Selective Reduction of Carboxylic Acid Derivatives by Catalytic Hydrosilylation

Abstract

In the last decade, an increasing number of useful catalytic reductions of carboxylic acid derivatives with hydrosilanes have been developed. Notably, the combination of an appropriate silane and catalyst enables unprecedented chemoselectivity that is not possible with traditional organometallic hydrides or hydrogenation catalysts. For example, amides and esters can be reduced preferentially in the presence of ketones or even aldehydes. We believe that catalytic hydrosilylations will be used more often in the future in challenging organic syntheses, as the reaction procedures are straightforward, and the reactivity of the silane can be fine-tuned. So far, the synthetic potential of these processes has clearly been underestimated. They even hold promise for industrial applications, as inexpensive and readily available silanes, such as polymethylhydrosiloxane, offer useful possibilities on a larger scale.

Ethers from esters; from exceptional transformation to synthetic method

“…Along the route (a) in the first step borane is coordinated to the sp 3 O-atom, followed by the transfer of the hydride ion to the carbonyl C-atom, elimination of alkoxyborane accompanied by intermediary formation of aldehyde, which in the fast step is reduced to alcohol. On the route (b) borane is in the first step coordinated to carbonyl sp 2 Oatom, then on transfer of hydride ion the best leaving group became oxoborane. In the last and fast step oxonium ion is reduced to ether.…”

“…2 Selectivity is referred to chemo-selectivity in the presence of other reducible functionalities such as aldehydes, ketones, imines, nitriles, nitro compounds, and multiple C-C bonds. In another mini-review recent developments in the homogeneous hydrogenation of carboxylic acid esters were highlighted.…”

Efficient Transition Metal-Catalyzed Reactions of Carboxylic Acid Derivatives with Hydrosilanes and Hydrosiloxanes, Afforded by Catalyst Design and the Proximity Effect of Two Si–H Groups

“…9 However, notable papers were reported by Buchwald, 10 Cutler, 11 Mimoun,12 Ito, 13a Fuchikami,13b,c and Ohta,13d until the early 2000s, which included reduction by titanium alkoxides, 10 manganese carbonyls, 11 zinc compounds, 12 rhodium, and other late transition metals. 13,14 Molybdenum- 15 and copper 16 -catalyzed reactions also appeared later.…”

Catalytic synthesis of silyl formates with 1 atm of CO2 and their utilization for synthesis of formyl compounds and formic acid

“…Hydrosilanes are readily available, easy-to-handle, nontoxic, and inexpensive reducing agents [12,13], and the reduction of CO 2 with hydrosilanes to produce silyl formates [14][15][16][17][18][19][20][21], formaldehyde [22], methoxysilanes [23][24][25], and methane [26,27] is thermodynamically favorable. In particular, methoxysilanes [23][24][25] and methane [26] have been obtained in 1 atm of CO 2 .…”