Phosphine-Catalyzed (3 + 2) Annulation of δ-Acetoxy Allenoates with 2-Sulfonamidomalonate: Synthesis of Highly Substituted 3-Pyrrolines and Mechanistic Insight
摘要:
A mild and efficient synthetic protocol for 3-pyrrolines via the phosphine-catalyzed (3 + 2) annulation of (delta-acetoxy allenoates with 2-sulfonamidomalonate is reported. The asymmetric version (up to 83% ee) is also achieved by using phosphine (R)-SITCP as the catalyst. Mechanistic experiments disclose that the involved deprotonation of amide N-H and aza-addition to vinyl phosphonium might proceed in a concerted manner.
Structurally Divergent Synthesis of Azetidines, 5,6‐Dihydro‐1,3‐oxazines and 2,3‐Dihydro‐1,4‐oxazines through Palladium‐Catalyzed Tandem Allylic Substitution Reaction
A regiodivergent synthesis of azetidines, 5,6-dihydro-1,3-oxazines and 2,3-dihydro-1,4-oxazines has been achieved through palladium-catalyzed tandem allylicsubstitution reaction. This protocol provides a variety of heterocycles in satisfactory yields with good to excellent regioselectivities under mild reaction conditions.