Reduction of epoxides
A magnetically separable palladium catalyst is highly active and selective for epoxide hydrogenolysis at room temperature under 1 atm H2 and can be recycled without loss of activity. The catalyst was synthesized simply through a sol-gel process incorporating palladium nanoparticles and superparamagnetic iron oxide nanoparticles in aluminum oxyhydroxide matrix.
M. S. Kwon, I. S. Park, J. S. Jang, J. S. Lee, J. Park, Org. Lett., 2007, 9, 3417-3419.
A readily available magnesium catalyst achieves a selective hydroboration of a wide range of epoxides and oxetanes yielding secondary and tertiary alcohols in excellent yields and regioselectivities.
M. Magre, E. Paffenholz, B. Maity, L. Cavallo, M. Rueping, J. Am. Chem. Soc., 2020, 142, 14286-14294.
Highly regioselective ring opening of epoxides with poor nucleophiles such as indole, borane, O-trimethylsilylhydroxylamine, p-nitroaniline and sterically hindered tert-butylamine is a fast and convenient reaction in the presence of 5.0 M lithium perchlorate-Et2O solution (LPDE).
A. Heydari, M. Mehrdad, A. Maleki, N. Ahmadi, Synthesis, 2004, 1557-1558.
Low-valent Cp2TiCl selectively reduces selected α,β-epoxy ketones to the corresponding aldol products under mild conditions. A chiral epoxide was converted without any loss of optical purity. The addition of collidine hydrochloride enables a system catalytic in titanocene.
C. Hardouin, F. Chevallier, B. Rousseau, E. Doris, J. Org. Chem., 2001, 66, 1046-1048.
The hydrogenation of α,β-epoxy ketones can be mediated by a catalytic amount of BNA+Br- using Na2S2O4 as primary reducing agent to form the corresponding β-hydroxy ketones in high yield. A radical mechanism has been proposed.
H.-J. Xu, Y.-C. Liu, Y. Fu, Y.-D. Wu, Org. Lett., 2006, 8, 3449-3451.
The of silica-coated magnetic nanoparticles allowed the construction of magnetically recoverable organic hydride compounds. Magnetic nanoparticle-supported BNAH (1-benzyl-1,4-dihydronicotinamide) showed efficient activity in the catalytic reduction of α,β-epoxy ketones. After reaction, the catalyst can be separated by simple magnetic separation and can be reused.
H.-J. Xu, X. Wan, Y.-Y. Shen, S. Xu, Y.-S. Feng, Org. Lett., 2012, 14, 1210-1213.
The catalytic generation of activated carboxylates from epoxyaldehydes enables a direct, anti-selective, convenient and mild synthesis of β-hydroxyesters.
K. Y.-K. Chow, J. W. Bode, J. Am. Chem. Soc., 2004, 126, 8126-8127.