Alkyl fluorosulphonates

Sulphonic esters have been obtained from the sulphonyl chlorides in high yields under mild conditions for a range of alcohols and phenols [e.g. 18, 19]. Of particular value is the protection of glycosides possessing a free hydroxyl group and hydroxy-steroids, which are tosylated readily under phase-transfer conditions [20-22]. Alkyl sulphinites have been obtained in a similar manner [23]. Alternatively, preformed tetra-rt-butylammonium sulphonates or their alkali metal salts have also been alkylated with haloalkanes or alkyl fluorosulphonates [24,25]. In contrast with more classical procedures, tosylation of alcohols, which are susceptible to E/Z-isomerism, e.g. Z-alk-2-en-l-ols, occurs with retention of their stereochemistry under phase-transfer catalysis [26]. 

C. The Fluorosulphonic Acid-Antimony Pentaflvoride and Hydrogen Fluoride-Antimony Perdaflvxyride Solvent Systems Attempts to generate simple alkyl-, arylalkyl-, and cycloalkyl-carbonium ions in sulphuric acid or oleum solution generally result in... 

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. 

Alkyl diazonium ions are very reactive intermediates, but have none the less been observed in superacid solution. Dissolving diazomethane in fluorosulphonic acid at -120 °C yielded the methyl diazonium ion (177) and the methylene diazenium ion (178) in the ratio 4 to 1. 

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. ... 

AT-chlorosuccinimide in MeOH (PhSCHRBRj - PhSCHROMe)/ methanolysis of 5-monomethyl dithioacetal fluorosulphonates, and addition of an alkyl-lithium to thiono-esters. Quantitative studies have been reported for an interesting variation on the simplest preparation, in which hemithioacetals exist in equilibrium with an aldehyde and a mixture of two thiols. ... 

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. 

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). ... 

The sulphur atom of penicillins and cephalosporins is normally presumed to be unreactive toward common alkylating agents. However, treatment of (55 f,y) with methyl fluorosulphonate produced the stable, optically active sulphonium... 

At very low temperature (-126 °C), the lithio-anion of sulphenic acid (83 t) has been trapped by alkylation (methyl fluorosulphonate) at higher temperature. 

Convenient methods for the S-alkylation of thiophens with the methyl or ethyl esters of fluorosulphonic acid, or with methyl iodide and AgBp4, have been worked out. The ylide from the methyl derivative has been obtained. ... 

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