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。
Alkylation of 3-nitropyridin-2(1H)-ones in the presence of bases affords N-alkylated products and sometimes O-alkylated products. The yields and relative amounts of N- and O-alkylated products depend substantially on the size of the substituent at the C(6) atom of pyridone.
Synthesis of 2,6-disubstituted pyrido[2,3-b][1,4]oxazines
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。