39626-31-8Relevant articles and documents
Substituent-Controlled Divergent Cascade Cycloaddition Reactions of Chalcones and Arylalkynols: Access to Spiroketals and Oxa-Bridged Fused Heterocycles
Chang, Weixing,Kong, Jingyang,Li, Jing,Liu, Lingyan,Wang, Hongkai,Zeng, Tianlong
supporting information, p. 4024 - 4032 (2021/07/12)
Herein, we report substituent-controlled divergent cascade cycloaddition reactions of chalcones and arylalkynols in the presence of PtI2. Depending on the substituent on the chalcone, either spiroketals or oxa-bridged fused heterocycles could be obtained in the ranges of 86–97% and 87–95% yields under identical reaction conditions. Control experiments were carried out to elucidate the origin of the high chemoselectivity. These provide a method for the synthesis of a diverse array of structurally complex oxygen-containing heterocycles. (Figure presented.).
Enzyme Promiscuity as a Remedy for the Common Problems with Knoevenagel Condensation
Koszelewski, Dominik,Ostaszewski, Ryszard
, p. 10156 - 10164 (2019/07/09)
A new protocol based on lipase-catalyzed tandem reaction toward α,β-enones/enoesters is presented. For the synthesis of the desired products the tandem process based on enzyme-catalyzed hydrolysis and Knoevenagel reaction starting from enol acetates and aldehyde is developed. The relevant impact of the reaction conditions including organic solvent, enzyme type, and temperature on the course of the reaction was revealed. It was shown that controllable release of the active methylene compound from the corresponding enol carboxylate ensured by enzymatic reaction diminishes significantly the formation of the unwanted co-products. Furthermore, this protocol was extended by including a second tandem chemoenzymatic transformation engaging various aldehyde precursors. After a careful optimization of the reaction conditions, the target products were obtained with yields up to 86 % and with excellent E/Z-selectivity.
CBr4 as a Halogen Bond Donor Catalyst for the Selective Activation of Benzaldehydes to Synthesize α,β-Unsaturated Ketones
Kazi, Imran,Guha, Somraj,Sekar, Govindasamy
supporting information, p. 1244 - 1247 (2017/03/14)
CBr4 has been employed as a halogen bond donor catalyst for the selective activation of aldehyde, to achieve an efficient solvent- and metal-free CC bond forming reaction in the presence of strong acid sensitive groups such as methoxy, cyanide, ester, and ketal for the synthesis of α,β-unsaturated ketones. This unique capability of CBr4 to act as a halogen bond donor has been explored and established using UV-vis as well as IR spectroscopy. Moreover, this unprecedented methodology enables the synthesis of the pharmaceutically important molecule licochalcone A.
