Mesylates preparation

Int. Ed. 2000, 39, 4355—4356 they also reported the organocopper-mediated 1,3-sub-stitution of a chiral propargyl mesylate, prepared by Baker s yeast reduction, to afford an optically active allene with 89% ... 

Sultana,Y.,Aqil,M.,and Ali,A. (2005), Ocular inserts for controlled delivery of pefloxacin mesylate Preparation and evaluation, Acta Pharma., 55(3), 305-314. 

We reported that Mn does, in fact, undergo oxidative addition to alkyl and benzylic tosylates and mesylates under mild conditions to yield the corresponding organomanganese tosylates and mesylates in excellent yields. To our knowledge, this is the first example of organomanganese tosylates and mesylates prepared via direct oxidative addition of manganese metal or by any metathesis approach. 

Naphthyl mesylate (prepared from / -naphthol and mesyl chloride in the presence of pyridine) in methanol hydrogenated at 25-40 with 5%-Pd-on-carbon until the calculated amount of has been absorbed naphthalene. Y 91%. F. e. s. K. Clauss and H. Jensen, Ang. Ch. 85, 981 (1973) via iminocarbonic acid esters cf. E. Vowinkel and C. Wolff, B. 107, 1739 (1974). 

Small pieces of Na added at -37 to -35° to a mixture of the startg. epoxy mesylate (prepared from geraniol), liq. NHg, and tetrahydrofuran until a blue color persists, and after another 10 min. solid NH4CI added linalool. Y 88%. - This is the last stage of a 3-step sequence for the isomerization of 2-ethylene-alcohols. F. e. s. A. Yasuda, H. Yamamoto, and H. Nozaki, Tetrah. Let. 1976, 2621. 

Mesylated and Tosylated Celluloses. It has been estabUshed that the flame resistance of ceUulose (qv) is improved by oxidation of —CH2OH groups to —COOH (58—60). To correct some of the shortcomings of this treatment, mesyl or tosyl ceUulose was prepared and then the mesyl (CH2SO2) or tosyl (CH2CgH4S02) group was replaced with bromine or iodine (58—60) ... 

Similar alkylations may be effected on oxygen. l-(2-Chloroethyl)imidazolidin-2-one (312) when treated with potassium hydroxide or sodium hydride underwent ring closure to the tetrahydroimidazo[2,l-6]oxazole (313) (57JA5276). This approach can be used for the preparation of bicyclic hydantoins and the corresponding dihydro derivatives of (313) using the mesylate of (312) and NaH (77JHC5U, 79JMC1030). 

Cram and Hogberg have prepared a number of compounds similar to 3, utilizing mesyl and tosyl as protecting groups. These syntheses are generally unequivocal, but removal of the sulfonamide has proved troublesome (see also Sect. 4.5). 

Ester eliminations are normally one of two types, base catalyzed or pyrolytic. The usual choice for base catalyzed j5-elimination is a sulfonate ester, generally the tosylate or mesylate. The traditional conditions for elimination are treatment with refluxing collidine or other pyridine base, and rearrangement may occur. Alternative conditions include treatment with variously prepared aluminas, amide-metal halide-carbonate combinations, and recently, the use of DMSO either alone or in the presence of potassium -butoxide. 

The method of choice for the preparation of cholesta-3,5-diene is treatment of cholesteryl tosylate with potassium /-butoxide in DMSO. The mesylate and chloride react similarly. 

Since alkaline decomposition of p-toluenesulfonylhydrazones of steroid 12-ketones leads directly to 14(13 I2) jr e >-13(17)-enes whereas solvolysis of 12j5-mesylates gives mixtures of 13(18)- and 13(17)-enes, the former approach is preferred for the preparation of C-nor-D-homosteroids. If the particular system under consideration is not stable to base at elevated temperatures, the milder solvolysis method could be used. Either approach starts with a 12-oxygenated steroid. Additional base-stable functional groups should be compatible under the conditions for the rearrangement process. 

A nonphotochemical method for the preparation of D-norsteroids involves the base-catalyzed pinacol rearrangement of a pregnane-16oc,17a-diol 16a-mesylate. ... 

Cleavage of mesyl or tosyl esters with K F in the presence of 18-crown-6 ether [46] or Kryptofix 222 [47] provides a reliable method for the preparation of F-labeled biologically active compounds... 

Trifluoromethyl thiirane is formed by the action of tris(diethylamino)-phosphineon l-chloromethyl-2,2,2-trifluoroethyldisulfide [S2] (equation 73) Difluoromethyl phenyl selenide is prepared by treatment of lithium phenyl-selemde with chlorodifluoroniethane via a carbene mechanism [Si] (equation 44) Bis(2,2,2-trifluoroethyl)diselenide is formed in the reaction of 2,2,2-trifluoroethyl mesylate with lithium diselenide [84] (equation 74). 

Azauridine was also synthesized using the knowledge of the course of alkylation of 6-azauracil 2-methylmercapto derivatives (e.g., Section II,B,4,b). The 1-ribofuranosyl derivative obtained by reaction of the mercury salt of the 2-methylmercapto derivative with tri-O-benzoyl-jS-D-ribofuranosyl chloride on removal of the methyl-mercapto and then benzoyl groups yielded crystalline 6-azauridine, The main difference between uracil and 6-azauracil nucleosides consists in the preparation of cyclic nucleosides. It is known that uridine can be readily converted to cyclic nucleosides by the reaction of 2 (50-O-mesyl derivatives with nucleophilic agents, Analogous... 

This tricyclic ring system was prepared from the functionalized pyrazo[l,5-n]pyridines. Thus, pyrazo[l,5-n]pyridine-3-carboxylate 462 gave 465 upon mesylation and subsequent reaction with 2-ethoxy-2-lithioxyethy-lene, whose cyclization afforded 466 (94AP435). Intramolecular aldol... 

Activity is also retained when oxygen at the 21 position is replaced by sulfur. Preparation of one of these compounds follows a route quite analogous to the foregoing thus, displacement of the mesylate group in the cortisone (56) derivative 57 with the anion from thiopivalic acid affords thioester 58. Reduction of the 11-ketone by means of borohydride affords tixocortol pivalate (59)[13j. 

The vibo or dl (124/35) quercitol (4) needed for the synthesis was prepared from rat/o-inositol (2) via the bromoquercitol (3) according to the method of McCasland and Horswill, (28). By acetonation, acetylation, deacetonation, and equatorial mesylation the mesyloxy derivative... 

Other imidoylnitrenes in which the cyano group is replaced by mesyl or triflyl groups were also prepared but failed to promote the ring expansion 1-arylisoureas were the only products.166... 

Tricarbonyl[>74-l-(phenoxycarbonyl)-l//-azepine]iron(0) [48% mp 108-109=C (dec.)] and tricarbonyl(i/4-1-mesyl-lW-azepine)iron(O) (69% mp 94-96 C) were prepared similarly. 

The methyl ether 10a is also formed in moderate yields (21-50%) by treating 8-chloro-l-(2-chlorophenyl)-5-mesyloxy-5//-2-benzazepine, prepared in situ from the 5-hydroxy derivative with mesyl chloride in triethylamine, with base.78... 

The earliest method developed for the preparation of nonracemic aziridine-2-car-boxylates was the cyclization of naturally occurring (3-hydroxy-a-amino acid derivatives (serine or threonine) [4]. The (3-hydroxy group is normally activated as a tosyl or mesyl group, which is ideal for an intramolecular SN2 displacement. The cyclization has been developed in both one-pot and stepwise fashion [4—9]. As an example, serine ester 3 (Scheme 3.2) was treated with tosyl chloride in the presence of triethylamine to afford aziridine-2-carboxylate 4 in 71% yield [9]. Cyclization of a-hydroxy- 3-amino esters to aziridine-2-carboxylates under similar conditions has also been described [10]. 

Aziridine-2-carboxylates 12 (Scheme 3.4) have also been prepared from 3-hy-droxy-a-amino esters 9 by treatment with sulfuryl chloride in place of tosyl or mesyl chloride. Treatment of 9 with thionyl chloride in the presence of triethylamine, followed by oxidation of 10 with sodium periodate and a catalytic amount of... 

The present route to (terminal alkynes reported by a group from the Chemical Process Department at the DuPont Pharmaceutical Company.2 This alcohol serves as a convenient starting material for the preparation of 1-acyloxy 4-mesylates 10 (eq 1). 

Transformation of bromocriptine free base 2 into water soluble salt -mesylate, is the only way to obtain a suitable therapeutical form. Crystallization of mesylate using alcohol as a solvent in the presence of excess of strong acid, e.g. methanesulphonic acid can induce formation of 12 -0-alkyl-derivative 2. Until now this derivatisation of ergot molecule has been practically unknown. In continuation we developed the preparative method for obtaining these compounds, (using tetrafluoroboric acid as a catalyst) (ref. 20). 

A carboxylic acid (not the salt) can be the nucleophile if F is present. Mesylates are readily displaced, for example, by benzoic acid/CsF. Dihalides have been converted to diesters by this method. A COOH group can be conveniently protected by reaction of its ion with a phenacyl bromide (ArCOCH2Br). The resulting ester is easily cleaved when desired with zinc and acetic acid. Dialkyl carbonates can be prepared without phosgene (see 10-21) by phase-transfer catalyzed treatment of primary alkyl halides with dry KHCO3 and K2C03- ... 

Carba-sugars of the a-L-altro and P-D-gluco modifications were prepared from 149 by way of 155. 0-Mesylation of 155 with an excess of mesyl chloride and pyridine resulted in formation of the cyclohexenealdehyde 159, accompanied by y -elimination. Reduction of 159 with sodium borohydride gave the cyclohexenemethanol 160, which is the antipode oP 141. 

Deoxy-3 -fluorothymidine (813), a selective inhibitor of DNA synthesis, was prepared " in moderate yields from 3 -0-mesyl- or 3, 5 -di-O-mesyl-thymidine, through 2,3 -anhydro-1 -(2-deoxy- -D-t/2reopentofur-anosyl)thymine (808), by treatment with hydrogen fluoride (0.1% HF in l,4-dioxane-AlF3, 3.764 hf in DMF-AlFj, or 10% HF in DMF ),... 

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