oxalyl dichloride in benzene 2 h; Ambient temperature;

1.1: oxalyl dichloride / 15 h / 20 °C 2.1: thien-2-yl-lithium; copper(l) iodide / tetrahydrofuran / 0.33 h / -40 - -30 °C / |Inert atmosphere 2.2: 4 h / -40 - 20 °C / |Inert atmosphere 3.1: (R)-tetrahydro-1-methyl-3,3-diphenyl-1H,3H-pyrrolo[1,2-c]-[1,3,2]oxazaborole; borane dimethyl sulfide complex / tetrahydrofuran; toluene / 11 h / 0 - 20 °C 4.1: dipotassium hydrogenphosphate; 3-chloro-benzenecarboperoxoic acid / tetrahydrofuran / 2 h / 20 °C 5.1: potassium hydroxide / 5 h / 20 °C View Scheme

With  lithium aluminium tetrahydride