Quinine-Based Trifunctional Organocatalyst for Tandem Aza-Henry Reaction-Cyclization: Asymmetric Synthesis of Spiroxindole-Pyrrolidine/Piperidines
作者:Saumen Hajra、Bibekananda Jana
DOI:10.1021/acs.orglett.7b02150
日期:2017.9.15
A quinine-derived trifunctional sulphonamide catalyst has been developed for the effective asymmetric organocatalytic tandem aza-Henry reaction-cyclization of isatin-derived ketimines and nitroalkane-mesylates for the synthesis of spiro-pyrrolidine/piperidine-oxindoles. Demethylation of traditional bifunctional catalyst to incorporate an additional hydrogen bonding C6′–OH group plays the key role toward
作者:Songsong Guo、Pei Dong、Yushuang Chen、Xiaoming Feng、Xiaohua Liu
DOI:10.1002/anie.201810679
日期:2018.12.17
copper(I) catalyst for the asymmetric azide‐alkynecycloaddition/[2+2] cascade reaction. Optically active spiroazetidinimine oxindoles were constructed by trapping the ketenimine species under mild reaction conditions. High level of enantioinduction and excellent isolated yields were achieved in the three‐component reaction of various isatin‐derived ketimines, sulfonyl azides, and terminal alkynes. Control
Enantioselective hydrophosphonylation of N - benzyl imines, isatin derived ketimines and isatins catalyzed by in-situ generated Ti(IV) macrocyclic salen complexes
作者:Mohd Nazish、Ajay Jakhar、Noor-ul H. Khan、Shailesh Verma、Rukhsana I. Kureshy、Sayed H.R. Abdi、Hari C. Bajaj
DOI:10.1016/j.apcata.2015.12.037
日期:2016.4
benzylimines, whereas for ketiminesdiphenylphosphite (IIb) gave best results with very good yield (up to 88%) and ee (up to 99%). The Ti(IV) complex was recoverable and recyclable with retention of its catalytic performance at gram scale level. To understand the reaction mechanism NMR studies have been carried out using benzylimine as a model substrate and dimethyl phosphite as a nucleophile.
Cobalt Used as a Novel and Reusable Catalyst: A New and One-Pot Synthesis of Isatin-Derived N,S-Acetals Using Substituted Isatins and Thiols
作者:Caren D. G. da Silva、Ramesh Katla、Beatriz F. dos Santos、José M. C. Tavares Junior、Tábata B. Albuquerque、Vicente L. Kupfer、Andrelson W. Rinaldi、Nelson L. C. Domingues
DOI:10.1055/s-0037-1611913
日期:2019.11
cleaner reaction profiles. The synthesis of isatin-derived N,S-acetals using cobalt as a recyclable heterogeneouscatalyst in batch and continuousflow is reported for the first time. The present protocol produced high yields, which can be observed from the reaction between ketimines and thiols. Such reactions can also be applied to a gram-scale. In addition, the catalyst is recyclable, economically-viable
Phosphine-mediated Highly Enantioselective Spirocyclization with Ketimines as Substrates
作者:Xiaoyu Han、Wai-Lun Chan、Weijun Yao、Yongjiang Wang、Yixin Lu
DOI:10.1002/anie.201600453
日期:2016.5.23
Phosphine‐catalyzed enantioselectiveannulation reactions involving ketimines are a daunting synthetic challenge owing to the intrinsic low reactivity of ketimine substrates. A highly enantioselective [3+2] cycloaddition reaction that makes use of isatin‐derived ketimines as reaction partners was developed. Notably, both simple and γ‐substituted allenoates could be utilized, and various 3,2′‐pyrrolidinyl