2-Phenallyl as a versatile protecting group for the asymmetric one-pot three-component synthesis of propargylamines
作者:Nina Gommermann、Paul Knochel
DOI:10.1039/b507810e
日期:——
2-Phenallyl was found to be a versatile protecting group of primary amines for the asymmetric one-pot three-component synthesis of propargylamines which leads to enantiomeric excess of up to 96%; it can be easily removed with a palladium(0)-catalyzed allylic substitution using 1,3-dimethylbarbituric acid as a nucleophile.
Two Approaches toward the Formal Total Synthesis of Oseltamivir Phosphate (Tamiflu): Catalytic Enantioselective Three-Component Reaction Strategy and <scp>l</scp>-Glutamic Acid Strategy
Two independent formal total syntheses of oseltamivir phosphate were successfully achieved: the first utilized a copper-catalyzed asymmetric three-component reaction strategy, and the second utilized L-glutamic acid gamma-ester as a chiral source to install the correct stereochemistry. Both strategies used Dieckmann condensation to construct a six-membered ring core, after which manipulation of the functional groups and protecting groups accessed Corey's intermediate for the synthesis of oseltamivir phosphate. While the first synthesis was accomplished via four purification steps in 25.7% overall yield, albeit with moderate optical purity (76% ee), the second strategy achieved the synthesis via six purification steps in 19.8% overall yield with perfect enantiocontrol.
Flavin-Mediated Visible-Light [2+2] Photocycloaddition of Nitrogen- and Sulfur-Containing Dienes
[2+2] Photocycloaddition mediated by 1-butyl-3-methyl-7,8-dimethoxyalloxazine (1) is shown as an effective tool to cyclise ω-phenyl and ω,ω'-diphenyl-4-aza-1,6-heptadienes, with the nitrogen atom protected by acylation or quaternisation, used towards the synthesis of variety of phenyl- and diphenyl-3-azabicyclo[3.2.0]heptanes and their corresponding quaternary salts. Thia-derivatives with the sulfur