Total Synthesis Of Natural Product Siphonazole And Stereocalpin A

Retro synthetic analysis and study on Chemicals synthesis of natural product Siphonazole and Stereocalpin A, which were described in this paper,.The synthesis route of Siphonazole start with L-Thr-OMe·HCl and Dichlorocyanogen to obtain Oxadiazoline intermediate under the Catalytic of sodium methoxide. The compound 1.4 were prepared through the processing of elimination reactions,acid catalysis and substitution reactions. Then, Wittig reagent was synthesis from compound 1.4 and triphenyl phosphine, then compound 1.7 was obtain from TBS-vanillin and Wittig reagent under the Wittig-Schlosser reactions in the over yield 44%. Aldehyde was obtained after compound 1.7 Oxidation Reactions , and mixted with the compound 1.4 to form C-C bond via Reformatsky reactions. The product was hydrolysis and coupling with compound 1.14 assisted by the coupling reagents BOP-Cl. After removing the TBS protecting group to afford the natural product of Siphonazole in an over yield 8%.The important compound 2.5 and 2.10 of the Stereocalpin A were completed. The coupling with each other and ring closure was in working progress. The synthesis route of the compound 2.5 start with D-Phe via Reduction reactins( NaBH₄/I₂ ) and cyclization with triphosgene under the alkaline condition to afford Evans chiral auxiliary.Then through condensation reactions,Alkylation reactions in the over yield 31%. The other compound 2.10 was beginning with L-Phe-O^tBu. It reduction by NaBH₄ after L-Phe-O^tBu formation imine with benzaldehyde and formaldehyde, and followed by removing of the Bn group with catalytichydro genolysis , then coupling with Cbz -L-Phe via BOP-Cl in the over yield 59%.