Dimethylaminopyridine, 4-

Physical Data colorless solid mp 108-110 °C pK 9.7. Solubility sol MeOH, CHCI3, CH2CI2, acetone, THF, pyridine, HOAc, EtOAc partly sol cold hexane or water. 

Form Supplied in colorless solid commercially available. Preparative Method prepared by heating 4-pyridone with HMPA at 220 °C, or from a number of 4-substituted (Cl, OPh, SO3H, OSiMe3) pyridines by heating with DMA. Prepared commercially from the 4-pyridylpyridinium salt (obtained from pyridine and SOCI2) by heating with DMF at 155 °C. Purification can be recrystalhzed from EtOAc. 

Handling, Storage, and Precautions skin irritant corrosive, toxic solid. 

Acylation of Alcohols. Several 4-aminopyridines speed up esterification of hindered alcohols with acid anhydrides by as much as 10 000 fold of these, DMAP is the most commonly used but 4-pyrrolidinopyridine (PPY) and 4-tetramethylguanidinop3ridine are somewhat more effective. DMAP is usually employed in 0.05-0.2 mol equiv amounts. 

DMAP catalyzes the acetylation of hindered 11/8- or 12a-hydroxy steroids. The alkynic tertiary alcohol acetal in eq 1 is acetylated at rt within 20 min in the presence of excess DMAP.  

Formation and Reaction of Alkynylaluminum Reagents. Lithium acetylides react with Me2AlCl to give dimethylaluminum acetylides that react analogously to the more commonly used diethylaluminum acetylides (see Diethylalu-minum Ethoxyacetylide). Addition of the aluminum acetylide to propiolactone results in an Sn2 reaction to give an alkynic acid (eq 1)  

Related Reagents. 1,8-Bis(dimethylamino)naphthalene Diethylaluminum Chloride Dimethylaluminum Iodide Ethyl-aluminum Dichloride Methylaluminum Bis(2,6-di-r-butyl-4-methylphenoxide) Methylaluminum Bis(4-bromo-2,6-di-t-butylphenoxide) Methylaluminum Bis(2,6-di-r-butylpheno-xide) Methylaluminum Dichloride Trimethylsilyl Trifluoro-methanesulfonate. 

Form Supplied in colorless solid commercially available. 

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Vinylpyridine (23) came into prominence around 1950 as a component of latex. Butadiene and styrene monomers were used with (23) to make a terpolymer that bonded fabric cords to the mbber matrix of automobile tires (25). More recendy, the abiUty of (23) to act as a Michael acceptor has been exploited in a synthesis of 4-dimethylaminopyridine (DMAP) (24) (26). The sequence consists of a Michael addition of (23) to 4-cyanopyridine (15), replacement of the 4-cyano substituent by dimethylamine (taking advantage of the activation of the cyano group by quatemization of the pyridine ring), and base-cataly2ed dequatemization (retro Michael addition). 4-r)imethyl aminopyri dine is one of the most effective acylation catalysts known (27). 

Dimethylaminopyridine [1122-58-3] (DMAP) (24) has emerged as the preferred catalyst for a variety of synthetic transformations under mild conditions, particularly acylations, alkylations, silylations, esterifications, polymeri2ations, and rearrangements (100). POLYDMAP resin [1122-58-3], a polymeric version of DMAP, is available, and is as effective as DMAP as a catalyst for acylation reactions. Furthermore, it can be recycled without regeneration more than 20 times with very Htde loss in activity. POLYDMAP is a trademark of Reilly Industries, Inc. 

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). 

DMAP = 4-dimethylaminopyridine (lO" times more effective than pyri- dine) ... 

PhCH20CO-imidazolyl, 4-dimethylaminopyridine, 16 h, it, 76% yield. Two primary amines were protected in the presence of a secondary amine. 

Oxiranes exhibit 1,3 [e,n] capacity. Therefore, seven-membered ring systems can be synthesized on reaction with hetero-1,3-dienes. The reaction is catalyzed by 4-dimethylaminopyridine. On catalysis with boron trifluonde, the regioche-mistry is reversed [263] (equation 58). 

These rate constants are for the hydrolysis of cinnamic anhydride in carbonate buffer, pH 8.45, total buffer concentration 0.024 M, in the presence of the catalysts pyridine, A -methylimidazole (NMIM), or 4-dimethylaminopyridine (DMAP). In the absence of added catalyst, but the presence of buffer, the rate constant was 0.005 24 s . You may assume that only the conjugate base form of each catalyst is catalytically effective. Calculate the catalytic rate constant for the three catalysts. What is the catalytic power of NMIM and of DMAP relative to pyridine ... 

By application of the Corey-Winter reaction,vicinal diols 1 can be converted into olefins 3. The key step is the cleavage of cyclic thionocarbonates 2 (1,3-dioxolanyl-2-thiones) upon treatment with trivalent phosphorus compounds. The required cyclic thionocarbonate 2 can be prepared from a 1,2-diol 1 and thio-phosgene 4 in the presence of 4-dimethylaminopyridine (DMtVP) ... 

Di-tert-butyl dicarbonate and 4-dimethylaminopyridine were purchased from Alfa-Aesar Chemical Company and used without further purification. 

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. 

Reaction of N,N-dimethylaniline with 1-cyanobenziodoxol 1783 to afford N-methyl-N-cyanomethylaniline 1784 in 97% yield has been discussed in Section 12.1 [31]. Analogously, oxidation of dimethylaniline with iodosobenzene and trimethylsilyl azide 19 at 0°C in CDCI3 gives the azido compound 2040 in 95% yield, iodobenzene, and HMDSO 7 [194, 195] (Scheme 12.56). Likewise, the nucleophilic catalyst 4-dimethylaminopyridine (DMAP) is oxidized, in 95% yield, to the azide 2041, which is too sensitive toward hydrolysis to 4-N-methylaminopyri-dine to enable isolation [194, 195]. Amides such as 2042, in combination with tri-... 

Figure 25 Synthesis of naturally occuring phenylpropenoid (3-D-glucopyranosides. (a) allyl alcohol/immobilized (3-glucosidase with ENTP-4000, (b) Ac20/4-dimethylaminopyridine/pyridine, (c) organoboron reagents/Pd(OAcyCu(OAc)2/LiOAc/DMF, (d) K2C03/Me0H.

An even stronger catalytic effect is obtained when 4-dimethylaminopyridine (DMAP) is used.104 The dimethylamino group acts as an electron donor, increasing both the nucleophilicity and basicity of the pyridine nitrogen. 

Dimethylaminopyridine 0.0010 Poly(butadlene-co-pyrrolidinopyridine) 0.0014 Poly(methyl vinyl ether-co-pyrrolidinopyridine) 0.0009 Poly(octadec-l-ene-co-pyrrolidinopyridine) b... 

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