Selenium-catalyzed Carbonylation To Diuron、4-pyridyl Ureas And Benzimidazole-2-yl-carbamates

Carbonylation is a reaction which can insert carbonyl group to organic compounds so as to canachieve the goals of molecular couplings and functional groups transformations, etc. It possesses theproperties of high atom economy, excellent selectivity and environmental benignancy; it is the cutting-edgefield of green chemistry and chemical engineering and also is the important way of efficient use of C1resource. As an important branch of C1chemistry, CO is the most noticeable carbonyl source among thevarious carbonylation reactions, which has many advantages such as broad sources, low price, high atomeconomy and environmental benignancy.When the carbonylation reaction is conducted with Se/CO catalytic system instead of traditionalmethods, nonmetal selenium which possesses advantages of low cost, benign environment, high catalystactive, convenient recycle can replace the noble transition metals in transition metal catalyzedcarbonylation methods as catalyst. While CO can replace phosgene in phosgene or its derivatives methodsas carbonylation reagent, what’s more, no corrosive waste generates during the carbonylation reaction.Therefore, Se/CO catalytic system has such advantages as low costs, environmental benignancy, nocorrosion to equipments, simple operation, etc. Most of the reactions catalyzed by Se/CO catalytic systemhave brief synthesis routes, excellent yield and mild conditions.As two important types of fine chemicals, most of ureas and carbamates show the excellent biologicalactivities due to their peptide linkages and are widely used in many areas such as agriculture, medicine,materials, chemical engineering and organic synthesis, etc. In this paper, we aim at applying Se/CO catalystsystem to the synthesis of diuron, substituted unsymmetrical4-pyridyl ureas and benzimidazole-2-yl-carbamates.Diuron is an herbicide with extensive uses and low toxicity. We use selenium as catalyst, CO ascarbonylation reagent,3,4-dichloronitrobenzene and dimethylamine hydrochloride as raw materials tosynthesis diuron via the selenium-catalyzed reductive carbonylation reaction of nitro-compounds andoxidative carbonylation reaction of amines. We optimized the reaction conditions and obtained diuron in yield of70%.Unsymmetrical4-pyridyl ureas are an important kind of fine chemicals. They are widely used asherbicides, plant cytokinins in agriculture and anticonvulsant drugs, anti-Alzheimer’s Disease drugs inmedicine. We used Se/CO catalytic system to develop two synthetic routes for4-pyridyl ureas underatmospheric pressure, which is safer, milder, more economical and manipulative than the high pressurecatalytic system. Firstly, we use selenium as catalyst, CO as carbonylation reagent, O2as oxidant,4-amniopyridine and amines as raw materials to prepare4-pyridyl ureas via the selenium-catalyzedoxidative carbonylation reaction of amines with4-amniopyridine. We obtain a series of correspondingureas with moderate to good yields, but the carbonylation reaction failed with aliphatic secondary amines.Secondly, we use selenium as catalyst, CO as carbonylation reagent,4-amniopyridine and aromaticnitro-compounds as raw materials to synthetize a series of4-pyridyl ureas with good yields via theselenium-catalyzed redox carbonylation reaction, the aliphatic nitro-compounds can not proceed in thisreaction.Benzimidazole-2-yl-carbamate compounds are a kind of natural product extracted from the plants, it isan important medicine intermediate and has extensive medicinal values. We conducted the Se/CO oxidativecarbonylation of2-aminobenzimidazole with series of alcohols to synthetize benzimidazole-2-yl-carbamates, most of the products can be obtained in good yields.