Chiral Co(II) and Mn(II) catalysts for the 1,3-dipolar cycloaddition reactions of azomethine ylides derived from arylidene imines of glycine

✍ Scribed by Philip Allway; Ronald Grigg

• Book ID: 104225912
• Publisher: Elsevier Science
• Year: 1991
• Tongue: French
• Weight: 189 KB
• Volume: 32
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)93563-9

✦ Synopsis

Anhydrous MnBr, and CoCi, in conjunclion with chiral ephedrine iigandr effecr subslantial asymmeurc induction in cycloadducts derivedfrom methyl acrylate and imines of glycine methyl esler. CoCl, is most effeclive and gives 96% e.e. We have shown that imines of a-amino esters undergo rapid regio-and stereo-specific cycloaddition reactions with electronegative olefins (1) + (2) at room temperature in the presence of a range of metal salts [AS(I), Tl(I), Li(I), Mn(II), Mg(II)] and a tertiary amine.',2 These processes are believed to involve metallodipoles. When Ti(IV) complexes are used [e.g. Ti(OPr'),Cl,] the regiochemistry of the cycloaddition is reversed and, in addition, regiospecific transesterification (1) + (3) occurs.3 Certain metal salts [Co(H), Zn(II), Mg(II)]" give imine'dimers (1) -+ (4) in which the imine functions as both dipole precursor and dipolarophile.'

In at least some cases the imidazolidines, which are obtained as a mixture of cis-and trans-