Reaction of Methyl 4,5-Epoxy-(2E)-pentenoate with Arenes. I. A Facile Synthesis of 4-Aryl-5-hydroxy-(2E)-pentenoate Derivatives.

Enzymatic Resolution of (.+-.)-5-Acetoxy-4-aryl-(2E)-pentenoate Derivatives

“…The NMR data of (S)-10 were identical with those of the reported (Ϯ)-10. 15) iii) Table 1, Entry 3: A suspension of (Ϯ)-13 (0.096 g) and lipase OF-360 (0.1 g) in H 2 O-saturated-diisopropyl ether (20 ml) was incubated at 33°C for 48 h. The reaction mixture was worked up in the same way as (Ϯ)-9 to give a crude oil, which was chromatographed on silica gel (15 g) to give (R)-13 {0.030 g, 31%, [a] D 24 ϩ7.1°(cϭ0.34, CHCl 3 ), corresponding to 80% ee, Chiralcel OD, eluent, n-hexane : EtOHϭ1000 : 2, t R ϭ83.6 min (10%), t R ϭ97.2 min (90%)} from n-hexane : AcOEtϭ8 : 1 eluate and (S)-12 {0.050 g, 61%, [a] D 25 Ϫ7.6°(cϭ0.49, CHCl 3 ), corresponding to 43% ee, Chiralpac AD, eluent, n-hexane : EtOHϭ10 : 1, t R ϭ13.3 min (72%), t R ϭ 15.1 min (29%)} as a homogeneous oil from n-hexane : AcOEtϭ3:1 eluate. The NMR data of (S)-12 were identical with those of the reported (Ϯ)-12.…”

“…The NMR data of (S)-12 were identical with those of the reported (Ϯ)-12. 15) iv) Table 1, Entry 4: A suspension of (Ϯ)-15 (6.75 g) and lipase OF-360 (0.6 g) in H 2 O-saturated-diisopropyl ether (600 ml) was incubated at 33°C for 48 h. This scale experiment was simultaneously carried out two times (total amount of (Ϯ)-15 was 13.5 g). The reaction mixture was worked up in the same way as (Ϯ)-9 to give a crude oil, which was chromatographed on silica gel (200 g) to give (R)-15 [(10.8 g, 80%, 15% ee, Chiralcel OD, eluent, n-hexane : EtOH : iso-PrOHϭ60 : 1 : 1, t R ϭ8.6 min (42.5%), t R ϭ9.9 min (57.5%)] from n-hexane : AcOEtϭ10 : 1 eluate and (S)-14 [(1.734 g, 13 %, 40% ee, Chiralcel OD, eluent, n-hexane : EtOH : iso-PrOHϭ60 : 1 : 1, t R ϭ 27.2 min (30%), t R ϭ34.4 min (70%)] as a homogeneous oil from nhexane : AcOEtϭ3 : 1 eluate.…”

“…The NMR data of (S)-14 were identical with those of the reported (Ϯ)-14. 15) v) Table 1, Entry 5: A suspension of (S)-14 (1.5 g, 40% ee) and lipase OF-360 (0.6 g) and isopropenyl acetate (3.06 g, 30.5 mmol) in diisopropyl ether (200 ml) was incubated at 33°C for 24 h. The reaction mixture was worked up in the same way as (Ϯ)-9 to give a crude oil, which was chromatographed on silica gel (50 g) to give (S)-15 (0.333 g, 19%, 67% ee) from n-hexane : AcOEtϭ10 : 1 eluate and (S)-14 (1.155 g, 77%, 34% ee) as a homogeneous oil from n-hexane : AcOEtϭ3 : 1 eluate. vi) Table 1, Entry 6: A suspension of (S)-15 (0.333 g, 67% ee) and lipase OF-360 (0.1 g) in H 2 O-saturated-diisopropyl ether (40 ml) was incubated at 33°C for 72 h. The reaction mixture was worked up in the same way as (Ϯ)-9 to give a crude oil, which was chromatographed on silica gel (10 g) to give (S)-15 (0.077 g, 23%, 36% ee) from n-hexane : AcOEtϭ10 : 1 eluate and (S)-14 {0.171 g, 60 %, [a] D 27 Ϫ4.5°(cϭ1.08, CHCl 3 ), corresponding to 79% ee)} as a homogeneous oil from n-hexane : AcOEtϭ3 : 1 eluate.…”

“…By applying the reported procedure, 15) the four (S)-4-aryl-5-hydroxy-(2E)-pentenoate derivatives 10, 12, 18, and 16 were obtained by the reaction of (4S)-(4,5)-epoxy-(2E)-pentenoate 26 16) and substituted benzene derivatives in the presence of BF 3 · Et 2 O. The reaction of (S)-26 (93% ee) and 1,3-dimethoxybenzene in the presence of BF 3 · Et 2 O gave (S)-10 {38%, [a] D 29 Ϫ15.2°(cϭ0.50, CHCl 3 ), corresponding to 93% ee}.…”

Total Synthesis of (S)-(+)-Curcudiol, and (S)-(+)-and (R)-(-)-Curcuphenol.

“…This was successfully achieved by carrying out enantioselective hydrolysis of the reported (Ϯ)-acetate 4 7) using immobilized lipase. The desired racemic (Ϯ)-3 had previously been obtained by us in the reaction of methyl (4,5)-epoxy-(2E)-pentenoate and m-methoxytoluene in the presence of BF 3 · Et 2 O.…”