Indium-Mediated Reduction of Hydroxylamines to Amines

Abstract

[reaction: see text] A novel and simple procedure for reduction of hydroxylamines to the corresponding amines by means of indium powder in aqueous media is reported. Applicability to one-pot reactions and isoxazolidine N-O bond reduction is also demonstrated. A catalytic version of the process using 2-5% In in the presence of other metals (Zn, Al) has been successfully developed.

Synthesis and Application of a New Fluorous‐Tagged Ammonia Equivalent

“…A range of different reagents have been used for reductive cleavage of N À O bonds, which included Li/4,4'-di-tert-butylbiphenyl (DTBB), [22,23] Na/Hg amalgam, [24,25] SmI 2 , [14,[26][27][28][29][30] TiCl 3 , [31][32][33][34] indium, [8,11] LiAlH 4 , [35,36] BH 3 , [37] [Mo(CO) 6 ], [13,24,[38][39][40][41][42][43][44][45][46][47][48][49] [Co 2 (CO) 8 ], [50] [Fe(CO) 5 ], [13,51] Zn/H +, [43,[52][53][54][55] NiB 2 , [56] Na 2 S 2 O 4 , [57] [TiA C H T U N G T R E N N U N G (iPrO) 4 ]/EtMgBr, [58] NiH 2 , [59] trimethylsilyl chloride/KI, …”

“…[11][12][13][14] 3) The NÀO bond is inert to a range of aggressive reagents, which include Grignard and organolithium reagents, [15] and to reducing reagents such as NaBH 3 CN and NaBH-…”

Enantioselective synthesis of the fragrance trans-magnolione under asymmetric phase transfer catalysis

“…The biphenyl-binaphthylazepine salt (S)-7 was similarly prepared from 2,2′-bis(bromomethyl)-1,1′-biphenyl (11) (Scheme 3), in turn easily obtainable from commercially available 1,1′-diphenic acid. The dibromide 11 was converted into the hydroxylamine 12 by reaction with hydroxylamine hydrochloride at reflux in triethylamine for 2 h. The hydroxylamine 12 was then reduced in 96% yield to the corresponding biphenylamine 13 by treatment with zinc metal in the presence of a catalytic amount of indium (0.05 equiv) in a 1:1 mixture of EtOH/NH 4 Cl [13]. Finally, the ammonium salt (S)-7 was obtained in 62% yield by reaction of biphenylamine 13 with the dibromide (S)-8.…”

“…4.3. 6,e]azepine (13) The hydroxylamine 12 (1.7 g, 8.0 mmol) was dissolved into a 1:1 solution of EtOH and saturated aqueous NH 4 Cl (40 ml; pH 6). Indium powder (5 mol%, 0.046 g, 0.4 mmol) and zinc powder (2 equiv, 1.04 g, 16.0 mmol) were added and the mixture was heated at reflux for 7 h. The mixture was cooled, filtered over Celite and concentrated.…”

Asymmetric conjugate additions of dialkylzinc reagents to enones promoted by new purely atropisomeric phosphoramidite ligands

“…(S)-2,2'-bis(bromomethyl)-1,1'-binaphthalene 4 was prepared from enantiopure (S)-BINOL following a reported procedure. 9 Unless otherwise specified the reagents were used without any purification.…”