Methanesulphonate esters

The structure proposed for septicine (20), the dehydroindolizidine constituent of Ficus septica, has recently been confirmed by two independent syntheses. The first synthesis proceeded from veratraldehyde, which was condensed with homoveratric acid to give the unsaturated acid (21) this was then converted into the primary chloride (22) by standard methods. Alkylation of L-prolinol with this chloride gave the amino-alcohol (23), which was converted into its O-methanesulphonate ester. Reaction of this ester with sodium hydride in anhydrous... 

Clapp NK (1973) Carcinogenicity of nitrosamines and methanesulphonate esters given intraperitoneally in RF mice. Int J Cancer 12 728-733... 

Buffered hydrolysis of the esters (110), (112), and (115) yielded the same mixture of alcohols (109) and (114), and the symmetrical homoallylic ion (117) is the suggested common intermediate.The high solvolysis rates of the methanesulphonate esters (111), (113), and (116) provide evidence for a-bond or rc-bond participation, as appropriate, in the transition states. An extensive study is reported of the reaction of a-d-pinene with a series of carboxylic acids under a variety of conditions the bridged ions (118) and (119) appear to be the significant product precursors. Acetolysis of the triflate ester (120 n = 1) is considered to occur by 7t-assisted ionization to give the bicyclo[2,2,l]hex-2-en-5-yl cation (122 n = 1) by way of (121 ... 

Aliphatic alcohols are not reducible under electrochemical conditions. Conversion to a suitable anionic leaving group however does allow carbon-oxygen bond cleavage. Thus, methanesulphonates are reduced at a lead electrode under constent current conditions and this affords an overall tw o step process for the conversion of alcohols to alkanes [9].Deoxygenation of alcohols by this route has been applied successMly in the presence of other functional groups which are difficult to reduce such as alkene, epoxide, ester and nitrile. Cyclopropanes are formed in 50-97 %... 

Deoxygenation of a-hydroxy esters is achieved under milder conditions by reaction of the methanesulphonate with electrochemically generated phenylselenium... 

Parallel work by Penczek and his co-workers (134) using esters of fluoro-methanesulphonic acid, e.g. Et-0S02CF3, to polymerise THF has shown that these initiators are more complex, polymerisations being characterised by a relatively slow initiation process. Rather interestingly, both kinetic data and independent 1HNMR studies indicate a further complication in that during polymerisation a polymeric ester species exists in equilibrium with a fully developed macroion. 

Augustamine, [109]. The stannylated inline 353 utilised in the synthesis of (-)-amabiline (346) also served as the advanced intermediate for the preparation (Scheme 65) of (-)-augustamine (493) [93,94]. Thus, treatment of the mixture of the lithium salts 355 and 356 with iodomethane furnished a 43 1 mixture of the two tertiaiy amines 494 and 495 respectively. The cij-diol, obtained on acid hydrolysis of the former was converted into the ortho ester 496, which on exposure to methanesulphonic acid underwent cyclisation via the carbenium ion 497 to (-)-augustamine (493) in 76% yield. 

Reactions of 3-substituted 2-(lV-phenylaminomethyl)piperazines with a slight excess of ethyl 2-chloroacetate under reflux afforded mixtures of 9-substituted 2-phenylperhydropyrido[l,2-a]pyrazin-3- and -4-ones, which could be separated by column chromatography [72JCS(P2)1374], When 2-[(3-trifluoromethylphenyl)aminomethyl]piperidine was heated with optically active ethyl 2-chloropropionate (87MIP1 91TA231), or lactic acid ethyl ester methanesulphonate (91TA231), the product was a C-9a epimeric mixture of 2-(3-trifluoromethylphenyl)-4-methylperhydropyrido[l,2-fl]-pyrazin-3-ones. The reaction between yV-methyl-2-piperidine-carboxamide and hydroxymaleic anhydride in pyridine resulted in 2,3-dimethyl-3-hydroxyperhydropyrido[l,2-a]pyrazine-l,4-dione (74CB2804). 

CHLOROETHYLMETHANESULFONATE CHLOROETHYL METHANESULPHONATE CHLORO-METHANE SULFONATE d ETHYLE (TRENCH) METHANESULFONIC ACID CHLOROETHYL ESTER NSC-18016... 

SYNS as-DLMETHYL SULPHATE METHANE-SULPHONTC ACID METHYL ESTER METHYL ESTER of METHANESULFONIC ACID METHYL ESTER of METHANESULPHONIC ACID METHYL METHANE-SULFONATE n METHYL METHANESULPHONATE METHYL METHANSULFONAT (GERMAN) METHYL METHANSULFONATE METHYL METHANSULPHON-ATE MMS NSC-50256... 

The potentials of methanesulphonic acid as initiator have by no means been exhausted. It seems a very interesting initiator and should be exploited in the future. The fact that it forms active ester molecules with p-methoxystyrene, a very basic monomer, suggests that the polymerisation of styrene with this acid is very probably pseudocationic. 

These two adds, which are stronger than sulphuric acid but weaker than trifluoro-methanesulphonic acid, have not been used in any detailed fundamental study in cationic polymerisation. Alkenes give the corresponding esters, but do not polymerise with these initiators Aromatic olefins, on the contrary, are readily polymerised. 

Many steroid secondary alcohols are resistant to acid-catalysed dehydration, but can be converted into olefins by elimination reactions of their sulphonate esters, usually the toluene 3 -sulphonate ( tosylate ) or methanesulphonate ( mesylate ). These elimination reactions always accompany attempted nucleophilic substitution of the sulphonate (p. 41), and can be made to predominate by appropriate choice of reaction conditions. Activated alkaline alumina has been used to prepare A - and AH-olehns from the sulphonates of 3 - [131] and i2a-alcohols [132]. In the latter case the naphthalene-i-sulphonate was most effective, and the methanesulphonate distinctly less so, suggesting that steric acceleration occurs with the more bulky naphthalenesulphonate [ 132c]. This view is strengthened by the enhanced efficiency of elimination of a i2a-sulphonate in the presence of a 17a-methyl group, which increases the compression at C(i2) [132b]. The mechanism and stereochemical features of these heterogeneous reactions have not been described in detail. 

HMPT has been reported to be a useful solvent for the photoreduction of esters. For example, perfluorinated esters give defluorinated esters as well as the corresponding alkeme and alkyl esters give alkanes alone,in processes which involve electron-transfer from HMPT to ester. Methanesulphonates, ROjSMeCR-S-cholesten-Sp-yl, 4,4-dimethyl-3/3-cholestanyl,... 

Reaction of 1-phosphinylimidazoles with methanesulphonic acid at — 60 °C gives the phosphinyl sulphonate esters 54. These compounds are unstable at ambient temperatures and undergo a [1,2] — O to S rearrangement of the phosphinyl moiety to yield phos-phinoyl sulphones 55105. Little is known about this reaction except that, if both R1 and R2 are alkoxy groups, the rearrangement is not observed. 

Sulphate ester conjugates can be converted to acetyl derivatives in much the same way. This is a relatively mild procedure by which esters which are too unstable to acid hydrolysis can be characterized. The sulphate ester (10 mg) is dissolved in a 1 40 solution of methanesulphonic acid in acetic anhydride (2 ml) at 0°C and the mixture is then heated at 100 °C for 30 min. The... 

Di-iododimethylsilane appears to be an effective reagent for the mild deoxygenation of a-arylalkanols to the corresponding hydrocarbon. Aliphatic alcohol methanesulphonates are selectively reduced in good yield by an electrochemical method. The reaction is performed in a divided cell with a lead cathode and a platinum anode in dry DMF containing tetraethylammonium toluene-p-sulphonate. Yields are in the range 57—87%, and groups such as esters, olefins, nitriles, and even epoxides are inert under these conditions. ... 

Thiol esters are reduced to primary alcohols by sodium borohydride in ethanol without significant transesterification.These conditions do not affect oxygen esters whereas sodium borohydride used either in polyethylene glycols such as PEG-400 at 65 or in DMSO containing methanesulphonic acid, has been shown to reduce esters to primary alcohols the borohydride-acidic DMSO system also reduces carboxylic acids, other than conjugated aromatic acids, to alcohols. An improved procedure for rapid reduction of esters to alcohols with borane-dimethylsulphide involves using THF as solvent at reflux, with an aqueous alkaline work-up. 

The synthesis of glycidic esters in a two-phase solid-liquid system has been reported yields of between 32 and 92 % are obtained for eleven examples. 2,3-Dibromoalkyl esters react with excess sodium azide on heating to give 2-azido-2-alkenoic esters in 71 to 87 % yield over five examples. The chiral formamido-ester (71) reacts with oxomethylenebis-(3 f+-imidazolium) bis(methanesulphon-ate) (72), a non-basic dehydrating agent, to give the a-isocyano-ester (73) in 80 % yield with only 1 % racemization, as shown by the re-hydration of the product (73) (Scheme 38). ... 

Sulphonyl Peroxides.—Continuing interest in this class of compound is a consequence of their value in aromatic sulphonoxylation and in their addition to alkenes to give sulphonate esters. A useful electrochemical preparation of bis(methanesulphonyl) peroxide from sodium methanesulphonate makes available a reagent for the synthesis of methanesulphonates of less reactive aromatic hydrocarbons. 

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