1654
P.R. Krishna et al. / Tetrahedron 69 (2013) 1649e1657
stirred for 10 min. A solution of 20 (1.28 g, 2.24 mmol) in dry CH2Cl2
(12 mL) was added and stirred for 2 h at ꢁ78 ꢀC. It was quenched
with Et3N (3.74 mL, 26.94 mmol) and extracted with CH2Cl2
(2ꢂ20 mL). Organic layer was washed with brine (50 mL), dried
(Na2SO4), evaporated and to obtain aldehyde as a colorless liquid.
The above aldehyde was dissolved in benzene (20 mL) and treated
with (methoxycarbonylmethylene)triphenyl phosphorane (0.862 g,
2.47 mmol) at reflux. After 2 h, solvent was evaporated and purified
the residue by column chromatography (silica gel, 60e120 mesh, Rf
CHaHbCOOMe), 2.42 (dd, J¼14.9, 6.4 Hz, 1H, CHaHbCOOMe),
2.27e2.22 (m, 1H, CHMe), 1.93e1.69 (m, 2H, CHCH2CH), 1.64e1.59
(m, 1H, CHMeCH2OSi), 1.57e1.21 (m, 8H, (CH2)4), 1.04 (s, 9H, t-BuSi),
0.92e0.87 (m, 6H, CHMeCH2OSi, CHMe); 13C NMR (75 MHz, CDCl3):
d
171.8, 135.6,134.0, 129.4, 127.5, 81.4, 72.9, 68.8, 51.5, 41.4, 39.7, 35.8,
33.2, 31.8, 30.1, 27.0, 26.8, 25.8, 19.2, 16.8, 13.8; MS (ESIMS) m/z 533
(MþNa)þ; HRMS (ESI) calcd for C31H46O4NaSi (MþNa)þ 533.30576,
found 533.30483. HPLC {Column: XDB-C18, 20% water in acetoni-
trile, flow rate: 1 mL/min, 210 nm, tR (major)¼1.595 min, tR (minor)¼
1.210 min}.
0.80 EtOAc/n-hexane 4:96) to afford 21 (1.1 g, 78%) as a colorless
25
liquid. [
a
]
ꢁ10.5 (c 1.5, CHCl3); IR (neat): 3745, 3610, 3070, 3050,
D
2929, 2856, 2309,1726,1656,1550,1515,1465,1430,1378,1361,1314,
1254, 1217, 1172, 937, 834, 772, 740, 702, 668, 613 cmꢁ1 1H NMR
(300 MHz, CDCl3): 7.66e7.64 (m, 4H, AreH), 7.41e7.28 (m, 6H,
2.1.13. 2-((2R,4S,5S)-5-((S)-6-(tert-Butyldiphenylsilyloxy)-5-methyl-
;
hexyl)-4-methyltetra-hydro-furan-2-yl)ethanol (24). To
a
cooled
d
(ꢁ40 ꢀC) solution of 23a (0.48 g, 0.94 mmol) in dry CH2Cl2 (5 mL),
DIBAL-H (1.50 mL, 2.07 mmol, 20% solution in toluene) was added
slowly. The reaction mixture was stirred at the same temperature for
1 h, cooled to 0 ꢀC, quenched with methanol (1 mL) and sodium po-
tassium tartrate solution (1 mL). The reaction mixture was passed
through a short pad of Celite. The filtrate was concentrated and pu-
rified the residue by column chromatography (silica gel,
AreH), 6.94 (quintet, J¼15.1, 7.5 Hz, 1H, OlefiniceH), 5.79 (d,
J¼15.9 Hz, 1H, OlefiniceH), 3.71 (s, 3H, OMe), 3.56e3.50 (m, 2H,
CH2OSi), 3.48e3.44 (m, 1H, CHOSi), 2.44e2.37 (m, 1H, CHaHbCH),
1.98e1.88 (m, 1H, CHaHbCH), 1.75e1.49 (m, 2H, CHMeCH2OSi,
CHMeCH2), 1.45e1.13 (m, 8H, (CH2)4), 1.11e0.95 (m, 12H, t-BuSi,
CHMeCH2OSi), 0.93e0.81 (m, 12H, t-BuSi, CHMeCH2), 0.02 (s, 6H,
MeSi (2)); 13C NMR (75 MHz, CDCl3):
d
167.0,149.3,135.5,134.0,129.4,
60e120 mesh, Rf 0.4 EtOAc/n-hexane 30:70) to furnish 24 (0.355 g,
25
127.5, 121.7, 75.4, 68.8, 51.3, 37.7, 35.6, 35.2, 33.1, 32.9, 27.1, 26.8, 26.2,
25.8,19.2,18.0,16.8,14.2, e4.3; MS (ESIMS) m/z 647 (MþNa)þ; HRMS
(ESI) calcd for C37H60O4NaSi2 (MþNa)þ 647.39223, found 647.39310.
78%) as a colorless liquid. [
a
]
ꢁ13.4 (c 2.0, CHCl3); IR (neat): 3610,
D
3049, 3016, 2930, 2855, 2308,1560,1550,1532,1470,1430,1387,1213,
1178, 1109, 824, 758, 724, 669, 615 cmꢁ1; 1H NMR (300 MHz, CDCl3):
d
7.65 (dd, J¼7.1, 1.5 Hz, 4H, AreH), 7.43e7.33 (m, 6H, AreH), 4.30e4.21
2.1.11. (5S,6S,11S,E)-Methyl 12-(tert-butyldiphenylsilyloxy)-6-hydroxy-
5,11-dimethyldo-dec-2-enoate (22). To a stirred solution of 21 (1.07 g,
1.71 mmol) in MeOH (10 mL) at 0 ꢀC, catalytic amount of PPTS was
added and stirred at room temperature for 12 h. The reaction mix-
ture was quenched with saturated NaHCO3 solution and MeOH was
evaporated. Water was added and extracted with EtOAc (2ꢂ15 mL).
The organic extracts were washed with brine (30 mL), dried
(Na2SO4), evaporated, and purified by column chromatography (sil-
ica gel, 60e120 mesh, Rf 0.60 EtOAc/n-hexane 20:80) to afford 22
(m,1H, OCHCH2CH2OH), 3.89e3.83 (m,1H, OCHCHMe), 3.80e3.75 (m,
2H, CH2OSi), 3.53e3.40 (m, 2H, CH2OH), 3.20 (br s,1H, OH), 2.25e2.13
(m, 1H, CHMe), 1.82e1.58 (m, 4H, CHCH2CH, CH2CH2OH), 1.47e1.20
(m, 9H, (CH2)4, CHMeCH2OSi), 1.05 (s, 9H, t-BuSi), 0.95e0.85 (m, 6H,
CHMeCH2OSi, CHMe); 13C NMR (75 MHz, CDCl3):
d 135.4,134.0,129.2,
127.3, 81.2, 76.4, 68.9, 61.8, 40.2, 37.8, 35.4, 32.8, 30.1, 26.9, 26.6, 19.1,
16.6, 14.0; MS (ESIMS) m/z 505 (MþNa)þ; HRMS (ESI) calcd for
C30H46O3NaSi (MþNa)þ 505.31084, found 505.31094.
(0.66 g, 75%) as a colorless liquid. [
a
]
25 ꢁ14.5 (c 1.1, CHCl3); IR (neat):
2.1.14. tert-Butyl((S)-6-((2S,3S,5R)-5-(2-(4-methoxybenzyloxy)
ethyl)-3-methyltetrahydro-furan-2-yl)-2-methylhexyloxy)diphenylsi-
lane (25). To a cooled (0 ꢀC) solution of 24 (0.33 g, 0.684 mmol) in
dry THF (4 mL), NaH (0.032 g, 1.36 mmol, 60% w/w dispersion in
paraffin oil) was added and stirred for 30 min. A solution of MPM-Br
(0.165 g, 0.82 mmol) in dry THF (2 mL) was added and stirredat room
temperature for 6 h. The reaction mixture was quenched with sat-
urated NH4Cl solution (5 mL) and extracted with EtOAc (2ꢂ20 mL).
The combined organic layers were dried (Na2SO4), evaporated, and
purified bycolumn chromatography (silica gel, 60e120 mesh, Rf 0.70
D
3744, 3501, 3070, 2929, 2856, 2311, 1724, 1655, 1462, 1430, 1388,
1315, 1314, 1270, 1213, 1172, 1109, 1044, 981, 824, 741, 703, 667,
613 cmꢁ1; 1H NMR (300 MHz, CDCl3):
d
7.80 (d, J¼6.4 Hz, 4H, AreH),
7.44e7.37 (m, 6H, AreH), 6.98 (quintet, J¼15.4, 7.4 Hz, 1H,
OlefiniceH), 5.80 (d, J¼15.4, 1H, OlefiniceH), 3.74 (s, 3H, OMe),
3.53e3.50 (m, 2H, CH2OSi), 3.48e3.44 (m,1H, CHOSi), 2.42e2.36 (m,
1H, CHaHbCH), 2.15e2.09 (m, 1H, CHaHbCH), 1.74e1.63 (m, 2H,
CHMeCH2OSi, CHMeCH2), 1.45e1.41 (m, 2H, CH2CHOSi), 1.27e1.25
(m, 6H, (CH2)3), 1.07 (s, 9H, t-BuSi), 0.93e0.96 (m, 6H, CHMeCH2OSi,
CHMeCH2); 13C NMR (75 MHz, CDCl3):
d
167.1, 148.6, 135.8, 134.2,
EtOAc/n-hexane 4:96) to afford alcohol 25 (0.33 g, 80%) as a light
25
129.4, 127.6, 122.1, 74.4, 68.8, 51.3, 37.8, 36.3, 35.7, 34.5, 33.1, 26.9,
26.4, 25.8, 19.3,16.8,13.3; MS (ESIMS) m/z 533 (MþNa)þ; HRMS (ESI)
calcd for C31H46O4NaSi (MþNa)þ 533.30576, found 533.30601.
yellow liquid. [
a
]
ꢁ13.08 (c 0.93, CHCl3); IR (neat): 3745, 3590,
D
2928, 2855, 2308,1712,1678,1612,1513,1464,1427,1361,1301,1247,
1213, 1173, 1108, 1037, 822, 753, 667, 614 cmꢁ1; 1H NMR (300 MHz,
CDCl3): d 7.67e7.64 (m, 4H, AreH), 7.43e7.34 (m, 6H, AreH), 7.26 (d,
2.1.12. Methyl 2-((2R,4S,5S)-5-(6-(tert-butyldiphenylsilyloxy)hexyl)-4-
methyltetrahydrofuran-2-yl)acetate (anti-23). To a cooled (ꢁ20 ꢀC)
solution of 22 (0.63 g, 1.23 mmol) in dry MeOH (7 mL), NaOMe
(0.073 g, 1.35 mmol) was added in small portions. The reaction
mixture was stirred at same temperature for 12 h quenched with
saturated ammonium chloride and MeOH was evaporated. Water
was added and extracted with EtOAc (2ꢂ20 mL). The organic ex-
tracts were washed with brine (40 mL), dried (Na2SO4), evaporated,
and purified by column chromatography (silica gel, 60e120 mesh, Rf
J¼8.6 Hz, 2H, C6H4OMe), 6.87 (d, J¼8.6 Hz, 2H, C6H4OMe), 4.49e4.42
(m, 2H, OCH2C6H4OMe), 4.18e4.06 (m, 1H, OCHCH2CH2OPMB),
3.80e3.78 (m, 4H, OMe, OCHCHMe), 3.57e3.40 (m, 4H, CH2OPMB,
CH2OSi), 2.24e2.08 (m,1H, CHMe),1.91e1.14 (m,13H, CH2CH2OPMB,
CHCH2CH, (CH2)4, CHMeCH2OSi), 1.04 (s, 9H, t-BuSi), 0.92e0.82 (m,
6H, CHMeCH2OSi, CHMe); 13C NMR (75 MHz, CDCl3):
d 159.4, 135.5,
134.1, 129.4, 127.5, 113.6, 80.9, 73.8, 72.6, 68.8, 67.6, 55.2, 40.1, 36.8,
35.6, 33.1, 31.9, 30.3, 29.6, 27.2, 26.8, 19.3, 16.8, 13.9; MS (ESIMS) m/z
625 (MþNa)þ; HRMS (ESI) calcd for C38H54O4NaSi (MþNa)þ
625.36840, found 625.36890.
0.50 EtOAc/n-hexane 25:75) to afford 23 (0.50 g, 81%) as a colorless
25
liquid. [
a
]
ꢁ15.5 (c 1.3, CHCl3); IR (neat): 3857, 3745, 3883, 3610,
D
3048, 3016, 2928, 2855, 2308, 1740, 1567, 1550, 1532, 1465, 1430,
1387, 1213, 1170, 1109, 1006, 824, 758, 704, 667, 614, 565 cmꢁ1 1H
NMR (500 MHz, CDCl3):
6H, AreH), 4.47e4.42 (m, 1H, OCHCH2COOMe), 3.86e3.82 (m, 1H,
OCHCHMe), 3.67 (s, 3H, OMe), 3.51e3.48 (m, 1H, CHaHbOSi),
3.44e3.41 (m, 1H, CHaHbOSi), 2.60 (dd, J¼14.9, 6.4 Hz, 1H,
2.1.15. (S)-6-((2S,3S,5R)-5-(2-(4-Methoxybenzyloxy)ethyl)-3-
methyltetrahydrofuran-2-yl)-2-methylhexan-1-ol (26). To a stirred
solution of compound 25 (0.30 g, 0.498 mmol) in anhydrous THF
was added TBAF (0.59 mL, 0.597 mmol, 1.0 M solution in THF) at
0 ꢀC and reaction mixture stirred at room temperature for 3 h then
reaction mixture adsorbed as such on silica and the crude residue
;
d
7.66 (d, J¼6.4 Hz, 4H, AreH), 7.45e7.35 (m,