Carbamates and ureas are very important carbonyl compounds in organic, bioorganic, supramolecular, and medicinal chemistry. To prepare both the carbamate and the urea from amine, one carbonyl source requires.
During the last 30 years there have been considerable interest toward novel carbonyl s...
Carbamates and ureas are very important carbonyl compounds in organic, bioorganic, supramolecular, and medicinal chemistry. To prepare both the carbamate and the urea from amine, one carbonyl source requires.
During the last 30 years there have been considerable interest toward novel carbonyl sources and the development of new efficient and selective protocols for the preparation of carbamates and unsymmetrical ureas.
Common carbonyl sources such as carbon monooxide and phosgene can be difficult to handle due to their toxicity, corrosiveness and gaseous form. Recently, there have been many reports on the carbonyl sources such as formamide, formic acid, formic anhydride, formates, aldehydes, metal carbonyls, carbamoylsilanes, carbamoylstannes, isocyanates, carbonates, diimidazoles and dichloromethanimines. Therefore, I attempted the development of a stable in air, convenient carbonyl source pyridazinone..
Although phenyl chloroformate (2) is a good carbonyl source to prepare symmetrical urea, it is not useful for preparation of unsymmetrical urea due to the too high reactivity. Actually, aniline was reacted with phenyl chloroformate (2) to give mainly symmetrical urea in stead of the corresponding carbamate.
Therefore, we designed and synthesized phenyl 4,5-dichloro-6-oxopyridazin-1(6H)-carboxylate (3) as carbonyl source.
Some aliphatic and aromatic amines were treated with compound 3 in THF under catalyst-free and neutral condition to give the corresponding carbamate in excellent yields. Carbonylation of aromatic amines and aliphatic amines with compound 3 gave the corresponding asymmetric ureas under catalyst-free and neutral conditions in good to excellent yields. On the other hand, carbonylation of two equivalents amines with compound 3 also afforded the corresponding symmetric ureas in the presence of NMP in THF in good yields.
In summary, the selective synthesis of carbamates, symmetric ureas and unsymmetric ureas have been accomplished by the reaction of amines with phenyl 4,5-dichloro-6-oxopyridazin- 1(6H)-carboxylate (3) as a carbonyl source under mild conditions. It is noteworthy that this process is mild, economic, and convenient.
Carbamates and ureas are very important carbonyl compounds in organic, bioorganic, supramolecular, and medicinal chemistry. To prepare both the carbamate and the urea from amine, one carbonyl source requires.
During the last 30 years there have been considerable interest toward novel carbonyl sources and the development of new efficient and selective protocols for the preparation of carbamates and unsymmetrical ureas.
Common carbonyl sources such as carbon monooxide and phosgene can be difficult to handle due to their toxicity, corrosiveness and gaseous form. Recently, there have been many reports on the carbonyl sources such as formamide, formic acid, formic anhydride, formates, aldehydes, metal carbonyls, carbamoylsilanes, carbamoylstannes, isocyanates, carbonates, diimidazoles and dichloromethanimines. Therefore, I attempted the development of a stable in air, convenient carbonyl source pyridazinone..
Although phenyl chloroformate (2) is a good carbonyl source to prepare symmetrical urea, it is not useful for preparation of unsymmetrical urea due to the too high reactivity. Actually, aniline was reacted with phenyl chloroformate (2) to give mainly symmetrical urea in stead of the corresponding carbamate.
Therefore, we designed and synthesized phenyl 4,5-dichloro-6-oxopyridazin-1(6H)-carboxylate (3) as carbonyl source.
Some aliphatic and aromatic amines were treated with compound 3 in THF under catalyst-free and neutral condition to give the corresponding carbamate in excellent yields. Carbonylation of aromatic amines and aliphatic amines with compound 3 gave the corresponding asymmetric ureas under catalyst-free and neutral conditions in good to excellent yields. On the other hand, carbonylation of two equivalents amines with compound 3 also afforded the corresponding symmetric ureas in the presence of NMP in THF in good yields.
In summary, the selective synthesis of carbamates, symmetric ureas and unsymmetric ureas have been accomplished by the reaction of amines with phenyl 4,5-dichloro-6-oxopyridazin- 1(6H)-carboxylate (3) as a carbonyl source under mild conditions. It is noteworthy that this process is mild, economic, and convenient.
주제어
#carbamate urea phenyl 4 5-dichloro-6-oxopyridazin-1(6H)-carboxylate
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