Stereoselective Construction of Complex Spirooxindoles via Bisthiourea Catalyzed Three-Component Reactions

A well-designed three-component reaction was developed to construct a class of optically active carbazolespirooxindole-urazoles in good yields with excellent stereoselectivities via tandem Diels-Alder reaction and ene-reaction. The driving force originating from aromatization with in situ generated carbazolespirooxindole and the high reactivity of 4-phenyl-3H-1,2,4-triazole-3,5-dione facilitate the ene-reaction in mild conditions. Control experiments indicated that the excellent stereoselectivities of ene-reaction most likely came from the spatial configuration of the carbazolespirooxindole. The obtained products could be converted to other synthetic useful structures via diverse functionalization.