Asymmetric hydrolysis of pro-chiral 3,3-disubstituted 2,4-diacetoxycyclohexa-1,4-dienes

Asymmetric catalysts

“…359-362 Prochiral enol ether hydrolysis provides an effective method for the asymmetric synthesis of compounds containing quaternary centres (Scheme 65). 363 In an interesting variation selective hydrolysis of one enantiomer of 54 resulted in conversion into an aldehyde 55 in 72% ee. 364 The opposite configuration of unreacted diacetate was recovered in 62% ee.…”

Asymmetric Synthesis of New Chiral Cyclic Ketols

“…In our preliminary studies, we synthesized ketol 3a (2 R ,3 R ) to assign the ( S ) absolute configuration to the quaternary stereogenic center of keto acetate 2a , which had been obtained by enzymatic hydrolysis . Our approach relyied on the NaBH 4 reduction of 2a followed by the cleavage of the enol ester function with methyllithium and purification to afford ketol 3a ( R , R ) in 40% overall yield (Scheme ).…”

“…In our previous work , we reported an asymmetric enantioselective synthesis of keto enol acetates 2 (>98% ee) bearing a quaternary stereogenic center by enzymatic hydrolysis of prochiral dienol diacetates 1 . In this paper, we now demonstrate that starting from these chiral materials 2 , the synthesis of new enantiopure compounds can be achieved with a total control of the absolute configuration.…”

Discovery of New Carbonyl Reductases Using Functional Metagenomics and Applications in Biocatalysis

“…88–90 °C [37] ]; R f 0.61 (33% EtOAc in 40–60 petroleum ether); [α] 25 D −112 (c 1.3, toluene) [lit. [α] 25 D −111 (c 1.3, benzene)]; [38] ν max (neat) 3427, 2963, 1638, 1600 cm −1 ; 1 H NMR (600 MHz; CDCl 3 ) δ 5.87 (1H, d, J =1.9 Hz, 1‐H), 3.65 (1H, t, J =2.7 Hz, 5‐H), 2.56–2.62 (1H, m, 4‐ H H), 2.44–2.52 (2H, m, 3‐H 2 ), 2.39–2.44 (1H, m, 8‐ H H), 2.24–2.32 (1H, m, 8‐H H ), 2.01–2.09 (1H, m, 6‐ H H), 1.82–1.93 (1H, m, 7‐ H H), 1.76–1.82 (1H, m, 6‐H H ), 1.67–1.75 (1H, m, 7‐ H H), 1.47–1.53 (1H, m, 4‐H H ), 1.24 (3H, s, CH 3 ); 13 C NMR (150 MHz; CDCl 3 ) δ 199.6, 168.0, 127.2, 75.4, 41.0, 34.1, 31.8, 30.9, 28.8, 21.9, 19.9; m/z (ES+) 181 ([M+H] + ). Analytical HPLC retention time 54.0 min (Chiralcel OJ, propanol/hexane at 0.5 mL/min; SI Figure S6).…”