Catalytic and highly enantioselective Diels-Alder reaction of cyclic and acyclic dienes with alpha-phthalimidoacroleins provides cyclic alpha-quaternary alpha-amino acid precursors. The conformationally flexible chiral ammonium salt of H-L-Phe-L-Leu-N(CH(2)CH(2)) 2-reduced triamine with pentafluorobenzensulfonic acid is very effective as an asymmetric catalyst for the Diels-Alder reaction.
Ruthenium(II) in ring closing metathesis for the stereoselective preparation of cyclic 1-amino-1-carboxylic acids
作者:Kristin Hammer、Kjell Undheim
DOI:10.1016/s0040-4020(96)01132-5
日期:1997.2
Stereoselective synthesis of α-aminoacids where the α-carbon of the amino acid is incorporated into a five-, six- or seven-membered ring is described. The stereoselective control results from stepwise bisalkenylation of (R)-2,5-dihydro-3,6-dimethoxy-2-isopropylpyrazine. Ring closing metathesis was effected by ruthenium(II)-catalysis. The spiro-cycloalkene intermediates were further transformed into