highly stereoselective de-Bruyn–Ekenstein rearrangement/aldol condensation/intramolecular oxa-Michael cascade reaction of unprotected ketoses with ketones was elaborated. By the utilization of this new and operationally simple methodology an access to β-C-glycosides is given. Extremely matched and mismatched cases were observed by using with natural or unnatural proline in these cascade reactions.
six heteroaromatic compounds, ethyl-/methyl- and dimethylfuranones, thiophenones, and cyclopentenones, was synthesized and condensed with a methyl methylpropionate substituted pyrrole, yielding the “right” half of open-chain tetrapyrroles. These compounds serve as light-inducible chromophores in the plant photoreceptor phytochrome. Three-dimensional structure analysis of the 10-oxapyrromethen-1-one