Construction Of 2-Vinyl 2-cyclopentenones By Sulfa-Michael Addition Initiated Tandem Sequence

Sulfa-Michael addition(SMA)is among the most efficient methods for the formation of C–S bonds,in which a diversity of organosulfur compounds can be prepared,and found wide application in both biological and synthetic processes.Among them,SMA-triggered intramolecular aldol sequence represents one type of practical and efficient approach to assemble complex functionalized organosulfur compounds.By virtue of the installation of a highly reactive carbonyl group,a range of organosulfur compounds bearing cyclic structural frameworks can be accessed in an intramolecular mannerDue to the structural diversity of organosulfur compounds in nature and various biological systems,the development of efficient approaches by the inclusion of less reactive carbonyl groups of esters or amides in a SMA triggered process,to access structurally diverse cyclic frameworks is still attractive.O-substituted cyanohydrins are valuable synthetic building blocks in organic synthesis and could undergo diverse transformations.On the other hand,O-substituted groups of cyanohydrins could participate in subsequent transformations as indispensable synthetic components to construct molecular frameworks.A part of our ongoing interest in the development of efficient metal-free processes to construct diverse cyclic frameworks by utilizing O-substituted cyanohydrins as valuable synthetic building blocks.The vinylated cyclopentene moiety is frequently found in natural products,and valuable building block in organic synthesis.This thesis mainly includes the following aspects:1.We have developed a SMA triggered one-pot tandem sequence to prepare highly substituted 2-vinyl 2-cyclopentenone derivatives.Under mild reaction conditions,various O-unsaturated acyl-substituted allylic cyanohydrins could undergo this SMA triggered intramolecular aldol sequence,followed by a DBU-catalyzed intramolecular Aldol reaction and the dehydroxylation provided a diverse range of functionalized vinylated cyclopentenones.2.O-3-methylcrotonoyol protected allylic cyanohydrin can undergo previously developed Lewis base-promoted intramolecular acylcyanation reaction to afford diketone which atom utilization is 100 %.The 1,4-diketone can be readily transformed into cyano substituted 2-vinyl 2-cyclopentenone in the presence of small molecular organic catalyst.