甲肟基团已成为多种 C-H 官能化的多功能导向基团。尽管甲肟作为一种强大的功能手柄很重要,但通常需要将甲肟转化为母酮,但通常需要苛刻且官能团不耐受的反应条件。因此,甲肟的应用及其随后在后期转化为相应的酮可能会出现问题。在这里,我们提出了一组替代条件,以使用光激发硝基芳烃实现甲肟到母酮的温和且官能团耐受的转化。该方法的实用性体现在其在头孢内酯 D 的全合成中的应用。此外,还提供了通过同位素标记研究以及反应副产物分析获得的这种转化的机制见解。
The Preparation of 1H-Pyrazole-1-carboxylic Acid, 1, 1-Dimethylethyl Esters from Dilithiated C(α), N-Hydrazones of Hydrazinecarboxylic Acid, 1, 1-Dimethylethyl Ester
摘要:
C(alpha),N-Hydrazones of hydrazinecarboxylic acid, 1,1-dimethylethyl ester [C(alpha),N-carbo-t-butoxyhydrazones] were metalated with excess lithium diisopropylamide, and the dianion-type intermediates were condensed with select aromatic esters followed by acid cyclization to substituted 1H-pyrazole-1-carboxylic acid, 1,1-dimethylethyl esters (N-carbo-t-butoxypyrazoles).
Preparation of 2<i>H</i>-spiro[benzo[<i>d</i>]isothiazole-3,3′-pyrazole]-1, 1-dioxide-2′(4′<i>H</i>)-carboxylates from dilithiated<i>C</i>(α),<i>N</i>-carboalkoxyhydrazones and methyl 2-(aminosulfonyl)benzoate
作者:Anna C. Dawsey、Chandra Potter、John D. Knight、Zachary C. Kennedy、Ellyn A. Smith、Amanda M. Acevedo-Jake、Andrew J. Puciaty、Clyde R. Metz、Charles F. Beam、William T. Pennington、Donald G. VanDerveer
DOI:10.1002/jhet.50
日期:2009.3
A variety of substituted spiro(benzoisothiazole-pyrazoles) have been prepared by the condensation of dilithiated C(α),N-carboalkoxyhydrazones with lithiated methyl 2-(aminosulfonyl)benzoate followed by the cyclization of intermediates with acetic anhydride, which also resulted in spiro N-acetylated products when carbomethoxyhydrazones or carboethoxyhydrazones were used, and spiro NH products when
Rhodium-Catalyzed Oxidative Cycloaddition of <i>N</i>
-<i>tert</i>
-Butoxycarbonylhydrazones with Alkynes for the Synthesis of Functionalized Pyrroles <i>via</i>
C(<i>sp</i>
<sup>3</sup>
)-H Bond Functionalization
作者:Chun-Ming Chan、Zhongyuan Zhou、Wing-Yiu Yu
DOI:10.1002/adsc.201600900
日期:2016.12.22
The reaction features a regioselective α‐imino alkyl C(sp3)−H bond functionalization resulting in selective formation of highlyfunctionalized NH‐free pyrroles. Our studies showed that utilizing the N‐tert‐butoxycarbonyl (N‐Boc) as the oxidizing directing group is critical for achieving the observed pyrrole formation versus the isoquinoline formation. To account for the pyrrole formation, we hypothesized
A C–H activation-based strategy has been developed for the synthesis of N-amino azaheterocycles. Rh(III)-catalyzed coupling of N-Boc hydrazones/N-Boc hydrazines with diazodiesters/diazoketoesters provides convenient access to synthetically and medicinally important compounds, N-amino isoquinolin-3-ones and N-amino indoles, by harnessing N-tert-butyloxycarbonyl (N-Boc) cleavage as an adaptable reactivity