Transformation of N , N -dimethylaniline- N -oxides into N -methylindolines by a tandem Polonovski–Mannich reaction

Synthesis of Halogenated Anilines by Treatment of N,N-Dialkylaniline N-Oxides with Thionyl Halides

“…1-( N , N -Dimethylamino)naphthalene N -oxide ( 4d ), 4-methoxy- N , N -dimethylaniline N -oxide ( 4p ), and 4-methyl- N , N -dimethylaniline N-oxide ( 4q ) were obtained using the procedure of Lewis et al 8 All other anilines were obtained using the following procedure modified from Chandrasekharam et al 14…”

“…N , N -Dimethylaniline N -oxide ( 1a ), 3-methoxy- N , N -dimethylaniline N -oxide ( 1b ), 3-methyl- N , N -dimethylaniline N -oxide ( 1c ), 1-( N , N -dimethylamino)naphthalene N -oxide ( 1d ), methyl 3-( N , N -dimethylamino)benzoate ( 1e ), 4-fluoro- N , N -dimethylaniline N -oxide ( 1l ), 4-chloro- N , N -dimethylaniline N -oxide ( 1n ), 4-methoxy- N , N -dimethylaniline N -oxide ( 1u ), and 4-methyl- N , N -dimethylaniline N -oxide ( 1v ) were previously synthesized and reported by Lewis et al 8 All other N , N -dimethylaniline N -oxides were synthesized using the same procedure. A solution of 3-bromo- N , N -dimethylaniline 4f (1.0 g, 5.0 mmol) in dichloromethane (25 mL) was added dropwise to a solution of m-CPBA (77%, 0.99 g, 6.0 mmol, 1.2 equiv) in dichloromethane (25 mL each) at 23 °C.…”

“…We have a longstanding interest in the manipulations of anilines at elevated oxidation levels (Scheme 1). 8 The functionalization of anilines by group transfer is known at the N -arylhydroxylamine oxidation level (Scheme 1, eqs 1 and 2), 9 and a small number of examples of ortho -chlorination reactions have been reported on that platform (Scheme 1, eq3). 10 We report here the practical and convenient syntheses of 2-chloro- N , N -dialkylanilines and 4-bromo- N , N -dialkylanilines as part of our ongoing interests in the reactivity of aniline N -oxides (Scheme 1, eq 4).…”

Transformation of N,N-Dimethylaniline N-Oxides into Diverse Tetrahydroquinoline Scaffolds via Formal Povarov Reactions

“…10 The aniline N -oxides undergo O -acylation events with a host of electrophiles, and we have developed chemistry by which the weak N–O bond is excised in a Polonovski-type reaction to give an iminium ion. 11 Following that event, the imine is captured by an electron-rich alkene, and the resultant cation is then attacked by the pendant aniline. Thus, the reaction constitutes the stepwise formal [4 + 2] cycloaddition (aza-Diels–Alder reaction) of the Povarov reaction.…”

“…For example, a silyl ketene acetal can capture the iminium ion in a Mannich-type 16 reaction (Scheme 7a) directly analogous to our previous work in the synthesis of indolines (Scheme 7b). 11…”