Synthesis of aldehydes by oxidation of alkenes
The use of tert-butyl nitrite as a simple organic redox cocatalyst instead of copper or silver salts enabled an aldehyde-selective aerobic Wacker-Tsuji oxidation. Various aldehydes could beg isolated as major products in up to 30/1 regioselectivity as well as good to high yields at room temperature.
X.-S. Ning, M.-M. Wang, C.-Z. Yao, X.-M. Chen, Y.-B. Kang, Org. Lett., 2016, 18, 2700-2703.
In the presence of PdCl2(MeCN)2, 1,4-benzoquinone, and t-BuOH, aryl-substituted olefins can selectively be oxidized to aldehydes. In this efficient and aldehyde-selective Wacker oxidation, very good yield of aldehyde can be obtained, and up to 99% selectivity can be achieved with styrene-related substrates.
P. Teo, Z. K. Wickens, G. Dong, R. H. Grubbs, Org. Lett., 2012, 14, 3237-3239.
Palladium-catalyzed oxygenation of allyl arenes or alkenes produce (E)-alkenyl aldehydes with high yields. Allylic C-H bond cleavages occur under mild conditions during this process. Mechanistic studies show that oxygen source is water.
H. Chen, H. Jiang, C. Cai, J. Dong, W. Fu, Org. Lett., 2011, 13, 992-994.
The use of Oxone allows the conversion of various aryl-, heteroaryl-, alkenyl-, and alkyltrifluoroborates into the corresponding oxidized products in excellent yields. This method tolerates a broad range of functional groups, and in secondary alkyl substrates it was demonstrated to be completely stereospecific.
G. A. Molander, L. N. Cavalcanti, J. Org. Chem., 2011, 76, 623-630.