Counterintuitive chemoselectivity in the reduction of carbonyl compounds

Chemoselective Hydrogenolysis of Urethanes to Formamides and Alcohols in the Presence of More Electrophilic Carbonyl Compounds

“…However, the chemoselective transformation of the less reactive carbonyl compounds against the generally accepted reactivity order remains an inherent issue in stateof-the-art organic synthesis. [42][43][44] Indeed, the tolerance of more electrophilic carbonyl compounds, such as esters and amides, has never been achieved in the hydrogenolysis of urethanes; furthermore, this is believed to be unfeasible. 22,[29][30][31][32][33][34][35][36][37][38] The polyurethane degradation methods using nucleophilic reagents (Scheme 1A) also face the obstacle of chemoselective urethanes degradation because of the facile nucleophilic substitution of esters and amides compared to urethane.…”

“…Under the reaction conditions, ester and amide functionalities were well tolerated; therefore, the Ir catalyst placed urethane above ester and amide in the reactivity order, in sharp contrast to the generally accepted reactivity order of carbonyl compounds. 40,41,44 a Reaction conditions: Urethane 1aa (0.5 mmol), Ir catalyst 6 (1 mol%), CsOt-Bu (3.3 mol%), and H2 (1 MPa) in toluene (3 mL) at 130 °C for 18 h. Conversion and yields were determined by 1 H NMR using dibromomethane as an internal standard. b Selectivity = yield of 2a / conversion of 1aa × 100 (%).…”