Chloride-Dimethylaminopyridine

Oxidation of Alcohols. Primary and secondary alcohols can be oxidized to aldehydes and ketones in good yields via treatment with methanesulfonic anhydride and dimethyl sulfoxide in HMPA (eqs 8 and 9). Dichloromethane can be substituted as the solvent, but the use of HMPA leads to cleaner products. Methanesulfonic anhydride works especially weU for the conversion of primary alcohols to aldehydes. Benzylic aldehydes can also be formed using this method. 

Related Reagents. Acetic Anhydride Benzoyl Chloride Dimethyl Sulfoxide-Methanesulfonic Anhydride Methane-sulfonyl Chloride p-Toluenesulfonyl Chloride Trifluoroacetic Anhydride. 

Valerie Vaillancourt Michele M. Cudahy The Upjohn Company, Kalamazoo, MI, USA 

Physical Data see methanesulfonyl chloride and 4-dimethyl-aminopyridine. 

Preparative Method MsCl (2.5 equiv), DMAP (1.25 equiv), H2O (1 equiv), and CH2CI2 are stirred at rt for 2-3 d. 

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Studies on reactions of various types of alcohols with the related tosyl chloride/dimethylaminopyridine (TsCl/DMAP) system have led to the following conclusions allylic, propargylic, and glycosidic hydroxyls quickly react to form the corresponding chlorides, 2,3-epoxy and selected primary alcohols )deld chlorides... 

However, this method is appHed only when esterification cannot be effected by the usual acid—alcohol reaction because of the higher cost of the anhydrides. The production of cellulose acetate (see Fibers, cellulose esters), phenyl acetate (used in acetaminophen production), and aspirin (acetylsahcyhc acid) (see Salicylic acid) are examples of the large-scale use of acetic anhydride. The speed of acylation is greatiy increased by the use of catalysts (68) such as sulfuric acid, perchloric acid, trifluoroacetic acid, phosphoms pentoxide, 2inc chloride, ferric chloride, sodium acetate, and tertiary amines, eg, 4-dimethylaminopyridine. 

Pyrrole and alkylpyrroles can be acylated by heating with acid anhydrides at temperatures above 100 °C. Pyrrole itself gives a mixture of 2-acetyl- and 2,5-diacetyl-pyrrole on heating with acetic anhydride at 150-200 °C. iV-Acylpyrroles are obtained by reaction of the alkali-metal salts of pyrrole with an acyl halide. AC-Acetylimidazole efficiently acetylates pyrrole on nitrogen (65CI(L)1426). Pyrrole-2-carbaldehyde is acetylated on nitrogen in 80% yield by reaction with acetic anhydride in methylene chloride and in the presence of triethylamine and 4-dimethylaminopyridine (80CB2036). 

Et3SiCl, Pyr. Triethylsilyl chloride is by far the most common reagent for the introduction of the TES group. Silylation also occurs with imidazole and DMF arid with dimethylaminopyridine as a catalyst. Phenols, carboxylic acids, and amines have also been silylated with TESCl. 

Giacomelli et al. constructed 3-propylisoxazole-5-yl-methanol via a [3-1-2] cycioaddition (Fig. 15) [158]. Nitrobutane was converted to nitrile oxide in the presence of 4-(4,6-dimethoxy [1,3,5]triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) and catalytic 4-dimethylaminopyridine (DMAP). Trityl chloride resin-bound propargyl alcohol was employed as the dipolarophile to trap the nitrile oxide, forming the cyclo adduct isoxazole ring under unusually mild conditions (i.e., microwave irradiation at 80 °C for five times 1 min). Disappearance of the starting material was monitored by FT-IR. 

One obvious synthetic route to isoxazoles and dihydroisoxazoles is by [3+2] cycloadditions of nitrile oxides with alkynes and alkenes, respectively. In the example elaborated by Giacomelli and coworkers shown in Scheme 6.206, nitroalkanes were converted in situ to nitrile oxides with 1.25 equivalents of the reagent 4-(4,6-di-methoxy[l,3,5]triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) and 10 mol% of N,N-dimethylaminopyridine (DMAP) as catalyst [373], In the presence of an alkene or alkyne dipolarophile (5.0 equivalents), the generated nitrile oxide 1,3-dipoles undergo cycloaddition with the double or triple bond, respectively, thereby furnishing 4,5-dihydroisoxazoles or isoxazoles. For these reactions, open-vessel microwave conditions were chosen and full conversion with very high isolated yields of products was achieved within 3 min at 80 °C. The reactions could also be carried out utilizing a resin-bound alkyne [373]. For a related example, see [477]. 

Tetrahydrobenzyl alcohol (( )3-cyclohexenene-l-methanol) and 30% aqueous hydrogen peroxide were purchased from Fluka, AG. 3-Cyclohexene-1-carboxylic acid and cis-4-cyclohexene-l,2-dicarboxylic acid were used as purchased from Lancaster Chemical Co. Methyl iodide, acetic anhydride, Oxone (potassium peroxymonosulfate), Aliquot 336 (methyl tri-n-octylammonium chloride), sodium tungstate dihydrate and N,N-dimethylaminopyridine (DMAP) were purchased from Aldrich Chemical Co. and used as received. 3,4-Epoxycyclohexylmethyl 3, 4 -epoxycyclohexane carboxylate (ERL 4221) and 4-vinylcyclohexene dioxide were used as purchased from the Union Carbide Corp. (4-n-Octyloxyphenyl)phenyliodonium hexafluoroantimonate used as a photoinitiator was prepared by a procedure described previously (4). 

In a NMR tube, to a solution of the epoxy alcohol (2.5 mg) in CDCI3 (0.5 mL) was added 4-dimethylaminopyridine (5 mg) and (R)-(+)-a-methoxy-a-(trifluor-omethyl)phenylacetyl chloride (5 mg). The mixture was allowed to stand overnight at room temperature. The reaction was monitored by TLC to ensure complete consumption of the starting material. H and 19F NMR spectra were carried out on the crude reaction mixture. In the 19F NMR spectrum, each enantiomer gave a signal an additional signal at —71.8 ppm was ascribed to residual MTPA. (19F NMR (250 MHz, CDCI3) 8 - 70.7 (s, (2R,3R)-enantio-mer) —72.0 (s, (25 ,3.S)-enantiomer)). 

Pyrrolizin-3-ones 75 were synthesized in one step from 2-formylpyrrole derivatives 228 and hydrocinnamoyl chloride in the presence of 4-dimethylaminopyridine (DMAP) and T,iV-diisopropylethylamine (DIPEA), in low to moderate yields (Scheme 57) <2002TL3673>. 

FIGURE 5.21 Methods for anchoring an Fmoc-amino acid to the hydroxymethyl group of a linker-resin. (A) 4-Dimethylaminopyridine-catalyzed acylation by the symmetrical anhydride.19 (B) Acylation by a mixed anhydride obtained from 2,6-dichlorobenzoyl chloride.39 (C) Acylation by the acid fluoride.50 (D) Dicyclohexylcarbodiimide-mediated acylation in the presence of 1-hydroxybenzotriazole.52... 

Dimethylamino-N-triphenylmethylpyridinium chloride Pyridinium, 4-(dimethylamino)-1-(triphenylmethyl)-, chloride (10) (78646-25-0) 4-Dimethylaminopyridine Highly TOXIC 4-Pyridinamine, N,N-dimethyl- (9) (1122-58-3)... 

It seems reasonable that polyester cyclics could be prepared by an extension of the /wendo-high-dilution [17] chemistry used for the preparation of cyclic carbonate oligomers [18, 19] however, such proved not to be the case. Brunelle et al. showed that the reaction of terephthaloyl chloride (TPC) with diols such as 1,4-butanediol did not occur quickly enough to prevent concentration of acid chlorides from building up during condensation [14]. Even slow addition of equimolar amounts of TPC and butanediol to an amine base (triethylamine, pyridine or dimethylaminopyridine) under anhydrous conditions did not form cyclic oligomers. (The products were identified by comparison to authentic materials isolated from commercial PBT by the method of Wick and Zeitler [9].)... 

Protection of an alcohol function by esterification sometimes offers advantages over use of acetal or ether groups. Generally, ester groups are stable under acidic conditions. Esters are especially useful in protection during oxidations. Acetates and benzoates are the most commonly used ester derivatives. They can be conveniently prepared by reaction of unhindered alcohols with acetic anhydride or benzoyl chloride, respectively, in the presence of pyridine or other tertiary amines. 4-Dimethylaminopyridine (DMAP) is often used as a catalyst. The use of A-acylimidazolides (see Section 3.4.1) allows the... 

Scheme 25. Reagents and conditions (a) R sAI, Cul-2 LiCI, THF, 0°C (b) PivCI, py (c) 4-dimethylaminopyridine (DMAP) (3 equiv.), NaNa (20 equiv.), methanesulfonyl chloride (MsCI) (3 equiv.), RT then DMSO 3 h (d) UAIH4 (e) B0C2O, EtgN, CH2CI2.

In 1998, Evans published an improved synthesis of bu-box 3 starting from the same amino acid. The updated synthesis began with sodium borohydride-iodine reduction to afford amino alcohol 23 followed again by treatment with dimethyl-malonyl dichloride 24 to afford 25 in 88% yield (from 23). Cyclization was achieved by treatment of 25 with toluenesulfonyl chloride and triethylamine in the presence of a catalytic amount of dimethylaminopyridine to afford bu-box 3 in 82% yield (Fig. 9.6). 

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