Cyclopropyl oxindole

Additionally, Charette and coworkers disclosed the synthesis of biologically active 3,3 -cyclopropyl oxindole 44 via a Pd-catalyzed, Ag-promoted C-H functionalization of cyclopropanecarboxamide 43 derived from 2-bromoaniline (Scheme 10) [31]. Substitution on the aryl ring or on the cyclopropane, including heterocycles such as furan or thiophene, was well tolerated. A mixmre of diaste-reomers was obtained when aryl substitution was present on the cyclopropane. X-ray crystallography confirmed the structure of both diastereomers. 

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... 

Ladd CL, Sustac Roman D, Charette AB (2013) Silver-promoted, palladium-catalyzed direct arylation of cyclopropanes facile access to spiro 3,3 -cyclopropyl oxindoles. Org Lett 15 (6) 1350-1353... 

SCHEME 2.46 Asymmetric synthesis of spiro-3,3 -cyclopropyl oxindoles via a Michael-aldol cascade reaction. 

An important achievement in this field has been realized during the total syntheses of the spiropyrrolidine-oxindole alkaloid (zt)-strychnofoline 107 (Scheme 41.23)." " Isolated from the leaves of Strychnos usambarensis, strych-nofoline displays antimitotic activities against cultures of mouse melanoma and Ehrlich tumor cells. Carreira and coworkers developed a methodology in which the key [3+2] annulation was performed by the treatment of spiro-cyclopropyl-3,3 -oxindole 102 with an iV-alkyl imine 103... 

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. 

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