Different hydrogen-bonded chains in the crystal structures of three alkylN-[(E)-1-(2-benzylidene-1-methylhydrazinyl)-3-hydroxy-1-oxopropan-2-yl]carbamates

Abstract

The crystal structures of three methylated hydrazine carbamate derivatives prepared by multi-step syntheses from L-serine are presented, namely benzylN-{(E)-1-[2-(4-cyanobenzylidene)-1-methylhydrazinyl]-3-hydroxy-1-oxopropan-2-yl}carbamate, C20H20N4O4,tert-butylN-{(E)-1-[2-(4-cyanobenzylidene)-1-methylhydrazinyl]-3-hydroxy-1-oxopropan-2-yl}carbamate, C17H22N4O4, andtert-butylN-[(E)-1-(2-benzylidene-1-methylhydrazinyl)-3-hydroxy-1-oxopropan-2-yl]carbamate, C16H23N3O4. One of them shows that an unexpected racemization has occurred during the mild-condition methylation reaction. In each crystal structure, the molecules are linked into chains by O—H...O hydrogen bonds, but with significant differences between them.