Substrate Range of the Titanium TADDOLate Catalyzed Asymmetric Fluorination of Activated Carbonyl Compounds
作者:Andreas Bertogg、Lukas Hintermann、Dominique P. Huber、Mauro Perseghini、Maria Sanna、Antonio Togni
DOI:10.1002/hlca.201100375
日期:2012.3
4‐diazoniabicyclo[2.2.2]octane bis‐[tetrafluoroborate]) at room temperature. A series of α‐methylated β‐keto esters (3‐oxobutanoates, 3‐oxopentanoates) with bulky benzyl ester groups (60–90% ee) or phenyl ester (67–88% ee) have been fluorinated readily, whereas α‐acyl lactones were also readily fluorinated, but gave lower inductions (13–46% ee). Double stereochemical differentiation in β‐keto esters with chiral
[TiCl 2(TADDOLate)]的底物范围(TADDOL = α,α,α ',α'-四芳基-1,3-二氧戊环-4,5-二甲醇)催化活化的β-羰基的不对称α-氟化化合物已被研究。在F-TEDA(1-(氯甲基)-4)饱和(0.14 mol / l)MeCN溶液中使用5 mol%的TiCl 2(萘-1-基)-TADDOLate作为催化剂来表征最佳的催化条件。-氟-1,4-二氮杂双环[2.2.2]辛烷双[四氟硼酸酯])。一系列α甲基化的β具有笨重的苄基酯基团(60-90%ee)或苯酯(67-88%ee)的酮基酯(3-氧代丁酸酯,3-氧代戊酸酯)已经很容易被氟化,而α-酰基内酯也很容易被氟化,但是产生较低的诱导(13–46%ee)。具有手性酯基的β-酮酯的双重立体化学分化将立体选择性提高到非对映体比率(dr)高达96.5:3.5。第一次,β-酮基S-硫代酸酯被不对称氟化(62-91.5%ee)和氯化(83%ee)。在1