title: 2-Phenyl-tetrahydropyrimidine-4(1H)-ones--cyclic benzaldehyde aminals as precursors for functionalised beta-amino acids.
abstract: 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.
authors: Bielefeld University, Department of Chemistry, Organic and Bioorganic Chemistry, Universitätsstr. 25, 33615 Bielefeld, Germany.
authors: Markus
authors: M
authors: Nahrwold
authors: Arvydas
authors: A
authors: Stoncius
authors: Anna
authors: A
authors: Penner
authors: Beate
authors: B
authors: Neumann
authors: Hans-Georg
authors: HG
authors: Stammler
authors: Norbert
authors: N
authors: Sewald