The natural amino acid L-Spinacine (4,5,6,7-tetrahydro-IH-imidazo[4,5-c]pyridine-6-carboxylic acid) has been synthesized following a new pathway which gives a chemically and optically pure product with an excellent yield. The crystal structures of a synthetic intermediate, N-hydroxymethyl-spinacine, and a spinacine derivative, N-methyl-spinaceamine, have been investigated through X-ray diffraction. Spi(MeOH) crystallizes with a water molecule and displays a zwitterionic character. The carboxylate group is in equatorial position and forms a short electrostatic interaction of 2.618(2) A, between one of its oxygens and the protonated nitrogen of the tetrahydropyridine ring. The crystal packing is assured by strong O-H- - -O, O-H-- -N, N-H- - -N intermolecular hydrogen bonds and C-H---O close contacts. The biprotonated compounds Spm(alpha-Me) crystallizes with two Cl- anions and a water molecule. The positive charge on the imidazole ring is delocalized on the conjugated moiety N=C-N. The crystal is built up by clusters formed by two biprotonated Spm(aMe) molecules, tour Cl- anions and two water molecules linked together by hydrogen bonds.
Synthesis of spinacine and spinacine derivatives: crystal and molecular structures of N-pi-hydroxymethyl spinacine and N-alpha-methyl spinaceamine
REMELLI, Maurizio;PULIDORI, Fernando;GUERRINI, Remo;BERTOLASI, Valerio
1997
Abstract
The natural amino acid L-Spinacine (4,5,6,7-tetrahydro-IH-imidazo[4,5-c]pyridine-6-carboxylic acid) has been synthesized following a new pathway which gives a chemically and optically pure product with an excellent yield. The crystal structures of a synthetic intermediate, N-hydroxymethyl-spinacine, and a spinacine derivative, N-methyl-spinaceamine, have been investigated through X-ray diffraction. Spi(MeOH) crystallizes with a water molecule and displays a zwitterionic character. The carboxylate group is in equatorial position and forms a short electrostatic interaction of 2.618(2) A, between one of its oxygens and the protonated nitrogen of the tetrahydropyridine ring. The crystal packing is assured by strong O-H- - -O, O-H-- -N, N-H- - -N intermolecular hydrogen bonds and C-H---O close contacts. The biprotonated compounds Spm(alpha-Me) crystallizes with two Cl- anions and a water molecule. The positive charge on the imidazole ring is delocalized on the conjugated moiety N=C-N. The crystal is built up by clusters formed by two biprotonated Spm(aMe) molecules, tour Cl- anions and two water molecules linked together by hydrogen bonds.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
