Carbon Atom Insertion: A One-Step Synthesis of Tricyclo[3.2.1.02,7]octanes and Tricyclo[4.1.0.02,7]heptanes from Cyclohexenes1

Reinarz and Fonken have reported² that the dibromocarbene adduct (1) of 1-methylcyclohexene, upon reaction with methylllthium at 0° in ether, produced exclusively the bicyclobutanes 2 and 3 in relative yields of 60% and 40%, respectively. We have prepared 1 by the phase-transfer method³ of Makosza and Fedorynski in a yield of 67%, found these previous results to be completely reproducible in our hands, and determined the combined yield of the two products (2 and 3) to be 67% also. Thus, the overall     

(E)-1,2-Difluoro-1-iodo-2-trialkylsilanes—A useful synthon for the addition of the [IFCCF] unit to activated electrophiles

Fluoride ion catalyzed reaction of (E)-IFCCFSiR₃ with activated aromatic aldehydes and ketones and activated perfluoroaromatics, such as pentafluoropyridine and perfluorotoluenes, transfers the [IFCCF] unit to the activated electrophiles to stereospecifically provide (E)-1,2-difluoro-1-iodosubstituted derivatives. Aluminum chloride catalyzed reaction of (E)-1,2-difluoro-1-iodo-2-trialkylsilanes with alkyl or aryl acyl halides gives the corresponding (E)-1,2-difluoro-1-iodoketones stereospecifically in excellent yield. The vinyl iodide product formed via this methodology could be coupled (with Pd(0)) catalysis to provide an entry to a polyfunctionalized derivative.     

Longitudinal double-spin asymmetry for inclusive jet production in p[over -->] + p[over -->] collisions at sqrt[s]=200 GeV

We report a new STAR measurement of the longitudinal double-spin asymmetry A(LL) for inclusive jet production at midrapidity in polarized p + p collisions at a center-of-mass energy of sqrt[s]=200 GeV. The data, which cover jet transverse momenta 5相似文献   

Primary kinetic hydrogen isotope effects in deprotonations of a nitroalkane by intramolecular phenolate groups

Rate constants and kinetic isotope effects have been determined for the formation of nitronate anions from the ethers 1‐(2‐methoxyphenyl)‐2‐nitropropane, 7 (X = H, L = H and D) and 1‐(2‐methoxy‐5‐nitrophenyl)‐2‐nitropropane, 7 (X = NO₂, L = H and D), and from the corresponding phenols, 1‐(2‐hydroxyphenyl)‐2‐nitropropane, 3 (X = H, L = H and D), and 1‐(2‐hydroxy‐5‐nitrophenyl)‐2‐nitropropane, 3 (X = NO₂, L = H and D), in aqueous basic medium. For the ethers 7 , rates of deprotonation by hydroxide are comparable with those found for deprotonations of 2‐nitropropane, with k^H/k^D (25 °C) = 7.7 and 7.8, respectively. In both the cases, the isotope effects are conventionally temperature dependent. For the corresponding phenols 3 , conditions have been established under which the deprotonations of the nitroalkane are dominated by intramolecular deprotonation by the kinetically first‐formed phenolate anion, with an estimated effective molarity EM ～ 250. For 3 (X = H, L = H or D), k^H/k^D (25 °C) = 7.8, with E ? E = 6.9 kJ mol^?1 and A^H/A^D = 0.5. For 3 (X = NO₂, L = H or D), rates of intramolecular deprotonation are reduced 30‐fold, and an elevated kinetic isotope effect is found (k^H/k^D (25 °C) = 10.7). Activation parameters (E ? E = 17.8 kJ mol^?1 and A^H/A^D = 0.008) are compatible with an enhanced tunnelling contribution to reactivity in the H‐isotopomer. Copyright © 2009 John Wiley & Sons, Ltd.     

The preparation and thermal dimerization study of a trifluorovinyl-containing imide. Application to the synthesis of a trifluorovinyl-containing polyimide precursor

Elaboration of 2-fluoro-α,β,β-trifluorostyrene 7, prepared by the palladium catalyzed coupling reaction of l-fluoro-2-iodobenzene with a trifluorovinylzinc reagent, yielded the trifluorovinyl-containing imide 1. Thermal dimerization of 1 at 140-160°C leads predominately to the corresponding E-cyclobutane 12, whose structure was established by x-ray crystallography. Similar methodology was utilized to prepare 2,2-bis{4-[4-amino-2-(l,2,2-trifluoroethenyl)phenoxy]phenyl)hexafluoropropane 19 , a precursor to the trifluorovinyl-containing polyimide 18 .