Phosphine-Catalyzed [2 + 4] Annulation of Allenoates with Thiazolone-Derived Alkenes: Synthesis of Functionalized 6,7-Dihydro‑5H‑pyrano­[2,3‑d]thiazoles

Phosphine-catalyzed [2 + 4] annulation of allenoates with thiazolone-derived alkenes has been achieved under mild conditions, giving biologically important 6,7-dihydro-5H-pyrano­[2,3-d]­thiazole derivatives in high to excellent yields. With the use of Kwon’s phosphine as the chiral catalyst, optically active products were obtained in good yields with excellent enantioselectivities.