29978-38-9Relevant articles and documents
Multisubstituted pyrazole synthesis via [3?+?2] cycloaddition/rearrangement/N[sbnd]H insertion cascade reaction of α-diazoesters and ynones
Feng, Xiaoming,Liu, Xiaohua,Zeng, Zi,Zhao, Peng
supporting information, p. 132 - 135 (2020/12/21)
The cascade reactions of alkyl α-diazoesters and ynones using Al(OTf)3 as the catalyst are described. A series of 4-substituted pyrazoles were obtained via [3 + 2] cycloaddition, 1,5-ester shift, 1,3-H shift, and N[sbnd]H insertion process. Deuterium labelling experiments, kinetic studies and control experiments were carried out for the rationalization of the mechanism.
Regioselectivity Switch in Palladium-Catalyzed Allenylic Cycloadditions of Allenic Esters: [4+1] or [4+3] Cycloaddition/Cross-Coupling
Li, Long,Luo, Pengfei,Deng, Yuhua,Shao, Zhihui
supporting information, p. 4710 - 4713 (2019/03/08)
The first Pd-catalyzed asymmetric allenylic [4+1] cycloaddition was successfully developed. Alternatively, tuning the Pd catalyst switched the reactivity toward an unprecedented [4+3] cycloaddition/cross-coupling. Ligands play a vital role in controlling the reaction pathway, allowing highly selective access to different products from identical substrates. Biological evaluation of the obtained compounds led to the discovery of new antitumor targets. A possible mechanism is proposed, suggesting two interesting catalytic cycles for the cycloaddition with palladium-butadienyls. This study also demonstrated the potential and utility of allenic esters as 1,4-biselectrophiles and C4 synthons for participating in cycloaddition reactions.
Copper- and borinic acid-catalyzed propargylic etherification of propargylic carbonates with benzyl alcohols
Tsuchida, Kohei,Yuki, Masahiro,Nakajima, Kazunari,Nishibayashi, Yoshiaki
supporting information, p. 671 - 673 (2018/04/30)
Propargylic substitution reactions have offered useful synthetic methods because further transformations based onthe alkyne moiety in the propargylic substituted products are readily achieved to construct more complex organic compounds. A large number of studies have been devoted to enantioselective propargylic substitution reactions with a variety of nucleophiles. However, successful examples of the use of alcohols as nucleophiles have been quite limited until now. To achieve utilization of aliphatic alcohols, herein we report the use of combined catalysis of a copper-pybox complex and a borinic acid. In this catalytic system, aliphatic alcohols such as benzyl alcohol derivatives were successfully applied to afford the corresponding propargylic etherified products in good yields with high enantioselectivities.
