title: Four oxoindole-linked α-alkoxy-β-amino acid derivatives.
abstract: Four structures of oxoindolyl α-hydroxy-β-amino acid derivatives, namely, methyl 2-{3-[(tert-butoxycarbonyl)amino]-1-methyl-2-oxoindolin-3-yl}-2-methoxy-2-phenylacetate, C24H28N2O6, (I), methyl 2-{3-[(tert-butoxycarbonyl)amino]-1-methyl-2-oxoindolin-3-yl}-2-ethoxy-2-phenylacetate, C25H30N2O6, (II), methyl 2-{3-[(tert-butoxycarbonyl)amino]-1-methyl-2-oxoindolin-3-yl}-2-[(4-methoxybenzyl)oxy]-2-phenylacetate, C31H34N2O7, (III), and methyl 2-[(anthracen-9-yl)methoxy]-2-{3-[(tert-butoxycarbonyl)amino]-1-methyl-2-oxoindolin-3-yl}-2-phenylacetate, C38H36N2O6, (IV), have been determined. The diastereoselectivity of the chemical reaction involving α-diazoesters and isatin imines in the presence of benzyl alcohol is confirmed through the relative configuration of the two stereogenic centres. In esters (I) and (III), the amide group adopts an anti conformation, whereas the conformation is syn in esters (II) and (IV). Nevertheless, the amide group forms intramolecular N-H···O hydrogen bonds with the ester and ether O atoms in all four structures. The ether-linked substituents are in the extended conformation in all four structures. Ester (II) is dominated by intermolecular N-H···O hydrogen-bond interactions. In contrast, the remaining three structures are sustained by C-H···O hydrogen-bond interactions.
authors.affiliation: X-ray Crystallography Division, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India.
authors.forename: Krishnan
authors.initials: K
authors.lastname: Ravikumar
authors.affiliation: X-ray Crystallography Division, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India.
authors.forename: Balasubramanian
authors.initials: B
authors.lastname: Sridhar
authors.affiliation: X-ray Crystallography Division, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India.
authors.forename: Jagadeesh Babu
authors.initials: JB
authors.lastname: Nanubolu
authors.affiliation: Natural Product Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India.
authors.forename: Tamilselvan
authors.initials: T
authors.lastname: Rajasekaran
authors.affiliation: Natural Product Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India.
authors.forename: Basi Venkata Subba
authors.initials: BV
authors.lastname: Reddy
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D000873:Anthracenes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D007211:Indoles / Q000737:chemistry*; D015394:Molecular Structure; D010648:Phenylacetates / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D000873:Anthracenes; D007211:Indoles; D010648:Phenylacetates; C000599437:methyl 2-(3-((tert-butoxycarbonyl)amino)-1-methyl-2-oxoindolin-3-yl)-2-methoxy-2-phenylacetate
keywords: crystal structure; diastereoselectivity; esters; hydrogen bonding; natural products; oxoindole; α-hydroxy-β-amino acid