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Synlett 2009(15): 2539-2541  
DOI: 10.1055/s-0029-1217735
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Acyclic Diene Metathesis Reactions of Carbohydrates

Eric J. Enholm*, Kalyan Mondal
Department of Chemistry, University of Florida, Gainesville, FL 32611, USA
Fax: +1(352)3928758; e-Mail: enholm@chem.ufl.edu;
Further Information

Publication History

Received 19 June 2009
Publication Date:
27 August 2009 (online)

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Abstract

Several examples of the ADMET reactions of carbo­hydrates have been studied. These syntheses prepare new hybrid biopolymers that are chiral, biodegradable, and use renewable sugar precursors.

Key words

carbohydrate - alkene - metathesis - ruthenium - polymer

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General Procedure for Carbohydrate Diene Preparation
To a solution of the carbohydrate (4.0 g, 15 mmol) in a 100 mL round-bottom flask was added at 0 ˚C, DIC (5.77 g, 45 mmol) and DMAP (0.53 g, 0.28 mol) in anhyd CH2Cl2 (30 mL, 0.50 equiv) under Ar. 4-Pentenoic acid (4.60 g, 0.05 mol) was added at 0 ˚C over the next 10 min. After completion of addition the reaction mixture was warmed to r.t. and stirred for the next 3.5 h. The reaction was monitored by TLC (hexane-EtOAc, 6:4). At the end of 3.5 h, the product was filtered and washed with H2O (2 × 50 mL) and brine (1 × 50 mL). The crude product was then dried over anhyd MgSO4, concentrated under reduced pressure, and purified by silica gel column chromatography using hexane-EtOAc (100:0 to 90:10) as eluents to give the desired product as a thick oil.
General Procedure for ADMET Reactions
A 25 mL round-bottom flask with a stir bar was placed under Ar atmosphere. A diester carbohydrate (2.86 g, 7 mmol) in CHCl3 (7.0 mL) was added to it. Grubbs second-generation catalyst 1 (56.93 mg) was added to the monomer and flask and stirred 1 h at r.t. The reaction was placed under Ar atmosphere and vacuum alternatively each hour until complete by TLC. With the first addition of the catalyst, there was evolution of ethylene gas bubbles. As the reaction progressed the medium became more and more viscous and it had been changed from alternate Ar atmosphere to total vacuum over the next 72 h. The polymerization was terminated by adding ethyl vinyl ether. Filtration and washing with Et2O gave an off-white powder.
Selected Spectral Data
Pentenoate Diester of Diacetone d -Mannitol 3
Yield 4.60 g, 71%; R f  = 0.53 (hexane-EtOAc, 6:4); [α]D ²5 +13.88 (c 2.33, MeOH). IR (KBr): 3081, 2987, 1747, 1642, 1455, 1418, 1372, 1156 cm-¹. ¹H NMR (300 MHz, CDCl3): δ = 5.95-5.85 (m, 2 H), 5.40-5.30 (m, 2 H), 5.10-4.90 (m, 4 H), 4.20-4.10 (dd, J = 8.2, 5.4 Hz, 2 H), 3.94-3.84 (dd, J = 9.5, 5.4 Hz, 2 H), 3.82-3.76 (dd, J = 12.5, 4.5 Hz, 2 H), 2.50-2.30 (m, 8 H), 1.38-1.30 (s, 6 H), 1.28-1.20 (s, 6 H). ¹³C NMR (75 MHz, CDCl3): δ = 171.8, 136.4, 115.9, 109.5, 74.4, 71.5, 68.1, 33.5, 28.8, 26.6, 25.3. ESI-HRMS (FT-ICR): m/z calcd for C22H34O8: 426.5006; found: 426.2354.
ADMET of 4-Pentenoate Diester of Diacetone d -mannitol 4
R f  = 0.22 (CHCl3-MeOH, 9:1); [α]D ²5 +15.65 (c 2.02, MeOH). IR (neat): 3071, 2977, 1767, 1647, 1465, 1438, 1382, 1186 cm-¹. ¹H NMR (300 MHz, CDCl3): δ = 5.30 (m, 4 H), 3.99 (m, 6 H), 2.40 (m, 8 H), 1.40 (s, 6 H), 1.30 (s, 6 H).
4-Pentenoate Diester of the Monoacetone d -Ribose 6
R f  = 0.52 (hexane-EtOAc, 6:4); [α]D ²5 -44.25 (c 2.13, MeOH). IR (neat): 3079, 2979, 2881, 1743, 1703, 1642, 1520, 1419, 1366, 1066 cm-¹. ¹H NMR (300 MHz, CDCl3): δ = 6.20-6.18 (s, 1 H), 5.84-5.70 (m, 2 H), 5.06-4.94 (m, 4 H), 4.68-4.64 (s, 2 H), 4.44-4.38 (t, J = 7.1 Hz, 1 H), 4.14-4.02 (m, 2 H), 2.46-2.26 (m, 8 H), 1.48-1.44 (s, 3 H), 1.32-1.28 (s, 3 H). ¹³C NMR (75 MHz, CDCl3): δ = 172.9, 171.7, 136.9, 136.8, 116.3, 116.2, 113.7, 102.6, 85.8, 85.6, 82.1, 64.5, 34.1, 33.8, 29.2, 28.9, 26.9, 25.5. HRMS (CI+): m/z calcd for C18H26O7: 354.1679; found: 354.1691.
ADMET of the 4-Pentenoate Diester of d -Ribose 7
R f  = 0.21 (CHCl3-MeOH, 9:1); [α]D ²5 +141.65 (c 1.76, MeOH). IR (neat): 3058, 2983, 1745, 1646, 1523, 1420, 1375, 1123 cm-¹. ¹H NMR (300 MHz, CDCl3): δ = 5.20-5.60 (m, 3 H) 3.80-4.15 (m, 5 H), 2.20-2.85 (m, 8 H), 1.15-1.25 (m, 6 H).
4-Pentenoate Diesterification of d -Isomannide 9
R f  = 0.39 (hexane-EtOAc, 6:4); [α]D ²5 +142.68 (c 2.20, CH2Cl2). IR (neat): 3079, 2979, 2881, 1743, 1703, 1642, 1520, 1419, 1366, 1066 cm-¹. ¹H NMR (300 MHz, CDCl3): δ = 5.80-5.64 (m, 1 H), 5.02-4.94 (m, 3 H), 4.94-4.88 (m, 1 H), 4.88-4.84 (dd, J = 10.1, 5.1 Hz, 1 H), 4.60-4.54 (m, 2 H), 3.94-3.86 (dd, J = 8.1, 2.1 Hz, 2 H), 3.71-3.64 (dd, J = 5.1, 2.1 Hz, 2 H), 2.42-2.34 (m, 4 H). ¹³C NMR (75 MHz, CDCl3): δ = 172.4, 136.5, 115.6, 80.4, 73.7, 70.4, 22.1, 28.8. ESI-HRMS (FT-ICR): m/z calcd for C16H22O6: 310.3423; found: 310.1416.
ADMET of the 4-Pentenoate Diester of d -Isomannide 10 R f  = 0.23 (CHCl3-MeOH, 9:1); [α]D ²5 +148.39 (c 2.01, MeOH). IR (neat): 3078, 2971, 2885, 1763, 1698, 1632, 1523, 1423, 1316 cm-¹. ¹H NMR (300 MHz, CDCl3): δ = 5.33 (d, 1 H, 20 Hz), 5.03 (m, 1 H), 4.82 (m, 1 H), 4.02 (m, 1 H), 3.80 (m, 1 H), 2.15-2.25 (m, 4 H). ¹³C NMR (75 MHz, CDCl3): δ = 172.3, 172.0, 136.5, 136.3, 115.8, 115.6, 85.9, 80.8, 78.0, 73.9, 73.4, 70.4, 33.4, 33.2, 31.6, 28.8, 22.7, 14.1. ESI-HRMS (FT-ICR): m/z calcd for C16H22O6: 310.1416; found: 310.3500.
4-Pentenoate Diesterification of d -Isosorbide 12
R f  = 0.42 (hexane-EtOAc, 6:4); [α]D ²5 +153.71.39 (c 2.10, CH2Cl2). IR (neat): 3060, 2980, 2877, 1741, 1703, 1642, 1520, 1419, 1365 cm-¹. ¹H NMR (300 MHz, CDCl3): δ = 5.86-5.68 (m, 2 H), 5.17-4.85 (m, 4 H), 3.94-3.85 (m, 6 H), 2.48-2.28 (m, 8 H). ¹³C NMR (75 MHz, CDCl3): δ = 172.4, 172.1, 136.5, 136.4, 115.9, 115.7, 86.0, 80.8, 78.0, 74.0, 73.5, 70.5, 33.4, 33.2, 28.8. ESI-HRMS (FT-ICR): m/z calcd for C16H22O6: 310.1416; found: 310.3500.
ADMET of the Diester of d -Isosorbide 13
R f  = 0.25 (CHCl3-MeOH, 9:1); [α]D ²5 +154.39 (c 2.26, MeOH). IR (film): 3061, 2988, 2857, 1743, 1709, 1644, 1412, 1375 cm-¹. ¹H NMR (300 MHz, CDCl3): δ = 5.30-5.00 (m, 6 H), 4.40-4.00 (m, 6 H), 4.00-3.50 (m, 18 H), 3.40-3.00 (m, 18 H), 2.50-2.20 (m, 28 H), 1.60-1.10 (m, 34 H).