T. Li et al. / Tetrahedron xxx (xxxx) xxx
3
1
(
.93 (ddd, J ¼ 14.2, 5.0, 2.4 Hz, 1H), 1.70 (td, J ¼ 14.5, 4.7 Hz, 1H), 1.58
dd, J ¼ 12.9, 3.0 Hz, 1H), 1.36 (ddd, J ¼ 11.4, 5.7, 3.0 Hz, 1H),
.31e1.27 (m, 1H), 1.26 (s, 3H), 1.25 (s, 3H), 0.99 (d, J ¼ 6.4 Hz, 3H).
1
1
3
C NMR (101 MHz, CDCl
3
)
d
¼ 214.1, 163.6, 83.0, 77.3, 77.0, 76.7,
5
(
4.2, 53.7, 48.3, 40.1, 34.9, 32.4, 23.9, 18.6, 18.5, 17.9, 14.7. HRMS
ESI): m/z [MþH]þ calcd for C14
2
H22NO : 236.1651, found: 236.1645.
4.1.3. Preparation and spectra data of alcohol 17
Scheme 2. Synthesis of tricyclic oxazole 13.
To a stirred solution of 16 (197 mg, 0.84 mmol) in dry THF
ꢁ
(
25 mL) at ꢀ78 C under Ar was added KHMDS (1.0 M, 2.1 mL)
ꢁ
dropwise. The resulting mixture was stirred at ꢀ78 C for 2 h, then
it was added the solution of PhNTf
THF. After it was completed, the reaction mixture was quenched
with saturated NH Cl (10 mL) and extracted with EtOAc
15 mL ꢂ 3). The organic extract was washed with saturated brine,
dried over anhydrous Na SO , filtered, concentrated to give the
2
(749 mg, 2.1 mmol) in 10 mL dry
4
(
2
4
crude residue, which was further purified by chromatography on
silical gel with EtOAc/petroleum (1 : 20) to afford compound 17 as a
2
2
ꢁ
1
colorless oil (231 mg, 75% yield). ½
aꢃ
¼ 34 (c ¼ 1.0, CH
2 2
Cl ) H
D
NMR (400 MHz, CDCl
3
)
d
¼ 4.14 (d, J ¼ 7.7 Hz, 1H), 3.77 (d, J ¼ 7.7 Hz,
1
5
1
H), 2.71 (ddd, J ¼ 15.2, 4.6, 2.3 Hz, 1H), 2.41 (ddd, J ¼ 15.2, 13.9,
.1 Hz, 1H), 2.32e2.17 (m, 2H), 2.13 (ddd, J ¼ 13.3, 5.1, 2.3 Hz, 1H),
.85e1.77 (m, 1H), 1.76 (d, J ¼ 1.3 Hz, 1H), 1.74 (s, 3H), 1.47 (td,
13
J ¼ 13.5, 4.4 Hz, 1H), 1.38e1.32 (m, 1H), 1.27 (s, 3H), 1.22 (s, 3H).
C
NMR (101 MHz, CDCl
3
)
d
¼ 163.8,149.2,125.7,120.2,117.1, 83.6, 77.3,
7
7.0, 76.7, 53.5, 52.3, 39.3, 33.9, 31.3, 20.7, 18.9, 17.9, 17.8, 17.5. HRMS
Scheme 3. Synthesis of the bicyclic vinyl triflate 7.
þ
(ESI): m/z [MþH] calcd for C15
21 3 4
H F NO S: 368.1143, found:
3
68.1138.
starting from commercially available (R)-carvone.
4.1.4. Preparation and spectra data of compound 18
4.1.2. Preparation and spectra data of compound 16
To a solution of enone 13 (1.3 mmol, 304 mg) in THF (20 mL)
To a solution of 17 (51 mg, 0.14 mmol) in 11 mL of 10:1 MeOH/
H O were added a wet slurry of Raney nickel (10 mg, 50% in water)
2
ꢁ
at ꢀ78 C was added dropwise L-selectride (1.0 M in THF;
1
.43 mmol) over 15 min and the resulting colorless solution was
and trimethyl borate (0.23 mL, 15 equiv). The suspension was stir-
ꢁ
ꢁ
stirred at ꢀ78 C for 5 h. The reaction mixture was quenched
red at 30 C under H
2
(1 atm) for about 1 h. The mixture was filtered
ꢁ
at ꢀ78 C by successive addition of MeOH (2 mL), aqueous 10%
through a Celite path and washed with EtOAc (20 mL). The com-
bined filtrate was washed with brine (20 mL), dried over anhydrous
NaOH (1 mL) and aqueous 30% H
2
O
2
(1 mL) and the resulting
mixture was allowed to slowly warm to rt overnight. The resulting
2
Na SO4, concentrated in vacuo, and purified by flash chromatog-
suspension was diluted with H
saturated aqueous Na
2
O (10 mL) and carefully treated with
solution (5 mL) at 0 C. The aqueous
raphy eluting with petroleum ether/ethyl acetate (3:1) to yield
ꢁ
22
D
ꢁ
2
S
2
O
3
compound 18 (colorless oil, 36 mg, 72% yield). ½
a
ꢃ
¼ 53 (c ¼ 1.0,
1
phase was extracted with EtOAc (3 ꢂ 10 mL) and the combined
CH
2
Cl
2
) H NMR (400 MHz, CDCl
3
)
d
¼ 3.71 (dd, J ¼ 11.2, 6.1 Hz, 1H),
organic phases were dried over anhydrous Na SO and concen-
2
4
3.37 (dd, J ¼ 11.2, 6.6 Hz, 1H), 2.61 (ddd, J ¼ 17.1, 12.4, 7.2 Hz, 1H),
2.44 (ddd, J ¼ 17.0, 6.3, 2.6 Hz, 1H), 2.32e2.19 (m, 4H), 2.11 (ddd,
J ¼ 13.4, 7.1, 2.6 Hz, 1H), 1.81 (dd, J ¼ 12.8, 6.5 Hz, 1H), 1.76 (s, 3H),
trated. The residual light-yellow oil was purified by column chro-
matography on silica gel (petro ether/EtOAc, 5:1) to give ketone 16
ꢁ
22
D
13
(
¼
251 mg, 82% yield) as a white solid. Mp: 83e86 C.
½
a
ꢃ
1.69e1.59 (m, 2H), 1.32 (s, 3H), 1.02 (s, 3H). C NMR (101 MHz,
ꢁ
1
ꢀ44 (c ¼ 1.0, CH
2
Cl
2
)
H NMR (400 MHz, CDCl
3
)
d
¼ 4.10 (d,
CDCl
3
)
d
¼ 216.6, 149.6, 126.2, 120.3, 117.1, 77.3, 77.0, 76.7, 67.0, 52.0,
J ¼ 7.8 Hz, 1H), 3.74 (d, J ¼ 7.8 Hz, 1H), 2.75e2.66 (m, 2H), 2.35 (td,
45.3, 38.7, 35.0, 32.6, 31.6, 18.8, 18.4, 17.4, 16.7. HRMS (ESI): m/z
J ¼ 14.6, 5.0 Hz,1H), 2.16e2.09 (m,1H), 2.01 (dd, J ¼ 13.1, 3.9 Hz,1H),
[MþH]þ calcd for C15
22 3 5
H F O S: 371.1140, found: 371.1135.