Article
Chemistry, Multidisciplinary
Xiaobo Bao, Wei Yu, Lilin Wang, Xu Dong, Guoli Wang, Weilin Chen, Fei Li, Dongyin Chen
Summary: In this study, an Er(OTf)(3)-catalyzed cascade cyclization reaction of para-quinone methides (p-QMs) with various 1,3-dicarbonyl compounds was developed, leading to the formation of a series of versatile 4-aryl-3,4-dihydrocoumarins and 4-aryl-4H-chromenes. This work not only presents a novel cyclization strategy for p-QMs, but also provides a facile access to structurally diverse coumarins and chromenes.
Article
Chemistry, Organic
Xi Xiao, Xiaobiao Lu, Ming Zhang, Haoqing Hou, Changfeng Wan, Jinbiao Liu
Summary: A novel synthetic method was successfully developed for the preparation of multisubstituted dihydrochromeno[2,3-b]indole derivatives in moderate to high yields using a catalytic environmentally benign iron salt.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Review
Chemistry, Applied
Samir Manna, Kanak Kanti Das, Debasis Aich, Santanu Panda
Summary: Organoboron compounds have been widely used in everyday organic synthesis due to their Lewis acidic properties, non-toxicity, stability, and easy commercial availability. Among them, allenylboron compounds have emerged as a promising scaffold for various synthetic transformations, and numerous synthetic methods have been developed to access substituted allenylboron compounds in good yield. This review highlights the chronological synthesis and reactivity methods of allenylboron compounds known to date.
ADVANCED SYNTHESIS & CATALYSIS
(2021)
Article
Chemistry, Multidisciplinary
Hongbo Qi, Yupeng Zhao, Wencong Li, Shufeng Chen
Summary: A convenient Y(OTf)(3)-catalyzed cascade formal [4 + 2] cyclization approach for the formation of 1,4-benzoxazine scaffolds from benzoxazoles and propargyl alcohols has been developed. The mild and practical protocol allows for the preparation of a broad range of aldehyde-containing 1,4-benzoxazine compounds in moderate to excellent yields. Mechanistic studies revealed an S(N)1 nucleophilic substitution of benzoxazole with a propargyl cation in this transformation.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Applied
Mingshuai Zhang, Zhuoyuan Liu, Longkun Chen, Donghan Liu, Yulin Sun, Zhangmengjie Chai, Xue-Bing Chen, Fuchao Yu
Summary: A silver-catalyzed protocol for the synthesis of 3-(1H-isochromen)-chromones is described, which shows excellent regioselectivity and high bond-forming efficiency.
ADVANCED SYNTHESIS & CATALYSIS
(2022)
Article
Chemistry, Organic
Ya Wu, Ming Wang, Mei Xu, Sheng Liu
Summary: The Pictet-Spengler reaction of tryptamine and (5-methoxy-2-nitrophenyl)-glyoxal in hot AcOH can lead to a redox-mediated cyclization and reduction sequence, resulting in the formation of iheyamine A with a yield of 52%.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Applied
Elisa Brambilla, Silvia Meraviglia, Edoardo Moneta, Donatella Nava, Silvia Rizzato, Giorgio Abbiati, Valentina Pirovano
Summary: A photoredox-promoted approach for the synthesis of [1,4]diazepino[1,7-a]indol-6(7H)-ones starting from N-indolyl phenylacrylamides and aroyl chlorides as radical source is reported. This method involves a cascade radical addition on C-C double bond followed by intramolecular cyclization at indole C2-position, resulting in the formation of two diastereomeric indole-fused 1,4-diazepinones characterized by a N-C(aryl) axial chirality, with yields ranging from 51% to 99%.
ADVANCED SYNTHESIS & CATALYSIS
(2023)
Review
Chemistry, Applied
Xian-Rong Song, Ruchun Yang, Qiang Xiao
Summary: Significant progress has been made in recent years in the construction of heterocyclic compounds using propargylic alcohols, with reactions divided into four categories based on different types of nucleophiles to capture allenyl carbocation.
ADVANCED SYNTHESIS & CATALYSIS
(2021)
Article
Chemistry, Organic
Shuling Yu, Chao Hong, Zhanxiang Liu, Yuhong Zhang
Summary: In this study, the efficient synthesis of pyranones was achieved through a three-component cascade reaction under ruthenium catalysis using readily available acrylic acids, ethyl glyoxylate, and p-toluenesulfonamide. For the first time, the nucleophilic addition of the vinylic C-H bond of acrylic acids across aldehyde was achieved, followed by intramolecular cyclization and subsequent second insertion to aldehyde to form substituted butenolides. The sulfonamides were eliminated at higher temperature to yield the pyranones.
Article
Chemistry, Organic
Lei Xie, Chenyi Zhao, Zhaoxue Wang, Zirui Chen, Yingying Zhao, Xinghan Liu, Xiangdong Xu, Wanxing Liu, Xiaojing Li, Lingang Wu
Summary: An Et3N-catalyzed cascade [3 + 2]-annulation of beta-oxo-acrylamides with cyclic N-sulfonyl ketimines or sulfamate-derived imines has been developed, providing a concise and efficient route to valuable sultam- or sulfamidate-fused imidazolidinone derivatives in good to excellent yields with excellent diastereoselectivities. The protocol features atom economy, a transition-metal-free process, and broad functional group tolerance. Moreover, the asymmetric variant of the [3 + 2]-cycloaddition reaction was achieved using chiral organocatalysts, giving the corresponding chiral polycyclic imidazolidinones in good yields with high enantioselectivities and diastereoselectivities.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Qi-Wen Shen, Wei Wen, Qi-Xiang Guo
Summary: The first catalytic asymmetric cascade Heck-alkylation reaction of NH2-unprotected amino acid esters with N-(2-iodophenyl)allenamides is reported in this work. The reaction proceeds smoothly using a combining catalytic system comprising a chiral aldehyde, a chiral palladium complex, and the Lewis acid ZnCl2, giving optically active alpha-alkyl tryptophan derivatives in moderate to good yields and excellent enantioselectivities. The target products can be converted into other structurally complex chiral indoles without the loss of enantioselectivities.
Article
Chemistry, Organic
Bingyue Zhao, Xiaoxian Li, Xiaofan Wang, Luchen Jiang, Zhe Li, Yunfei Du
Summary: The treatment of 2-alkenylanilines with PIDA and LiBr or KI in HFIP leads to the formation of 3-haloindoles via cascade oxidative cyclization/halogenation involving C-N/C-X (X = Br, I) bond formations. A proposed mechanism suggests the in situ formation of reactive AcO-X (X = Br, I) from the reaction of PIDA and LiBr/KI.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Genlai Zhou, Jingwen Su, Tianbo Shang, Xiaojuan Wang, Yihui Bai, Zheliang Yuan, Gangguo Zhu
Summary: A novel transformation of N-allyl ynamides was developed, enabling the synthesis of nitrogen-fused tricyclic compounds under mild reaction conditions through cascade reactions. This represents a rare example of 4-exo-dig radical cyclization, providing a new opportunity for the construction of synthetically appealing azetidines from readily available N-allyl ynamides.
ORGANIC CHEMISTRY FRONTIERS
(2021)
Article
Chemistry, Organic
Matteo Faltracco, Said Ortega-Rosales, Elwin Janssen, Razvan C. Cioc, Christophe M. L. Vande Velde, Eelco Ruijter
Summary: The unexpected discovery in a seemingly trivial reaction led to the selective formation of a new carbazole product. This reaction, by carefully varying substituents, revealed a complex cascade mechanism with at least 10 elementary steps that could be directed towards different carbazole derivatives.
Article
Chemistry, Organic
Siqi Dong, Shaofeng Xu, Yashi Zou, Zhaodi Li, Kai Xu, Daxu Fu, Delong Liu, Wanbin Zhang
Summary: A RuPHOX/Pd catalyzed asymmetric allylic substitution cascade of α-carbonylamides with an allylic meso-dicarbonate has been developed to synthesize chiral 3-acyl bicyclolactams bearing three vicinal carbon stereocenters in high yields. The products exhibited excellent enantioselectivity with up to 99% ee and high diastereoselectivity with >20:1 dr. Mechanistic studies revealed a dynamic kinetic resolution process during the second step of the cascade reaction, which contributed to the high diastereoselectivity. The protocol can be scaled up and the resulting products are versatile for further transformations, especially in the synthesis of natural products.
ORGANIC CHEMISTRY FRONTIERS
(2023)
