Application of Dess-Martin reagent in synthesis of key intermediate of Ocotillol type saponin derivative

The invention provides an application of a Dess-Martin reagent in synthesis of a key intermediate of an Ocotillol type saponin derivative. The application method includes: (1) performing a reaction on(20S,24R/24S)-epoxydammarane -3beta,12beta,25-triol (shown in the formula 1-R or 1-S) and the Dess-Martin reagent according to the molar ratio of 1:1-1.2 to generate the (20S,24R/24S)-epoxy-25-hydroxyl-3beta-dammarane-3-ketone shown as the corresponding formula (2-R) or a formula (2-S); and (2) performing a reaction on the (20S,24R/24S)-epoxy dammarane-3beta,12beta,25-triol shown as a formula (1-R) or a formula (1-S) reacts with the Dess-Martin reagent according to the mass ratio of 1:(2-3) to prepare the corresponding (20S,24R/24S)-epoxy-25-hydroxy-dammarane-3,12-dione shown as a formula (3). According to the method, DMP is adopted as an oxidizing agent, post-treatment is convenient, selectivity is high, the yield is good, the yield of a single oxidation product reaches 96% under the condition of low dosage, and