References
Reviews:
<A NAME="RG44804ST-1A">1a</A>
Christoffers J. In
Encyclopedia of Catalysis
Vol. 5:
Horvath I.
Wiley;
New York:
2003.
p.99
<A NAME="RG44804ST-1B">1b</A>
Krause N.
Hoffmann-Röder A.
Synthesis
2001,
171
<A NAME="RG44804ST-1C">1c</A>
Perlmutter P.
Conjugate Addition Reactions in Organic Synthesis
Vol. 9:
Tetrahedron Organic Chemistry Series, Pergamon;
Oxford:
1992.
<A NAME="RG44804ST-1D">1d</A>
Oare DA.
Heathcock CH. In
Topics in Stereochemistry
Vol. 19:
Eliel EL.
Wilen SH.
Wiley Interscience;
New York:
1989.
p.227
<A NAME="RG44804ST-1E">1e</A>
Bergmann ED.
Ginsburg D.
Pappo R.
Org. React.
1959,
10:
179
<A NAME="RG44804ST-1F">1f</A>
Rossiter BE.
Swingle NM.
Chem. Rev.
1992,
92:
771
Reviews:
<A NAME="RG44804ST-2A">2a</A>
Denissova I.
Barriault L.
Tetrahedron
2003,
59:
10105
<A NAME="RG44804ST-2B">2b</A>
Christoffers J.
Mann A.
Angew. Chem. Int. Ed.
2001,
40:
4591 ; Angew. Chem. 2001, 113, 4725
<A NAME="RG44804ST-2C">2c</A>
Corey EJ.
Guzman-Perez A.
Angew. Chem. Int. Ed.
1998,
37:
388 ; Angew. Chem. 1998, 110, 402
<A NAME="RG44804ST-3A">3a</A>
Hermann K.
Wynberg H.
Helv. Chim. Acta
1977,
60:
2208
<A NAME="RG44804ST-3B">3b</A>
Kobayashi N.
Iwai K.
J. Am. Chem. Soc.
1978,
100:
7071
<A NAME="RG44804ST-3C">3c</A>
Kobayashi N.
Iwai K.
J. Polym. Sci., Polym. Chem.
1980,
18:
923
<A NAME="RG44804ST-3D">3d</A>
Inagaki M.
Hiratake J.
Yamamoto Y.
Oda J.
Bull. Chem. Soc. Jpn.
1987,
60:
4121
<A NAME="RG44804ST-3E">3e</A>
Hodge P.
Khoshdel E.
Waterhouse J.
J. Chem. Soc., Perkin Trans. 1
1983,
2205
<A NAME="RG44804ST-3F">3f</A>
Alvarez R.
Hourdin M.-A.
Cavé C.
d’Angelo J.
Chaminade P.
Tetrahedron Lett.
1999,
40:
7091
<A NAME="RG44804ST-4A">4a</A>
Christoffers J.
Mann A.
Angew. Chem. Int. Ed.
2000,
39:
2752 ; Angew. Chem. 2000, 112, 2871
<A NAME="RG44804ST-4B">4b</A>
Christoffers J.
Mann A.
Chem.-Eur. J.
2001,
7:
1014
<A NAME="RG44804ST-4C">4c</A>
Christoffers J.
Scharl H.
Eur. J. Org. Chem.
2002,
1505
<A NAME="RG44804ST-4D">4d</A>
Christoffers J.
Kreidler B.
Oertling H.
Unger S.
Frey W.
Synlett
2003,
493
<A NAME="RG44804ST-4E">4e</A>
Christoffers J.
Kreidler B.
Unger S.
Frey W.
Eur. J. Org. Chem.
2003,
2845
<A NAME="RG44804ST-4F">4f</A>
Christoffers J.
Schuster K.
Chirality
2003,
15:
777
<A NAME="RG44804ST-4G">4g</A> Review:
Christoffers J.
Chem.-Eur. J.
2003,
9:
4862
<A NAME="RG44804ST-5A">5a</A>
Mutter M.
Hagenmaier H.
Bayer E.
Angew. Chem., Int. Ed. Engl.
1971,
10:
811 ; Angew. Chem. 1971, 83, 883
<A NAME="RG44804ST-5B">5b</A>
Bayer E.
Mutter M.
Nature
1972,
237:
512
<A NAME="RG44804ST-5C">5c</A>
Wentworth P.
Janda KD.
Chem. Commun.
1999,
1917
<A NAME="RG44804ST-6A">6a</A>
Benaglia M.
Puglisi A.
Cozzi F.
Chem. Rev.
2003,
103:
3401
<A NAME="RG44804ST-6B">6b</A> See also the thematic issue 10, 2002:
Gladysz JA.
Chem. Rev.
2002,
102:
3215
<A NAME="RG44804ST-7">7</A>
Tsogoeva SB.
Wöltinger J.
Jost C.
Reichert D.
Kühnle A.
Krimmer H.-P.
Drauz K.
Synlett
2002,
707
<A NAME="RG44804ST-8">8</A>
Load values were calculated by 1H NMR integrals with the polymer signal at δ = 3.45-3.80 ppm as a standard. In the
case of 13b the signal at δ = 4.13 ppm (2 H) and for 15b the signal at δ = 2.22 ppm (3 H) were used for integration.
<A NAME="RG44804ST-9">9</A>
Supported N
-(2-Ethoxycarbonyl-1-cyclohexenyl)-l-
valine(4-hydroxypiperidide) (13b).
Immobilized auxiliary 10 (2.50 g, 1.54 mmol), 12b (3.00 g, 17.6 mmol) and one drop of TFA in abs. toluene (8 mL) were heated at 55
ºC for 16 h. Two fold precipitation from abs. Et2O (80 mL) yielded 13b (2.58 g, 99%) as a pale yellow polymer. 1H NMR (300 MHz, CDCl3): δ = 1.00 (d, 3
J = 6.9 Hz, 3 H, CH3), 1.03 (d, 3
J = 6.9 Hz, 3 H, CH3), 1.26 (t, 3
J = 7.1 Hz, 3 H, CH2CH
3), 1.47-1.68 (m, 6 H), 1.77-1.92 (m, 2 H), 1.95-2.14 (m, 2 H), 2.21-2.32 (m, 3 H),
3.23-3.36 (m, 2 H), 3.50-3.74 (m, 140 H, PEG-H), 3.91-4.01 (m, 1 H), 4.13 (q, 3
J = 7.2 Hz, 2 H, OCH2), 9.31 (d, br, 3
J = 8.8 Hz, 1 H, NH) ppm. All other signals are overlapped by resonances of the polymer
backbone. 13C{1H} NMR (75 MHz, CDCl3): δ = 14.65 (CH3), 18.42 (CH3), 19.90 (CH2
CH3), 22.35 (CH2), 22.57 (CH2), 23.91 (CH2), 26.75 (CH2), 30.74 (CH2, br, C-3′), 31.81 (CH2, br, C-3′), 31.98 (CH, CHCH3), 39.45 (CH2, br, C-2′), 42.69 (CH2, br, C-2′), 58.38 (CH, CHNH), 58.74 (CH2, OCH2), 74.36 (CH, OCH), 91.47 (C, C-2′′), 157.51 (C, br, CNH), 170.48 (C, CON), 170.62
(C, COO) ppm. IR (ATR): 1/λ = 3483 (w, br), 2882 (s), 1645 (m), 1592 (m), 1466 (m),
1359 (m), 1341 (s), 1279 (m), 1233 (s), 1146 (m), 1103 (vs), 1063 (vs), 948 (s), 841
(s) cm-1. Anal. Calcd for 13b assuming 44 ethylene oxide units in a polymeric backbone of 2000 Da at 72% load:
C, 56.77; H, 9.18; N, 1.62. Found: C, 56.42; H, 9.18; N, 1.57.
<A NAME="RG44804ST-10">10</A>
Supported (
R
)-
N
-[2-Ethoxycarbonyl-2-(3-oxobutyl)-1-
cyclohexyliden
e-l-valine (4-hydroxypiperidide)]
(15b).
To a solution of polymer 13b (0.40 g) in acetone (2 mL) was added Cu(OAc)2·H2O (4.0 mg, 0.02 mmol). The mixture was stirred for 1 h at 23 ºC, then 2 (1.00 g, 14.3 mmol) was added. After stirring of the mixture for 2 d, the product
polymer was precipitated from Et2O (50 mL) to yield a brown polymer 15b (0.39 g, 99%). 1H NMR (300 MHz, CDCl3): δ = 0.88 (d, 3
J = 6.2 Hz, 3 H, CHCH
3), 0.92-1.02 (m, 3 H, CHCH
3), 1.25 (t, 3
J = 7.1 Hz, 3 H, CH2CH
3), 1.41-1.90 (m, 8 H), 2.09-2.16 (m, 7 H), 2.22 (s, 3 H, COCH3), 2.31-2.70 (m, 2 H), 2.51 (t, 3
J = 6.2 Hz, 2 H), 2.72-3.38 (m, 2 H), 3.44-3.81 (m, 131 H, PEG-H), 3.98-4.23 (m, 2
H), 4.11-4.21 (m, 2 H, OCH2) ppm. 13C{1H} NMR (75 MHz, CDCl3): δ = 18.92 (CH3), 25.19 (CH2), 28.40 (CH2), 29.96 (CH2), 32.58 (CH2), 38.87 (CH2, NCH2), 42.87 (CH2, NCH2) 60.82 (CH, CHN), 67.55 (CH, OCH), 141.78 (C, CN), 173.91 (C, COO), 208.46 (C, CO)
ppm. Missing signals cannot be identified from background noise.
<A NAME="RG44804ST-11">11</A>
Ethyl (
R
)-2-Oxo-1-(3-oxobutyl)cyclohexanecarboxylate (
3b).
[15]
Polymer 15b (1.00 g, 0.52 mmol) was stirred in HCl (2 mL, c = 1 mol dm-3) at 0 ºC for 3 h. H2O (20 mL) was added, and the mixture was then extracted with Et2O (3 × 20 mL). The combined ether layers were washed with H2O (50 mL), dried (MgSO4) and evaporated to give 3b (108 mg, 0.45 mmol, 87% reg. 15b) as a colorless oil with 97% purity (determined by 1H NMR spectroscopy). GC for determination of ee value: Bondex unβ
[16]
[20 m × 0.3 mm with hydrogen carrier gas (0.4 bar)], 120 °C isotherm; t
R(R) = 29.75 min; t
R(S) = 30.88 min, 97% ee.
Extraction of the water layers with CH2Cl2 (3 × 50 mL), subsequent washing of the combined CH2Cl2 layers with H2O (50 mL), drying (MgSO4) and removal of all volatile materials under high vacuum gave the re-isolated polymer
10 (867 mg).
<A NAME="RG44804ST-12">12</A>
Christoffers J.
Rößler U.
Werner T.
Eur. J. Org. Chem.
2000,
701
<A NAME="RG44804ST-13">13</A>
Hermann K.
Wynberg H.
J. Org. Chem.
1979,
44:
2238
<A NAME="RG44804ST-14">14</A>
Christoffers J.
Frey W.
Scharl H.
Baro A.
Z. Naturforsch., B: Chem. Sci.
2004,
59:
375
<A NAME="RG44804ST-15">15</A>
Christoffers J.
J. Chem. Soc., Perkin Trans. 1
1997,
3141
<A NAME="RG44804ST-16">16</A> Bondex-unβ-5.5-et-105 is a chiral poly(dimethylsiloxane) phase which is modified
with 0.55 mol% permethyl β-cyclodextrin, covalently bonded by an undecamethylene spacer
between one 2-O-function of the cyclodextrin and the polysiloxane backbone. The polysiloxane
additionally has 5.25% Si(C2H5)2 instead of Si(CH3)2 groups in the backbone. See:
Karpf M.
Dissertation
Universität;
Stuttgart:
1995.