- Tandem multi-step synthesis of C-carboxyazlactones promoted by N-heterocyclic carbenes
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Cascade reaction sequences incorporating N-heterocyclic carbene-based organocatalysis have been developed that allow the direct preparation of a range of (±)-4-phenoxycarbonylazlactones in good isolated yields (66-84%) from the corresponding N-p-anisoyl amino acids. The Royal Society of Chemistry.
- Campbell, Craig D.,Duguet, Nicolas,Gallagher, Katherine A.,Thomson, Jennifer E.,Lindsay, Anita G.,O'Donoghue, AnnMarie C.,Smith, Andrew D.
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supporting information; body text
p. 3528 - 3530
(2009/02/05)
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- Enantioselective TADMAP-catalyzed carboxyl migration reactions for the synthesis of stereogenic quaternary carbon
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The chiral, nucleophilic catalyst TADMAP [1, 3-(2,2,2-triphenyl-1- acetoxyethyl)-4-(dimethylamino)-pyridine] has been prepared from 3-lithio-4-(dimethylamino)pyridine (5) and triphenylacetaldehyde (3), followed by acylation and resolution. TADMAP catalyzes the carboxyl migration of oxazolyl, furanyl, and benzofuranyl enol carbonates with good to excellent levels of enantioselection. The oxazole reactions are especially efficient and are used to prepare chiral lactams (23) and lactones (30) containing a quaternary asymmetric carbon. TADMAP-catalyzed carboxyl migrations in the indole series are relatively slow and proceed with inconsistent enantioselectivity. Modeling studies (B3LYP/6-31G*) have been used in qualitative correlations of catalyst conformation, reactivity, and enantioselectivity.
- Shaw, Scott A.,Aleman, Pedro,Christy, Justin,Kampf, Jeff W.,Va, Porino,Vedejs, Edwin
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p. 925 - 934
(2007/10/03)
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- Development of Chiral Nucleophilic Pyridine Catalysts: Applications in Asymmetric Quaternary Carbon Synthesis
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TADMAP (1a), a new chiral DMAP catalyst, has been designed to place a C(3)-benzylic trityl group over one face of the pyridine ring, while a C(3)-benzylic acetoxy group creates a chirotopic environment on the other face. TADMAP was prepared in four steps
- Shaw, Scott A.,Aleman, Pedro,Vedejs, Edwin
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p. 13368 - 13369
(2007/10/03)
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