Pd-catalyzed asymmetric allylic alkylation of 3-acetoxy-N-(tert-butyloxycarbonyl)-1,2,3,6-tetrahydropyridine - Preparation of key intermediates for natural product synthesis

A convenient synthesis of racemic tetrahydropyridine 1 was developed. Pd-ca talyzed allylic alkylation of 1 with malonate and dimethylacetoxymalonate a s nucleophiles with the phosphanylcarboxylic acid L1 and the dihydrooxazol L2 as ligands, were carried out and gave enantiomeric excesses of up to 98% . Absolute configurations were determined for all compounds described. From the alkylation products (+)- and (-)-2a, and (+)- and (-)-2b a variety of versatile, nonracemic chiral intermediates were prepared.