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。
Transition-Metal-Free Synthesis of <i>N</i>-Aryl Hydroxamic Acids via Insertion of Arynes
作者:Lanlan Zhang、Yu Geng、Zhong Jin
DOI:10.1021/acs.joc.6b00111
日期:2016.5.6
carbon–carbon double bonds, and free N–H bond of indole are found to be compatible with this process. In particular, the protocol is applicable in the synthesis of structurally diverse N-aryl hydroxamates and hydroxamicacids derived from N-protecting amino acids and peptides. In the presence of multiple amide N–H bonds, the N-arylation reaction can proceed selectively in the N–H bonds of terminal N-OBn amides
Propargyl Alcohols as One-Carbon Synthons: Redox-Neutral Rhodium(III)-Catalyzed C–H Bond Activation for the Synthesis of Isoindolinones Bearing a Quaternary Carbon
作者:Xiaowei Wu、Bao Wang、Yu Zhou、Hong Liu
DOI:10.1021/acs.orglett.7b00089
日期:2017.3.17
C–H activation/subsequent [4 + 1] cyclization reactions between benzamides and propargyl alcohols are reported in which propargyl alcohols serve as unusual one-carbon units. This title transformation led to a series of isoindolinones bearing a quaternary carbon with moderate to good yields without the requirement for external metal oxidants. Due to the mild and simple reaction conditions, this reaction
Alcohols and aldehydes are oxidised to the corresponding methyl esters by reaction with methanol in the presence of crotononitrile as a hydrogen acceptor using a catalyst combination of Ru(PPh3)3(CO)H2 with xantphos. alcohols - esters - ruthenium - catalysis - hydrogen transfer
A novel Pd-catalysed CâH activation reaction for the synthesis of biaryl imino/keto carboxylic acids is developed. This reaction underwent aryl amide directed CâH activation ortho-acylation followed by ring closing and ring opening processes to give a range of biaryl imino/keto carboxylic acids. Our methodology features the utilization of a cheap and green oxidant (TBHP) as well as readily available aldehydes.