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water, cold 10% hydrochloric acid solution, water, and brine
(2!10 mL each), dried over anhydrous Na2SO4, and
concentrated to yield an oil. Chromatography (flash column,
hexane/EtOAc) afforded the corresponding triflates as
colorless oils. The following known compounds, included
in Table 1, were characterized by comparison of their
chromatographic and spectroscopic data (1H and 13C NMR,
and MS) with those described in the literature: decyl
trifluoromethanesulfonate (entry 5),31 dodecyl trifluoro-
methanesulfonate (entries 6 and 7),32 4-(tert-butyl)cyclo-
hexyl trifluoromethanesulfonate (entry 9),33 (K)-menthyl
trifluoromethanesulfonate (entry 10).34 For new compound,
physical and spectroscopic data follow:
ArC), 147.2 (CO); MS: m/zZ328 (MC, 53%), 195 (32), 168
(14), 167 (100), 166 (28), 165 (75), 153 (10), 152 (43), 139
(20), 69 (27). HRMS: calcd for C15H11F3O3S 328.3117,
found 328.3111.
4.5. Synthesis of cholesta-3,5-dien-3-yl
trifluoromethanesulfonate39
2,6-Di-tert-butylpyridine (0.226 g, 1.1 mmol) and triflic
anhydride (0.186 mL, 0.111 g, 1.1 mmol) were added to a
solution of cholest-5-en-3-one (0.384 g, 1 mmol) in chloro-
form (10 mL). The reaction mixture was stirred under reflux
for 12 h. The reaction solvent was distilled and the crude
reaction mixture was diluted with hexane (20 mL). The
hexane solution was washed with water (20 mL) and brine
(20 mL). The organic layer was filtered through basic
alumina with hexane elution, and then solvents were
removed by rotatory evaporation to yield the corresponding
vinyl triflate pure enough to be used for the reduction
reaction. The crystallized triflate (hexane) was characterized
by comparison of its physical and spectroscopic data (1H,
13C NMR) with those described in the literature.10c
4.3.1. 1-Butylpentyl trifluoromethanesulfonate. Colorless
oil; tr 14.24; IR (film): nZ2936, 2877, 1471, 1425, 1302,
1210, 1137, 1118, 968, 718 cmK1; 1H NMR: dZ0.76 (6H, t,
JZ6.8 Hz, 2!CH3), 1.22 (8H, m, 2!CH2CH2CH3), 1.96
(4H, m, 2!CH2CH), 4.15 (1H, m, CH); 13C NMR: dCZ
12.6 (2!CH3), 21.0 (2!CH2CH3), 26.7 (2!CH2CH2-
CH3), 34.2 (2!CH2CH), 86.0 (CH), 119.7 (q, JZ320.0 Hz,
CF3); MS: m/zZ276 (MC, 1%), 127 (10), 85 (77), 71 (93),
70 (11), 69 (43), 57 (100), 56 (18), 55 (48), 44 (62), 43 (92),
42 (15), 41 (79), 39 (25). HRMS: calcd for C10H19F3O3S
276.3203, found 276.3209.
4.6. Reduction of sulfonates using the CuCl2$2H2O–Li–
DTBB(cat.) combination. General procedure
4.4. Synthesis of the starting enol triflates35
A solution of the corresponding sulfonate (1 mmol) in THF
(5 mL) was added to a mixture of CuCl2$2H2O (170 mg,
1 mmol) or its deuterated salt (174 mg, 1 mmol), lithium
sand (56 mg, 8.0 mmol) and DTBB (27 mg, 0.1 mmol) in
THF (5 mL) at room temperature under a nitrogen
atmosphere. The reaction mixture, which was initially
dark green, changed to black, thus indicating the formation
of activated copper(0). After total conversion of the starting
material (TLC or GLC), the resulting suspension was
diluted with diethyl ether (20 mL) and filtered off through a
pad containing silica gel and celite (ca. 3:1). The filtrate was
dried over anhydrous sodium sulfate, the solvents were
evaporated (15 Torr), and the resulting residue was purified
by column chromatography (silica gel, hexane/EtOAc). For
volatile products, the dried organic layer was analyzed by
GLC using an internal standard (dodecane for alkyl triflates
and cycloocta-1,5-diene for enol triflates) (see Table
footnotes). The reduction products in Tables 1 and 2, were
fully characterized by comparison of their chromatographic
and spectral data with those of the corresponding commer-
cially available pure samples [n-dodecane (Table 1, entries
1 and 6), adamantane (Table 1, entry 3), n-nonane (Table 1,
entries 4 and 8), n-decane (Table 1, entry 5), tert-
butylcyclohexane (Table 1, entry 9), (E)-non-4-ene (Table
2, entry 1), cholesta-3,5-diene (Table 2, entry 8)]. For the
rest of compounds included in Tables 1 and 2, literature
references for all known compounds follow: p-menthane
(Table 1, entries 2 and 10),40 1-deuteriododecane (Table 1,
entry 7),41 4-tert-butylcyclohexene (Table 2, entry 2),11a
4-tert-butyl-1-deuteriocyclohexene (Table 2, entry 3),42
1,2,3,4,4a,5,6,8a-octahydronaphtalene (Table 2, entry 4),43
3,4-dihydrophenantrene (Table 2, entry 5),44 3-methyl-6-(1-
methylethylidene)cyclohex-1-ene (isoterpinolene) (Table 2,
entry 6),45 3,5,5-trimethylcyclohexa-1,3-diene (Table 2,
entry 7).46
For all the starting enol triflates included in Table 2, except
for enol triflate derived from cholest-5-en-3-one (Table 2,
entry 8), a solution of the corresponding ketone (1.6 mmol)
in THF (3 mL) was added to a solution of LDA (1.76 mmol)
in THF (3 mmol) at K78 8C, and the resulting solution was
allowed to be stirred for 2 h at the same temperature. A
solution of N-phenyltrifluoromethanesulfonimide (0.63 g,
1.76 mmol) in THF (3 mL) was then added; the reaction
mixture was stirred at 0 8C for 1 h and allowed to warm to
room temperature. Stirring was maintained during 9 h. After
solvent removal at the rotatory evaporator, the resultant
yellow oil was purified by column chromatography on silica
gel (hexane) to yield the enol triflate product. The following
known compounds, included in Table 2, were characterized
by comparison of their chromatographic and spectroscopic
data (1H and 13C NMR, and MS) with those described in the
literature: (Z)-1-butyl-1-pentenyl trifluoromethanesulfonate
(entry 1),36 4-tert-butylcyclohexen-1-yl trifluoromethane-
sulfonate (entries 2 and 3),35 trans-3,4,4a,5,6,7,8,8a-octa-
hydronaphthalen-1-yl trifluoromethanesulfonate (entry 4),9b
3-methyl-6-(1-methylethylidene)cyclohexen-1-yl trifluoro-
methanesulfonate (entry 6),37 3,5,5-trimethyl-1,3-cyclohex-
adien-1-yl trifluoromethanesulfonate (entry 7).38 For new
compound, physical and spectroscopic data follow.
4.4.1. Dihydrophenanthrenyl trifluoromethanesulfonate.
Pale brown oil; tr 35.43; IR (film): nZ3067, 2970, 2890,
1650, 1596, 1491, 1394, 1207, 1133, 1067, 910, 815, 761,
695 cmK1; 1H NMR: dZ2.55 (2H, m, CH2CH) 3.69 (2H, t,
JZ7.1 Hz, CH2C), 6.01 (1H, t, JZ4.8 Hz, CHCH2), 7.11–
7.51 (3H, m, ArH), 7.68 (1H, d, JZ8.8 Hz, ArH), 7.74 (1H,
d, JZ7.6 Hz, ArH), 7.93 (1H, d, JZ8.2 Hz, ArH); 13C
NMR: dZ22.6 (CH2CH), 30.7 (CH2C), 117.2 (CHCH2),
119.1 (q, JZ320.4 Hz, CF3), 119.3, 124.1, 126.8, 127.2,
127.5, 129.4 (6!ArCH), 131.4, 133.0, 134.3, 137.3 (4!