Cascade Reactions Of 2-(1-alkynyl)-2-en-1-ones With Bis-nucleophiles

Cascade reactions are one of the hot topics in modern organic synthesis due to their operational simplicity,step efficiency,atom economy,and product complexity.2-(1-Alkynyl)-2-alken-l-ones,bearing one C-C triple bond,one C-C double bond,and one C-O double bond in the same molecule,recently have emerged as a versatile substrate for novel cascade reaction design and complex molecule preparation.In this thesis,we mainly investigate the cascade reactions between 2-(1-alkynyl)-2-en-l-ones and bis-nucleophiles via transition-metal catalysis or organocatalysis to afford polycyclic compounds in a stereoselective manner.There are three chapters in this thesis:In chapter 1 we first briefly introduce cascade reactions and the reactivities of 2-(1-alkynyl)-2-alken-1-ones,then intensively describe two major reaction modes of 2-(1-alkynyl)-2-en-1-ones and their reactions to provide various products.In chapter 2 we have investigated a novel silver trifluoroacetate catalyzed cascade reaction of 2-(1-alkynyl)-2-alken-1-ones with 2-naphthols to furnish a series of 1,2-dihydronaphtho[2,1-b]furans with moderate to good yields.Controlled experiments reveal that the key step is the oxygen participated oxidative ring-opening reaction.Additional gram-scale preparation and chirality induction reactions demonstrate the potential for industrial application and asymmetric synthesis of chiral 1,2-dihydronaphtho[2,1-b]furans.In chapter 3 we have explored a quinine-derived thiourea bifunctional catalyst promoted asymmetric cascade reaction of 2-(1-alkynyl)-2-alken-1-ones with 3-aminobenzofurans to deliver a variety of polycyclic 1,4-dihydropyridines with moderate to good yields and excellent enantioselectivities.Further scale up reaction and derivatization of the products show good practicality and applicability.