91839-89-3Relevant academic research and scientific papers
Formation of Cyclopropanes via Activation of (γ-Methoxy)alkyl Gold(I) Complexes with Lewis Acids
Kim, Nana,Widenhoefer, Ross A.
, p. 3160 - 3167 (2020/09/12)
Treatment of the gold 3-methoxy-3-phenylpropyl complex (P)AuCH2CH2CH(OMe)Ph [P = P(t-Bu)2o-biphenyl] with AlCl3 at -78 °C led to the immediate (≤5 min) formation of a 4:1 mixture of phenylcyclopropane and (1-methoxypropyl)benzene in 86 ± 5% combined yield. Lewis acid activation of the stereochemically pure isotopomer erythro-(P)AuCH2CHDCH(OMe)Ph led to the formation of cis-2-deuterio-1-phenylcyclopropane in 84 ± 5% yield as a single stereoisomer, which established that cyclopropanation occurred with inversion of the γ-stereocenter. Similarly, ionization of the stereochemically pure cyclohexyl gold complex cis-(P)AuCHCH2CH(OMe)CH2CH2CH2 at -78 °C formed bicyclo[3.1.0]hexane in 82% ± 5% yield, which validated a low energy pathway for cyclopropanation involving inversion of the α-stereocenter. Taken together, these observations are consistent with a mechanism for cyclopropane formation involving backside displacement of both the Cγleaving group and the Cα (L)Au+ fragment via a W-shaped transition state.
A versatile tripodal Cu(I) reagent for C-N bond construction via nitrene-transfer chemistry: Catalytic perspectives and mechanistic insights on C-H aminations/amidinations and olefin aziridinations
Bagchi, Vivek,Paraskevopoulou, Patrina,Das, Purak,Chi, Lingyu,Wang, Qiuwen,Choudhury, Amitava,Mathieson, Jennifer S.,Cronin, Leroy,Pardue, Daniel B.,Cundari, Thomas R.,Mitrikas, George,Sanakis, Yiannis,Stavropoulos, Pericles
, p. 11362 - 11381 (2014/09/17)
A CuI catalyst (1), supported by a framework of strongly basic guanidinato moieties, mediates nitrene-transfer from PhI=NR sources to a wide variety of aliphatic hydrocarbons (C-H amination or amidination in the presence of nitriles) and olefins (aziridination). Product profiles are consistent with a stepwise rather than concerted C-N bond formation. Mechanistic investigations with the aid of Hammett plots, kinetic isotope effects, labeled stereochemical probes, and radical traps and clocks allow us to conclude that carboradical intermediates play a major role and are generated by hydrogen-atom abstraction from substrate C-H bonds or initial nitrene-addition to one of the olefinic carbons. Subsequent processes include solvent-caged radical recombination to afford the major amination and aziridination products but also one-electron oxidation of diffusively free carboradicals to generate amidination products due to carbocation participation. Analyses of metal- and ligand-centered events by variable temperature electrospray mass spectrometry, cyclic voltammetry, and electron paramagnetic resonance spectroscopy, coupled with computational studies, indicate that an active, but still elusive, copper-nitrene (S = 1) intermediate initially abstracts a hydrogen atom from, or adds nitrene to, C-H and C=C bonds, respectively, followed by a spin flip and radical rebound to afford intra- and intermolecular C-N containing products.
Partial Loss of Deuterium Label in Wilkinson's Catalyst Promoted Decarbonylations of Deuterioaldehydes
Baldwin, John E.,Barden, Timothy C.,Pugh, Ruth L.,Widdison, Wayne C.
, p. 3303 - 3307 (2007/10/02)
Decarbonylations of trans-2-phenylcyclopropanedeuteriocarboxaldehyde and cycloheptanedeuteriocarboxaldehyde with Wilkinson's catalyst give phenylcyclopropane and cycloheptane with partial loss of deuterium label.Loss of deuterium label is not a consequence of orthometalation of deuteriotris(triphenylphosphine)rhodium(I), a plausible reactive intermediate, for the loss is observed even when RhCl(P(C6D5)3)3 is used to effect the decarbonylation.Decarbonylations of trans-2-phenylcyclopropanecarboxaldehyde with Wilkinson's catalyst in benzene containing O-deuterioethanolafford d0 and d1 phenylcyclopropane and d0 and d1 aldehyde; neither hydrocarbon product nor recovered aldehyde is deuterium labeled when 1,1-dideuterioethanol is present in the decarbonylation reaction mixture.The hydroxyl hydrogen of ethanol associated with RhCl(P(C6H5)3)3 as normally synthesized, however, is not the hydrogen source: ethanol is not detected by 1H NMR in solutions of the catalyst, loss of deuterium label occurs even when RhCl(PPh3)3 is prepared free of possible contamination by ethanol from 2, and it is seen as well with an alternative ethanol-free decarbonylation catalyst, ClRh(dppp)2.The hydrogen source is water retained in commercial Wilkinson's catalyst.Decarbonylations of deuterioaldehyde in the presence of excess D2O give d1 product with high preservation of label.
Absolute Configurations, Maximum Rotations, and Kinetics of Thermal Racemization of the 1-Phenyl-2-deuteriocyclopropanes
Baldwin, John E.,Barden, Timothy C.
, p. 6364 - 6367 (2007/10/02)
From precursors of known absolute configurations and optical purities have been prepared (1S,2R)-(-)-cis-1-phenyl-2-deuteriocyclopropane and the (1R,2R)-(+)-trans isomer.The predicted kinetics of racemization for the (-)-cis isomer at 309.3 deg C based on
CYCLOPROPYL HALIDES. ELECTRON TRANSFER IN THE LITHIUM ALUMINIUM HYDRIDE REDUCTION OF GEM-DIBROMO AND MONOBROMOCYCLOPROPANES.
McKinney, Michael A.,Anderson, Steve W.,Keyes, Michael,Schmidt, Ronald
, p. 3443 - 3446 (2007/10/02)
The stereochemistry of reduction of mixtures of r-1-bromo-1-deuterio-c- and t-2-phenylcyclopropane and the cyclized products from 1,1-dibromo-2-(3-butenyl) cyclopropane upon reduction with lithium aluminium hydride give evidence of a configurationally equilibrated cyclopropyl radical as a reaction intermediate.
