Total Synthsis Of Natural Products Cryptopyranmoscatone B2 And Ascospiroketals Based On Carbohydrates

Tetrahydropyran compounds are the core skeleton of many natural products and active drug molecules.Because of their good biological activities,such as cytotoxicity,anti proliferative activity and cyclooxygenase activity,they have attracted extensive attention of researchers.The thesis is separated into three parts:In Chapter 1,we mainly summarized the one pot reaction related to olefin metathesis including the classification and application of related reaction types.In Chapter 2,we introduced the convergent total synthesis of cryptopyranomoscatone B2 using D-ribose as chiral source.During our work,we took the commercially available carbohydrate 2,3-o-isopropylidene-d-ribose as raw material and completed the simple and efficient total synthesis of cryptopyranmoscatone B2 in 8 steps,with an overall yield of 14.9%.The key step of our synthesis is the one pot reaction of olefin cross metathesis double bond migration intramolecular o-michael addition,which could quickly construct 2,6-disubstituted tetrahydropyran units.Moreover,all the spectroscopic and specific rotation data of our synthetic cryptopyranmoscatone B2 were in good agreement with those of the natural product.In Chapter 3,we introduced the study on the convergent total synthesis of ascospiroketals family a and B using D-Glucolactone as chiral source.The total synthesis of ascospiroketal B was completed in 10 steps with D-Glucolactone as raw material,and the total yield was 2.3%.Using the key method of Wacker oxidation combined with Lewis acid catalytic ring closing,we obtained the skeleton of 5,5-spiro ketal.Furthermore,all the spectroscopic and specific rotation data of our synthetic ascospiroketal B agreed well with those of the natural product.