[2 + 2] cycloreversion of the anti-o,o'-benzene dimer 1 and the syn-o,o'-naphthalene-benzene dimer 2 through thermal and photoinduced electron transfer is studied using experimental and computational methods. The reaction of the radical cations formed by electron transfer is at least 10(5) times faster than the thermal background reaction. It is demonstrated that the photoinduced electron transfer
cis-3,5-Cyclohexadiene-1,2-diol derivatives: facial selectivity in their Diels–Alder reactions with ethylenic, acetylenic and azo dienophiles
作者:Sunny M. Ogbomo、D. Jean Burnell
DOI:10.1039/b607938e
日期:——
The Diels-Alderreactions of maleimide with the acetonide derivative (6a) of cis-3,5-cyclohexadiene-1,2-diol (1a) in various solvents showed facial selectivities ranging from 1 : 1 to 1 : 9. The same derivative 6a reacted in benzene with ethylenic dienophiles with generally modest facial selectivity, but acetylenic dienophiles added exclusively anti to the oxygen functions of 6a. Dimerization of cyclic
Utilising a Bryce-Smith-Gilbert photoamination of benzene as a key step, a synthesis of (±)-conduramine E was carried out. A highly regioselective dihydroxylation of a cyclic diene was effected utilising Sharpless AD-mix-β.
利用苯的 Bryce-Smith-Gilbert 光胺化作为关键步骤,进行了 (±)-conduramine E 的合成。使用 Sharpless AD-mix-β 实现了环状二烯的高度区域选择性二羟基化。
Asymmetric dihydroxylation of a meso-symmetric cyclic diene using AD-mix reagents: a new enantiocontrolled route to conduritol E
The asymmetric dihydroxylation of two symmetric cyclohexa-1,3-diene derivatives, including a meso-symmetric substrate, has been investigated for the first time using the Sharpless AD-mix reagents. Although cyclohexa-1,3-diene, itself showed unsatisfactory enantioselectivity, meso-symmetric 1,2-O-benzylidene-cis-cyclohexa-3,5-diene-1,2-diol showed a practical level of enantioselectivity and furnished the optically active diol in good yield. The diol obtained could be transformed into optically pure (+)-conduritol E in good yield, after a single recrystallization. The stereochemical outcome of the dihydroxylation was in harmony with the observations so far reported.
Gillard, James R.; Burnell, D. Jean, Canadian Journal of Chemistry, 1992, vol. 70, # 5, p. 1296 - 1307