0000000000726928
AUTHOR
Marcus Blümel
Asymmetric Synthesis of Spiro Tetrahydrothiophene-indan-1,3-diones via a Squaramide-Catalyzed Sulfa-Michael/Aldol Domino Reaction
Synthesis 48(08), 1131-1138(2016). doi:10.1055/s-0035-1560412
Asymmetric Synthesis of Spirobenzazepinones with Atroposelectivity and Spiro-1,2-Diazepinones by NHC-Catalyzed [3+4] Annulation Reactions
A strategy for the NHC-catalyzed asymmetric synthesis of spirobenzazepinones, spiro-1,2-diazepinones, and spiro-1,2-oxazepinones has been developed via [3+4]-cycloaddition reactions of isatin-derived enals (3C component) with in-situ-generated aza-o-quinone methides, azoalkenes, and nitrosoalkenes (4atom components). The [3+4] annulation strategy leads to the seven-membered target spiro heterocycles bearing an oxindole moiety in high yields and excellent enantioselectivities with a wide variety of substrates. Notably, the benzazepinone synthesis is atroposelective and an all-carbon spiro stereocenter is generated.
Switchable Access to Different Spirocyclopentane Oxindoles by N-Heterocyclic Carbene Catalyzed Reactions of Isatin-Derived Enals and N-Sulfonyl Ketimines
A novel NHC-catalyzed annulation protocol for the asymmetric synthesis of biologically important β-lactam fused spirocyclopentane oxindoles with four contiguous stereocenters, including two quaternary carbon centers, was developed. Alternatively, spirocyclopentane oxindoles containing an enaminone moiety can be achieved using the same starting materials, isatin-derived enals, and N-sulfonyl ketimines, in the presence of a slightly different NHC catalytic system. This switchable annulation strategy enables the selective assembly of both heterocyclic scaffolds with good yields and excellent enantioselectivities for a broad range of substrates.
CCDC 1534938: Experimental Crystal Structure Determination
Related Article: Lei Wang, Sun Li, Marcus Blümel, Rakesh Puttreddy, Anssi Peuronen, Kari Rissanen, Dieter Enders|2017|Angew.Chem.,Int.Ed.|56|8516|doi:10.1002/anie.201704210
CCDC 1453056: Experimental Crystal Structure Determination
Related Article: Lei Wang, Sun Li, Marcus Blümel, Arne R. Philipps, Ai Wang, Rakesh Puttreddy, Kari Rissanen, Dieter Enders|2016|Angew.Chem.,Int.Ed.|55|11110|doi:10.1002/anie.201604819
CCDC 1413502: Experimental Crystal Structure Determination
Related Article: Lei Wang, Sun Li, Marcus Blümel, Arne R. Philipps, Ai Wang, Rakesh Puttreddy, Kari Rissanen, Dieter Enders|2016|Angew.Chem.,Int.Ed.|55|11110|doi:10.1002/anie.201604819
CCDC 1437740: Experimental Crystal Structure Determination
Related Article: Suruchi Mahajan, Pankaj Chauhan, Marcus Blümel, Rakesh Puttreddy, Kari Rissanen, Gerhard Raabe, Dieter Enders|2016|Synthesis|48|1131|doi:10.1055/s-0035-1560412
CCDC 1527542: Experimental Crystal Structure Determination
Related Article: Lei Wang, Sun Li, Marcus Blümel, Rakesh Puttreddy, Anssi Peuronen, Kari Rissanen, Dieter Enders|2017|Angew.Chem.,Int.Ed.|56|8516|doi:10.1002/anie.201704210