Unsymmetrical ozonolysis of carbohydrate derived norbornene systems

Oxidative Functionalization of Trinor-18α-olean-17(22)-ene Derivatives. Annulation of the E-Ring by an Intramolecular Aldol Reaction

cis-Dihydroxylation of trinor-18α-olean-17(22)-ene 2 with osmium tetroxide led to diol 9. Its cleavage with lead tetraacetate gave tetracyclic ketoaldehyde 10. By comparison, the ozonation of trinor-18α-olean-17(22)-ene 2 in the presence of p-toluenesulfonic acid gave the corresponding ketoacetal 12. Both products were subjected to an intramolecular aldol reaction under the acidic conditions and yielded unusual triterpenes bearing a bicyclo[4.3.1]decane fragment (22). Further manipulation of the protective groups afforded compounds useful in triterpene synthesis, especially in the preparation of potentially biologically active saponins based on a tetracyclic terpene core.

A Survey of Recent Synthetic Applications of 2,3-Dideoxy-Hex-2-enopyranosides

Unsaturated carbohydrate derivatives are useful intermediates in synthetic transformations leading to a variety of compounds. The aim of this review is to highlight the rich chemistry of ∆-2,3 unsaturated pyranosides, emphasizing the variety of transformations that have been carried out in these substrates during the last decade.

End-group differentiating ozonolysis of furocoumarins

Ozonolysis of furocoumarins followed by reductive work-up yields not only common symmetrical dialdehydes, but also o-formylumbelliferones with moderate-to-high yields.