title: Experimental and computational mechanistic investigation of chlorocarbene additions to bridgehead carbene-anti-Bredt systems: noradamantylcarbene-adamantene and adamantylcarbene-homoadamantene.
abstract: Cophotolysis of noradamantyldiazirine with the phenanthride precursor of dichlorocarbene or phenylchlorodiazirine in pentane at room temperature produces noradamantylethylenes in 11% yield with slight diastereoselectivity. Cophotolysis of adamantyldiazirine with phenylchlorodiazirine in pentane at room temperature generates adamantylethylenes in 6% yield with no diastereoselectivity. (1)H NMR showed the reaction of noradamantyldiazirine + phenylchlorodiazirine to be independent of solvent, and the rate of noradamantyldiazirine consumption correlated with the rate of ethylene formation. Laser flash photolysis showed that reaction of phenylchlorocarbene + adamantene was independent of adamantene concentration. The reaction of phenylchlorocarbene + homoadamantene produces the ethylene products with k = 9.6 × 10(5) M(-1) s(-1). Calculations at the UB3LYP/6-31+G(d,p) and UM062X/6-31+G(d,p)//UB3LYP/6-31+G(d,p) levels show the formation of exocyclic ethylenes to proceed (a) on the singlet surface via stepwise addition of phenylchlorocarbene (PhCCl) to bridgehead alkenes adamantene and homoadamantene, respectively, producing an intermediate singlet diradical in each case, or (b) via addition of PhCCl to the diazo analogues of noradamantyl- and adamantyldiazirine. Preliminary direct dynamics calculations on adamantene + PhCCl show a high degree of recrossing (68%), indicative of a flat transition state surface. Overall, 9% of the total trajectories formed noradamantylethylene product, each proceeding via the computed singlet diradical.
authors.affiliation: †Department of Chemistry, University of California-Davis, 1 Shields Avenue, Davis, California 95616, United States.
authors.forename: Stephanie R
authors.initials: SR
authors.lastname: Hare
authors.affiliation: ‡Department of Chemistry, Barnard College, 3009 Broadway, New York, New York 10027, United States.
authors.forename: Marina
authors.initials: M
authors.lastname: Orman
authors.affiliation: ‡Department of Chemistry, Barnard College, 3009 Broadway, New York, New York 10027, United States.
authors.forename: Faizunnahar
authors.initials: F
authors.lastname: Dewan
authors.affiliation: ‡Department of Chemistry, Barnard College, 3009 Broadway, New York, New York 10027, United States.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Dalchand
authors.affiliation: ‡Department of Chemistry, Barnard College, 3009 Broadway, New York, New York 10027, United States.
authors.forename: Camilla
authors.initials: C
authors.lastname: Buzard
authors.affiliation: ‡Department of Chemistry, Barnard College, 3009 Broadway, New York, New York 10027, United States.
authors.forename: Sadia
authors.initials: S
authors.lastname: Ahmed
authors.affiliation: ‡Department of Chemistry, Barnard College, 3009 Broadway, New York, New York 10027, United States.
authors.forename: Julia C
authors.initials: JC
authors.lastname: Tolentino
authors.affiliation: ‡Department of Chemistry, Barnard College, 3009 Broadway, New York, New York 10027, United States.
authors.forename: Ulweena
authors.initials: U
authors.lastname: Sethi
authors.affiliation: ‡Department of Chemistry, Barnard College, 3009 Broadway, New York, New York 10027, United States.
authors.forename: Kelly
authors.initials: K
authors.lastname: Terlizzi
authors.affiliation: ‡Department of Chemistry, Barnard College, 3009 Broadway, New York, New York 10027, United States.
authors.forename: Camille
authors.initials: C
authors.lastname: Houferak
authors.affiliation: ‡Department of Chemistry, Barnard College, 3009 Broadway, New York, New York 10027, United States.
authors.forename: Aliza M
authors.initials: AM
authors.lastname: Stein
authors.affiliation: ‡Department of Chemistry, Barnard College, 3009 Broadway, New York, New York 10027, United States.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Stedronsky
authors.affiliation: §Department of Chemistry, Colby College, 5750 Mayflower Hill, Waterville, Maine 04901, United States.
authors.forename: Dasan M
authors.initials: DM
authors.lastname: Thamattoor
authors.affiliation: †Department of Chemistry, University of California-Davis, 1 Shields Avenue, Davis, California 95616, United States.
authors.forename: Dean J
authors.initials: DJ
authors.lastname: Tantillo
authors.affiliation: ‡Department of Chemistry, Barnard College, 3009 Broadway, New York, New York 10027, United States.
authors.forename: Dina C
authors.initials: DC
authors.lastname: Merrer
mesh_terms: D000218:Adamantane / Q000031:analogs & derivatives* / Q000737:chemistry*; D000475:Alkenes / Q000737:chemistry*; D005030:Ethylenes / Q000737:chemistry; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D010782:Photolysis; D012997:Solvents / Q000737:chemistry
chemical_list: D000475:Alkenes; D005030:Ethylenes; D012997:Solvents; C030011:carbene; D008697:Methane; D000218:Adamantane