Nitroxyl‐Radical‐Catalyzed Oxidative Coupling of Amides with Silylated Nucleophiles through N‐Halogenation

Abstract

A nitroxyl-radical-catalyzed oxidative coupling reaction between amines with an N-protecting electron-withdrawing group (EWG) and silylated nucleophiles was developed to furnish coupling products in high yields, thus opening up new frontiers in organocatalyzed reactions. This reaction proceeded through the activation of N-halogenated amides by a nitroxyl-radical catalyst, followed by carbon-carbon coupling with silylated nucleophiles. Studies of the reaction mechanism indicated that the nitroxyl radical activates N-halogenated amides, which are generated from N-EWG-protected amides and a halogenation reagent, to give the corresponding imines.

Tandem Oxidative Derivatization of Nitrene Insertion Products for the Highly Diastereoselective Synthesis of 1,3‐aminoalcohols

“…We hypothesize that PhIO may be necessary to activate amine 12 for more facile oxidation to 13 , as the electron‐withdrawing nature of the sulfamate group decreases the nucleophilicity of the nitrogen. Recently, Moriyama and co‐workers have shown that t BuOCl is able to pre‐activate an electron‐poor amine towards oxidation through the formation of a N ‐chlorinated intermediate . In our previous studies of Ag‐catalyzed nitrene transfer reactions utilizing PhIO as the oxidant, we have shown that Ag I salts play a role in breaking up the polymeric PhIO to furnish the activated monomeric species…”

A Mechanochemical Zinc-Mediated Barbier-Type Allylation Reaction under Ball-Milling Conditions

“…Data is consistent with literature values but the NMR data indicates presence of minor impurities. 14 1-cyclohexylbut-3-en-1-ol ( 16 23 N-(1-phenylbut-3-en-1-yl)aniline (37): Prepared according to General Procedure A. Purified by column chromatography (Ethyl Acetate/Hexane = 8:92) to give the product (yield: 46%, 103 mg) as white solids. Note: a mixture of rotamers (5.7:1) was observed in the purified NMR.…”

Metal-free C(sp3)–H functionalization of sulfonamidesviastrain-release rearrangement

“… 35 Actually, the oxidation of amides is more difficult than that of amines because their nitrogen atoms have much lower electron density. 36 Moreover, it is very important 37 and challenging to directly synthesize unsaturated imines through dehydrogenation of amine derivatives. Hence, we report an efficient metal-free system for the synthesis of α,β-unsaturated imines with high geometrical selectivities through multiple C–H bond functionalization of N -fluoro sulfonamides under mild conditions ( Scheme 1B ).…”