APPLICATIONS OF PHOSPHINE CATALYSIS IN ENANTIOSELECTIVE ANNULATIONS OF ALKYNE DERIVATIVES

Abstract

PHOSPHINE-CATALYZED ANNULATIONS FORM THE PIONEER STUDY OF ORGANOCATALYZED ENANTIOSELECTIVE TRANSFORMATIONS AND HAVE DEMONSTRATED EXCELLENT REACTIVITY AND SELECTIVITY IN MANY EXAMPLES. HIGHLY FUNCTIONALIZED CYCLOPENTENE SCAFFOLD IS AN IMPORTANT FEATURE IN NATURAL PRODUCTS AND BIOLOGICALLY ACTIVE MOLECULES; THE ACHIEVEMENT OF SUCH SCAFFOLD IS A DRIVING FORCE FOR THE EXTENSIVE EXPLORATION OF ORGANOCATALYTIC SYSTEMS.CHIRAL AMINO ACID-BASED PHOSPHINE CATALYSTS ARE EMPLOYED TO INVESTIGATE THEIR CATALYTIC CAPABILITY FOR ENANTIOSELECTIVE ANNULATION OF ALKYNES. ALKYNES ARE MORE STABLE THAN ALLENES AND REPRESENT A CLASS OF VERSATILE BUILDING BLOCKS. TWO HIGHLY ENANTIOSELECTIVE PHOSPHINE-CATALYZED [3+2] ANNULATIONS OF INTERNAL UNACTIVATED ALKYNES WITH ELECTRON-DEFICIENT OLEFINS SUCH AS <FONT FACE="SYMBOL">A</FONT>,<FONT FACE="SYMBOL">B</FONT>-UNSATURATED KETONE ESTERS AND ARYLIDENEOXINDOLES ARE ACHIEVED, FORMING FUNCTIONALIZED CYCLOPENTENE SCAFFOLDS IN GOOD TO EXCELLENT REGIO- AND ENANTIOSELECTIV