Enantioselective Synthesis of α-Fluoro-β3-amino Esters: Synthesis of Enantiopure, Orthogonally Protected α-Fluoro-β3-lysine
摘要:
The scope of a tandem conjugate addition fluorination sequence performed on alpha,beta-unsaturated esters using the enantiopure lithium amide derived from (S)-N-benzyl-N-(alpha-methylbenzyl)amine, and the electrophilic fluorinating agent N-fluorobenzenesulfonimide has been investigated. Using this method, a-fluoro-beta(3)-amino esters can be obtained in up to quantitative yield and 80:20 to >99:1 dr. This simple methodology does not rely on the use of alpha-amino acids from the chiral pool and thus provides the potential for the preparation of enantiopure alpha-fluoro-beta(3)-amino acids with a wide variety of side chains. Its utility was demonstrated through the synthesis of orthogonally protected (2S,3S)-alpha-fluoro-beta(3)-lysine.
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
Highly Efficient and Stereoselective Julia-Kocienski Protocol for the Synthesis of α-Fluoro-α,β-unsaturated Esters and Weinreb Amides Employing 3,5-Bis(trifluoromethyl)phenyl (BTFP) Sulfones
作者:Diego A. Alonso、Mónica Fuensanta、Enrique Gómez-Bengoa、Carmen Nájera
DOI:10.1002/adsc.200800194
日期:2008.8.4
α-Fluoroacetates 3 and Weinreb amide 4, bearing a α-[3,5-bis(trifluoromethyl)phenyl]sulfonyl (BTFP-sulfonyl) group at the α-position, are employed in the highly stereoselective synthesis of α-fluoro-α,β-unsaturated alkenoates and Weinrebamides, respectively. Aromatic and aliphatic aldehydes are condensed under extremely mild and simple reaction conditions using potassium carbonate in dimethylformamide