Nickel-catalyzed [4+2] cycloaddition of Enones with Alkynes

Presented by: Hee Ling PungA0093766A

Outline

• Introduction• Synthesis of metal-catalyzed [4+2]

cycloaddition• Discussion• Conclusion

Introduction• Enone: unsaturated

chemical compound or functional group consisting of a conjugated system of an alkene and ketone.

• Alkyne: hydrocarbons that have a triple bond between two carbon atom.

Introduction• In this study, enones act as a nucleophile and

alkynes (heterodienophiles) act as an electrophile.

• The cycloaddition would proceed via heterometallacycle intermediates, which formed by oxidative cyclization of low valent transition metals to ,-unsaturated carbonyl compounds , and subsequent insertion of alkynes.

Introduction

The reaction between Enone 1 and Alkyne 2 using nickel(0) catalyst to form polysubstituted pyranes 3

Synthesis of metal-catalyzed [4+2] cycloaddition

Discussion

Discussion

Discussion

Discussion

RL RS

Conclusion

• A new nickel-catalyzed [4+2 ] cycloaddition of enones with alkynes to provide polysubstituted pyrans was developed.

• Enones are susceptible to oxidative cyclization of nickel(0)

• This reaction allow inter or intramolecular cycloaddition with alkynes.