Exceptionally Mild, High-Yield Synthesis of α-Fluoro Acrylates
作者:Barbara Zajc、Shivani Kake
DOI:10.1021/ol0616236
日期:2006.9.1
chiral alkyl alpha-(1,3-benzothiazol-2-ylsulfonyl)-alpha-fluoroacetates can be readily synthesized by metalation-fluorination of (1,3-benzothiazol-2-ylsulfonyl)acetates. DBU-mediated condensations of these fluorinated synthons with aldehydes proceed in a facile manner at 0 degrees C or at room temperature giving high yields of alpha-fluoro acrylates. Ketones are unreactive under these conditions. The
Asymmetric Photodeconjugation: Highly Stereoselective Synthesis of α-Fluorocarboxylic Derivatives
作者:Frédéric Bargiggia、Sylvia Dos Santos、Olivier Piva
DOI:10.1055/s-2002-20028
日期:——
Irradiations of α-fluoro-α,β-unsaturated esters lead to the corresponding α-fluoro-β,γ-unsaturated isomers in good yields. The reaction required the use of an achiral base (typically an amine) to promote the protonation of the photodienolic intermediate. By replacing the ethyl group with a diacetone-d-glucose moiety, the reaction can be carried out in a diastereoselective manner to furnish the deconjugated esters with similar yields and selectivities up to 95%. The adducts were submitted to osmylation conditions to deliver α-fluoro-β-hydroxy-butyrolactones in one single step.