作者:Nagatoshi Nishiwaki、Masataka Hisaki、Masaki Ono、Masahiro Ariga
DOI:10.1016/j.tet.2009.07.024
日期:2009.9
A new preparative method for pyrido[2,3-b][1,4]oxazines from 6-substituted 3-nitro-2-pyridones is demonstrated. This method consists of two steps: O-alkylation and reductive cyclization. In the former step, the bulkiness of both starting nitropyridones and C2 reagents is found to be essential for avoiding N-alkylation, which undergoes O-alkylation efficiently. The subsequent reductive cyclization affords
提出了一种由6-取代的3-硝基-2-吡啶酮制备吡啶并[2,3- b ] [1,4]恶嗪的新方法。该方法包括两个步骤:O-烷基化和还原环化。在前一步中,发现硝基吡啶酮和C2试剂的庞大体积对于避免N-烷基化至关重要,因为N-烷基化会有效地进行O-烷基化。随后的还原环化作用提供了在2和6位上都没有碳取代基的吡嗪并嗪。