Different levers were tested to achieve higher yields and selectivity for this carbonylation. Applying a higher temperature was counterproductive, and reduced the catalytic activity of the carbonylation (see S.I., section 2.1). In our previous study, 12 the addition of H2 in the gas phase favoured the carbonylation of AA to SA, so catalytic experiments were also run with syngas in the best performing solvents (Table ). Gratifyingly, under a pressure of 50 bar of CO/H2 (90:10), after 6 h of heating at 90 °C, an excellent yield of SA was obtained in MeCN (91%, Table , entry 1), and even a quantitative yield was measured in acetone (Table , entry 2). In acetone, lowering the total pressure from 50 to 15 bar reduced the selectivity to 77% (Table , entry 3).