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Synlett 2008(10): 1557-1561  
DOI: 10.1055/s-2008-1078422
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© Georg Thieme Verlag Stuttgart · New York

Allylic Substitution of meso-1,4-Diacetoxycycloalkenes in Water with an Amphiphilic Resin-Supported Chiral Palladium Complex

Yasuhiro Uozumi*, Hiroe Takenaka, Toshimasa Suzuka
Institute for Molecular Science (IMS) and CREST, Higashiyama 5-1, Myodaiji, Okazaki 444-8787, Japan
Fax: +81(564)595574; e-Mail: uo@ims.ac.jp;
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Publikationsverlauf

Received 11 January 2008
Publikationsdatum:
16. Mai 2008 (online)

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Abstract

Asymmetric π-allylic substitution of meso-1,4-diacet­oxycyclopentene and meso-1,4-diacetoxycyclohexene with various nucleophiles was performed with an amphiphilic polystyrene-poly(ethylene glycol) (PS-PEG) resin-supported chiral imidazoindolephosphine-palladium complex in water as a single reaction medium under heterogeneous conditions to give the corresponding 1-acetoxy-4-substituted cycloalkenes with up to 99% ee.

Key words

π-allylpalladium - asymmetric catalysis - aqueous media - polymer support - palladium catalyst

10

Tenta Gel SNH2 (purchased from Rapp Polymere) was used as the polymer support.

11

Chemical yield of the monosubstituted product 4 was lowered to <30% with Li2CO3, NaHCO3, Na2CO3, or K2CO3.

12

The absolute configuration of 4 was determined by chemical correlation with (1R,4S)-cis-1-acetoxy-4-[bis(methoxy-carbonyl)methyl]-2-cyclopentene (see ref. 8a).

14

The absolute configuration of 6a was determined to be 1R,4S by measurement of the specific rotation (see, ref. 12). The configurations of 6b-g were tentatively assigned on the basis of the mechanistic similarity of the asymmetric induction, as depicted in Table [1] .

15

Palladium-Catalyzed Asymmetric Desymmetrization of meso -Cycloalkene-1,4-diacetate: Reaction conditions and results are shown in Table [1] . A typical procedure is given for the reaction with cis-1,4-diacetoxycyclopentene (meso-2) and phenol (a) in H2O (entry 3).
To a mixture of the catalyst 1 (89 mg, 0.025 mmol) and meso-2 (92 mg, 0.5 mmol) in H2O (2.5 mL) was added phenol (48 mg, 0.5 mmol), and the mixture was shaken at 0 °C for 18 h. The reaction mixture was filtered and the recovered resin beads were rinsed with EtOAc (3 ×). The combined filtrate was dried over anhyd Na2SO4. The solvent was evaporated and the residue was chromatographed on silica gel (hexane-EtOAc, 10:1) to give 1-acetoxy-4-phenoxycyclopentene (6a; 70 mg, 64% yield) and 1,4-diphenoxycyclopentene (8; 18 mg). The enantiomeric excess was determined to be 99% ee by GC analysis using a chiral stationary phase capillary column (Cyclodex CB).
Spectral and analytical data for compounds 6 are shown below, where the enantiomeric excesses were determined by GC (Cyclodex CB), unless otherwise noted: 1-Acetoxy-4-phenoxycyclopentene (6a): [α]D 23 +63.8 (c = 1.0, CHCl3). 1H NMR (CDCl3): δ = 7.29 (t, J = 7.8 Hz, 2 H), 6.96 (t, J = 7.3 Hz, 1 H), 6.92 (d, J = 7.8 Hz, 2 H), 6.24 (d, J = 5.8 Hz, 1 H), 6.12 (d, J = 5.3 Hz, 1 H), 5.61 (br, 1 H), 5.17 (br, 1 H), 2.97 (dt, J = 7.3, 14.6 Hz, 1 H), 2.05 (s, 3 H), 1.89 (dt, J = 4.0, 14.6 Hz, 1 H). 13C NMR (CDCl3): δ = 170.77, 157.77, 135.05, 134.06, 129.53, 115.34, 79.55, 76.74, 37.94, 21.08. IR (ATR): 1733, 1493, 1366, 1228, 1087, 889, 754, 692, 628 cm-1. MS (EI): m/z (%rel intensity) = 218 (0.7) [M+], 43 (base peak). Anal. Calcd for C13H14O3: C, 71.54; H, 6.47. Found: C, 71.49; H, 6.53. CAS registry number: 210701-09-0.
1-Acetoxy-4-(2-benzyloxyphenoxy)-2-cyclopentene (6b): [α]D 28 -20.5 (c = 1.0, CHCl3); 97% ee. 1H NMR (CDCl3): δ = 7.43-7.27 (m, 4 H), 6.89-6.98 (m, 5 H), 6.26 (br d, J = 4.8 Hz, 1 H), 6.09 (br d, J = 4.8 Hz, 1 H), 5.57 (br, 1 H), 5.17 (br, 1 H), 5.12 (s, 2 H), 2.93 (dt, J = 7.3, 14.6 Hz, 1 H), 2.04 (s, 3 H), 1.98 (dt, J = 4.3, 14.6 Hz, 1 H). 13C NMR (CDCl3): δ = 170.88, 149.49, 148.28, 137.32, 134.67, 133.73, 128.45, 127.78, 127.29, 122.21, 121.70, 117.09, 115.60, 81.72, 76.79, 71.31, 38.08, 21.13. IR (ATR): 1732, 1499, 1452, 1366, 1236, 1212, 1083, 1012, 896, 742, 697, 627 cm-1. MS (EI): m/z (%rel intensity) = 324 (1) [M+], 91 (base peak). Anal Calcd for C20H20O4: C, 74.06; H, 6.21. Found: C, 73.94; H, 6.28.
1-Acetoxy-4-(2-chlorophenoxy)-2-cyclopentene (6c): [α]D 26 -58.0 (c = 1.0, CHCl3). 1H NMR (CDCl3): δ = 7.37 (dd, J = 1.8, 7.9 Hz, 1 H), 7.20 (dt, J = 1.8, 7.9 Hz, 1 H), 6.95 (d, J = 7.9 Hz, 1 H), 6.92 (t, J = 7.9 Hz, 1 H), 6.26 (d, J = 5.5 Hz, 1 H), 6.14 (J = 5.5 Hz, 1 H), 5.60 (br, 1 H), 5.17 (br, 1 H), 2.99 (dt, J = 7.3, 14.6 Hz, 1 H), 2.06 (s, 3 H), 1.96 (dt, J = 4.3, 14.6 Hz, 1 H). 13C NMR (CDCl3): δ = 170.84, 153.65, 134.65, 134.46, 130.57, 127.66, 123.71, 121.94, 115.26, 81.33, 76.61, 38.02, 21.11. IR (ATR): 1237, 1090, 902, 730, 649, 630 cm-1. MS (EI): m/z (%rel intensity): = 252 (0.02) [M+], 43 (base peak).
1-Acetoxy-4-(2-bromophenoxy)-2-cyclopentene (6d): [α]D 25 -100.8 (c = 1.1, CHCl3); 95% ee. 1H NMR (CDCl3): δ = 7.55 (dd, J = 1.2, 7.9 Hz, 1 H), 7.25 (td, J = 1.2, 7.3 Hz, 1 H), 6.94 (d, J = 1.2 Hz, 1 H), 6.85 (td, J = 1.2, 7.9 Hz, 1 H), 6.26 (d, J = 5.5 Hz, 1 H), 6.14 (d, J = 5.5 Hz, 1 H), 5.60 (br t, J = 5.5 Hz, 1 H), 5.17 (br t, J = 5.5 Hz, 1 H), 2.07 (s, 3 H), 2.00 (dt, J = 7.3, 14.6 Hz, 1 H), 1.96 (dt, J = 4.2, 14.6 Hz, 1 H). 13C NMR (CDCl3): δ = 170.79, 154.52, 134.60, 134.39, 133.61, 128.37, 122.34, 114.99, 113.00, 81.34, 76.55, 38.00, 21.07. IR (ATR): 1733, 1584, 1573, 1474, 1442, 1366, 1085, 1029, 895, 748, 627 cm-1. MS (EI): m/z (%rel intensity) = 296 (0.02) [M+], 43 (base peak). Anal. Calcd for C13H13BrO3: C, 52.55; H, 4.41. Found: C, 52.37; H, 4.37.
1-Acetoxy-4-(2,6-dimethylphenoxy)-2-cyclopentene (6e): [α]D 27 -41.4 (c = 1.1, CHCl3). 1H NMR (CDCl3): δ = 7.02 (d, J = 7.3 Hz, 2 H), 6.92 (t, J = 7.3 Hz, 1 H), 6.16 (d, J = 5.4 Hz, 1 H), 6.05 (d, J = 5.4 Hz, 1 H), 5.52 (br t, J = 4.4 Hz, 1 H), 4.81 (br t, J = 6.3 Hz, 1 H), 2.88 (dt, J = 7.3, 14.6 Hz, 1 H), 2.30 (s, 6 H), 2.09 (s, 3 H), 2.06 (dt, J = 4.4, 14.6 Hz, 1 H). 13C NMR (CDCl3): δ = 171.09, 155.79, 136.60, 133.37, 131.06, 129.16, 123.95, 84.66, 76.73, 38.51, 21.39, 17.46. IR (ATR): 1730, 1365, 1237, 1198, 1091, 903, 730, 649, 630 cm-1. MS (EI): m/z (%rel intensity) = 246 (0.09) [M+], 43 (base peak). HRMS (EI): m/z [M+] calcd for C15H18O3: 246.1256; found: 246.1251. The enantiomeric excess was determined by HPLC analysis using a chiral stationary phase column [Chiralcel OD-H, eluent: n-hexane-2-propanol, 50:1; flow rate: 0.5 mL/min; t R (major isomer) = 14.73 min and t R (minor isomer) = 13.98 min] to be 90% ee.
1-Acetoxy-4-(3-methoxyphenoxy)-2-cyclopentene (6f): [α]D 26 +57.5 (c = 1.1, CHCl3); 96% ee. 1H NMR (CDCl3): δ = 7.18 (t, J = 8.5 Hz, 1 H), 6.52 [td, J = 2.4, 8.5 Hz (overlapped), 2 H], 6.48 (t, J = 2.4 Hz, 1 H), 6.24 (d, J = 5.5 Hz, 1 H), 6.13 (d, J = 5.5 Hz, 1 H), 5.60 (br, 1 H), 5.16 (br, 1 H), 3.78 (s, 3 H), 2.96 (dt, J = 7.3, 14.6 Hz, 1 H), 2.05 (s, 3 H), 1.88 (dt, J = 3.9, 14.6 Hz, 1 H). 13C NMR (CDCl3): δ = 170.77, 160.87, 158.99, 134.98, 134.12, 129.95, 107.35, 106.54, 101.88, 79.62, 55.24, 37.90, 21.04. IR (ATR): 1733, 1602, 1491, 1366, 1235, 1199, 1150, 1087, 1015, 891, 837, 765, 687, 629 cm-1. MS (EI): m/z (%rel intensity) = 248 (1) [M+], 43 (base peak). Anal. Calcd for C14H16O4: C, 67.73; H, 6.50. Found: C, 67.51; H, 6.45.
1-Acetoxy-4-(4-tert-buthylphenoxy)-2-cyclopentene (6g): [α]D 27 +148.7 (c = 1.4, CHCl3); 94% ee. 1H NMR (CDCl3): δ = 7.30 (d, J = 8.5 Hz, 2 H), 6.85 (d, J = 8.5 Hz, 2 H), 6.24 (d, J = 5.5 Hz, 1 H), 6.11 (d, J = 5.5 Hz, 1 H), 5.60 (s, 1 H), 5.14 (s, 1 H), 2.96 (dt, J = 7.3, 14.6 Hz, 1 H), 2.05 (s, 3 H), 1.89 (dt, J = 3.9, 14.6 Hz, 1 H), 1.37 (s, 9 H). 13C NMR (CDCl3): δ = 170.79, 155.51, 143.66, 135.25, 133.90, 126.30, 114.78, 79.61, 76.79, 37.98, 34.05, 31.48, 21.08. IR (ATR): 1736, 1511, 1365, 1232, 1185, 1087, 1013, 898, 829, 732, 630 cm-1. MS (EI): m/z (%rel intensity) = 274 (0.2) [M+], 43 (base peak). Anal. Calcd for C17H22O3: C, 74.42; H, 8.08. Found: C, 74.56; H, 8.22.
1-Acetoxy-4-phenoxy-2-cyclohexene (7): 1H NMR (CDCl3): δ = 7.26-7.31 (m, 2 H), 6.92-6.97 (m, 3 H), 6.08 (ddd, J = 1.2, 3.7, 10.0 Hz, 1 H), 6.07 (ddd, J = 1.2, 3.0, 10.0 Hz, 1 H), 5.25 (br s, 1 H), 4.76 (br s, 1 H), 2.07 (s, 3 H), 1.87-2.02 (m, 4 H). 13C NMR (CDCl3): δ = 170.72, 157.52, 131.10, 129.59, 121.06, 115.84, 70.27, 67.38, 24.92, 24.75, 21.27. IR (ATR): 1730, 1597, 1492, 1371, 1226, 1079, 1035, 958, 903, 754, 692 cm-1. MS (EI): m/z = 232 [M+]. The enantiomeric excess was determined by HPLC analysis using a chiral stationary phase column [Chiralcel OD-H, eluent: n-hexane-2-propanol, 50:1; flow rate: 0.5 mL/min; t R (major isomer) = 21.33 min and t R (minor isomer) = 18.48 min] to be 95% ee.