Diastereoselective concise syntheses of the polyhydroxylated alkaloids DMDP and DAB

作者：Bouillon Marc E^*; Pyne Stephen G

来源：Tetrahedron Letters, 2014, 55(2): 475-478.

DOI：10.1016/j.tetlet.2013.11.068

• Polyhydroxylated alkaloids
• Iminosugars
• Petasis reaction
• 2,5-Dideoxy-2,5-imino-D-mannitol
• 1,4-Dideoxy-1,4-imino-D-arabinitol

A diastereoselective concise synthesis of the iminosugars DMDP and DAB is presented starting from L-xylose and affording the two alkaloids in good yields of 35% and 22% over seven and eight steps, respectively. The Petasis borono-Mannich reaction of 3,5-di-O-benzyl-L-xylofuranose with benzylamine and (E)-styrylboronic acid served as the nitrogen-introducing key step furnishing the new C-N bond in an entirely diastereoselective manner. A chemo- and regioselective O-mesylation followed by an intramolecular S(N)2-cyclisation allowed the formation of the pyrrolidine ring. Ozonolysis of the styryl double bond and subsequent reduction to form the C-5 hydroxymethyl substituent followed by hydrogenolysis of the benzyl protecting groups concluded the DMDP synthesis. Furthermore, an unexpected fragmentation process during the ozonolysis reaction also gave access to the C-5 decarbinolated DMDP derivative DAB.

• 出版日期2014-1-8