DABCO development

However, the transition from "imitation swiss cheese" to one of the most important cellular materials required tenacity, optimism, and expert knowledge. Organic tin compounds developed by Presswork were used to catalyze the reaction of diisocyanates with glycols, triethylenediamine (Dabco), developed by Houdry, was used to catalyze the reaction of diisocyanates with water and silicon surfactants were used to produce uniform cells. 

A practical and efficient set of conditions were developed using a stoichiometric base catalyst, l,4-diazabicyclo[2,2,2]octane (DABCO)... 

An efficient and convenient methodology for the aerobic oxidation of alcohols catalysed by sol-gel trapped perruthenate and promoted by an encapsulated ionic liquid in supercritical carbon dioxide solution has been reported. The reaction is highly selective and useful for substrates otherwise difficult to oxidize.263 A four-component system consisting of acetamido-TEMPO-Cu(C104)2-TMDP-DABCO has been developed for aerobic alcohol oxidation at room temperature. The catalytic system shows excellent selectivity towards the oxidation of benzylic and allylic alcohols and is not deactivated by heteroatom-containing (S, N) compounds. The use of DMSO as the reaction medium allows the catalysts to be recycled and reused for three runs with no significant loss of catalytic activity.264... 

During the course of the Baylis-Hillman-reaction two stereocenters are formed, one of which remains in the Baylis-Hillman-product. An obvious concept for the development of an asymmetric version of the reaction represents the use of an enantiomerically pure acrylic acid derivative. The use of enantiomerically pure menthyl acrylates resulted, but only in certain cases, to respectable diastereomeric excesses [21]. A significant improvement was reported in 1997 by Leahy and coworkers who used the Oppolzer-sultame as a chiral auxiliary in DABCO-catalyzed Baylis-Hillman-reactions (Scheme 2) [22]. In this reaction, the... 

The first chiral catalysts were developed from achiral molecules such as DABCO, quinuclidine, indolizine or pyrrolizine-derived catalysts by introducing asymmetric functions. Hirama and co-workers examined chiral C2-symmetric 2,3-disubstituted l,4-diazabicyclo[2.2.2]octanes such as 2,3-(dibenzoxymethyl)-DABCO (29) as catalysts for asymmetric MBH reaction between 4-nitro-benzaldehyde 27 and methyl vinyl ketone (MVK, 28) (Scheme 5.6) [57]. The additive function of the catalyst compared to the achiral DABCO resulted, however, in diminished reactivity, and the reaction required high pressure in order to... 

As an example, the methyl group in thioanisole can be metalated using n-butyllithium to produce phenylthiomethyllithium by contrast, anisole under the same conditions is metalated at an ortho position. This reaction has been of little practical use in synthesis since the maximum yield of the lithium intermediate is only about 35%. However, Corey and Seebach (23) recently developed an excellent procedure for generating phenylthiomethyllithium in essentially quantitative yield by reaction between equimolar amounts of thioanisole, n-butyllithium, and DABCO in tetrahydrofuran at 0°C. 

Chiral 2,3-disubstituted DABCOs proc high pressure. While the yields are accept The Darzens condensation of (-)-8-ph examined.Good diastereoselectivities ai Substitutions. Radical displacemc -eaction with allyltributylstannane is ur 4-diphenylmethyloxazolidin-2-one moiec The asymmetric allylic substitubon -egarding chiral ligand development. gands 11 , and 21 are ex... 

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. 

Nucleophilic Attack at Other Atoms. - Routes for the preparation of borane adducts of polyfunctional phosphines have been developed. The bicyclic base DABCO is recommended... 

The Merck Process Group has developed a new method for indole synthesis involving a Pd-catalyzed annulation between o-iodoanilines 55 and ketones 56 <97JOC2676>. The reaction presumably involves formation of the enamine 57 followed by an intramolecular Heck reaction in the presence of a non-oxidizable amine base such as DABCO. The reaction is especially effective for cyclic ketones and tolerates a variety of functional groups in the product indole 58. 

Dabco BL-53 Newly developed tertiary amine, which provides blowing and cell opening capabilities. APCI... 

Dabco NE1060 Newly developed non-fugitive gelling catalyst for flexible moulded applications. APCI... 

---