131.4, 110.2, 72.9, 70.3, 69.6, 66.3, 52.3, 27.4, 25.7, 20.8, 20.7 ppm;
MS (EI) m/z (%): 313(M+-CH3, 52), 211(19), 169(36), 168(12),
137(11), 85(43), 83(58), 47(12), 43(100); HRMS (M+-CH3) calcd
for C14H17O8 313.0923, found 313.0919.
to stir at room temperature for 2h, then it was diluted with
ethyl acetate (5 mL) and washed with saturated NaHCO3 (3 ¥
2 mL). The organic layer was washed with brine (1 ¥ 3 mL)
then dried with Na2SO4. The crude material was purified via flash
column chromatography with a solvent gradient of 2:1 hexanes-
ethyl acetate.
6,7-Diacetoxy-2,2-dimethyl-hexahydro-benzo[1,3]dioxole-4-car-
boxylic acid methyl ester (25). To a solution of ester 24 (40 mg,
0.122 mmol) in ethanol (3 mL) was added 5% Rh/Al2O3 (40 mg).
The reaction was stirred under an atmosphere of H2 (60 psi,
24 h). The reaction was filtered through celite by elution with
EtOH and concentrated. The crude material was purified via flash
column chromatography with a solvent gradient of 5:1 hexanes-
ethyl acetate. (28 mg, 70%), colorless oil. Rf 0.60 (1:1 hexanes/ethyl
(3aR,7aS)-Ethyl-3a,7a-dihydro-2,2-dimethylbenzo[d][1,3]dioxo-
le-4-carboxylate (28). (173 mg, 92%) colorless oil; Rf 0.56 (1:1
23
hexanes/ethyl acetate); [a]D +74.6 (c 4.02, CHCl3); IR (film):
n 3018, 2987, 2936, 1712, 1651, 1425, 1380, 1259, 1155, 1031,
1
917, 856, 697, 667, 512 cm-1; H NMR (300 MHz, CDCl3) d
7.06 (dd, J = 5.3, J = 3.1 Hz, 1H), 4.84 (d, J = 5.7 Hz, 1H),
4.28–4.41 (m, 1H), 4.07–4.26 (m, 2H), 2.21–2.45 (m, 1H), 1.99–
2.16 (m, 1H), 1.86–1.99 (m, 1H), 1.58–1.72 (m, 1H), 1.33 (d,
J = 10.2 Hz, 6H), 1.24 (t, J = 7.2 Hz, 3H) ppm; 13C NMR
(75 MHz, CDCl3) d 166.2, 142.3, 130.0, 108.5, 72.6, 70.4, 60.5,
27.8, 26.2, 25.1, 20.9, 14.2 ppm; MS (EI) m/z (%): 226 (M+-
CH3), 211(77), 181(15), 169(17), 123(100), 105(17), 95(13), 83(11),
79(76), 67(14), 59(10), 55(11), 43(82), 41(14); HRMS (M+-CH3)
calcd for C12H16O4 211.0970, found 211.0969; Anal. calcd: C 64.27;
H 7.19. Found C 64.52; H 7.08.
20
acetate); [a]D -71.56 (c 0.93, CHCl3); IR (film): n 2976, 2954,
1
2938, 1750, 1734, 1732, 14337, 1372, 11240, 1221, 1195 cm-1; H
NMR (600 MHz, CDCl3) d 5.40 (m, 1H), 4.93 (dd, J = 7.9, J =
2.6 Hz, 1H), 4.69 (t, J = 4.9 Hz, 1H), 4.23 (dd, J = 8.0, J = 5.0 Hz,
1H), 3.78 (s, 3H), 3.13 (dt, J = 12.8, J = 4.5 Hz, 1H), 2.21 (dt,
J = 14.9, J = 12.9 Hz, 1H), 2.12–2.06 (m, 4H), 1.52 (s, 3H), 1.38
(s, 3H) ppm; 13C NMR (150 MHz, CDCl3) d 171.4, 170.3, 169.7,
109.9, 75.5, 73.9, 7.1, 68.7, 52.2, 38.11, 27.9, 26.2, 24.9, 20.9 ppm;
MS (EI) m/z (%): 313 (M+-CH3, 13), 241(15), 171(23), 153(47),
43(100); HRMS (M+-CH3) calcd for C14H19O8 315.1080, found
315.1082.
(3aR,7aS)-Prop-2-ynyl-3a,7a-dihydro-2,2-dimethylbenzo[d][1,
3]dioxole-4-carboxylate (29). (764 mg, 63%) colorless oil; Rf =
22
7-Hydroxymethyl-2,2-dimethyl-hexahydro-benzo[1,3]dioxole-4,
5-diol (27). LAH (26 mg, 0.73 mmol) was added to a solution
of ester 25 (40 mg, 0.121 mmol) in dry THF (2 mL). The reaction
mixture was brought to reflux and stirred for 4 hours, allowed
to cool to room temperature, and quenched with a mixture of
THF/H2O. The reaction was filtered, dried over Na2SO4, filtered
again, and concentrated. The crude material was purified via
flash column chromatography with a solvent gradient of 5:1
hexanes-ethyl acetate. (23 mg, 86%), colorless oil. Rf 0.14 (9:1
0.54 (2:8 ethyl acetate/hexane); [a]D +112.70 (c 1.3, CHCl3); IR
(KBr) n 2987, 2935, 1718, 1030 cm-1; 1H NMR (300 MHz, CDCl3)
d 7.22 (dd, J = 5.3, 1.1 Hz, 1H), 6.19–6.09 (series of m, 2H), 4.95
(d, J = 8.4 Hz, 1H), 4.89 (dd, J = 8.4, J = 2.4 Hz, 1H), 4.84 (dd,
J = 2.5, J = 1.0 Hz, 2H), 2.50 (t, J = 2.5 Hz, 1H), 1.47 (s, 3H), 1.41
(s, 3H) ppm; 13C NMR (75 MHz, CDCl3) d 165.3, 134.8, 134.4,
125.5, 121.2, 105.7, 77.7, 74.9, 71.8, 68.0, 52.3, 26.7, 25.0 ppm; MS
(EI) m/z (%): 219(M+-Me, 42), 177(41), 163(17), 121(83), 43(100).
HRMS (EI) calcd for C12H11O4: m/z 219.0657, found: 219.0659.
Anal. Calcd. for C13H14O4: C, 66.66; H, 6.02. Found: C, 66.68; H,
6.08.
20
1
chloroform/methanol); [a]D -57.08 (c 0.70, MeOH); H NMR
(600 MHz, acetone-d6) d 4.30 (t, J = 4.4, 1H), 4.01 (dd, J =
6.9, 5.5 Hz, 1H), 4.00–3.94 (m, 2H), 3.70–3.60 (m, 2H), 3.58–
3.48 (m, 3H), 2.44–2.37 (m, 1H), 1.75 (dt, J = 13.0, 4.6 Hz,
1H), 1.48 (dt, J = 6.6, 2.8 Hz, 1H), 1.40 (s, 3H), 1.28 (s, 3H)
ppm; 13C NMR (150 MHz, CDCl3) d 107.8, 79.4, 74.6, 73.7, 68.9,
63.58, 34.2, 28.3, 27.7, 25.7 ppm; MS (EI) m/z (%) 203 (M+-
CH3, 100), 204(10), 203(100), 125(19), 107(11), 100(13), 97(13),
95(21), 83(32), 79(33), 73(14), 71(11), 70(14), 69(20), 67(16),
60(17), 59(55), 57(18), 55(18), 43(53), 41(22); HRMS (M+-CH3)
calcd for C9H15O5 203.0933, found 203.0926.
(1S,2R,3S,4S,4aS,5S,6R,8aR)-1,2,3,4,4a,5,6,8a-Octahydro-
2,3,5,6-tetrahydroxy-O,O-diisopropylyden-1,4-ethenonaphthalene-
1,7-diethyldicarboxylate (30). Neat 24 (400 mg, 1.78 mmol) was
maintained for 7 days at r.t., purified by flash-chromatography
22
(eluant 3:7 ethyl acetate/hexane); [a]D +62.90 (c 1.3, CHCl3).
1
IR (KBr) n 2984, 2938, 1722, 1262, 1221, 1071 cm-1; H NMR
(600 MHz, CDCl3) d 6.44 (d, J = 3.7 Hz, 1H), 6.39 (d, J = 8.5 Hz,
1H), 6.05 (dd, J = 8.5, J = 6.3 Hz, 1H), 4.61 (dd, J = 7.2, J =
1.2 Hz, 1H), 4.59 (d, J = 4.9 Hz, 1H), 4.43 (ddd, J = 7.2, J =
3.4, J = 0.5 Hz, 1H), 4.36 (qd, J = 7.1, J = 1.7 Hz, 2H), 4.28–
4.18 (m, 2H), 4.17 (dd, J = 4.9, J = 2.5 Hz, 1H), 3.02 (1 H, m),
2.95 (ddd, J = 9.2, J = 3.7, J = 1.3 Hz, 1H), 2.34 (ddd, J = 9.2,
J = 1.3, J = 1.2 Hz, 1H), 1.37 (s, 3H), 1.36 (t, J = 7.1 Hz, 3H),
1.31 (s, 3H), 1.30 (s, 3H), 1.28 (t, J = 7.1 Hz, 3H), 1.28 (s, 3H)
ppm. 13C NMR (150 MHz, CDCl3) d 171.5, 165.8, 136.4, 131.4,
130.2, 128.8, 109.7, 108.2, 80.7, 78.3, 76.9, 69.2, 61.4, 60.7, 53.9,
40.4, 38.6, 34.9, 28.1, 26.5, 25.3, 25.1, 14.20, 14.15 ppm;; MS (EI)
m/z (%): 433(M+-Me, 6), 390(8), 375(7), 345(4), 100(17), 61(21),
43(100). HRMS (EI) calcd for C24H32O8: m/z 448.20972, found:
448.20863.
General procedure for the trans-esterification of PAD-reduced diols
A solution of PAD-reduced diol (0.79 mmol), conc. H2SO4 (5
drops) in dry ethanol (10 mL) was refluxed for 4 days. The
mixture was concentrated, diluted in satd. NaHCO3 (2 mL) and
extracted with ethyl acetate (3 ¥ 20 mL). The organic extracts were
combined, dried over MgSO4, filtered, concentrated, and purified
by flash chromatography (eluant 1:1 ethyl acetate/hexanes) and
recrystallized from ethyl acetate/hexanes.
General procedure for the ketalization of diols
To
a
stirring solution of diol (0.832 mmol) and 2,2
(1S,2R,3S,4S,4aS,5S,6R,8aR)-1,2,3,4,4a,5,6,8a-Octahydro-2,
3,5,6-tetrahydroxy-O,O-diisopropylyden-1,4-ethenonaphthalene-1,
7-dipropargyldicarboxylate (31). A solution of 29 (390 mg,
dimethoxypropane (0.71 mL, 5.83 mmol) in acetone (1 mL) was
added a catalytic amount of p-TsOH. The reaction was allowed
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The Royal Society of Chemistry 2009
Org. Biomol. Chem., 2009, 7, 2619–2627 | 2625
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