Synlett 2011(18): 2667-2670  
DOI: 10.1055/s-0031-1289529
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

First Total Syntheses of (3R,5R)-Sonnerlactone and (3R,5S)-Sonnerlactone

Barla Thirupathi, Raghava R. Gundapaneni, Debendra K. Mohapatra*
Organic Chemistry Division-I, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India
Fax: +91(40)27160512; e-Mail: mohapatra@iict.res.in;
Further Information

Publication History

Received 27 August 2011
Publication Date:
19 October 2011 (online)

Abstract

First total syntheses of the macrocyclic natural products (3R,5R)-sonnerlactone and (3R,5S)-sonnerlactone, two new metabolites isolated from the endophytic fungus strain Zh6-B1, have been accomplished in eleven steps with 22% overall yield starting from enantiomerically pure (R)-propylene oxide prepared by hydrolytic kinetic resolution. Other key steps are Sharpless epoxidation, reductive elimination of iodo epoxide, and ring-closing-metathesis reaction for the construction of the macrolactone.

13

Spectral and Analytical Data of 8a
[α]D ²5 -103.5 (c 2.0, CHCl3). IR (neat): ν = 3433, 2934, 1415, 1153, 1097, 1034, 925, 850. cm. ¹H NMR (300 MHz, CDCl3): δ = 5.72 (m, 1 H, CH=CH2), 5.20 (m, 2 H, CH=CH 2), 4.58 (ABq, J = 37.8, 6.6 Hz, 2 H, OCH 2OCH3), 4.28 (m, 1 H, CHOCH2OCH3), 4.04 (m, 1 H, CH3CHO), 3.39 (s, 3 H, OCH2OCH 3), 2.60 (br s,1 H, OH), 1.71-1.56 (m, 2 H, CHCH 2CH), 1.19 (d, J = 6.2 Hz, 3 H, CH3) ppm. ¹³C NMR (75 MHz, CDCl3): δ = 137.6, 116.8, 94.2, 72.3, 64.2, 55.6, 43.9, 23.3 ppm. ESI-MS: m/z = 183 C8H16O3Na [M + Na]+.

14

Spectral and Analytical Data of 8b
[α]D ²5 +6.1 (c 1.0, CHCl3). IR (neat): 3432, 2933, 1644, 1153, 1098, 1034, 925, 767 cm. ¹H NMR (300 MHz, CDCl3): δ = 5.67 (m, 1 H, CH=CH2), 5.28-5.16 (m, 2 H, CH=CH 2), 4.59 (ABq, J = 59.0, 6.8 Hz, 2 H, OCH 2OCH3), 4.24 (m, 1 H, CH3CHOSi), 3.98 (m, 1 H, CHOCH2OCH3), 3.39 (s, 3 H, CH2OCH 3), 1.78-1.57 (m, 2 H, CHCH 2CH), 1.18 (d, J = 6.0 Hz, 3 H, CH3) ppm. ¹³C NMR (75 MHz, CDCl3): δ = 137.6, 116.7, 94.1, 75.1, 66.6, 55.6, 43.9, 23.3 ppm. ESI-MS: m/z (C8H16O3Na) =183 [M + Na]+.

19

Spectral and Analytical Data of 7a
[α]D ²7 -59.6 (c 1.1, CHCl3). IR (neat): 3417, 2929, 1731, 1647, 1607, 1576, 1315, 1255, 1162, 1030, 967, 697 cm. ¹H NMR (300 MHz, CDCl3): δ = 11.71 (br s, 1 H, ArOH), 7.41-7.27 (m, 5 H, ArH), 6.37 (d, J = 2.2 Hz, 1 H, ArH), 6.34 (d, J = 2.2 Hz, 1 H, ArH), 5.89 (m, 1 H, CH=CH2), 5.65 (m, 1 H, CH=CH2), 5.45-5.16 (m, 4 H, CH=CH 2, CH=CH 2), 5.07-4.91 (s, 2 H, ArOCH2), 5.04 (s, 2 H), 4.64 (m, 1 H, CH3CHOC=O), 4.50 (dd, J = 6.7, 2.8 Hz, 1 H, CHOCH2OCH3), 4.10 (m, 1 H, ArCH2), 3.64 (m, 1 H, ArCH2), 3.34 (s, 3 H, OCH3), 1.88-1.80 (dd, J = 6.6, 1.5 Hz, 2 H, OCHCH 2CHO), 1.40 (d, J = 6.2 Hz, 3 H, CH3) ppm. ¹³C NMR (75 MHz, CDCl3): δ = 170.8, 165.5, 163.0, 144.5, 137.4, 137.6, 137.3, 128.6, 128.1, 127.5, 117.8, 117.6, 115.6, 111.35, 100.1, 93.7, 73.7, 69.9, 69.5, 55.6, 42.0, 40.3, 20.6 ppm. ESI-HRMS: calcd for C25H30O6Na [M + Na]+: 449.1940; found: 449.1922. Spectral and Analytical Data of 7b
[α]D ²7 -23.12 (c 1.2, CHCl3). IR (neat): 2934, 1646, 1610, 1575, 1452, 1315, 1255, 1162, 1030, 966, 918, 695 cm. ¹H NMR (300 MHz, CDCl3): δ = 11.72 (br s, 1 H, ArOH), 7.40-7.31 (m, 5 H, ArH), 6.44 (d, J = 2.4 Hz, 1 H, ArH), 6.34 (d, J = 2.2 Hz, 1 H, ArH), 5.91 (m, 1 H, CH=CH2), 5.66 (m, 1 H, CH=CH2), 5.34-5.16 (m, 4 H, CH=CH 2, CH=CH 2), 5.07-4.91 (m, 2 H, ArOCH2), 5.04 (s, 2 H, OCH 2OCH3), 4.64 (m, 1 H, CH3CHOC=O), 4.45 (dd, J = 6.7, 2.8 Hz, 1 H), 4.11 (m, 1 H), 3.65 (m, 1 H) 3.34 (s, 3 H, OCH2OCH 3), 1.88-1.81 (dd, J = 8.3, 1.5 Hz, 2 H, OCHCH 2CHO), 1.41 (d, J = 6.2 Hz, 3 H, CH3) ppm. ¹³C NMR (75 MHz, CDCl3): δ = 170.5, 164.8, 163.0, 143.6, 137.7, 137.2, 136.1, 128.5, 128.1, 127.4, 126.9, 117.5, 115.5, 108.7, 100.5, 93.6, 74.5, 69.8, 55.5, 42.1, 40.2, 20.1 ppm. ESI-HRMS: m/z calcd for C25H30O6Na [M + Na]+: 449.1940; found: 449.1927.

20

Spectral and Analytical Data of 1
Mp 144-145 ˚C. [α]D ²0 +8.6 (c 1.0, EtOH). IR (KBr): 3504, 3423, 3179, 2941, 1657, 1609, 1458, 1391, 1318, 1264, 1207, 1165 cm. ¹H NMR (500 MHz, acetone-d 6): δ = 11.02 (br s, 1 H), 9.29 (br s, 1 H) 6.28 (d, J = 2.1 Hz, 1 H), 6.24 (d, J = 2.1 Hz, 1 H), 4.96 (m, 1 H), 3.83 (m, 1 H), 3.72 (s, 1 H), 3.23 (dt, J = 13.4, 7.2 Hz, 1 H), 2.56 (ddd, J = 13.4, 8.2, 6.0 Hz, 1 H), 2.09 (m, 1 H), 2.01 (m, 2 H), 1.78 (m, 1 H), 1.53 (m, 1 H), 1.44 (d, J = 6.2 Hz, 3 H), 1.30 (m, 1 H) ppm. ¹³C NMR (75 MHz, acetone-d 6): δ = 171.9, 163.4, 163.1, 149.5, 111.9, 106.2, 101.7, 73.2, 72.0, 45.9, 37.5, 37.0, 27.1, 21.5.ppm. ESI-MS: m/z = 267 C14H18O5 [M + H]+. ESI-HRMS: m/z calcd for C14H18O5 [M + H]+: 267.1227; found: 267.1255.

21

Spectral and Analytical Data of 2
Mp 154-155 ˚C. [α]D ²5 +55.0 (c 1.1, EtOH). IR (KBr): 3455, 2926, 1653, 1457, 1319, 1262, 1204, 1163, 1102 cm. ¹H NMR (300 MHz, acetone-d 6): δ = 11.6 (br s, 1 H), 9.25 (br s, 1 H), 6.31 (d, J = 2.2 Hz, 1 H), 6.24 (d, J = 2.2 Hz, 1 H), 5.40 (m, 1 H), 4.22 (m, 1 H), 3.39 (ddd, J = 12.6, 4.3, 3.9 Hz, 1 H), 2.40 (m, 1 H), 2.16 (m, 1 H), 1.70-1.91 (m, 3 H), 1.50 (m, 1 H), 1.45 (d, J = 6.4 Hz, 3 H), 1.31 (m, 1 H) ppm. ¹³C NMR (75 MHz, acetone-d 6): δ = 172.6, 167.6, 164.6, 150.1, 113.1, 106.2, 102.8, 71.4, 67.8, 43.9, 38.2, 37.2, 29.5, 21.2 ppm. ESI-MS: m/z = 267 C14H18O5 [M + H]+. ESI-HRMS: m/z calcd for C14H18O5 [M + H]+: 267.1227; found: 267.1206.