Pictet Spengler-type reactions in 3-arylmethylpiperazine-2,5-diones. Synthesis of pyrazinotetrahydroisoquinolines
作者:Juan Francisco González、Elena de la Cuesta、Carmen Avendaño
DOI:10.1016/j.tet.2004.05.073
日期:2004.7
of aldehydes and acetals as N-alkylating agents of 1-acetyl-3-arylmethylpiperazine-2,5-diones and the subsequent cyclization of the N-alkylated products was studied. Use of paraformaldehyde in different reaction conditions gave 6-unsubstituted 3,6,11,11a-tetrahydro-2H-pyrazino[1,2-b]isoquinoline-1,4-diones and, in some cases, benzo[f]pyrazino[1,2-c]1,3-oxazepine-1,4-diones. Succesful reactions with
研究了醛和缩醛作为1-乙酰基-3-芳基甲基哌嗪-2,5-二酮的N-烷基化剂的行为以及随后N-烷基化产物的环化。在不同的反应条件下使用低聚甲醛得到6-未取代的3,6,11,11a-四氢-2 H-吡嗪并[1,2 - b ]异喹啉-1,4-二酮,在某些情况下还会得到苯并[ f ]吡嗪并[1,2 - c ] 1,3-氧杂氮杂-1,4-二酮。与苯甲醛的成功反应需要首先活化内酰胺功能,并用醛二甲基乙缩醛催化N-烷基化。孤立的O,N将如此获得的酰胺基乙缩醛进行非对映选择性的Pictet Spengler型反应,该反应与在几个环活化度的芳烃和噻吩一起产生6-苯基吡嗪并异喹啉二酮和相应的噻吩类似物。