General steps:
1. In a dry reaction flask, 2-methyl-5-nitrobenzyl alcohol (20 mmol) was dissolved in dichloromethane (DCM, 100 mL).
2. Pyridinium chlorochromate (PCC, 28-40 mmol) was added to the above solution.
3. The reaction mixture was heated to reflux (oil bath temperature was maintained at 55 °C) and the reaction lasted for 1-4 hours.
4. The progress of the reaction was monitored by thin layer chromatography (TLC) and/or liquid chromatography-mass spectrometry (LCMS) during the reaction.
5. Upon completion of the reaction, the mixture was cooled to room temperature.
6. post-processing, including isolation and purification of the product, is carried out according to the method described in variant B.
