Organic Isocyanates and Isothiocyanates: Versatile Intermediates in Agrochemistry

Abstract

In the recent decades, organic isocyanates and isothiocyanates have been often applied as reactive intermediates in the research syntheses or manufacturing routes of many agrochemicals. These heterocumulenes allowed the installation of crucial carboxylic functions, such as carbamates, ureas and semicarbazones, but were also used for the construction of five- and six-membered heterocycles, such as tetrazolones, thiazoles and uracils.

Metal-Free N–H/C–H Carbonylation by Phenyl Isocyanate: Divergent Synthesis of Six-Membered N-Heterocycles

“…59 The title compound was synthesized according to the general procedure and obtained as a white solid (40.5 mg, 85%); 3:7 (EA/ Hexane) as the eluent; 3-(p-Tolyl)quinazoline-2,4(1H,3H)-dione (2b). 59 The title compound was synthesized according to the general procedure and obtained as a white solid (35.3 mg, 70%); 3:7 (EA/Hexane) as the eluent; 1 H-NMR (400 MHz, DMSO-d 6 ) 11.52 (s, 1H), 7.93 (dd, J = 8.0 Hz, 1.4 Hz, 1H), 7.69 (td, J = 8.0 Hz, 1.2 Hz, 1H), 7.28−7.17 (m, 6H), 2.37 (s, 3H); 13 3-(4-Ethylphenyl)quinazoline-2,4(1H,3H)-dione (2c). 60 The title compound was synthesized according to the general procedure and obtained as a white solid (35.6 mg, 67%); 3:7 (EA/Hexane) as the eluent; 1 H-NMR (400 MHz, DMSO-d 6 ) δ 11.53 (s, 1H), 7.94 (dd, J = 8.0 Hz, 1.6 Hz, 1H), 7.70 (td, J = 8.0 Hz, 1.2 Hz, 1H), 7.33−7.30 (m, 2H), 7.25−7.19 (m, 4H), 2.67 (q, J = 8.0 Hz, 2H), 1.24 (t, J = 8.0 Hz, 3H).…”

“…60 The title compound was synthesized according to the general procedure and obtained as a white solid (35.6 mg, 67%); 3:7 (EA/Hexane) as the eluent; 1 H-NMR (400 MHz, DMSO-d 6 ) δ 11.53 (s, 1H), 7.94 (dd, J = 8.0 Hz, 1.6 Hz, 1H), 7.70 (td, J = 8.0 Hz, 1.2 Hz, 1H), 7.33−7.30 (m, 2H), 7.25−7.19 (m, 4H), 2.67 (q, J = 8.0 Hz, 2H), 1.24 (t, J = 8.0 Hz, 3H). 13 3-(4-Methoxyphenyl)quinazoline-2,4(1H,3H)-dione (2d). 59 The title compound was synthesized according to the general procedure and obtained as a white solid (45 mg, 73%); 3:7 (EA/Hexane) as the eluent; 1 H-NMR (400 MHz, DMSO-d 6 ) δ 11.50 (s, 1H), 7.93 (dd, J = 8.0 Hz, 1.2 Hz, 1H), 7.69 (td, J = 8.0 Hz, 1.6 Hz, 1H), 7.23−7.20 (m, 4H), 7.03−6.99 (m, 2H), 3.81 (s, 3H); 13 3-(2,5-Dimethoxyphenyl)quinazoline-2,4(1H,3H)-dione (2e).…”

“…13 3-(4-Methoxyphenyl)quinazoline-2,4(1H,3H)-dione (2d). 59 The title compound was synthesized according to the general procedure and obtained as a white solid (45 mg, 73%); 3:7 (EA/Hexane) as the eluent; 1 H-NMR (400 MHz, DMSO-d 6 ) δ 11.50 (s, 1H), 7.93 (dd, J = 8.0 Hz, 1.2 Hz, 1H), 7.69 (td, J = 8.0 Hz, 1.6 Hz, 1H), 7.23−7.20 (m, 4H), 7.03−6.99 (m, 2H), 3.81 (s, 3H); 13 3-(2,5-Dimethoxyphenyl)quinazoline-2,4(1H,3H)-dione (2e). 61 The title compound was synthesized according to the general procedure and obtained as a white solid (39 mg, 75%); 3:7 (EA/ Hexane) as the eluent; 1 H-NMR (400 MHz, DMSO-d 6 ) δ 11.48 (s, Table 3.…”

“…Constructing pre-eminent carbonyl-containing heterocycles via the carbonylation process is of great significance in organic and biological applications. − Over a half century, in organic synthesis, CO gas serves as the most direct C 1 source, especially in the transition metal-catalyzed reactions and has received extraordinary attention. ,− Parallelly in organic synthesis, phenyl isocyanates are the most valuable reagents due to their habitual reactivity with numerous organic compounds, which portrays wide applications in synthetic chemistry. − Using this reagent, many synthetic transformations were carried out. − The other important application is that it has been a carbonylation source for developing synthetically useful intermediates and bioactive compounds. Moreover, phenyl isocyanate with transition metal-free protocol in C–H and N–H carbonylation processes has been less explored.…”

“…13 C{ 1 H}-NMR (100 MHz, DMSO-d 6 ) δ 171.9, 154.2, 144.9, 135.4, 131.3, 127.7, 126.9, 126.1, 124.5, 123.1, 121.2, 119.9, 116.0, 114.1, 113.7, 49.8, 21.7, 10.9. HRMS (ESI) m/z: [M + H] + calcd for C 24 H 26 N 3 O 4 S 452.1644; found, 452.1642. sı Supporting InformationThe Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.joc.2c01026.Additional experimental procedures, characterization data, and NMR spectra of compounds (PDF)…”