25118-23-4Relevant articles and documents
α-Ethoxycarbonyl and α-methoxy substituted radical clocks
Newcomb, Martin,Filipkowski, Michelle A.,Johnson, Cathy C.
, p. 3643 - 3646 (1995)
Rate constants and Arrhenius functions for 5-exo cyclizations of the 1-(ethoxycarbonyl)-5-hexenyl radical, the 1-(ethoxycarbonyl)-1-methyl-5-hexenyl radical and the 1-methoxy-5-hexenyl radical were determined by indirect kinetic methods.
Cyclization Reactions of Oxyallyl Cation. A Method for Cyclopentane Ring Formation
Vulovic, Bojan,Trmcic, Milena,Matovic, Radomir,Saicic, Radomir N.
, p. 9618 - 9621 (2019/12/24)
Unsaturated oxyallyl cations with a suitably positioned alkene bond undergo 5-exo-cyclization with the formation of vinylcyclopentane derivatives. Alkyne analogues provide allenes. The reaction proceeds with a moderate to excellent level of stereoselectiv
Treasures from the Free Radical Renaissance Period - Miscellaneous hexenyl radical kinetic data
Beckwith, Athelstan L. J.,Schiesser, Carl H.
, p. 1736 - 1743 (2011/05/03)
Rate constant data and Arrhenius parameters have been determined for a series of substituted hexenyl radicals of differing electronic and steric demand. Electron-withdrawing groups (CF3, CO2Et) directly attached to the radical centre slighly accelerate 5-exo ring-closure (k cis + ktrans ～ 2.1 × 105 s -1 at 25°) relative to donating groups (OMe; 1.6 × 10 5 s-1 at 25°). Sterically demanding groups (tert-Bu), as expected, slow the cyclization process (1 × 105 s -1). These observations are consistent with subtle changes in activation energy for 5-exo ring-closure. Interestingly, the nature of the solvent would appear to have a significant influence on this chemistry with the cis/trans stereoselectivity sometimes improved as the solvent polarity is increased. Except for the system containing the CF3 (electron-withdrawing) group which displays an increase in the cyclization/capture rate constant (kc/kH), a general decrease in the kc/kH ratio as solvent polarity is increased is noted; these changes have been speculated to arise mainly from changes in kH in the various solvents employed.
