Environmental regulations boost the search for new safer and less toxic bio-based solvents to replace controversial high-boiling solvents such as N-methyl-2-pyrrolidone and N,N-dimethylformamide in the chemical industry. Recently, N-alkyl-2-pyrrolidones and 5-methyl-N-alkyl-2-pyrrolidones were proposed as attractive alternative solvents for many applications. Here, we report a bio-based two-step chemocatalytic system for the synthesis of a broad range of N-alkyl-2-pyrrolidones starting from glutamic acid and C₃–C₅ carbonyl compounds. In the first step N-mono-alkylated derivatives of glutamic acid were synthesized in high yields (>85%) by a mild and efficient Pd-catalyzed reductive N-alkylation. Subsequently, thermally induced lactamization to the corresponding N-alkylpyroglutamic acid followed by Pd-catalyzed decarboxylation at 250 °C under inert atmosphere resulted in N-alkyl-2-pyrrolidones. Hydrolytic degradation was partially counteracted by the neutralization of the N-alkylpyroglutamic acid substrate with a base, resulting in yields up to 82%. Finally, both reaction steps were successfully combined in a one-pot process using the same Pd/Al₂O₃ catalyst in different conditions of gas atmosphere and temperature.

中文翻译：

---

钯催化的谷氨酸还原性N-烷基化和脱羧的生物基N-烷基-2-吡咯烷酮

环保法规推动新的更安全，毒性较低的生物基溶剂的查找替换争议的高沸点溶剂，如ñ甲基-2-吡咯烷酮和ñ，ñ在化工行业二甲基甲酰胺。最近，N-烷基-2-吡咯烷酮和5-甲基-N-烷基-2-吡咯烷酮被提议作为许多应用的有吸引力的替代溶剂。在这里，我们报告了一种基于生物的两步化学催化系统，该系统可以从谷氨酸和C ₃ -C ₅羰基化合物开始合成范围广泛的N-烷基-2-吡咯烷酮。第一步N通过温和且有效的Pd催化的还原性N-烷基化以高产率（＞ 85％）合成了谷氨酸的α-单烷基化衍生物。随后，在惰性气氛下在250℃下热诱导内酰胺化成相应的N-烷基焦谷氨酸，然后Pd催化脱羧，得到N-烷基-2-吡咯烷酮。通过用碱中和N-烷基焦谷氨酸底物，部分抵消了水解降解，导致产率高达82％。最后，两个反应步骤在相同的Pd / Al ₂ O ₃催化剂下，在不同的气体气氛和温度条件下，通过一锅法成功地结合在一起。