One-Pot Synthesis of 4H-Chromenes by Tandem Benzylation and Cyclization in the Presence of Sodium Bisulfate on Silica Gel
摘要:
A simple and efficient method has been developed for the synthesis of 4H-chromenes from o-hydroxybenzylic alcohols and dicarbonyl compounds containing active methylene groups by using silica gel supported sodium bisulfate. Various dicarbonyl compounds such as diketones, keto esters, and keto amides can be used in the synthesis of the 4H-chromenes.
Naphthalene-catalysed lithiation of functionalized chloroarenes: regioselective preparation and reactivity of functionalized lithioarenes
摘要:
The lithiation of different functionalized chloroarenes (dichlorobenzenes 1 and 3. mono and dichlorophenols 9 and 14, and chloropivalanilides 18) in the presence of a catalytic amount of naphthalene leads to the corresponding functionalized lithioarenes, which react with electrophiles to give the expected polyfunctionalized aromatic molecules 2, 4, 10. 19, 21, 22 and 24 in a regioselective manner. In the case of starting from chlorinated phenols or anilides a deprotonation of the functional group is carried out prior to the lithiation process; only for 2-chloropivalanilide 18o a coupling reaction leading to 2-n-butylpivalanilide is observed when an excess of n-butyllithium is used in the deprotonation step.
Low-energy collision-induced fragmentation of negative ions derived fromortho-,meta-, andpara-hydroxyphenyl carbaldehydes, ketones, and related compounds
作者:Athula B. Attygalle、Josef Ruzicka、Deepu Varughese、Jason B. Bialecki、Sayed Jafri
DOI:10.1002/jms.1252
日期:2007.9
2-hydroxy-1-naphthaldehyde, both of which show two consecutive CO eliminations, specifically lose the carbonyloxygen first, followed by that of the phenolic group. Anions from 2-hydroxyphenyl alkyl ketones lose a ketene by a hydrogen transfer predominantly from the alpha position. Interestingly, a very significant charge-remote 1,4-elimination of a H(2) molecule was observed from the anion derived from 2,4-dihydroxybenzaldehyde
记录了几种羟基苯基甲醛和酮产生的阴离子的碰撞诱导解离(CID)质谱,并进行了机械合理化。例如,去质子化的邻羟基苯甲醛的m / z 121离子光谱在m / z 93处显示一个强烈的峰,表明一氧化碳的损失归因于由电荷定向的杂化断裂机制介导的邻位效应。相反,衍生自间位和对位异构体的m / z 121离子经过电荷远程均质裂解以消除* H并形成distonic阴离子自由基,最终使CO丢失,从而在m / z 92处出现一个峰。对于对位异构体,这种两步均质机制是最主要的片段化途径。另一方面,间位异构体的光谱 图1b显示了分别在m / z 92和93处的两个主要峰,分别代表了同质和异质碎片。(18)O-同位素标记研究证实,从间羟基苯甲醛的阴离子中消除的CO分子中的氧源自醛基或酚基。相反,邻羟基苯甲醛和2-羟基-1-萘醛的阴离子,都显示出连续的两次CO消除,首先是先失去羰基氧,然后才失去酚基团的羰基氧。
A Simple Synthesis of Densely Substituted Benzofurans by Domino Reaction of 2-Hydroxybenzyl Alcohols with 2-Substituted Furans
作者:Anton S. Makarov、Anna E. Kekhvaeva、Petrakis N. Chalikidi、Vladimir T. Abaev、Igor V. Trushkov、Maxim G. Uchuskin
DOI:10.1055/s-0039-1690000
日期:2019.10
Brönsted acid-catalyzed cascade synthesis of densely substituted benzofurans from easily available salicyl alcohols and biomass-derived furans has been developed. The disclosed sequence includes the intermediate formation of 2-(2-hydroxybenzyl)furans that quickly rearrange into functionalized benzofurans. The established protocol was applied for the total synthesis of sugikurojinol B. The Brönsted
Ferrocene-Decorated Phenol Derivatives by Trapping <i>ortho</i>
-Quinone Methide Intermediates with Ferrocene
作者:Silvia González-Pelayo、Enol López、Javier Borge、Noemí de-los-Santos-Álvarez、Luis A. López
DOI:10.1002/ejoc.201800396
日期:2018.6.15
The InCl3‐catalyzed reaction of ortho‐hydroxybenzyl alcohols with ferrocene provided ferrocenyl phenols. Control experiments support the participation of ortho‐quinone methides as key intermediates. A preliminary study revealed that some of the functionalized ferrocene derivatives prepared display significant cytotoxicity against various cancer cell lines.
formal [4 + 2] cycloaddition of oximes with o-hydroxybenzyl alcohols was developed to easily synthesize diverse 1,3-benzoxazine derivatives. This synthesis was achieved under visible light-based organocatalytic and TsOH conditions. The reaction proceeds through the photoisomerization of oximes via visible light-mediated energy transfer, followed by the nucleophilic attack of o-QMs to oximes as a 1,2-dipole