Cyclopropyl spirooxindoles

Scheme 10 Pd-catalyzed, Ag-mediated synthesis of 3,3 -cyclopropyl spirooxindoles...

Diastereodivergent synthesis of 3-spirocyclopropyl-2-oxindoles has been accomplished through the direct enantioselective cyclopropanation of oxindoles with bromonitroolefins in the presence of a tertiary amine-thiourea catalyst. Using DABCO as a nucleophilic catalyst, a stereochemically retentive conversion of different diastereomers of cyclopropyl spirooxindoles has been discovered. 

A related synthesis of 3,3 -cyclopropyl oxindoles was reported by Takemoto et al. [32], Carbamoyl chloride 47, containing a cyclopropyl ring at the ortho position, undergoes a Pd-catalyzed cyclization onto the benzylic C-H bond of the cyclopropane to provide the corresponding spirooxindole 44 in 60% yield (Scheme 13). Intramolecular competition reactions investigated the chemoselectivity of the... 

Tsukano C, Okuno M, Takemoto Y (2013) Synthesis of spirooxindoles from carbamoyl chlorides via cyclopropyl methine C(sp )-H activation using palladium catalyst. Chem Lett 42(7) 753-755... 

---