title: Nitrone Cycloadditions of 1,2-Cyclohexadiene.
abstract: We report the first 1,3-dipolar cycloadditions of 1,2-cyclohexadiene, a rarely exploited strained allene. 1,2-Cyclohexadiene is generated in situ under mild conditions and trapped with nitrones to give isoxazolidine products in synthetically useful yields. The reactions occur regioselectively and exhibit a notable endo preference, thus resulting in the controlled formation of two new bonds and two stereogenic centers. DFT calculations of stepwise and concerted reaction pathways are used to rationalize the observed selectivities. Moreover, the strategic manipulation of nitrone cycloadducts demonstrates the utility of this methodology for the assembly of compounds bearing multiple heterocyclic units. These studies showcase the exploitation of a traditionally avoided reactive intermediate in chemical synthesis.
authors: Department of Chemistry and Biochemistry, University of California , Los Angeles, California 90095, United States.
authors: Joyann S
authors: JS
authors: Barber
authors: Department of Chemistry and Biochemistry, University of California , Los Angeles, California 90095, United States.
authors: Evan D
authors: ED
authors: Styduhar
authors: Department of Chemistry and Biochemistry, University of California , Los Angeles, California 90095, United States.
authors: Hung V
authors: HV
authors: Pham
authors: Department of Chemistry and Biochemistry, University of California , Los Angeles, California 90095, United States.
authors: Travis C
authors: TC
authors: McMahon
authors: Department of Chemistry and Biochemistry, University of California , Los Angeles, California 90095, United States.
authors: K N
authors: KN
authors: Houk
authors: Department of Chemistry and Biochemistry, University of California , Los Angeles, California 90095, United States.
authors: Neil K
authors: NK
authors: Garg
mesh_terms: D000498:Allyl Compounds / Q000737:chemistry; D061565:Cycloaddition Reaction; D053138:Cyclohexenes / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000138:chemical synthesis*; D009589:Nitrogen Oxides / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000498:Allyl Compounds; D053138:Cyclohexenes; D006571:Heterocyclic Compounds; D009589:Nitrogen Oxides; C015388:nitrones