Annuloselectivity in Reactions of Diacyl Dichlorides and Imines: Combined Experimental and Theoretical Studies
Annuloselectivity in Reactions of Diacyl Dichlorides and Imines: Combined Experimental and Theoretical Studies
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二酰二氯和亚胺反应的环选择性：实验和理论相结合的研究
DOI：
10.1021/acs.joc.5b00573
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发表时间：
2015
影响因子：
3.6
通讯作者：
Xu Jiaxi
中科院分区：
文献类型：
--
作者：
Li Xinyao;Jin Xin;Xu Jiaxi
环化选择性是指二酰二氯和亚胺在有机碱存在下[2 + 2]环化和级联环化生成双β-内酰胺和2，3-二氢-1，3-恶嗪-4-酮的选择性。结果表明，在有机碱存在下，二酰二氯优先生成环状α-氧代烯酮，这是控制环状选择性的因素。己二酰和庚二酰二氯的级联成环反应是在三乙胺存在下，氯离子辅助下，ω-氯羰基烷基烯酮的环化反应，而不是先生成双烯酮再二聚，得到五元和六元环α-氧代烯酮，然后与亚胺进行[4 + 2]成环反应，得到2，3-二氢-1，3-恶嗪-4-酮。这是一个积极的竞争途径正常施陶丁格环加成。进一步减少（戊二酰二氯）或增加连接基长度（辛二酰和壬二酰二氯）导致环化的能量屏障增强，这与直接施陶丁格环加成相比竞争力较小，以提供双-反式-β-内酰胺作为唯一产物。目前的结果提供了一个洞察环选择性控制在二酰二氯和亚胺的反应。
The annuloselectivity defined as the annulation selectivity between [2 + 2] and cascade annulations of diacyl dichlorides and imines in the presence of organic bases to afford bis-β-lactams and 2,3-dihydro-1,3-oxazin-4-ones has been studied extensively with a combination of experiments and density functional theory (DFT) calculations. The present results indicate that it is the preference of diacyl dichlorides in the formation of cyclic α-oxoketenes in the presence of organic bases that controls the annuloselectivity. The cascade annulations of hexanedioyl and heptanedioyl dichlorides undergo the chloride-assisted cyclization of the corresponding ω-chlorocarbonylalkylketenes as the rate-determining step in the presence of triethylamine, rather than the generation of bisketenes followed by dimerization, affording five- and six-membered cyclic α-oxoketenes followed by the [4 + 2] annulations with imines to furnish 2,3-dihydro-1,3-oxazin-4-ones. This is an energetically competitive pathway to the normal Staudinger cycloaddition. Further decreasing (pentanedioyl dichloride) or increasing the linker length (octanedioyl and nonanedioyl dichlorides) results in the enhanced energetic barriers for the cyclization, which is less competitive to the direct Staudinger cycloaddition to afford bis-trans-β-lactams as the sole products. The current results provide an insight into the annuloselective control in the reactions of diacyl dichlorides and imines.