Diazabicyclooctane DABCO

Normally the reaction Is useful for the conversion of alkyl halides to primary amines without concomitant formation of secondary amines.29 Treatment of polymer 17 with hexamethylenetetramine in a mixture of ethanol/THF afforded an insoluble resin. Using diazabicyclooctane (DABCO), we demonstrated that the reaction could be limited to attack by a single nitrogen in a multifunctional amine, so we did not anticipate crosslinking via bis-quat salt formation. Hydrolysis of 2 with anhydrous HC1 in ethanol generated free amino groups as evidenced by a positive ninhydrin test, but quantitative hydrolysis could not be achieved and the product remained insoluble. One would have expected a simple bis-quat to hydrolyse and open the crosslinked structure. 

A-Halogeno-amides are familiar and convenient sources of positive halogen for the organic chemist, and the 2 1 complex formed in benzene between diazabicyclooctane (DABCO) and /V-bromsuccinimide (NBS) [48] (the numbers are the observed interatomic distances in angstroms) in effect shows one such reagent in action (Crowston et al., 1984). The N-Br-N angle is close to linear [175.1(2) A], and the bromine is poised almost midway between the two nitrogen atoms, which are of similar basicity. The... 

We have investigated a variety of clusters with ethers and amines as the Rydberg donor systems and polar solvents as the acceptors. The donors we have studied include dioxane (C4H802), azabicyclooctane (ABCO), diazabicyclooctane (DABCO), hexamethylenetetramine (HMT), and others (Moreno et al. 1992 Shang and Bernstein 1994 Shang et al. 1993a,b,c, 1994a,b,c). The acceptors include ethers, amines, and aromatics. 

Molecular complexes can be prepared from some tertiary amines and 90 or 30% solutions of hydrogen peroxide. 1,4-Diazabicyclooctane (Dabco) forms an adduct with two molecules of hydrogen peroxide. The adduct consists of hygroscopic crystals melting at 112 °C (dec), is stable for a limited time at room temperature, and can be used as a source of hydrogen peroxide in oxidations [727]. 

Fused heterocyclic 1,2,3,4,5-pentathiepins have been prepared by treatment of p3nroles and related heterocycles with disulfur dichloride in the presence of diazabicyclooctane (DABCO) <05OBC3496>. Thus, pentathiepin 64 was prepared from 2,5-dimethylp3UTole 63 using this... 

The diazabicyclooctane (DABCO) catalysed aldol type reaction of acrylic esters with aldehydes has now been extended to use methyl... 

In an important development, simple a-methylene ketones (cyclic ketones work much better than acyclic ketones) and ort/to-iodoarylamines react under palladium catalysis to give indoles directly. The use of dimethylformamide as solvent and diazabicyclooctane (DABCO) as the base are crucial to the success of the route. Mechanistically, the sequence certainly proceeds through the enamine. As well as being conceptually and practically simple, this method tolerates functional groups which would be sensitive to the acid of the traditional Fischer sequence. 

Alkyl substitution at position 3 slows the rate of diazabicyclooctane (DABCO)-catalyzed isomerization of l-methyl-3-substituted indenes in pyridine solution. At 30°C, the relative rates of isomerization of 1 -methyl-3-R-indenes decreased in the order R = H, 70 R = Pr, 1.25 R = CD3, 1.11 ... 

Diazabicyclooctane (DABCO) was used as purchased from Aldrich Chemical Company, Inc. 

Saturated Analogs. A number of other ligands have also been exploited for the generation of coordination polymers. These include saturated analogs of pz such as piperidine and diazabicyclooctane, DABCO. However, no examples involving... 

Coupling Processes. The coupling can be carried out as in Equation 1 by preparing a sulfonylisocyanate by treating the sulfonamide with phosgene in the presence of butyl isocyanate (BuNCO) in xylene at reflux. Frequently 1,4-diazabicyclooctane (DABCO) aids in catalyzing this reaction. The sulfonyl isocyanate which is usually an oil can be added to a solution or sus nsion of the aminoheterocycle in a solvent such as methylene chloride or acetonitrile. The desired sulfonylurea usually precipitates as a white crystalline solid. Dry conditions are essential to avoid hydrolysis of the extremely water sensitive isocyanate. 

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