Osmium Catalyst for the Borrowing Hydrogen Methodology: α-Alkylation of Arylacetonitriles and Methyl Ketones

Abstract

Complex [Os(η 6 -p-cymene)(OH)(IPr)]OTf is an efficient catalyst precursor for the α-alkylation of arylacetonitriles and methyl ketones with alcohols, which works with turnover frequencies between 675 and 176 h −1 for nitriles and between 194 and 28 h −1 for ketones.

Base‐Promoted α‐Alkylation of Arylacetonitriles with Alcohols

“…[3] In last decade, following the hydrogen borrowing methodology transition metal catalysed severalC ÀCa nd CÀNb ond forming reactions were explored. [4] Inspired by this protocol, synthesis of alkylated nitrile by replacing the alkyl halidesw ith alcohols as greener alkylat-ing agentsw as explored by various groups using different precious Ir, [5] Ru, [6] Rh, [7] Pd [8] and Os [9] metal based complexes (Scheme 1). Recently Mn catalysed a-olefination and a-alkylation of nitriles using primary alcohols were described by Milstein et al and Maji et al respectively.…”

Iron‐Catalyzed Alkylation of Nitriles with Alcohols

“…Thus, unprotected indole‐ ( 9 a – 9 d ), furan‐ ( 9 e ) and pyridine‐bearing alcohols ( 9 f – 9 i ) all proved to be viable. These substrates are problematic even for some noble‐metal catalysts …”

Atmosphere‐Controlled Chemoselectivity: Rhodium‐Catalyzed Alkylation and Olefination of Alkylnitriles with Alcohols

“…Nitriles are useful buildingb locks in organic synthesis. [8] With watera st he only by-product,t he alkylation of alkylnitriles with alcohols through hydrogen borrowing provides a" green" route for the synthesis of new nitrile compounds.T ransition-metal catalysts, including Ru, [3,9] Os, [10] Ir, [11] Rh, [12] and Pd, [13] have been employed for this reaction. The olefination of alkylnitriles with alcohols could afford a,b-unsaturated nitriles, which are also valuable intermediates in organic synthesis.…”