Organocatalyzed Enantioselective Direct Mannich Reaction of α‑Styrylacetates

An organocatalyzed direct Mannich reaction of unactivated α-styrylacetates was realized for the first time. By using a quinidine-derived C6′-urea catalyst, the direct Mannich reaction of α-styrylacetates and N-tosylimines gave the desired β-amino esters in high yields, diastereoselectivities, and ee values. The reaction provides a highly stereoselective (up to 96:4 dr and 97% ee) and the most straightforward synthesis of functionalized N-tosylated β-amino esters. The products can be used as precursors for the highly selective synthesis of tetrahydrofuran derivatives.