted with 2-methylthio-l,3-dithiolium salts 123 to give heterocyclic organometallic carbenes 129. Reactions of allylic carbanions 130 afforded a mixture of mono- and diheterocyclic condensation products 131 and 132, respectively (Scheme 11) <2004TL7843>. 

The carbyne carbon atoms in both [W(CO)2 HB(pz)3)(CSMe)] (449) (266) and [W(CMe)Cp(CO)2] (450) (267) are nucleophilic and react with protons and the methylthio cation, SMe , to form cationic carbene complexes. Whereas the first type of carbene complex is typically electrophilic (257), the latter one, 451, is nucleophilic, and treatment with trifluoroace-tic acid produces a cationic metallathia cyclopropane complex (452) (268). 

Convenient methods have been developed for the synthesis of triazolium salts. The 3-methylthio-substituted triazolium compounds 138 are readily accessible by the reaction of 5-methyl-1,4-diphenylisothiosemi-carbazide with acid chlorides, or (in the presence of phosphorus oxychloride) with carboxylic acids (74TL2649). Deprotonation of 138 (R = H) yields the nucleophilic carbene 139, which is readily alkylated to yield... 

Dihydrobenzo[b]thiophene may be obtained by reduction of ben-zo[b]thiophene (Section III,A,1) by treating 2-o-(benzylthio)phenyIethanol with SOCl2-pyridine (91%),208 and by cyclization of o-(methylthio)phenyl-carbene at 250°C (45%) the last procedure is mainly of academic interest.304 Substituted phenyl vinyl sulfides undergo photocyclization to the expected... 

Methylthio(chloro)carbene has been generated under phase transfer conditions from dichloromethyl methyl sulfide. This carbene cyclopropanates tetramethyl-ethylene in 43%yield, accompanied by a 24%yield of l,2-dichloro-l,2-Z /5-methyl-thioethylene [24]. 

Reaction of dimethylvinylidene carbene with 3-methyl-2-butenyl-methylsulfide leads to 4-methylthio-3,3,6-trimethylhept-5-ene-l-yne (36%). The reaction sequence, illustrated in equation 4.15, has been proposed to account for the product obtained. Apparently, the unsaturated carbene favors reaction with sulfur rather than the carbon-carbon double bond [28]. 

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