Catalytic Asymmetric Synthesis of Bis-armed Aromatic Amino Acid Derivatives. Problems Related to the Synthesis of Enantiomerically Pure Bis-methyl Ester of the (S,S)-Pyridine-2,6-diyl Bis-alanine.
摘要:
(S,S)-Pyridine-2,6-diyl bis-alanines 8 and 9 carrying protecting groups suitable for peptide synthesis have been synthesised Rom 2,6-pyridinedicarbaldehyde by the phosphonoglycine condensation route followed by catalytic by hydrogenation with Rh{(COD)[(R,R)-DIPAMP]}BF4. The alternative route via double Heck coupling of 2,6-dibromopyridine and benzyl Boc-amidoacrylate was unsuccessful although mono-coupling could be achieved. The reasons for this failure are discussed as well as the failure of two mono-armed didehydroamino acid derivatives to undergo hydrogenation with Rh-bisphosphine catalysts. The CuCl2 and RhCl3 complexes of the bis-amino derivative 9 were prepared; a 20% e.e. was achieved in the cyclopropanation of styrene with ethyl diazoacetate using the Cu(II)-complex as a catalyst.
Catalytic Asymmetric Synthesis of Bis-armed Aromatic Amino Acid Derivatives. Problems Related to the Synthesis of Enantiomerically Pure Bis-methyl Ester of the (S,S)-Pyridine-2,6-diyl Bis-alanine.
摘要:
(S,S)-Pyridine-2,6-diyl bis-alanines 8 and 9 carrying protecting groups suitable for peptide synthesis have been synthesised Rom 2,6-pyridinedicarbaldehyde by the phosphonoglycine condensation route followed by catalytic by hydrogenation with Rh{(COD)[(R,R)-DIPAMP]}BF4. The alternative route via double Heck coupling of 2,6-dibromopyridine and benzyl Boc-amidoacrylate was unsuccessful although mono-coupling could be achieved. The reasons for this failure are discussed as well as the failure of two mono-armed didehydroamino acid derivatives to undergo hydrogenation with Rh-bisphosphine catalysts. The CuCl2 and RhCl3 complexes of the bis-amino derivative 9 were prepared; a 20% e.e. was achieved in the cyclopropanation of styrene with ethyl diazoacetate using the Cu(II)-complex as a catalyst.
Preparation of (S)-2-quinolylalanine by asymmetric hydrogenation
作者:Stephen W. Jones、Christopher F. Palmer、Jane M. Paul、Peter D. Tiffin
DOI:10.1016/s0040-4039(98)02568-4
日期:1999.2
The synthesis of (S)-2-quinolylalanine through asymmetrichydrogenation with (S,S)-Et-DuPHOS-Rh is described. The reaction has been extended to other 2-pyridylalanie derivatives.