Vigante Brigita, Rucins Martins, Plotniece Aiva, Pajuste Karlis, Luntena Iveta, Cekavicus Brigita, Bisenieks Egils, Smits Rufus, Duburs Gunars, Sobolev Arkadij
Latvian Institute of Organic Synthesis, Aizkraukles str. 21, Riga LV-1006, Latvia.
Molecules. 2015 Nov 12;20(11):20341-54. doi: 10.3390/molecules201119697.
The ethoxycarbonylmethyl esters of 1,4-dihydropyridines were directly converted into carbamoylmethyl esters in the presence of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) in good to excellent yields under mild conditions. The use of TBD is crucial for the successful aminolysis of ethoxycarbonylmethyl ester of 1,4-dihydropyridines with secondary amines as without it the reaction does not proceed at all. The aminolysis reaction proceeded regioselectively, as the alkyl ester conjugated with the 1,4-dihydropyridine cycle was not involved in the reaction. Screening of other N-containing bases, such as triethylamine (TEA), pyridine, 4-(N,N-dimethylamino)pyridine (DMAP), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), imidazole, tetramethyl guanidine (TMG) and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) as catalysts revealed no activity in the studied reaction.
在温和条件下，1,4 - 二氢吡啶的乙氧羰基甲酯在1,5,7 - 三氮杂双环[4.4.0]癸 - 5 - 烯（TBD）存在下可直接转化为氨基甲酰甲酯，产率良好至优异。使用TBD对于1,4 - 二氢吡啶的乙氧羰基甲酯与仲胺的成功氨解反应至关重要，因为没有它反应根本无法进行。氨解反应具有区域选择性，因为与1,4 - 二氢吡啶环共轭的烷基酯不参与反应。对其他含氮碱进行筛选，如三乙胺（TEA）、吡啶、4 -（N，N - 二甲基氨基）吡啶（DMAP）、1,8 - 二氮杂双环[5.4.0]十一 - 7 - 烯（DBU）、1,5 - 二氮杂双环[4.3.0]壬 - 5 - 烯（DBN）、咪唑、四甲基胍（TMG）和7 - 甲基 - 1,5,7 - 三氮杂双环[4.4.0]癸 - 5 - 烯（MTBD）作为催化剂，结果表明在所研究的反应中没有活性。
