Synthesis of alcohols
β-Alkylation of various secondary alcohols with primary alcohols has been achieved in the presence of [Cp*IrCl2]2 (Cp* = pentamethylcyclopentadienyl) catalyst and a base. This reaction proceeds in good to excellent yield via successive hydrogen-transfer reactions and aldol condensation.
K.-I. Fujita, C. Asai, T. Yamaguchi, F. Hanasaka, R. Yamaguchi, Org. Lett., 2005, 7, 4017-4019.
An asymmetric α-alkylative reduction of prochiral ketones with primary alcohols has been disclosed. The reaction is catalyzed by both iridium and ruthenium complexes and gave optically active alcohols with elongation of the carbon skeleton with high enantioselectivity.
G. Onodera, Y. Nishibayashi, S. Uemura, Angew. Chem. Int. Ed., 2006, 45, 3819-3822.
A simple method for the chemo- and regioselective, direct catalytic allylic alkylation of aldehydes and cyclic ketones has been developed. The combination of palladium and enamine catalysis furnished α-allylic alkylated aldehydes and cyclic ketones in high yields.
I. Ibrahem, A. Córdova, Angew. Chem. Int. Ed., 2006, 45, 1952-1956.
A bipyridine-ligated nickel mediates the addition of functionalized aryl halides, a vinyl halide, and a vinyl triflate to epoxides under reducing conditions. For terminal epoxides, the regioselectivity of the reaction depends upon the cocatalyst employed. Iodide cocatalysis results in opening at the less hindered position via an iodohydrin intermediate. Titanocene cocatalysis results in opening at the more hindered position.
Y. Zhao, D. J. Weix, J. Am. Chem. Soc., 2014, 136, 48-51.
An enantioselective α-arylation of aldehydes has been accomplished using diaryliodonium salts and a combination of copper and organic catalysts. These mild catalytic conditions allow the enantioselective construction and retention of enolizable α-formyl benzylic stereocenters, a valuable synthon for the production of medicinal agents.
A. E. Allen, D. W. C. MacMillan, J. Am. Chem. Soc., 2011, 133, 4260-4263.
A one-pot alkylation-silylation reaction of various epoxides with R3Al-R'3SiOTf occurs stereospecifically to give the corresponding alkylation-silylation products in excellent yields.
P. Shanmugam, M. Miyashita, Org. Lett., 2003, 3265-3268.
In a rhenium-catalyzed oxyalkylation of alkenes, hypervalent iodine(III) reagents derived from widely occurring aliphatic carboxylic acids were not only an oxygenation source but also an alkylation source via decarboxylation. The reaction offers a wide substrate scope, totally regiospecific difunctionalization, mild reaction conditions, and ready availability of both substrates.
Y. Wang, L. Zhang, Y. Yang, P. Zhang, Z. Du, C. Wang, J. Am. Chem. Soc., 2013, 135, 18048-18051.
The reaction of dianions, derived from the reductive opening of phthalan (n=1) or isochroman (n=2) with lithium and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB) at 0°C, with several epoxides gave 1,6- and 1,7-diols, respectively.
M. Yus, T. Soler, F. Foubelo, Tetrahedron, 2002, 58, 7009-7016.