T-BuPHOX

More recently Stoltz has described the application of an electron-deficient PHOX ligand, namely (5)-(CF3)3-t-BuPHOX (L3) in the DAAA of... 

Although pleased with this improvement we thought we could improve the enantioselectivity further using the (S)-(CF3)3-t-BuPHOX ligand. Gratifyingly this... 

Meldrum s acid added during complex formation Meldmm s acld/substrate solution added dropwise 0.10 M TFIF, 1 equiv. Meldrum s acid Using (5)-t-BuPHOX... 

Pdadbas CHCH (7.8 mg, 0.0075 mmol) and (5)-(CF3)3-t-BuPHOX (11.1 mg, 0.0188 mmol) were dissolved in freshly distilled THF in a flame dried Schlenk flask and stirred at 40 °C for 30 min. a-Aryl- 3-keto aUyl ester (0.15 mmol) and Meldmm s acid (0.375 mmol) were dissolved in THF in a flame dried round bottom flask (10 mL, 2-neck) and added to the Pd-complex solution, maintained at 40 °C, in one portion. The reaction mixture was stirred at 40 °C for 2 h, filtered through a bed of charcoal on a plug of Cehte and washed with EtOAc. The filtrate was concentrated in vacuo and purified by silica gel column chromatography (pentane/EtaO). 

Table 3 Solvent screen of the allylic alkylation reaction using (S)-t-BuPHOX...

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