title: Development of Chiral, Bifunctional Thiosquaramides: Enantioselective Michael Additions of Barbituric Acids to Nitroalkenes.
abstract: We report a general method for the synthesis of chiral thiosquaramides, a class of bifunctional catalysts not previously described in the literature. Thiosquaramides are found to be more acidic and significantly more soluble in nonpolar solvents than their oxosquaramide counterparts, and they are excellent catalysts for the unreported, enantioselective conjugate addition reaction of the barbituric acid pharmacaphore to nitroalkenes, delivering the chiral barbiturate derivatives in high yields and high enantioselectivities, even with catalyst loadings as low as 0.05 mol%.
authors.affiliation: Department of Chemistry, University of Chicago , 5735 South Ellis Avenue, Chicago, Illinois 60637, United States.
authors.forename: Michael
authors.identifier: 0000-0002-4402-5619
authors.initials: M
authors.lastname: Rombola
authors.affiliation: Department of Chemistry, University of Chicago , 5735 South Ellis Avenue, Chicago, Illinois 60637, United States.
authors.forename: Chintan S
authors.initials: CS
authors.lastname: Sumaria
authors.affiliation: Department of Chemistry, University of Chicago , 5735 South Ellis Avenue, Chicago, Illinois 60637, United States.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Montgomery
authors.affiliation: Department of Chemistry, University of Chicago , 5735 South Ellis Avenue, Chicago, Illinois 60637, United States.
authors.forename: Viresh H
authors.initials: VH
authors.lastname: Rawal
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D001463:Barbiturates / Q000737:chemistry*; D015394:Molecular Structure; D009574:Nitro Compounds / Q000737:chemistry*; D011803:Quinine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D013237:Stereoisomerism; D013438:Sulfhydryl Compounds / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000475:Alkenes; D001463:Barbiturates; D009574:Nitro Compounds; D013438:Sulfhydryl Compounds; C000609819:squaramide; D011803:Quinine; C032232:barbituric acid