N-酰氧基-N-烷氧基酰胺1a是不寻常的异头异构酰胺,其由于双氧基取代而在氮上呈锥体状。通过这种构型,它们失去了大部分酰胺特性,并且在反应性上类似于α-卤代酮。它们在氮气下易受S N 2反应的影响,这是导致其诱变行为的原因。动力学研究已经进行了与亲核试剂Ñ甲基苯胺,显示的是,最喜欢S ñ在碳中心,速率常数为S 2个的反应Ñ通过将β分支到氮中心或烷氧基侧链上的大体积基团,可降低2羧酸盐的置换。然而,羧酸酯离去基团上的支链或大体积基团不影响取代率,其主要由离去的羧酸酯基团的p K A控制。这些结果与氨与N-乙酰氧基-N-甲氧基乙酰胺的模型反应的计算性质相符,但与空间效应对其致突变性的作用相反。
Hindered ester formation by S<sub>N</sub>2 azidation of N-acetoxy-N-alkoxyamides and N-alkoxy-N-chloroamides—novel application of HERON rearrangements
作者:Stephen A. Glover、Guoning Mo
DOI:10.1039/b111250n
日期:——
Treatment of N-acetoxy-N-alkoxyamides or N-alkoxy-N-chloroamides with sodium azide in aqueous acetonitrile results in SN2 displacement of chloride and the formation of reactive N-alkoxy-N-azidoamides. The reaction with N-acetoxy-N-benzyloxybenzamide has been studied kinetically (k294
= 2 L molâ1 sâ1) and azidation of N-formyloxy-N-methoxyformamide has been modeled computationally at the pBP/DN*//HF/6-31G* level of theory. The anomeric amides N-alkoxy-N-azidoamides decompose intramolecularly and spontaneously to esters and two equivalents of nitrogen. This extremely exothermic process facilitates the formation, in excellent yields, of highly hindered esters.
在水合乙腈中,N-乙酸氧基-N-烷氧基酰胺或N-烷氧基-N-氯酰胺与叠氮化钠反应会导致氯的SN2取代,并形成反应性N-烷氧基-N-叠氮酰胺。对N-乙酸氧基-N-苄氧基苯甲酰胺的反应动力学进行了研究(k294 = 2 L mol⁻¹ s⁻¹),并在pBP/DN*//HF/6-31G*理论水平上对N-甲酸氧基-N-甲氧基甲酰胺的叠氮化反应进行了计算模拟。异头酰胺N-烷氧基-N-叠氮酰胺会自发地发生分子内分解,生成酯和两分子氮气。这一极放热过程促进了高阻碍酯的高产率形成。
SN2 Substitution Reactions at the Amide Nitrogen in the Anomeric Mutagens, N-Acyloxy-N-alkoxyamides
作者:Katie L. Cavanagh、Stephen A. Glover、Helen L. Price、Rhiannon R. Schumacher
DOI:10.1071/ch09166
日期:——
amide character and resemble α-haloketones in reactivity. They are susceptible to SN2reactions at nitrogen, a process that is responsible for their mutagenic behaviour. Kinetic studies have been carried out with the nucleophile N-methylaniline that show that, like SN2reactions at carbon centres, the rate constant for SN2 displacement of carboxylate is lowered by branching β to the nitrogen centre, or
N-酰氧基-N-烷氧基酰胺1a是不寻常的异头异构酰胺,其由于双氧基取代而在氮上呈锥体状。通过这种构型,它们失去了大部分酰胺特性,并且在反应性上类似于α-卤代酮。它们在氮气下易受S N 2反应的影响,这是导致其诱变行为的原因。动力学研究已经进行了与亲核试剂Ñ甲基苯胺,显示的是,最喜欢S ñ在碳中心,速率常数为S 2个的反应Ñ通过将β分支到氮中心或烷氧基侧链上的大体积基团,可降低2羧酸盐的置换。然而,羧酸酯离去基团上的支链或大体积基团不影响取代率,其主要由离去的羧酸酯基团的p K A控制。这些结果与氨与N-乙酰氧基-N-甲氧基乙酰胺的模型反应的计算性质相符,但与空间效应对其致突变性的作用相反。