Stereoselective Synthesis of 3-Alkylideneoxindoles by Palladium-Catalyzed Cyclization Reaction of 2-(Alkynyl)aryl Isocyanates with Organoboron Reagents
A palladium(0)/monophosphine catalystpromotes a cyclization reaction of 2-(alkynyl)aryl isocyanates with organoboron reagents to produce stereodefined 3-alkylideneoxindoles. The alkynyl and isocyanato groups undergo oxidative cyclization with Pd(0) to form an oxapalladacycle intermediate. Subsequent transmetalation and reductive elimination afford the product.
reaction occurred on treatment of 2-(alkynyl)aryl isocyanates with amides in the presence of a palladium(0)/diphosphine catalyst to stereoselectively form 3-(amidoalkylidene)oxindoles. A carbon−nitrogen bond as well as a carbon−carbon bond were simultaneously introduced onto the alkyne moiety to construct an oxindole skeleton with stereoselective placement of the amino substituent cis to the carbonyl group
Stereoselective Synthesis of 3-(1-Cyanoalkylidene)oxindoles by Palladium-catalyzed Cyclization Reaction of 2-(Alkynyl)aryl Isocyanates with Copper(I) Cyanide
A palladium-catalyzed cyclization reaction of 2-(alkynyl)-aryl isocyanates with copper(I) cyanide provides an efficient method for the stereoselective synthesis of (Z)-configured 3-(1-cyanoalkylidene)oxindoles.
Triflic acid-promoted cycloisomerization of 2-alkynylphenyl isothiocyanates and isocyanates: a novel synthetic method for a variety of indole derivatives
A new approach towards the synthesis of indolederivatives via triflic acid-promoted cycloisomerization with rearrangement of 2-(alkyn-1-yl)phenylisothiocyanates and 2-(alkyn-1-yl)phenylisocyanates has been achieved. By this methodology, structurally diverse types of indolederivatives such as thieno- and furo-indoles, spiro-indolethiones, spiro-oxindoles, and 3-alkylidene-oxindoles were synthesized