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 Weinreb amides, respectively. Aromatic and aliphatic aldehydes are condensed under extremely mild and simple reaction conditions using potassium carbonate in dimethylformamide
α-氟-α的高度立体选择性合成中使用了在α位带有α-[3,5-双(三氟甲基)苯基]磺酰基(BTFP-磺酰基)基团的α-氟乙酸酯3和Weinreb酰胺4。 ,β-不饱和链烯酸酯和Weinreb酰胺。使用碳酸钾在二甲基甲酰胺中,在室温下,在固液相转移催化条件下,在极温和和简单的反应条件下,以高收率和高Z值缩合芳族和脂肪族醛-非对映选择性,特别是在氟化的Weinreb酰胺的情况下。一项详细的计算机理研究表明,最终应避免消除二氧化硫和3,5-双(三氟甲基)苯酚氧化物,并基于热力学和动力学方面的考虑,解释了该反应所观察到的高立体选择性。