Iron Trichloride-Promoted Cyclization of o-Alkynylaryl Isocyanates: Synthesis of 3-(Chloromethylene)oxindoles

Abstract

Iron trichloride promotes the cationic cyclization of o-(arylethynyl)aryl isocyanates leading to 3-(arylchloromethylene)oxindoles which can be stereoselectively converted to (Z)-3-(aminomethylene)oxindoles under straightforward conditions. When the alkyne is substituted by an alkyl group, activation of the allylic C-H bond also occurs producing 1,2-(dichloroalkylidene)oxindoles.

Synthesis of binuclear iridium(III) and rhodium(III) complexes bearing methylnaphthalene-linked N-heterocyclic carbenes, and application to intramolecular hydroamination

“…Dichloromethane was distilled over CaH 2 prior to use. 1,8-Dibromomethylnaphthalene [10], [Cp*IrCl 2 ] 2 [11], alkyne 5a [12], 5b [13], 5c [14], 5d [13], 5e [15], 5f [16], 5g [17], 5h [14], 5i [18], 5j [19], 5k [20] and 5l [21] were prepared according to the literature methods. Other reagents employed in this research were commercially available and used without further purification.…”

Mechanistic insights on the Pd-catalyzed addition of C–X bonds across alkynes – a combined experimental and computational study

“…1–8 Despite their use in medicinal chemistry and natural product synthesis, methods to access methylene oxindoles in a highly stereoselective manner are limited. 9–15 In this context, Lautens and co-workers have developed the synthesis of methylene oxindoles via Pd(0)-catalyzed carbohalogenation of alkynes, which involves an unusual and remarkable reductive elimination of C(sp 2 )–X (X = I, Br, Cl) from Pd( ii ) as key step. 16 …”

3‐Alkenyl‐oxindoles: Natural Products, Pharmaceuticals, and Recent Synthetic Advances in Tandem/Telescoped Approaches

“…Recently, Meyer, Cossy, and co-workers have further enhanced the isocyanate methodology by introducing an iron(III) chloride variant (Scheme 8). [57] The authors propose that a cationic cyclisation occurs to generate 3-(arylchloromethylene)oxindoles such as 71 which could be converted into (Z)-3-(aminomethylene)oxindoles such as 72 upon treatment with amines under microwave (MW). In all cases, products 72 are obtained exclusively as the Z-stereoisomer.…”