1,3-Dipolar Cycloadditions of Carbonyl Ylides to Aldimines: Scope, Limitations and Asymmetric Cycloadditions.
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Hydroxycarboxylic acids (ether carboxylic acids) and estersQ 0450 1,3-Dipolar Cycloadditions of Carbonyl Ylides to Aldimines: Scope, Limitations
and Asymmetric Cycloadditions. A three-component approach for the highly dia-stereoselective synthesis of syn--hydroxy--amino esters involves the Rh-catalyzed 1,3-dipolar cycloaddition of carbonyl ylides, generated in situ, to imines.The use of chiral -methylbenzylimines (IV) as dipolarophiles is a promising approach to an asymmetric version (up to 80% diastereoselectivity). Another possibility is the use of Rh2((S)-DOSP)4 (up to 64% e.e.). (TORSSELL, S.; SOMFAI*, P.; Adv. Synth. Catal. 348 (2006) 16-17, 2421-2430; KTH Chem. Sci. Eng., Org. Chem., R. Inst. Technol., S-100 44 Stockholm, Swed.; Eng.) Mischke