Diastereoselective Synthesis of Lincosamine Precursors
作者:Fiona Serra、Philippe Coutrot、Mélanie Estève-Quelquejeu、Patrick Herson、Tomasz K. Olszewski、Claude Grison
DOI:10.1002/ejoc.201001740
日期:2011.4
strategy is a three-step synthesis that is based on the treatment of the β-iodo-α-keto ester with dibenzylamine. Subsequent reduction of the β-amino-α-keto ester provides the pure D-erythro, L -threo, L-erythro, and D-threo aminodiols after chromatographic purification. Further classical transformations afford the N-acetyl derivatives, which are key precursors of the lincosamine diastereomers.
Preparation of unsaturated α,α-dichloro acid chlorides and intramolecular [2 + 2] cycloadditions of the α-chloroketenes reductively generated from them. Effect of double bond geometry on the cycloaddition
作者:Barry B. Snider、Marleen Walner
DOI:10.1016/s0040-4020(01)80143-5
日期:1989.1
Reduction of unsaturatedα,α-dichloracid chlorides with zinc dust in THF at reflux generates an unsaturated α-chloroketene which undergoes an intramolecular [2 + 2] cycloaddition in good yield. This reaction can be used with three carbon tethers to prepare 5-chlorobicyclo[3.2.0]heptan-6-ones and 1-chlorobicyclo[3.1.1]heptan-6-ones but fails with larger tethers. Unsaturated ketenes 18 and 28, with a
The chain extension with an α-hydroxyester unit of various carbonylcompounds was realized, in two steps, via α-chloroglycidic esters. Synthesis, results and expected mechanisms are reported.
Two synthetic routes are proposed to prepare phosphoenolpyruvate derivatives of xylose as models of potent phosphoenol pyruvate lyase inhibitors: a Perkow reaction between β-bromo-α-ketoester derivatives of xylose 4 and trimethylphosphite, and a new reaction between α-bromoglycidic ester derivatives of xylose 3 and trimethylphosphite.
Concise Photochemical Synthesis of the Antimalarial Indole Alkaloid Decursivine
作者:Mark Mascal、Kyle V. Modes、Asuman Durmus
DOI:10.1002/anie.201006423
日期:2011.5.2
A four‐step synthesis of the extracyclic, antimalarialindole natural product decursivine is described starting from commercial piperonyl bromide and serotonin (see scheme). A photoinitiated reaction cascade involving indole radical cation formation, rearrangement, radical recombination, rearomatization, elimination, and diastereoselective auto‐acid‐catalyzed closure of the dihydrofuran ring combine