One pot synthesis of ureas and carbamates via oxidative carbonylation of aniline-type substrates by CO/O2 mixture catalyzed by Pd-complexes

Pd Nanoparticles and Mixture of CO2/CO/O2 Applied in the Carbonylation of Aniline

“…Based on our previous results, we proposed the mechanism of AN carbonylation by CO/O 2 in the presence PdCl 2 (X n Py) 2 complexes (where: Py = pyridine, X = -Cl or -CH 3 , n = 0-2), with Pd(II) reduced to Pd(0) in situ in the catalytic cycle, see Scheme 1. Partial precipitation of inactive Pd black reported by Ragaini [57] is one of the proofs of the Pd 0 presence in the system, further supported by our isolation of palladium black precipitated during the reaction of PdCl 2 (PhNH 2 ) 2 complex with carbon monoxide [15]. The next step is reoxidation of Pd(0) to Pd(II) and in this cycle both molecular oxygen and iodine are supposed to be potential oxidants responsible for recycling Pd(II) from Pd(0), step 1a-1b.…”

“…Alternatively, Pd(0) in 1a may be oxidized during the oxidative addition of I 2 to Pd(0), according to the equation: Pd(0) + I 2 → PdI 2 . Then, HI (instead of water) is released and this HI is oxidized by molecular oxygen: [15]. According to the proposed mechanism presented in Scheme 1, Pd(0) stabilized by pyridine ligands plays a crucial role as an acceptor of oxidizing agent (O 2 or I 2 ).…”

“…Over the past few years, our studies have been focused on the carbonylation of aromatic nitrocompounds and amines by CO in the presence of the PdCl 2 (X n Py) 2 /Fe/I 2 /X n Py catalytic system, where Py = pyridine, X = Cl or CH 3 , n = 0-2 [14][15][16][17]. We have successfully optimized the reaction conditions and proposed detailed mechanisms for carbonylation of aniline (AN) to N,N -diphenylurea (DPU, equation 1), or to ethyl N-phenylcarbamate (EPC, Equation (2)), by CO/O 2 .…”

Dual Behavior of Iodine Species in Condensation of Anilines and Vinyl Ethers Affording 2-Methylquinolines

“…With the optimized conditions in hand, we applied the reaction to the syntheses of 2-methylquinolines 3b – h [29,45,46,47,48,49,50] using anilines 1b – h (Table 2). The reaction was influenced by substituents on the benzene ring.…”

“…2-Methylquinoline ( 3h ) [50]: 1 H-NMR (400 MHz, CDCl 3 ): δ 8.04 (d, J = 5.0 Hz, 1H), 8.02 (d, J = 5.0 Hz, 1H), 7.77 (d, J = 8.0 Hz, 1H), 7.68 (dd, J = 8.4, 7.0 Hz, 1H), 7.48 (dd, J = 8.0, 7.0 Hz, 1H), 7.28 (d, J = 8.4 Hz, 1H), 2.75 (s, 3H).…”