Exploration of a Novel, Enamine-Solid-Base Catalyzed Aldol Condensation with C-Glycosidic Pyranoses and Furanoses

A variety of unprotected C-glycosidic ketones were employed in a novel enamine-solid-base catalyzed (ESBC) aldol condensation to expand the scope and scalability of a previously reported reaction. The starting ketones were obtained from unprotected pyranoses and furanoses following Lubineau's method via a Knoevenagel condensation. The aldol condensation reaction of the C-glycosidic ketones was performed with a nontoxic and abundant amino acid, L-proline, along with magnesium oxide (MgO) as a recyclable and sustainable catalyst. The enamine-solid-base catalyzed aldol condensations provided the corresponding (E)-α,β-unsaturated ketones in excellent isolated yields (91–100%).