289891-10-7Relevant articles and documents
A Novel Catalytic and Highly Enantioselective Approach for the Synthesis of Optically Active Carbohydrate Derivatives
Audrain, Helene,Thorhauge, Jacob,Hazell, Rita G.,Jorgensen, Karl Anker
, p. 4487 - 4497 (2007/10/03)
A catalytic enantioselective inverse-electron demand hetero-Diels-Alder reaction of α,β-unsaturated carbonyl compounds with electron-rich alkenes catalyzed by chiral bisoxazolines in combination with Cu(OTf)2 as the Lewis acid is presented. The reaction of γ-substituted β,γ-unsaturated α-keto esters with vinyl ethers and various types of cis-disubstituted alkenes proceeds in good yield, high diastereoselectivity, and excellent enantioselectivity. The potential of the reaction is demonstrated by the synthesis of optically active carbohydrates such as spiro-carbohydrates, an ethyl β-D-mannoside tetraacetate, and acetal-protected C-2-branched carbohydrates. On the basis of X-ray crystallographic data and the absolute configuration of the products, it is proposed that the alkene approaches the si-face of the reacting α,β-unsaturated carbonyl functionality when coordinated to the catalyst.
