Diethylsilane
Recent Literature
Reduction of secondary amides to imines and secondary amines has been achieved
using low catalyst loadings of readily available iridium catalysts such as
[Ir(COE)2Cl]2 with diethylsilane as reductant. The
stepwise reduction to secondary amine proceeds through an imine intermediate
that can be isolated when only 2 equiv of silane is used. This system shows high
efficiency and an appreciable level of functional group tolerance.
C. Cheng, M. Brookhart, J. Am. Chem. Soc., 2012,
134, 11304-11307.
Silylative reduction of nitriles under transition metal-free conditions converts
alkyl and (hetero)aryl nitriles efficiently to primary amines under mild
conditions. The use of sterically bulky silanes enabled a partial reduction
leading to N-silylimines.
N. Gandhamsetty, J. Jeong, Y. Park, S. Park, S. Chang, J. Org. Chem.,
2015,
80, 7281-7287.
In an operationally convenient, mechanistically unique protocol, Lewis base
activation of silyl acetals generates putative pentacoordinate silicate acetals,
which fragment into aldehydes, silanes, and alkoxides in situ. Subsequent
deprotonative metalation of phosphonate esters followed by HWE with aldehydes
furnishes enoates.
U. S. Dakarapu, A. Bokka, P. Asgari, G. Trog, Y. Hua, H. H. Nguyen, N. Rahman,
J. Jeon, Org. Lett.,
2015,
17, 5792-5795.
After an iridium-catalyzed reduction of secondary amides, the resulting
imines can undergo the Strecker reaction, the Mannich reaction, allylation, and
[3 + 2]-cycloaddition. The method shows high chemoselectivity in the presence of
other functional groups such as methyl ester.
Y. Takahashi, R. Yoshii, T. Sato, N. Chida, Org. Lett.,
2018, 20, 5705-5708.
B(C6F5) enables a metal-free hydrogenative reduction of
substituted N-heteroaromatics using hydrosilanes as reducing agents. The
optimized conditions were successfully applied to quinolines, quinoxalines, and
quinoline N-oxides. The initial step in the catalytic cycle involves
1,4-addition of the hydrosilane to the quinoline to give a 1,4-dihydroquinoline
followed by (transfer) hydrogenation to deliver the tetrahydroquinoline.
N. Gandhamsetty, S. Park, S. Chang,
Synlett, 2017, 28, 2396-2400.
