N-Dimethylaminopyridine

AC2O, AcCl, Pyr, DMAP, 24-80°, 1-40 h, 72-95% yield. The use of DMAP increases the rate of acylation by a factor of 10. These conditions will acylate most alcohols, including tertiary alcohols. The use of DMAP (4-N,N-dimethylaminopyridine) as a catalyst to improve the rate of esterification is quite general and works for other esters as well. 

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]. 

The desired polymer-bound tryptophan was rapidly generated under microwave irradiation, employing a classical esterification protocol using N,N -dicydohexylcar-bodiimide (DCC) and a catalytic amount of N,N-dimethylaminopyridine (DMAP), followed by subsequent Fmoc deprotection (Scheme 7.68). Cyclocondensations with various carbonyl compounds were performed with catalytic amounts of p-toluene-... 

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). 

From Srivatsava et al (248). Reaction conditions catalyst (TS-1 Si/Ti = 36, Ti-MCM-41 Si/Ti = 46), 100 mg co-catalyst, 0.0072 mmol epoxide, 18 mmol CH2CI2, 20 mL CO2, 6.9 bar. DMAP N,N-dimethylaminopyridine EC epichlorohydrin PO propylene oxide SO stytene oxide BO a-butylene oxide TOF turnover frequency (moles epoxide converted per mole of Ti per hour. 

R = BOM, = MOM. (TMS = trimethylsilyl, KHMDS = potassium hexamethyidisilazide, MOM = methoxymethyl, DIBAL-H = diisobutylaluminium hydride, Tr = triphenylmethyl, DMAP = 4-N,N-dimethylaminopyridine, TBAE = tetrabutylammonium fluoride, BOM = benzyloxym ethyl)... 

LDA = lithium diisopropylamide DMAP = 4-N,N-dimethylaminopyridine PPTS = pyridinium p-toluenesulfonate... 

Dicarboxyethyl dextran 2-(Diethylamino)ethyl 2-Hydroxyoctyl- and 2-hydroxydodecyl Poly(ethylene glycol)-alkyl dextran ether 2-Hydroxy-3-phenoxy propyl dextran ethers Dynamic light scattering N,N- Dime thylace tamide 4-N.N-Dimethylaminopyridine Dextran propionate acetate... 

L acetone, dimethylcarbamyl chloride (2.83 mol), TEA (2.83 mol), N,N-dimethylaminopyridine (0.156 mol) added, and the mixture stirred 2 hours. Thereafter, an additional 265 ml dimethylcarbamyl chloride and 25 g of N,N-dimethylaminopyridine were added, the mixture refluxed 16 hours, then poured into an ice brine solution. The mixture rested 40 hours and the product isolated by filtration. H-NMR, MS, and HPLC data supplied. 

The product from Step 1 (0.1 mol) was dissolved in 1L DMF, N,N-dimethylaminopyridine (0.2 mol) and 12.2 ml acetyl chloride added, and the mixture stirred at 0°C. Thereafter, TEA (0.2 mol) was added dropwise and the mixture refluxed 3 days. The product was isolated by precipitation in an ice brine solution and purified by flash chromatography using silica gel. MS, H-NMR, UV-Vis data supplied. 

Reactivity studies reveal that the bis(indenyl)zirconium sandwich complexes serve as isolable, modular precursors to the rich chemistry of divalent zirconocene. Addition of 1 atm of carbon monoxide generates the bis(indenyl)-zirconocene dicarbonyl complex, 307, while treatment with N,N-dimethylaminopyridine results in C-H activation to form the zirconocene pyridyl hydride complex 308. Crystallographic characterization of both complexes as well as multinuclear NMR spectroscopy establishes that the more familiar 77s, 77s hapticity for the indenyl ligands has been restored. Alkyne coupling reactions are also observed as addition of 2-butyne to 302 allows observation of the alkyne complex, 208, and ultimately the zirconacyclopentadiene 309 (Scheme 50).104... 

Preparation of alkoxysilanes is carried out by the treatment of alcohols with tri-alkylhalosilanes and tertiary amine (eq (58)) [53]. Trialkylsilyltriflates are also employed for the silation, in which N,N-dimethylaminopyridine is frequently used as a catalyst. 

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