3-isothiocyanato oxindoles

Yuan and co-workers used a similar strategy to synthesize spirooxindoles by a domino aldol/cyclization of 3-isothiocyanato oxindoles with simple ketones catalyzed by a bifunctional thiourea-tertiary amine catalyst [55]. An interesting feature of this methodology is the creation of two adjacent quaternary carbon atoms with high stereocontrol. 

Chen et al. reported that oxindole-type a-isothiocyanato imides 271 had high activities in the aldol-cyclization reaction with inactive simple ketones. With the promotion of thiourea catalyst 1401, the cascade process of either aromatic or aliphatic ketones 206 with 3-isothiocyanato oxindoles 271 proceeded smoothly to afford spirooxindoles 272 bearing a quaternary stereogenic center with perfect stereoselectivity (Scheme 2.72) [102],... 

Matsunaga et al. have developed an asymmetric Mannich-lype synthesis of imines (508) and 3-isothiocyanato oxindoles (511), catalysed by a strontium/Schiff base (513) complex, which provided a concise access to enantiomerically enriched spiro[imidazolidine-4,3 -oxindole] compounds (512) (Scheme 170). ... 

The Michael addition/cyclization of isothiocyanato oxindoles (296), catalysed by the quinine-derived thiourea (288b) and its analogues, has been employed for the preparation of a variety of 3,2 -pyrrolidinyl spirooxindoles (297) and bis-spirooxindoles (298) with <98% ee and >20 1 dr (Scheme 15). " ... 

SCHEME 2.72 Asymmetric cascade processes of oxindole-type a-isothiocyanato imides with inactive ketones. 

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