2-Phenyl-tetrahydropyrimidine-4(1H)-ones--cyclic benzaldehyde aminals as precursors for functionalised beta-amino acids.
Novel procedures have been developed to condense benzaldehyde effectively with beta-amino acid amides to cyclic benzyl aminals. Double carbamate protection of the heterocycle resulted in fully protected chiral beta-alanine derivatives. These serve as universal precursors for the asymmetric synthesis of functionalised beta(2)-amino acids containing acid-labile protected side chains. Diastereoselective alkylation of the tetrahydropyrimidinone is followed by a chemoselective two step degradation of the heterocycle to release the free beta(2)-amino acid. In the course of this study, an L-asparagine derivative was condensed with benzaldehyde and subsequently converted to orthogonally protected (R)-beta(2)-homoaspartate.
Nahrwold
Markus
M
Bielefeld University, Department of Chemistry, Organic and Bioorganic Chemistry, Universitätsstr. 25, 33615 Bielefeld, Germany.
Stoncius
Arvydas
A
Penner
Anna
A
Neumann
Beate
B
Stammler
Hans-Georg
HG
Sewald
Norbert
N