2439-79-4Relevant academic research and scientific papers
Recyclable scavengers for photo-cyclopropanation via an in situ crystallization process
Lee, Haeri,Choi, Eunkyung,Noh, Tae Hwan,Jung, Ok-Sang
, p. 18476 - 18483 (2016)
The palladium(ii) cyclophane systems, constructed by previously reported proof-of-concept self-assembly, represent a crucial landmark in the field of effective and recyclable scavenging of triiodide (I3?) in the photo-cyclopropanation of alkenes with CH2I2. The scavenger's driving force behind photo-cyclopropanation is the efficient in situ crystallization of triiodide-exchanged species. The exact quantitative photoreaction yields according to the mole ratios of the cyclophane system are impressive. The recycling behavior can be ascribed to the rigidity and stability of the four-layered tripalladium(ii)cyclophane.
Photoreaction of adsorbed dIIodomethane: Halide effects of a series of neutral palladium(II) coordination cages
Noh, Tae Hwan,Lee, Haeri,Kim, Doeon,Moon, Dohyun,Lee, Young-A,Jung, Ok-Sang
, p. 8574 - 9581 (2016)
A series of Pd6L4-type neutral coordination cages, [Pd6X12L4] (X- = Cl- and Br-), are constructed via self-assembly of (COD)PdCl2 and K2PdBr4 with C3-symmetric N,N′,N′′-tris(2-pyridinylmethyl)-1,3,5-benzenetricarboxamide (L), respectively. The iodide analogue [Pd6I12L4] is smoothly synthesized from [Pd6Br12L4] in the presence of CH2I2 under mild conditions. The replacement of bromide to iodide in the nanocage system represents a landmark achievement in synthetic-methodology development. The CH2I2 molecules are adsorbed in the order [Pd6I12L4] > [Pd6Br12L4] > [Pd6Cl12L4] and in the "like-attracts-like" pattern, presumably owing to the van der Waals force. Irradiation of [Pd6I12L4]·3.5CH2I2 with 1-methylcyclohexene in chloroform at 350 nm preferentially affords the cyclopropanation product.
Six- vs seven-membered ring formation from the 1- bicyclo[4.1.0]heptanylmethyl radical: Synthetic and ab initio studies
Kantorowski, Eric J.,Eisenberg, Shawn W. E.,Fink, William H.,Kurth, Mark J.
, p. 570 - 580 (2007/10/03)
The viability of utilizing 1-bicyclo[4.1.0]heptanylmethyl radical (3) to serve as a progenitor of seven-membered carbocycles was examined. Rate constants for the rearrangement of this radical to 3-methylenecycloheptyl radical (4) and 2-methylenecyclohexyl-1-methyl radical (6) were measured using the competition method of 3 with thiophenol over the temperature range of -75 to 59 °C. Arrhenius functions were calculated for the conversions of 3 to 4 and 3 to 6 and found to be log(k/s-1) = (12.38 ± 0.20) - (5.63 ± 0.23)/θ and log(k/s-1) = (11.54 ± 0.32) - (5.26 ± 0.37)/θ, respectively. The rate constants for these conversions at 25 °C are 1.86 x 108 s-1 and 5.11 x 107 s-1, respectively. Hence, the seven-membered ring-expanded carbocycle is formed 3.6 times faster at 25 °C than the nonexpanded species. This suggests that the 1-bicyclo[4.1.0]heptanylmethyl radical system may be synthetically useful in seven-membered ring-forming methodology. Preliminary theoretical examination of this radical system qualitatively predicted the experimentally determined energies of activation: PMP4/6-31G*//HF/6-31G*ΔE(a) (3 → 6 - 3 → 4) = 3.0 kcal/mol with zero point energy correction. The HF/6-31G* optimized reaction coordinate stationary points suggest cyclopropyl substituent eclipsing interactions play an important role in determining the kinetic outcome of these rearrangements.
Hydrogenolysis of Small Cycloalkanes, X. - Catalytic Hydrogenation of Bicycloalkanes
Stahl, Karl-Johannes,Hertzsch, Winfried,Musso, Hans
, p. 1474 - 1484 (2007/10/02)
Dependent on n different products are obtained from bicycloalkanes by hydrogenation on Pt and Pd/C catalysts: from n = 5 onward only methylcycloalkanes of the same ring size; with n = 4 additionally 2-7 percent of cycloheptane is formed; with n = 3 ring enlargement increases to 5-20 percent and with n = 2 cyclopentane is the only product.Mainly butane is formed from bicyclobutane and no intermediate could be detected.Explanations are attempted.The expected products are produced on hydrogenation of methyl-substituted derivatives and spiroalkanes.
PHOTOCHEMISTRY OF ALKYL HALIDES - VII. CYCLOPROPANATION OF ALKENES
Kropp, Paul J.,Pienta, Norbert J.,Sawyer, Joy A.,Polniaszek, Richard P.
, p. 3229 - 3236 (2007/10/02)
The previously observed cyclopropanation of alkenes by irradiation of diiodomethane (1) in their presence has been studied in more detail and found to be a synthetically useful procedure which is significantly less subject to steric effects than the traditional Simmons-Smith method.The results from photocyclopropanation of a variety of alkenes are summarized in Tables 1 and 3-4.In a number of cases the photochemical procedure afforded improved results over the Simmons-Smith method, particularly with sterically congested alkenes.Cycloalkenes showed relative rates of photocyclopropanation as a function of ring size similar to those of the Simmons-Smith method (Table 5).However, the photocyclopropanation reaction exhibited steadily increasing relative rates with increasing substitution about the double bond-in contrast with the Simmons-Smith method (Table 6), in which steric effects offset increasing nucleophilicity of the alkene with increasing substitution.The α-iodocation 2 is suggested as the methylene transfer species.In the presence of lithium bromide cation 2 was trapped to afford bromoiodomethane.
