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Different hydrogen-bonded chains in the crystal structures of three alkyl N-[(E)-1-(2-benzyl-idene-1-methyl-hydrazin-yl)-3-hy-droxy-1-oxopropan-2-yl]carbamates.

Noguiera TC, Pinheiro AC, Wardell JL, de Souza MV, Abberley JP, Harrison WT - Acta Crystallogr E Crystallogr Commun (2015)

Bottom Line: The crystal structures of three methyl-ated hydrazine carbamate derivatives prepared by multi-step syntheses from l-serine are presented, namely benzyl N-{(E)-1-[2-(4-cyanobenzylidene)-1-methylhydrazinyl]-3-hydroxy-1-oxopro-pan-2-yl}carbamate, C20H20N4O4, tert-butyl N-{(E)-1-[2-(4-cyanobenzylidene)-1-methylhydrazinyl]-3-hydroxy-1-oxopropan-2-yl}carbamate, C17H22N4O4, and tert-butyl N-[(E)-1-(2-benzylidene-1-methylhydrazinyl)-3-hydroxy-1-oxopro-pan-2-yl]carbamate, C16H23N3O4.One of them shows that an unexpected racemization has occurred during the mild-condition methyl-ation reaction.In each crystal structure, the mol-ecules are linked into chains by O-H⋯O hydrogen bonds, but with significant differences between them.

View Article: PubMed Central - HTML - PubMed

Affiliation: Fundação Oswaldo Cruz, Instituto de Tecnologia em Fármacos-FarManguinhos, Rua Sizenando Nabuco, 100, Manguinhos, 21041-250 Rio de Janeiro, RJ, Brazil.

ABSTRACT
The crystal structures of three methyl-ated hydrazine carbamate derivatives prepared by multi-step syntheses from l-serine are presented, namely benzyl N-{(E)-1-[2-(4-cyanobenzylidene)-1-methylhydrazinyl]-3-hydroxy-1-oxopro-pan-2-yl}carbamate, C20H20N4O4, tert-butyl N-{(E)-1-[2-(4-cyanobenzylidene)-1-methylhydrazinyl]-3-hydroxy-1-oxopropan-2-yl}carbamate, C17H22N4O4, and tert-butyl N-[(E)-1-(2-benzylidene-1-methylhydrazinyl)-3-hydroxy-1-oxopro-pan-2-yl]carbamate, C16H23N3O4. One of them shows that an unexpected racemization has occurred during the mild-condition methyl-ation reaction. In each crystal structure, the mol-ecules are linked into chains by O-H⋯O hydrogen bonds, but with significant differences between them.

No MeSH data available.


The mol­ecular structure of (I) showing 50% displacement ellipsoids.
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fig1: The mol­ecular structure of (I) showing 50% displacement ellipsoids.

Mentions: The mol­ecular structure of (I) is shown in Fig. 1 ▸, which confirms that methyl­ation has occurred at N2 but no cyclization to an oxazolidin-2-one has occurred (Noguiera et al., 2015 ▸). Compound (I) crystallizes in a chiral space group but its absolute structure was indeterminate in the present experiment and C10 was assumed to have an S configuration to match the corresponding atom in the l-serine starting mat­erial. The atoms of the C14 benzene ring show notably larger displacement ellipsoids than the rest of the mol­ecule, but attempts to model this as disorder did not lead to a significant improvement in fit. Atom N2 is statistically planar (bond-angle sum = 360°), which implies sp2 hybridization for this atom. The C9—N2 bond length of 1.358 (6)Å is typical of an amide and the N1—N2 bond length of 1.374 (5) is shorter than the reference value of 1.40 Å for a nominal N(sp2)—N(sp2) single bond. This suggests at least some electronic conjugation over the almost planar C7/N1/N2/C9/O1 grouping (r.m.s. deviation = 0.010 Å): the C1 benzene ring is twisted by 6.1 (2)° with respect to these atoms. The C7—N1—N2—C8 torsion angle of −1.9 (6)° shows that the carbon atoms are almost eclipsed with respect to the N—N bond whereas the C9—C10—C11—O2 torsion angle of −50.9 (5)° indicates a gauche conformation about the C10—C11 bond. The C9—C10—N3—H3A torsion angle is 38° and the separation between H2A (bonded to O2) and H3A is 2.5 Å.


Different hydrogen-bonded chains in the crystal structures of three alkyl N-[(E)-1-(2-benzyl-idene-1-methyl-hydrazin-yl)-3-hy-droxy-1-oxopropan-2-yl]carbamates.

Noguiera TC, Pinheiro AC, Wardell JL, de Souza MV, Abberley JP, Harrison WT - Acta Crystallogr E Crystallogr Commun (2015)

The mol­ecular structure of (I) showing 50% displacement ellipsoids.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4518986&req=5

fig1: The mol­ecular structure of (I) showing 50% displacement ellipsoids.
Mentions: The mol­ecular structure of (I) is shown in Fig. 1 ▸, which confirms that methyl­ation has occurred at N2 but no cyclization to an oxazolidin-2-one has occurred (Noguiera et al., 2015 ▸). Compound (I) crystallizes in a chiral space group but its absolute structure was indeterminate in the present experiment and C10 was assumed to have an S configuration to match the corresponding atom in the l-serine starting mat­erial. The atoms of the C14 benzene ring show notably larger displacement ellipsoids than the rest of the mol­ecule, but attempts to model this as disorder did not lead to a significant improvement in fit. Atom N2 is statistically planar (bond-angle sum = 360°), which implies sp2 hybridization for this atom. The C9—N2 bond length of 1.358 (6)Å is typical of an amide and the N1—N2 bond length of 1.374 (5) is shorter than the reference value of 1.40 Å for a nominal N(sp2)—N(sp2) single bond. This suggests at least some electronic conjugation over the almost planar C7/N1/N2/C9/O1 grouping (r.m.s. deviation = 0.010 Å): the C1 benzene ring is twisted by 6.1 (2)° with respect to these atoms. The C7—N1—N2—C8 torsion angle of −1.9 (6)° shows that the carbon atoms are almost eclipsed with respect to the N—N bond whereas the C9—C10—C11—O2 torsion angle of −50.9 (5)° indicates a gauche conformation about the C10—C11 bond. The C9—C10—N3—H3A torsion angle is 38° and the separation between H2A (bonded to O2) and H3A is 2.5 Å.

Bottom Line: The crystal structures of three methyl-ated hydrazine carbamate derivatives prepared by multi-step syntheses from l-serine are presented, namely benzyl N-{(E)-1-[2-(4-cyanobenzylidene)-1-methylhydrazinyl]-3-hydroxy-1-oxopro-pan-2-yl}carbamate, C20H20N4O4, tert-butyl N-{(E)-1-[2-(4-cyanobenzylidene)-1-methylhydrazinyl]-3-hydroxy-1-oxopropan-2-yl}carbamate, C17H22N4O4, and tert-butyl N-[(E)-1-(2-benzylidene-1-methylhydrazinyl)-3-hydroxy-1-oxopro-pan-2-yl]carbamate, C16H23N3O4.One of them shows that an unexpected racemization has occurred during the mild-condition methyl-ation reaction.In each crystal structure, the mol-ecules are linked into chains by O-H⋯O hydrogen bonds, but with significant differences between them.

View Article: PubMed Central - HTML - PubMed

Affiliation: Fundação Oswaldo Cruz, Instituto de Tecnologia em Fármacos-FarManguinhos, Rua Sizenando Nabuco, 100, Manguinhos, 21041-250 Rio de Janeiro, RJ, Brazil.

ABSTRACT
The crystal structures of three methyl-ated hydrazine carbamate derivatives prepared by multi-step syntheses from l-serine are presented, namely benzyl N-{(E)-1-[2-(4-cyanobenzylidene)-1-methylhydrazinyl]-3-hydroxy-1-oxopro-pan-2-yl}carbamate, C20H20N4O4, tert-butyl N-{(E)-1-[2-(4-cyanobenzylidene)-1-methylhydrazinyl]-3-hydroxy-1-oxopropan-2-yl}carbamate, C17H22N4O4, and tert-butyl N-[(E)-1-(2-benzylidene-1-methylhydrazinyl)-3-hydroxy-1-oxopro-pan-2-yl]carbamate, C16H23N3O4. One of them shows that an unexpected racemization has occurred during the mild-condition methyl-ation reaction. In each crystal structure, the mol-ecules are linked into chains by O-H⋯O hydrogen bonds, but with significant differences between them.

No MeSH data available.