Download PDF
Synlett 2005(9): 1397-1400  
DOI: 10.1055/s-2005-868501
LETTER
© Georg Thieme Verlag Stuttgart · New York

Asymmetric Synthesis of Dihydrofurans via Rh(II)-Catalyzed Cyclopropanation-Rearrangement of Enol Ethers with 1-(Silanyloxy)vinyl Diazoacetates

Paul Müller*, Gérald Bernardinelli, Yves F. Allenbach, Maria Ferri, Stéphane Grass
Department of Organic Chemistry, University of Geneva, 30, Quai Ernest Ansermet, 1211 Geneva 4, Switzerland
Fax: +41(22)3793215; e-Mail: paul.muller@chiorg.unige.ch;
Further Information

Publication History

Received 14 February 2005
Publication Date:
29 April 2005 (online)

    Permissions and Reprints All articles of this category

Abstract

The cyclopropanation of dihydrofuran and dihydropy­ran with methyl 1-(silanyloxy)vinyl diazoacetates in the presence of chiral Rh(II)-catalysts affords cyclopropanes with high diastereo- and enantioselectivitiy. The cyclopropanes, in turn, rearrange to ­dihydrofurans upon desilylation with TBAF.

Key words

carbenes - catalysis - diazo compounds - transition ­metals - stereoselectivity

10

Data of Methyl (1 R * ,5 S * ,6 S * )-6-{1-[( tert -Butyldi-methyl)silanyloxy]vinyl}-2-oxabicyclo[3.1.0]hexane-6-carboxylate ( 5a). [α]D 18 -19 (c 1.12, EtOH, for 64% ee). IR (film): 2952 (w), 2855 (w), 1715 (s), 1632 (m), 1251 (s). 1H NMR (500 MHz, CDCl3): δ = 0.21 (d, J = 1.6 Hz, 6 H), 0.92 (s, 9 H), 2.14-2.19 (m, 1 H), 2.22-2.30 (m, 1 H), 2.41 (t, J = 6.0 Hz, 1 H), 3.65 (s, 3 H), 3.80 (dd, J = 8.5, 17.5 Hz, 1 H), 4.09 (ddd, J = 8.5, 10.1, 17.5 Hz, 1 H), 4.23 (d, J = 5.7 Hz, 1 H). 13C NMR (125 MHz, CDCl3): δ = -5.3 (q), -4.7 (q), 18.0 (s), 25.5 (q), 26.0 (t), 32.4 (d), 39.5 (s), 51.9 (q), 70.7 (d), 71.8 (t), 96.0 (t), 150.5 (s), 171.2 (s). MS: m/z (%) = 298 (7)[M+], 242 (23), 241 (100), 209 (12), 166 (12), 89 (58), 75 (36), 73 (78), 59 (30). HRMS: m/z calcd for C15H26O4Si+: 298.1601; found: 298.1642.

11

Data of Methyl (1 R * ,5 S * ,6 S * )-6-{1-[Tri(isopropyl)silanyl-oxy]vinyl}-2-oxabicyclo[3.1.0]hexane-6-carboxylate ( 5b).
[α]D 20 -8 (c 1.09, CHCl3, for 82% ee). IR (film): 2946 (m), 2895 (w), 2867 (m), 1716 (s), 1631 (m), 1464 (m), 1331 (s), 1256 (s), 1181 (m), 1133 (m), 1113 (w). 1H NMR (500 MHz, CDCl3): δ = 1.10 (d, J = 7.3 Hz, 9 H), 1.11 (d, J = 7.4 Hz, 9 H), 1.25 (sept, J = 7.4 Hz, 3 H), 2.18-2.31 (m, 2 H), 2.43 (br t, J = 5.8 Hz, 1 H), 3.64 (s, 3 H), 3.85 (dd, J = 8.4, 17.1 Hz, 1 H), 4.10 (ddd, J = 8.4, 10.3, 17.1 Hz, 1 H), 4.22 (d, J = 5.7 Hz, 1 H), 4.36 (d, J = 1.0 Hz, 1 H), 4.39 (d, J = 1.0 Hz, 1 H). 13C NMR (125 MHz, CDCl3): δ = 12.7 (d), 17.9 (q), 18.0 (q), 26.0 (t), 32.4 (d), 39.8 (s), 51.8 (s), 70.8 (d), 71.9 (t), 95.3 (t), 150.6 (s), 171.3 (s). MS: m/z (%) = 340 (4)[M+], 297 (100), 117 (14), 115 (12), 89 (21), 87 (13), 77 (10), 75 (34), 73 (18), 61 (13), 59 (38). HRMS: m/z calcd for C18H32O4Si+: 340.2070; found: 340.2062.

14

Data of Methyl cis -2-Methyl-3a,4,5,6a-tetrahydro-furo[2,3- b ]furan-3-carboxylate ( 3).
[α]D 18 +147 (c 1.12, EtOH, for 64% ee); [α]D 18 +223 (c 1.13, for 84% ee). IR (film): 2952 (w), 1653 (s), 1641 (s), 1230 (s), 1080 (s). 1H NMR (300 MHz, CDCl3): δ = 2.06-2.13 (m, 2 H), 2.26 (d, J = 1.4 Hz, 3 H), 3.67-3.76 (m, 1 H), 3.76 (s, 3 H), 4.05-4.11 (m, 1 H), 6.12 (d, J = 6.2 Hz, 1 H). 13C NMR (125 MHz, CDCl3): δ = 14.2 (q), 31.7 (t), 47.0 (d), 50.9 (d), 67.1 (t), 103.4 (s), 109.7 (d), 165.9 (s). MS: m/z (%) = 184 (31)[M+], 153 (30), 152 (100), 125 (14), 124 (16), 110 (41), 109(16), 96 (17), 95 (15), 82 (29), 81 (14), 53 (18). HRMS: m/z calcd for C9H12O4 +: 184.0736; found: 184.0731. Enantiomer separation: GC (β-Dex, isothermal, 120 °C, τ1 = 20.1 min, τ2 = 22.0 min or β-Dex, isothermal, 130 °C, τ1 = 12.6 min, τ2 = 13.7 min). For data of ethyl ester corresponding to 3, see ref. [15]

16

Data of Methyl (1 R * ,6 S * ,7 S * )-7-{1-[Tri(isopropyl)silanyl-oxy]vinyl}-2-oxabicyclo[4.1.0]heptane-7-carboxylate ( 9). Colorless oil. [α]D 20 -22 (c 1.07, CHCl3, for 84% ee), [α]D 20 -32 (c 0.56, Et2O, for 95% ee). IR (film): 2945 (m), 2866 (m), 1717 (s), 1633 (m), 1464 (m), 1390 (w), 1335 (m), 1282 (w), 1254 (s), 1237 (s), 1219 (m), 1204 (m), 1159 (m), 1133 (m), 1076 (s), 1042 (m), 1020 (s), 912 (w), 881 (m), 745 (s), 680 (s). 1H NMR (500 MHz, CDCl3): δ = 0.95-1.09 (m, 1 H), 1.22 (d, J = 6.6 Hz, 9 H), 1.23 (d, J = 6.6 Hz, 9 H), 1.24-1.31 (m, 3 H), 1.59-1.73 (m, 2 H), 1.96-1.99 (m, 1 H), 2.02-2.06 (m, 1 H), 3.11-3.17 (m, 1 H), 3.41 (s, 3 H), 3.51-3.56 (m, 1 H), 4.15 (d, J = 7.4 Hz, 1 H), 4.56 (d, J = 0.7 Hz, 1 H), 4.64 (d, J = 0.7 Hz, 1 H). 13C NMR (125 MHz, CDCl3): δ = 13.1 (d), 17.1 (t), 18.2 (q), 18.3 (q), 22.1 (t), 24.9 (d), 36.8 (s), 51.4 (q), 62.2 (d), 64.3 (t), 96.5 (d), 151.6 (s), 172.4 (s). MS: m/z (%) = 354 (2)[M+], 312 (23), 311 (100), 117 (10), 89 (15), 75 (23), 73 (10), 59 (26). HRMS: m/z calcd for C19H34O4Si+: 354.2226; found: 354.2181.

17

Data of Methyl cis -6-Tri(isopropyl)silanyloxy-2,3,4,4a,7,7a-hexahydrocyclopenta[ b ]pyran-5-carboxylate ( 10).
IR (film): 2944 (m), 2866 (m), 1716 (w), 1693 (s), 1614 (s), 1463 (w), 1437 (m), 1383 (s), 1287 (w), 1233 (s), 1212 (s), 1188 (m), 1141 (m), 1105 (m), 1082 (s), 1050 (m), 1009 (w), 996 (w), 881 (s), 843 (w), 807 (s), 781 (s), 682 (s). 1H NMR (500 MHz, CDCl3): δ = 1.10 (d, J = 7.3 Hz,1 9 H), 1.11 (d, J = 7.5 Hz, 9 H), 1.17-1.25 (m, 3 H), 1.39-1.47 (m, 1 H), 1.54-1.62 (m, 1 H), 1.86-1.98 (m, 2 H), 2.53 (dd, J = 0.6, 5.5 Hz, 2 H), 2.85 (dd, J =12.1, 6.0 Hz, 1 H), 3.49-3.54 (m, 1 H), 3.66-3.73 (m, 1 H), 3.69 (s, 3 H), 4.15 (dd, J = 11.0, 5.5 Hz, 1 H). 13C NMR (125 MHz, CDCl3): δ = 12.9 (d), 17.7 (q), 17.8 (q), 22.2 (t), 24.0 (t), 40.4 (d), 40.6 (t), 50.4 (q), 64.4 (t), 72.9 (d), 109.4 (s), 163.9 (s), 165.5 (s). MS: m/z (%) = 354 (1)[M+], 312 (22), 311 (100), 89 (10), 75 (14), 59 (18). HRMS: m/z calcd for C19H34O4Si+:354.2226; found: 354.2255.

20

Crystal data for (C25H36N2O8Si), rac-13: M = 520.7, triclinic, P, a = 10.0195 (7), b = 13.3063 (8), c = 21.6204 (14)Å, α = 81.287 (7), β = 85.175 (8), γ = 75.576 (7)°, U = 2756.2 (3)Å3, T = 200 K, Z = 4, µ (MoKα) = 0.133 mm-1 . The final R(F) = 0.047, wR(F)= 0.043 and S = 1.05. Both molecules of the asymmetric unit show similar conformations. CCDC-258850.

21

Data of Methyl cis -2-Methyl-3 a ,5,6,7 a -tetrahydro-4 H -furo[2,3- b ]pyran-3-carboxylate ( 11).
[α]D 18 +144 (c 1.06, CHCl3, for 95% ee). IR (film): 2950 (w), 1693 (s), 1633 (w), 1436 (m), 1381 (m), 1359 (w), 1333 (m), 1311 (w), 1259 (m), 1222 (w), 1187 (m), 1163 (m), 1139 (m), 1117 (m), 1085 (s), 1041 (w), 993 (m), 922 (m), 893 (m), 852 (s). 1H NMR (400 MHz, CDCl3): δ = 1.56-1.67 (m, 3 H), 1.92-1.98 (m, 1 H), 2.23 (d, J = 1.4 Hz, 3 H), 2.96-3.01 (m, 1 H), 3.70 (s, 3 H), 3.74-3.81 (m, 2 H), 5.77 (d, J = 7.6 Hz, 1 H). 13C NMR (100 MHz, CDCl3): δ = 14.3 (q), 19.8 (t), 22.1 (t), 37.9 (d), 50.8 (q), 60.8 (t), 104.1 (d), 106.7 (s), 166.2 (s), 167.7 (s). MS: m/z (%) = 198 (18)[M+], 167 (20), 166 (100), 139 (10), 138 (15), 124 (45), 110 (14), 96 (16), 95 (16), 82 (13), 67 (11). HRMS: m/z calcd for C10H14O4 +: 198.0892; found: 198.0903. Enantiomer separation: GC (β-Dex, isothermal, 130 °C, τ1 = 19.0 min, τ2 = 19.7 min). For data of ethyl ester corresponding to 11 see ref. 1, 15, 22.