A practical protocol for the large-scale preparation of 2-diazo-1,3-dicarbonyl compounds is described by diazo-transfer reactions with tosyl azide followed by efficient chromatographic purifications on silica gel and/or alumina. diazo compounds - ketones - esters - Regitz reaction - chromatography
The stereoselective syntheses of spirobicyclic and tetracyclic pyrazolidinones are reported based on a (3+2) annu- lation between hydrazones and α-oxoketenes. Some of these conformationally constrained molecules were resolved as enantiopure materials by HPLC techniques and evaluated as amino- catalysts for iminium activation in a model Diels–Alder cyclo- addition.
Copper Triflate Mediated α-Monohalogenation of α-Diazo β-Ketosulfones with Ammonium Halides
作者:Ru-Ting Hsu、Meng-Yang Chang、Chieh-Kai Chan、Heui-Sin Wang
DOI:10.1055/s-0036-1589479
日期:——
Abstract Copper triflate mediated α-monohalogenation of α-diazo β-ketosulfones with ammonium halides provides the corresponding α-halo β-ketosulfones. Different metal triflates are investigated for this facile and efficient transformation. A plausible mechanism is proposed. Copper triflate mediated α-monohalogenation of α-diazo β-ketosulfones with ammonium halides provides the corresponding α-halo
Metal-Triflate-Catalyzed Synthesis of Polycyclic Tertiary Alcohols by Cyclization of γ-Allenic Ketones
作者:Ilhem Diaf、Gilles Lemière、Elisabet Duñach
DOI:10.1002/anie.201310724
日期:2014.4.14
It has been established that bismuth(III) triflate catalyzes the cyclization of γ‐allenic ketones under mild reaction conditions. This reaction allows the selective formation of polycyclic tertiary alcohols from cyclic ketone derivatives. The resulting dienols can engage in stereoselective cycloadditions to efficiently afford complex polycyclic systems.
Synthesis of Polysubstituted Phenols by Rhodium‐Catalyzed C−H/Diazo Coupling and Tandem Annulation
作者:Min Liu、Kelu Yan、Jiangwei Wen、Xue Li、Xiaoyu Wang、Fengjie Lu、Xiu Wang、Hua Wang
DOI:10.1002/adsc.202001456
日期:2021.3.29
rhodium(III)‐catalyzed C−H/diazo coupling and tandem annulation of 3‐oxopent‐4‐enenitriles have been proposed for the synthesis of polysubstituted phenols. Most products of phenols are obtained in good yields. Several preliminary mechanistic studies and derivatization reactions of phenol products were also performed. This method offers an alternative approach for the synthesis of useful diverse phenols.