Ritter-type iodo(iii)amidation of unactivated alkynes for the stereoselective synthesis of multisubstituted enamides

Abstract

Ritter-type trans-selective iodo(iii)amidation of internal alkynes with benziodoxole triflate and various nitriles has been achieved for the stereocontrolled synthesis of multisubstituted enamides.

One-pot synthesis of 4-substituted 2-fluoroalkyloxazoles from NH-1,2,3-triazoles and fluoroalkylated acid anhydrides

“…This result represents further indirect proof of the formation of intermediate vinyl cation after triazole cleavage. 28 Upon silica gel column chromatography 4' underwent hydrolysis to 1,2diamidoalkenes 4, which were isolated in moderate yields (Scheme 5). However, both products 4' and 4 easily hydrolysed to complex mixture of products upon water extraction.…”

Exploring New Reactions and Syntheses of Trivalent Iodine Compounds

“…Building on this observation and after careful optimization, we were able to establish two sets of reaction conditions for the iodo(III)amidation of alkynes with nitrile and water (Scheme 18). 31 Thus, the desired reaction was achieved by using the nitrile (mostly acetonitrile) as the solvent or an excess amount of the nitrile in 1,1,1,3,3,3─ hexa uoro-propan─ 2─ ol (HFIP). For the latter conditions, HFIP was supposed to bene t the reaction by its cation─ stabilizing nature and low nucleophilicity.…”

Lewis/Brønsted acid-mediated cyclization/amidation of 1,6-enynes with nitriles: access to 3-enamide substituted dihydrobenzofurans

“…8 Current methods for the synthesis of enamides mainly include acylation of imines, Curtius rearrangement of unsaturated acyl azides, condensation of amides with aldehydes, 9 direct N -dehydrogenation of amides 10 and Ritter-type amination of alkynes with nitrile. 11 Despite methods that have been developed for the construction of enamides, simple and efficient methods of providing enamides are highly desirable. Based on continuous interest in the transformations of nitriles, 12 we envisage that the electron-rich 1,6-enynes could undergo electrophilic addition and 5- exo-dig cyclization with a Brønsted acid in the presence of a Lewis acid to produce an alkenyl cation, which would be trapped by a nitrile to form enamide-substituted benzofurans.…”