in dichloromethane; toluene T=-50°C;

<b>Multi-step reaction with 2 steps<br /> </b>1: 90 percent / triethylamine / toluene / 0.5 h / 0 &deg;C<br />2: ozone / toluene; CH₂Cl₂ / -78 &deg;C<br /> <br /> &nbsp;