Categories: C=O Bond Formation >
Synthesis of enones
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α,β-unsaturated compounds (C-C Coupling) |
Recent Literature
Dirhodium(II) caprolactamate effectively catalyzes the allylic oxidation of
a variety of olefins and enones with tert-butyl hydroperoxide as
terminal oxidant. The reaction is completely selective, tolerant of air and
moisture, and can be performed with as little as 0.1 mol % catalyst in
minutes.
A. E. Lurain, A. Maestri, A. R. Kelli, P. J. Carroll, P. J. Walsh, J. Am. Chem. Soc.,
2004, 126, 13622-13623.
The use of cationic silver (AgSbF4) as a catalyst for intra- and
intermolecular alkyne-carbonyl coupling is described. Intermolecular coupling proceeds
stereoselectively to afford trisubstituted enones.
J. U. Rhee, M. J. Krische, Org. Lett., 2005, 7, 2493-2495.
Catalytic (1,4-diazabicyclo[2.2.2]octane (DABCO) was found to be effective
for the isomerization of electron-deficient propargylic alcohols to E-enones
under mild conditions. When the substrate is conjugated with an amide,
addition of sodium acetate catalyzed the isomerization.
J. P. Sonye, K. Koide, J. Org. Chem., 2006, 71, 6254-6257.
A new and simple method is described for the one-step oxidation of α,β-enones
to 1,4-enediones in good yields using t-butylhydroperoxide as
stoichiometric oxidant and 20% Pd(OH)2 on carbon as catalyst. The same reagents have been used to convert ethylene ketals
of α,β-enones
to the corresponding monoethylene ketals of 1,4-enediones. The mechanism is
discussed.
J.-Q. Yu, E. J. Corey, J. Am. Chem. Soc., 2003, 125, 3232-3233.
A catalytic amount of Au(PPh3)NTf2 converts readily
accessible propargylic acetates into versatile linear α-iodoenones in good to
excellent yields. Very good Z-selectivities are observed for aliphatic
propargylic acetates.
M. Yu, G. Zhang, L. Zhang, Org. Lett., 2007,
9, 2087-2090.
A sequence of two gold(I)-catalyzed isomerization steps allows the synthesis
of
functionalized acetoxy bicyclo[3.1.0]hexenes from 5-en-2-yn-1-yl acetates.
Acetoxy bicyclo[3.1.0]hexene products can be further transformed to
2-cycloalkenones by simple methanolysis.
A. Buzas, F. Gagosz, J. Am. Chem. Soc., 2006, 128, 12614-12615.
A highly efficient carbon-carbon triple bond cleavage reaction of (Z)-enynols
offered a new route to highly substituted butenolides through a
gold(I)-catalyzed tandem cyclization/oxidative cleavage.
Y. Liu, F. Song, S. Guo, J. Am. Chem. Soc., 2006, 128, 11332-11333.
