Asymmetric Allylic Monofluoromethylation and Methylation of Morita–Baylis–Hillman Carbonates with FBSM and BSM by Cooperative Cinchona Alkaloid/FeCl₂ Catalysis

Kinetic Resolution of Allyl Fluorides by Enantioselective Allylic Trifluoromethylation Based on Silicon‐Assisted CF Bond Cleavage

“…Asymmetric reactions of MBH adducts have hitherto been studied by many groups,13 including by ourselves 10. 14 Rios and co‐workers described an organocatalyzed kinetic resolution of MBH carbonates,15 as did several other groups 16. The basic framework of MBH adducts contains an OR group (acetate or carbonate) at the allylic position, which can act as a leaving group.…”

“…The product 2 is formed by a second S N 2′ substitution reaction of E ‐configured I , which was generated from ( S )‐ 1 , with CF 3 − as the nucleophile (Figure 1). 10, 14, 20 A thorough investigation of the ee values of 1 a and 2 a at different conversions revealed that the enantiopurity of 2 a is not related to the conversion (Figure 2). Excellent enantioselectivities were persistently observed and found to be independent of the conversion and the ee of 1 a .…”

Kinetic Resolution of Allyl Fluorides by Enantioselective Allylic Trifluoromethylation Based on Silicon‐Assisted CF Bond Cleavage

“…The product 2 is formed by a second S N 2' substitution reaction of E-configured I, which was generated from (S)-1, with CF 3 À as the nucleophile (Figure 1). [10,14,20] A thorough investigation of the ee values of 1 a and 2 a at different conversions revealed that the enantiopurity of 2 a is not related to the conversion (Figure 2). Excellent enantioselectivities were persistently observed and found to be independent of the conversion and the ee of 1 a.…”

“…Asymmetric reactions of MBH adducts have hitherto been studied by many groups, [13] including by ourselves. [10,14] Rios and co-workers described an organocatalyzed kinetic resolution of MBH carbonates, [15] as did several other groups. [16] The basic framework of MBH adducts contains an OR group (acetate or carbonate) at the allylic position, which can act as a leaving group.…”

“…[10] Increasing the amount of (DHQD) 2 PHAL (30 mol %) slightly improved the reactivity to afford (S)-2 l in 82 % ee and 22 % yield after 120 h (s = 18; entry 12). A series of bulky tert-butyl esters 1 m-p were converted into the corresponding products (S)-2 m-p with good selectivity (87-96 % ee, s = 14-105; entries [13][14][15][16], even though the reactivity was lower than for the methyl esters 1 a-l. The reaction of phenyl-substituted allyl fluoride 1 m proceeded particularly well; (S)-2 m was obtained in 94 % ee and 48 % yield, and 1 m was recovered in 93 % ee and 42 % yield.…”