title: Asymmetric, Three-Component, One-Pot Synthesis of Spiropyrazolones and 2,5-Chromenediones from Aldol Condensation/NHC-Catalyzed Annulation Reactions.
abstract: A novel one-pot, three-component diastereo- and enantioselective synthesis of spiropyrazolones has been developed involving the aldol condensation of an enal to generate α,β-unsaturated pyrazolones, which react with a second equivalent of enal through an N-heterocyclic carbene (NHC)-catalyzed [3+2] annulation. The desired spirocyclopentane pyrazolones are obtained in moderate to good yields and good to excellent stereoselectivities. Alternatively, starting from cyclic 1,3-diketones, 2,5-chromenediones are available through [2+4] annulation.
authors: Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany.
authors: Lei
authors: L
authors: Wang
authors: Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany.
authors: Sun
authors: S
authors: Li
authors: Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany.
authors: Pankaj
authors: P
authors: Chauhan
authors: Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany.
authors: Daniel
authors: D
authors: Hack
authors: Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany.
authors: Arne R
authors: AR
authors: Philipps
authors: Department of Chemistry, Nanoscience Center, University of Jyvaskyla, 40014, JYU, Finland.
authors: Rakesh
authors: R
authors: Puttreddy
authors: Department of Chemistry, Nanoscience Center, University of Jyvaskyla, 40014, JYU, Finland.
authors: Kari
authors: K
authors: Rissanen
authors: Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany.
authors: Gerhard
authors: G
authors: Raabe
authors: Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany. enders@rwth-aachen.de.
authors: Dieter
authors: D
authors: Enders
keywords: N-heterocyclic carbene; asymmetric synthesis; chromenedione; multicomponent reaction; spiropyrazolone