RuO4-mediated oxidation of secondary amines 2. imines as main reaction intermediates

Abstract

Oxidation by RuO 4 (generated in situ from RuO 2 and NaIO 4) of secondary amines such as Bn-NH-CH 2 R (1; R=H, Me) gave complex reaction mixtures, but mainly amides. In the presence of cyanide, the leading products were α-aminonitriles. Comparison of the oxidation products of 1 with those from the corresponding imines PhCH=N-CH 2 R and Bn-N=CH-R showed that formation of the indicated imines is the first main step in the oxidation of 1. A detailed mechanism is proposed.

Sodium Periodate (NaIO4) in Organic Synthesis

“…Florea and associates completed this task (Table 1, P). 23 Using a crucial oxidative dearomatization approach, Vosburg and his team synthesized the corresponding epoxy ketone from salicyl alcohol driven oxidation via NaIO 4 /H 2 O. 24 Because of its plentiful supply, renewable nature, superior mechanical qualities, and adjustable surface chemistry, cellulose is a perfect starting material for the creation of functional materials.…”

RuO4-Mediated oxidation of N-benzylated tertiary amines. Four- and three-membered azacycloalkanes as substrates

“…8 For simplicity, the desired entry (x) of Table 1 will be cited as T-x. Since free benzoic acid is always derived from benzaldehyde (BzH), [8][9][10]15,16 the amount quoted in Table 1 for BzH actually refers to the sum BzH+benzoic acid.…”

“…35,36 1 H-NMR (300 MHz, CDCl3) δ (ppm) 2.07 (2H, quintet, 3 1,4-Dibenzyl-2,3-piperazinedione (16). 16 1 H-NMR (300 MHz, CDCl3) δ (ppm) 3.34 (4H, s, CH2-CH2), 4.67 (4H, s, Ph-CH2), 7.20-7.33 (10H, m, arom.). 13 C-NMR (75 MHz, CDCl3) δ (ppm) 43.6 (CH2-CH2), 50.7 (Ph-CH2), 128.2 (p), 128.6 (o), 129.0 (m), 135.6 (i), 157.6 (CO).…”

“…4,7,11,12,14 Regarding the oxidation of amines, primary or secondary ones (R2CH-NH-R) are transformed by RuO4 into imines (R2C=N-R), by a formal 1,2-dehydrogenation process. 15,16 In addition, a less common 1,1dehydrogenation reaction transforms tertiary amines (R-CH2-NR2) to amides (R-CO-NR2), with iminium ions as intermediates. [7][8][9][10][11] Our previous research on oxidation of tertiary amines focused on the oxidative behaviour of medium-size azacycloalkanes, namely 1-benzylpiperidine (1a) and 1-benzylpyrrolidine (1b).…”

Homolytic pathway for the RuO4-oxidation of amines

“…It is well known that secondary amines carrying C-H bonds in α to N atom (R-NH-CHR 2 ) undergo oxidation by ruthenium-based catalysts 1,2 (including ruthenium tetroxide) [3][4][5] to yield imines (R-N=CR 2 ), by a formal 1,2-dehydrogenation process. By analogy with the oxidation of secondary alcohols, the advanced mechanism 3 involves two distinct hydrogen-transfer processes: the first for the N-H proton, the second for the C-H one (Scheme 1).…”