Methyl fluorosulphonate

Finally, the remaining steps were accomplished by methylation of 26a with methyl fluorosulphonate in ether to give the methylammonium salt 25, reductive cleavage of the N-0 bond with LAH and oxidation of the resulting alcohol with Jones reagent. The yields of the last three steps are almost quantitative and the overall yield of the seven steps synthetic sequence leading to optically pure (+)-luciduline (1) is 33%. 

Methyl fluorosulphonate was obtained by Meyer in 1932 by the action of fluorosulphonic acid on dimethyl ether ... 

Methyl fluorosulphonate is a liquid with an ethereal odour, boiling at 92° C. at ordinary pressure. It has a specific gravity of 1-427 at 16° C., and attacks glass. In the cold it has very little attack on rubber, cork and other organic substances. 

The formation and the oxidative properties of an oxaziridinium salt have been reported. With methyl fluorosulphonate the oxaziridine (30) led to the oxaziridinium salt (36) which was stable as a crystalline product at room temperature, but unstable in solution, giving (37), also obtained from (38) with methyl fluorosulphonate. NaBHt reduction of (36) led to (35). Peroxidic reactivity of (36) was shown by oxygen transfer from (36) to the imine (38) with formation of the nitrone (39) (Scheme 5). 

When ( + )-l-methyl-2-phenylethyl isocyanate is heated with triethyloxonium tetrafluoroborate or boron trifluoride diethyl etherate, a high yield of a dihydroisoquinolin-l-one is obtained, but heating with methyl fluorosulphonate leads to 3,4 ihydro-l-methoxy-3-methylisoquinoline [2935]. 

Reaction of hydroxy- and alkoxy-substituted aromatic compounds with methyl fluorosulphonate leads to the preparation of a sulphonate ester by carbon-sulphur bond formation342, as shown in equation 77. In the case of the hydroxy-substituted aromatic compounds, the synthetic utility is limited since side-reactions involving O-alkylation readily occur. 

The dithian depicted underwent simultaneous demethylation and dethiolation in dichloromethane by treatment with methyl fluorosulphonate initially at OX and subsequently at ambient temperature for 3 hours to give the corresponding dihydroxyketone in 92% yield (ref.146). 

Methyl fluorosulphonate, an exceptionally powerful methylating agent, transforms 3jff-acetamido-steroids (440) into their 0-methyl derivatives (441). These products are readily reduced by NaBH4 to give the 3 -ethylamino-steroids. ... 

Heteropentalenes.—N-2-Methylation of arylhydrazones of isothiazole-5-aldehyde, using methyl fluorosulphonate, gave salts which react with aqueous sodium bicarbonate to give the thiatriazapentalenes (35 = N, = NAr),... 

Thermolysis of the 3,4-dihydro-2//-thiopyran (82) in the presence of dienophiles such as maleic anhydride, styrene, and norbornene gave adducts such as (84) and (85). The thiochalcone (83) is assumed to be an intermediate. The ylide (87), prepared from methyl 6-vinylthian-2-carboxylate (86) and methyl fluorosulphonate, undergoes a 2,3-sigmatropic ring-expansion to methyl l-(methylthio)cyclohept-3-enecarboxylate (88) the cyclopentane (89) is formed as a by-product. ... 

The l,2,4-benzotriazepin-5-one (217) did not react with methyl iodide, dimethyl sulphate, or diazomethane, but with methyl fluorosulphonate it gave not the expected 1-methyl-derivative but the relatively stable quaternary salt (218). This underwent ring-contraction to form (219) on treatment with acid. ... 

Methyl fluorosulphonate reacts with tetramethyltin, forming trimethyltin fluorosulphate. Two general synthetic routes to methyltin chlorofluoro-sulphates and trifluoromethanesulphonates of the general type Me SnCl -(S03X)4 , (n, m = 0, 1, or 2 X = F or CF3) have been described solvolysis of the corresponding methyltin chlorides in the appropriate... 

Hindered di-t-aUcylamines RNHBu (R = t-Bu, t-octyl or 1-adamantyl) have been synthesized from t-alkylamines as follows. Reaction with peracetic acid gave the nitrosoalkanes RNO, which were treated with t-butyl radicals, generated from t-butylhydrazine and lead(IV) oxide, to yield t-butyloxyhydroxylamines. Reduction with sodium naphthalide in THF gave the products (equation 12). The di-r-alkyl-amines are inert to methyl iodide and dimethyl sulphate but can be alkylated by methyl fluorosulphonate. ... 

Dimethylaminotropone reacts with methyl iodide to give a quaternary ammonium compound but is predominantly methylated on the oxygen atom, giving a tropylium ion, by methyl fluorosulphonate. 

The thermolysis of azetidinone ( -lactam) disulphides (89) yields the iso-thiazolin-3-ones (90), amongst other products these, in turn, can be converted (in high yield) into 3-alkyl-(or aryl-)aminoisothiazoles (91) by reaction with methyl fluorosulphonate followed by ammonia, as shown in Scheme 6. 

Further mild methods have been reported for the regeneration of carbonyl compounds from ethylene and propylene thioacetals. Conditions include reaction with methyl iodide in aqueous acetone or methanol, methyl fluorosulphonate and water in liquid sulphur dioxide, ceric ammonium nitrate in aqueous acetonitrile, and silver oxide in aqueous methanol a number of papers report the dialkylation of such acetals with methyl... 

Benzylidene acetals can be formed under essentially neutral conditions using the bis-sulphonium ion (62) obtained by methylation of benzaldehyde ethylene dithioacetal with methyl fluorosulphonate (Magic Methyl ). Thus, methyl -d-glucopyranoside afforded a 4,6-0-benzylidene derivative (25%) when treated with (62) in pyridine. In the absence of an acid catalyst, it is unlikely that the thermodynamically favoured acetal would be obtained in high yield. 

Arylethylisothiocyanates underwent an intramolecular cyclization to give 1-ethylthio- or l-methylthio-3,4-dihydroisoquinolines when treated with triethyloxo-nium fluoroborate or ethyl- and methyl-fluorosulphonate respectively. Cyclization with aluminium chloride or polyphosphoric acid followed by alkylation of the resultant thiolactam gave the same products (Scheme 96). ... 

Acyclic sulphides handled during a continuing study of the reactions of penicillins and cephalosporins are the result of reaction of methyl fluorosulphonate, methyl chloroformate, and acetyl chloride with penicillin-derived thiazine S -oxides. 4-Methylthioazetidinones formed by treatment of penicillin esters with Mel and strong base suffer replacement of the MeS group by acetoxy on treatment with Pb(OAc)4. The MeS group turns up unexpectedly on the... 

Squaric dithiones (16 X = S) react with an amine to give transamination with intramolecular migration of a sulphur atom. -Methylated cations are obtained with methyl fluorosulphonate, and on hydrolysis lose a dimethylamino-group to give a ketone. Reactions of a cyclobutenedithione with a thiocyanate and reaction of a monothiosquarate dianion have been reported. 

The methylsulphonylammonium ion (7 R = H, X = NRR Me), prepared from the AW-disubstituted methanesulphonamide and methyl fluorosulphonate, also reacted by the reversible mechanism. These quaternary ammonium salts mesylate amines and alcohols in high yield under very mild conditions, and have... 

Various Side-chain Reactions.—2-(2-Thienyl)ethyl isocyanate has been prepared from the corresponding primary amine, carbonyi suiphide, and. S-ethyl chloro-thioformate. Cyclization of 2-(2-thienyl)ethyl isothiocyanate with methyl fluorosulphonate or triethyloxonium tetrafluoroborate gave (178a) and (178b), respectively. The 3-thienyl isomer reacted in the same way. Monoesters of aliphatic dicarboxylic acids and 2-(2-thienyl)ethanol have been prepared in con-... 

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