The Pd-catalyzed intramolecular alpha-arylation of alpha-amino acid esters is described. Starting from readily available amino acids, the synthesis of a variety of isoindolines and tetrahydroisoquinoline carboxylic acid esters has been accomplished. Additionally, fused tricyclic systems can be efficiently prepared from cyclic amino acid esters. Reaction conditions have been found that allow the use of tert-butyl ester and N-(benzyloxycarbonyl) protecting groups.

Lewis acid mediated cleavage of substituted 2,9-dioxabicyclo[3.3.1]nonan-3-ones affords enantiopure 2,6-trans-C-glycosides in excellent yield. Variation of nucleophile, solvent and Lewis acid were investigated.

No abstract

2002 ring closure reactions ring closure reactions O 0130 -044Palladium-Catalyzed Intramolecular α-Arylation of α-Amino Acid Esters. -tert-Butyl-α-amino acid esters, substituted at the amino group with o-bromobenzyl or (o-bromophenyl)ethyl groups, undergo palladium-catalyzed ring-closure to isoindoline and tetrahydroisoquinoline carboxylic acid esters. The best results in the cyclization reactions are obtained using either ligands CPB or PPB in combination with Pd 2 (dba) 3 and tBuOLi as base. The reaction conditions are compatible with the Cbz protecting group at the nitrogen and the tert-butyl ester group. -(GAERTZEN, OLIVER; BUCHWALD, STEPHEN L.; J.