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first example of transition-metal-catalyzed C–H activations of 2-phenylisatogens with alkynes and sulfonyl azides has been developed using N-oxide as the directing group. Ru(II)-Catalyzed C–H alkenylation/cyclization and Ir(III)-catalyzed direct C–H sulfamidation proceeded with good yields and excellent functional group tolerance. Importantly, these two transformations provided straightforward routes
N-Heterocyclic Carbene-Catalyzed Umpolung Formal [3+3] Cycloaddition of Enals with Isatogens: Access to Fused Indolin-3-ones with a Tetrasubstituted Carbon Stereocenter
作者:Junyu Xu、Shihe Hu、Yingyan Lu、Ying Dong、Weifang Tang、Tao Lu、Ding Du
DOI:10.1002/adsc.201401070
日期:2015.3.23
A novel synthetic method to accessfused indolin‐3‐ones with a tetrasubstitutedcarbonstereocenter has been developed via NHC‐catalyzed umpolungformal [3+3] cycloaddtion of enals with isatogens. This methodology could be also applied for the quick construction of the 6‐5‐5 tricyclic pyrrolo[1,2‐a]indole skeleton which is frequently found as a core structure of many indole alkaloids.
The enantioselectiveredoxannulation of nitroalkynes with indoles is enabled by gold/chiral phosphoric acid dualcatalysis. A range of indolin‐3‐one derivatives bearingquaternarystereocenters at the C2 position were afforded in good yields and excellent enantioselectivities (up to 96 % ee) from readily available starting materials.