Synthesis of β-Cyanohydrins
Cooperative catalysis of a cationic Ru complex, DBU, and NaPF6 enabled activation of acetonitrile as a nucleophile under mild basic conditions. The nucleophilic 1,2-addition of in situ-generated, Ru-bound, metalated nitrile to aldehydes and imines proceeded smoothly.
N. Kumagai, S. Matsunaga, M. Shibasaki, J. Am. Chem. Soc., 2004, 126, 13632-13633.
α-Alkylated (dimethylsilyl)acetonitriles react spontaneously with aldehydes in DMSO to give β-hydroxynitriles in very good yields. The addition to ketones is effectively promoted by using MgCl2 or CaCl2. (Dimethylsilyl)acetonitrile, which shows lower reactivity, adds efficiently to aldehydes and ketones under catalysis by AcOLi or MgCl2.
T. Jinzaki, M. Arakawa, H. Kinoshita, J. Ichikawa, K. Miura, Org. Lett., 2013, 15, 3750-3753.
In the presence of SiCl4 and a catalytic amount of a chiral phosphoramide, silyl ketene imines undergo extremely rapid and high yielding addition to a wide variety of aromatic aldehydes with excellent diastereo- and enantioselectivity. The nitrile function serves as a useful precursor for further synthetic manipulation.
S. E. Denmark, T. W. Wilson, M. T. Burk, J. R. Heemstra, Jr., J. Am. Chem. Soc., 2007, 129, 14864-14865.
An iridium-catalyzed, chemoselective, asymmetric transfer hydrogenation of α-substituted acetophenones using formic acid as reductant can be performed in water and open to air.
O. Soltani, M. A. Ariger, H. Vázquez-Villa, E. M. Carreira, Org. Lett., 2010, 12, 2893-2895.
(R)-β-Hydroxy nitriles were obtained via a reduction catalyzed by a recombinant carbonyl reductase with excellent optical purity and were further converted to (R)-β-hydroxy carboxylic acids via a nitrilase-catalyzed hydrolysis. The present study allows ready access to both chiral β-hydroxy nitriles and β-hydroxy carboxylic acids of pharmaceutical importance.
D. Zhu, H. Ankati, C. Mukherjee, Y. Yang, E. R. Biehl, L. Hua, Org. Lett., 2007, 9, 2561-2563.