885912-22-1Relevant articles and documents
Highly chemoselective reduction of amides (primary, secondary, tertiary) to alcohols using SmI2/amine/H2O under mild conditions
Szostak, Michal,Spain, Malcolm,Eberhart, Andrew J.,Procter, David J.
, p. 2268 - 2271 (2014)
Highly chemoselective direct reduction of primary, secondary, and tertiary amides to alcohols using SmI2/amine/H2O is reported. The reaction proceeds with C-N bond cleavage in the carbinolamine intermediate, shows excellent functional group tolerance, and delivers the alcohol products in very high yields. The expected C-O cleavage products are not formed under the reaction conditions. The observed reactivity is opposite to the electrophilicity of polar carbonyl groups resulting from the nX → πC=O (X = O, N) conjugation. Mechanistic studies suggest that coordination of Sm to the carbonyl and then to Lewis basic nitrogen in the tetrahedral intermediate facilitate electron transfer and control the selectivity of the C-N/C-O cleavage. Notably, the method provides direct access to acyl-type radicals from unactivated amides under mild electron transfer conditions.
Palladium-catalyzed selective hydrogenolysis of N-alkyl(aryl)-substituted γ-keto amides as an approach to γ-lactams or linear amides
Turova,Berezhnaya,Starodubtseva,Vinogradov
, p. 1065 - 1068 (2016/02/09)
A palladium-catalyzed hydrogenolysis of N-substituted γ-keto amides can proceed with participation of tautomeric 5-hydroxypyrrolidin-2-ones and give either pyrrolidin-2-ones, or linear amides, or their mixtures, depending on the substrate structure.
Mechanism of SmI2/amine/H2O-promoted chemoselective reductions of carboxylic acid derivatives (esters, acids, and amides) to alcohols
Szostak, Michal,Spain, Malcolm,Eberhart, Andrew J.,Procter, David J.
, p. 11988 - 12003 (2015/01/16)
Samarium(II) iodide-water-amine reagents have emerged as some of the most powerful reagents (E° = -2.8 V) for the reduction of unactivated carboxylic acid derivatives to primary alcohols under single electron transfer conditions, a transformation that had been considered to lie outside the scope of the classic SmI2 reductant for more than 30 years. In this article, we present a detailed mechanistic investigation of the reduction of unactivated esters, carboxylic acids, and amides using SmI2-water-amine reagents, in which we compare the reactivity of three functional groups. The mechanism has been studied using the following: (i) kinetic, (ii) reactivity, (iii) radical clock, and (iv) isotopic labeling experiments. The kinetic data indicate that for the three functional groups all reaction components (SmI2, amine, water) are involved in the rate equation and that the rate of electron transfer is facilitated by base assisted deprotonation of water. Notably, the mechanistic details presented herein indicate that complexation between SmI2, water, and amines can result in a new class of structurally diverse, thermodynamically powerful reductants for efficient electron transfer to a variety of carboxylic acid derivatives. These observations will have important implications for the design and optimization of new processes involving Sm(II)-reduction of ketyl radicals. (Chemical Equation Presented).
