Synlett 2009(2): 249-252  
DOI: 10.1055/s-0028-1087524
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

A Facile Total Synthesis of All Stereoisomers of Tarchonanthuslactone and Euscapholide from Chiral Epichlorohydrin

Hee-Yoon Lee*, Vasu Sampath, Yeokwon Yoon
School of Molecular Science (BK21) and Department of Chemistry, Korea Advanced Institute of Science & Technology (KAIST), Daejon, 305-701, Korea
Fax: +82(42)8698370; e-Mail: leehy@kaist.ac.kr;
Further Information

Publication History

Received 10 October 2008
Publication Date:
15 January 2009 (online)

Abstract

A versatile and facile synthetic route to all the stereoisomers of tarchonanthuslactone and euscapholide was developed using epichlorohydrin as the source of all the chiral centers.

17

All new compounds showed satisfactory analytical data for the assigned structure and purity. Spectroscopic Data for Selected Compounds
Compound 1d: [α]D +142.8 (c 0.55, CHCl3), lit. [²] [α]³0 +115.5 (c 1.52, MeOH). ¹H NMR (400 MHz, CDCl3): δ = 6.88-6.84 (dt, J = 10.1, 3.4 Hz, 1 H), 6.01-5.98 (dt, J = 9.8, 1.8 Hz, 1 H), 4.65-4.58 (m, 1 H), 4.09-4.04 (m, 1 H), 2.40-2.37 (m, 2 H), 2.02-1.95 (m, 1 H), 1.77-1.72 (dt, J = 12.6, 4.1 Hz, 1 H), 1.23 (d, J = 6.3 Hz, 3 H). ¹³C NMR (100 MHz, CDCl3): δ = 163.9, 145.1, 121.2, 76.8, 65.2, 43.6, 29.5, 23.7.
Compound 1a: [α]D -115.5 (c 0.17, CHCl3), lit. [²²] [α]²5 -111 (c 1, CHCl3). ¹H NMR (400 MHz, CDCl3): δ = 6.89-6.84 (ddd, J = 13.9, 6.7, 4.6 Hz, 1 H), 6.01-5.97 (dt, J = 9.7, 1.7 Hz, 1 H), 4.65-4.58 (m, 1 H), 4.08-4.03 (m, 2 H), 2.40-2.36 (m, 2 H), 2.07 (br, 1 H), 2.02-1.95 (m, 1 H), 1.76-1.71 (dt, J = 12.6, 4.2 Hz, 1 H), 1.23 (d, J = 6.2 Hz, 3 H). ¹³C NMR (100 MHz, CDCl3): δ = 164.0, 145.2, 121.2, 76.8, 65.2, 43.5, 29.4, 23.7.
Compound 4a: [α]D -76.2 (c 0.22, CHCl3), [α]²5 -76
(c 0.6, CHCl3). ¹H NMR (400 MHz, CDCl3): δ = 6.81-6.78 (ddd, J = 10.0, 5.0, 2.4 Hz, 1 H), 6.73-6.70 (m, 2 H), 6.59-6.56 (dd, J = 8.1, 2.0 Hz, 1 H), 5.99-5.96 (ddd, J = 10.0, 3.0, 1.0 Hz, 1 H), 5.05-5.01 (m, 1 H), 4.16 (m, 1 H), 2.81 (t, J = 6.5 Hz, 2 H), 2.58 (t, J = 7.2 Hz, 2 H), 2.29 (m, 1 H), 2.20 (m, 1 H), 2.04-2.01 (m, 1 H), 1.76-1.70 (m, 1 H), 1.23 (d, J = 6.3 Hz, 3 H), 0.95 (s, 9 H), 0.94 (s, 9 H), 0.15 (s, 6 H), 0.14 (s, 6 H). ¹³C NMR (100 MHz, CDCl3): δ = 172.7, 165.0, 145.4, 143.9, 142.2, 132.8, 120.9, 120.4, 115.4, 115.2, 75.2, 67.0, 41.0, 35.8, 30.1, 29.0, 20.5.
Compound 4b: [α]D -9.5 (c 0.2, CHCl3). ¹H NMR (400 MHz, CDCl3): δ = 6.85-6.81 (m, 1 H), 6.72 (d, J = 8.1 Hz,
1 H), 6.66 (d, J = 2.0 Hz, 1 H), 6.57-6.55 (dd, J = 8.1, 2.1 Hz, 1 H), 6.01-5.97 (ddd, J = 11.6, 5.8, 1.9 Hz, 1 H), 5.13-5.09 (m, 1 H), 4.22-4.18 (m, 1 H), 2.84-2.77 (m, 2 H), 2.55 (t, J = 6.9 Hz, 2 H), 2.26-2.22 (m, 2 H), 1.89-1.86 (dd, J = 9.4, 3.2 Hz, 1 H), 1.81-1.77 (dd, J = 9.7, 3.2 Hz, 1 H), 1.22 (d, J = 6.3 Hz, 3 H). ¹³C NMR (100 MHz, CDCl3): δ = 172.4, 164.8, 145.3, 143.6, 142.6, 132.6, 121.1, 120.4, 115.29, 74.3, 66.9, 41.2, 36.2, 30.3, 29.5, 20.4.
Compound 4c: [α]D +9.7 (c 0.3, CHCl3). ¹H NMR (300 MHz, CDCl3): δ = 6.85-6.82 (m, 1 H), 6.74-6.65 (m, 2 H), 6.58-6.54 (dd, J = 8.0, 2.0 Hz, 1 H), 6.01-5.97 (ddd, J = 11.6, 5.8, 1.8 Hz, 1 H), 5.15-5.08 (m, 1 H), 4.21-4.18 (m,
1 H), 2.82-2.77 (m, 2 H), 2.55 (t, J = 6.8 Hz, 2 H), 2.25-2.21 (m, 2 H), 1.89-1.85 (dd, J = 9.3, 3.3 Hz, 1 H), 1.81-1.77 (dd, J = 9.5, 3.4 Hz, 1 H), 1.22 (d, J = 6.3 Hz, 3 H). ¹³C NMR (100 MHz, CDCl3): δ = 172.5, 164.9, 145.4, 143.6, 142.5, 132.6, 121.0, 120.4, 115.2, 74.4, 66.9, 41.2, 36.1, 30.3, 29.5, 20.4.
Compound 4d: [α]D +91.5 (c 0.5, CHCl3). ¹H NMR (400 MHz, CDCl3): δ = 6.82-6.79 (ddd, J = 10.3, 5.4, 2.5 Hz,
1 H), 6.73-6.70 (m, 2 H), 6.58-6.55 (dd, J = 8.0, 2.0 Hz, 1 H), 5.99-5.96 (m, 1 H), 5.05-5.01 (m, 1 H), 4.16 (m, 1 H), 2.81 (m, 2 H), 2.58 (t, J = 7.2 Hz, 2 H), 2.28 (m, 1 H), 2.20 (m, 1 H), 2.04-2.01 (m, 1 H), 1.76-1.71 (m, 1 H), 1.23 (d, J = 6.43 Hz, 3 H). ¹³C NMR (100 MHz, CDCl3): δ = 172.7, 165.0, 145.5, 143.9, 142.2, 132.8, 120.9, 120.3, 115.4, 75.2, 67.1, 40.9, 35.8, 30.1, 28.9, 20.4. Compound 12: ¹H NMR (400 MHz, C6D6-CDCl3, 1:1): δ = 4.36-4.34 (m, 1 H), 3.84 (m, 1 H), 3.63-3.58 (m, 1 H), 2.55-2.51 (br d, J = 19.0 Hz, 1 H), 2.30-2.23 (dd, J = 19.1, 5.4 Hz, 1 H), 1.64-1.60 (br d, J = 13.9 Hz, 1 H), 1.46-1.42 (m, 1 H), 1.31 (m, 1 H), 1.10-1.03 (m, 1 H), 0.91 (d, J = 6.0 Hz, 3 H). ¹³C NMR (100 MHz, CDCl3): δ = 169.4, 72.9, 65.9, 61.9, 38.6, 36.5, 29.4, 21.4.