Synthesis of the caloporoside glycon and a new fluorous protocol for dehydrogenation of carbonyl compounds.

摘要

Part A of this thesis is concerned with application of a new method discovered by this research group for attaining the beta-mannosidic linkage of saccharides. A highly convergent synthesis of the isopropyl ester of the unusual beta-mannopyranosyl-(1 → 5)-D-mannonate portion of caloporoside, a biologically interesting fungal metabolite, is described as an application of this new synthetic method. The key beta-mannosidic linkage is achieved directly, stereoselectively and in good yield, through reaction of the mannosyl sulfoxide as the mannosyl donor with an isopropyl-opened mannoside as acceptor; the coupling is mediated by triflic anhydride. This direct approach is the most convergent and efficient synthesis to date of the caloporoside glycon.;Part B of this thesis describes a novel methodology toward alpha,beta-unsaturated carbonyl compounds. This method involves introduction of a recoverable, fluorous organo-selenium appendage adjacent to a carbonyl group with oxidative elimination and subsequent recovery of the fluorous selenium ligand using bi-(or multi-) phase extraction into a highly fluorous solvent.