title: Three structures of dispirooxindole derivatives generated in situ through a three-component one-pot strategy with complete regio- and stereoselectivity.
abstract: The challenging molecular architecture of spirooxindoles is appealing to chemists because it evokes novel synthetic strategies that address configurational demands and provides platforms for further reaction development. The [3+2] cycloaddition of the carbonyl ylide with arylideneoxindole via a five-membered cyclic transition state gave a novel class of dispirooxindole derivatives, namely tert-butyl 4'-(4-bromophenyl)-1''-methyl-2,2''-dioxo-5'-phenyl-4',5'-dihydrodispiro[indoline-3,2'-furan-3',3''-indoline]-1-carboxylate, C36H31BrN2O, (Ia), 5'-(4-bromophenyl)-1,1''-dimethyl-4'-phenyl-4',5'-dihydrodispiro[indoline-3,2'-furan-3',3''-indoline]-2,2''-dione, C32H25BrN2O3, (Ib), and tert-butyl 1''-methyl-2,2''-dioxo-4'-phenyl-5'-(p-tolyl)-4',5'-dihydrodispiro[indoline-3,2'-furan-3',3''-indoline]-1-carboxylate, C37H34N2O5, (Ic). Crystal structure analyses of these dispirooxindoles revealed the formation of two diastereoisomers selectively and confirmed their relative stereochemistry (SSSR and RRRS). In all three structures, intramolecular C-H···O and π-π interactions between oxindole and dihydrofuran rings are the key factors governing the regio- and stereoselectivity, and in the absence of conventional hydrogen bonds, their crystal packings are strengthened by intermolecular C-H···π 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: Govindaraju
authors.initials: G
authors.lastname: Karthik
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: D018360:Crystallography, X-Ray; D061565:Cycloaddition Reaction; D005663:Furans / Q000737:chemistry*; D006860:Hydrogen Bonding; D007211:Indoles / Q000737:chemistry*; D015394:Molecular Structure; D000078183:Oxindoles; D013237:Stereoisomerism
chemical_list: D005663:Furans; D007211:Indoles; D000078183:Oxindoles; C022960:2-oxindole
keywords: C—H...O interactions; NMR analysis; crystal structure; cycloaddition; diastereoselectivity; dispiro compounds; dispiroxoindole; drug discovery; in situ synthesis; privileged structures; π–π interactions