were recorded on a Nicolet 205 Fourier-transform instrument.
Ether refers to diethyl ether. X-Ray data for 9 and 10 were
collected at 120 K and 150 K, respectively, by the EPSRC ser-
vice, based at the University of Wales, Cardiff.
by analogy to the 13C NMR shifts of cholesterol.34 119Sn NMR
data are displayed in Table 4.
3â-Triphenylstannylcholest-5-ene 2 (Method 1)
(a) Preparation of cholesterylmagnesium chloride. A concen-
trated solution of cholesteryl chloride 16 (2.0 g) in anhydrous
THF (2 cm3) was added to magnesium ribbon (1.2 g, 0.049
mol), activated by iodine. The reaction mixture was gently
heated and the remaining cholesteryl chloride (in total 10.0 g,
0.025 mol) in anhydrous THF added. The solution was refluxed
for 4 h and used immediately.
(b) Reaction of the Grignard reagent. To the cholesterylmag-
nesium chloride solution was added triphenyltin chloride (9.52
g, 0.025 mol) in anhydrous THF. The reaction mixture was
refluxed for 24 h, and hydrolysed with saturated aqueous
ammonium chloride. The ether layer was collected, washed
with saturated aqueous sodium hydrogen carbonate, dried over
magnesium sulfate and evaporated in vacuo to leave an oil. The
oil was purified by column chromatography (eluent CHCl3),
followed by recrystallisation from dichloromethane–ethanol or
acetone to yield colourless needles, mp 151–152 ЊC.
3â-Tosyloxycholest-5-ene (cholesteryl toluene-p-sulfonate) 13
Toluene-p-sulfonyl chloride (14.6 g, 0.076 mol) was added to a
solution of cholesterol 14 (14.6 g, 0.038 mol) in dry pyridine (17
cm3). The solution was left standing overnight at room tem-
perature after which time needles were produced. Ether was
added to dissolve the solid, and the resulting solution was
washed with water, dried and evaporated in vacuo. Recrystal-
lisation of the residue from acetone yielded the product (15.4 g,
75.6%), mp 132–134 ЊC (lit.,27 mp 131.5–132.5 ЊC); δH(CDCl3)
0.67 (s, 3H, Me-18), 0.87 (d, 6H, J 6.6, Me-26 and Me-27),
0.91 (d, 3H, J 6.5, Me-21), 0.98 (s, 3H, Me-19), 1.05–2.80 (m,
26H), 2.46 (s, 3H, C6H4Me-p), 4.3–4.4 (m, 1H, J 5.6, H-3), 5.31
(d, 1H, J 5.2, H-6), 7.34 (d, 2H, J 8.0, aryl-H), 7.8 (d, 2H, J 8.0,
aryl-H). 13C NMR data are displayed in Table 4.
3â-Mesyloxycholest-5-ene (cholesteryl methanesulfonate) 15
Methanesulfonyl chloride (5.4 cm3) was added to a solution of
14 (16.4 g, 0.42 mol) in dry pyridine. The solution was left
overnight at Ϫ5 ЊC before being allowed to return to room tem-
perature and extracted with ether. The ether extract was washed
with water and evaporated in vacuo. The resulting solid was
further washed with water. Ether and methanol were added and
the solution cooled to Ϫ5 ЊC to yield the product (15.1 g,
81.6%), mp 120–122 ЊC (lit.,28 mp 121–123 ЊC); δH(CDCl3) 0.68
(s, 3H, Me-18), 0.86 (d, 3H, J 6.6, Me-26), 0.87 (d, 3H, J 6.6,
Me-27), 0.91 (d, 3H, J 6.5, Me-21), 1.02 (s, 3H, Me-19), 1.06–
2.73 (m, 26H), 3.00 (s, 3H, MeSO2), 4.46–4.59 (m, 1H, J 6.3,
H-3), 5.42 (d, 1H, J 5.1, H-6). 13C NMR data are displayed in
Table 4.
3â-Triphenylstannylcholest-5-ene 2 (Method 2)
A reaction mixture containing 15 (3.8 g, 0.0098 mol), triphenyl-
tin chloride (4 g, 0.0098 mol) and magnesium ribbon (0.61 g,
0.025 mol), activated by iodine, in anhydrous THF was refluxed
until TLC [eluent: 10% ethyl acetate–light petroleum (bp 60–
80 ЊC)] indicated consumption of the cholesteryl chloride. The
solution was hydrolysed with saturated aqueous ammonium
chloride and extracted with ether. The ether layer was washed
with saturated aqueous sodium hydrogen carbonate and dried
over magnesium sulfate. Evaporation of the solvent in vacuo left
a yellow coloured oil. The oil was redissolved in ether and the
solution was left to allow the remaining hexaphenylditin by-
product to precipitate out. The ether solution was filtered and
evacuated in vacuo to leave a glassy oil, which was crystallised
from dichloromethane–ethanol (1:5) to give needles, mp 147–
148 ЊC (lit.,29 mp 151–153 ЊC) (Found: C, 75.3; H, 8.7%.
C45H60Sn requires C, 75.1; H, 8.4%); δH(CDCl3) 0.66 (s, 3H,
Me-18), 0.85 (d, 3H, J 6.5, Me-26), 0.86 (d, 3H, J 6.6, Me-27),
0.90 (d, 3H, J 6.5, Me-21), 0.96 (s, 3H, Me-19), 0.98–2.72 (m,
26H), 5.24 (d, 1H, J 5.2, H-6), 7.34–7.39 (m, 10H, p- ϩ m-aryl
H), 7.40–7.62 (m, 5H, o-aryl H). 13C and 119Sn NMR data are
displayed in Table 4.
3â-Chlorocholest-5-ene (cholesteryl chloride) 1629,30
A mixture of 14 (12.5 g, 32 mmol) and thionyl chloride (15 ml,
0.2 mol) was stirred for 24 h at 0 ЊC. The reaction mixture was
dissolved in ether and water was added until gas evolution
ceased. The ether layer was collected, washed, dried over mag-
nesium sulfate and evacuated under reduced pressure. The resi-
due was recrystallised from acetone to yield 8.9 g (67.9%) of a
yellow solid, mp 93–95 ЊC; δH(CDCl3) 0.68 (s, 3H, Me-18), 0.86
(d, 3H, J 6.6, Me-26), 0.87 (d, 3H, J 6.6, Me-27), 0.91 (d, 3H, J
6.5, Me-21), 1.03 (s, 3H, Me-19), 1.06–2.62 (m, 26H), 3.7–3.8
(m, 1H, H-3), 5.36 (d, 1H, J 5.2, H-6). 13C NMR data are
displayed in Table 4.
Preparation of 3-(iodophenyl)stannylcholest-5-ene derivatives
3α- or 3β-Triphenylstannylcholest-5-ene (1 or 2) was dissolved
in chloroform and a solution containing a calculated quantity
of iodine (1 or 2 mol equiv.) in chloroform was then added
dropwise with stirring. The reaction was stirred until all the
iodine had reacted. All volatiles were removed under vacuum to
leave oily solid residues.
3á-(Iododiphenyl)stannylcholest-5-ene 9. From 1 (0.5 g, 0.70
mmol) and I2 (0.176 g, was recrystallised from chloroform–
methanol as needles, 0.24 g, 44.9%, mp 120–121 ЊC; δH(CDCl3)
0.60 (s, 3H Me-18), 0.87 (d, 3H, J 6.5, Me-26), 0.87 (d, 3H, J
6.5, Me-27), 0.88 (d, 3H, J 6.4, Me-21), 0.96 (s, 3H, Me-19),
1.00–2.90 (m, 26H), 5.25 (d, 1H, J 5.0, H-6), 7.26–7.41 (m, 10H,
p- ϩ m-aryl H), 7.51–7.73 (m, 5H, o-aryl H). 13C and 119Sn
NMR data are displayed in Table 4.
3á-(Diiodophenyl)stannylcholest-5-ene (10). From 1 (0.204 g,
0.283 mmol) and I2 (0.144 g, 0.567 mmol), was crystallised from
chloroform–methanol as platelets, 0.14 g, 60%, mp 120.5–
121.5 ЊC; δH(CDCl3) 0.60 (3H, s, Me-18), 0.87 (d, 3H, J 6.5, Me-
26), 0.87 (d, 3H, J 6.6, Me-27), 0.88 (3H, d, Me-21, J 6.3 Hz),
0.96 (s, 3H, Me-19), 1.02–3.7 (m, 26H), 5.40 (d, 1H, J 5.0, H-6),
7.33–7.47 (m, 10H, p- ϩ m-aryl H), 7.61–7.78 (m, 5H, o-aryl
H). 13C and 119Sn NMR data are displayed in Table 4.
3á-Triphenylstannylcholest-5-ene 1
Triphenylstannyllithium was prepared31 from Li (1.6 g, 0.23 mol)
and triphenyltin chloride (10.0 g, 0.023 mol) in anhydrous THF
(30 cm3) in an ultrasonic bath with a typical reaction time of 18
h. The olive-green solution of triphenylstannyllithium was fil-
tered through glass-wool, cooled to Ϫ68 ЊC (acetone–ice slush
bath) and 13 (5.0 g, 0.007 mol) in dry THF (25 cm3) added. The
reaction mixture was stirred under nitrogen and allowed to
reach room temperature overnight, hydrolysed with saturated
aqueous ammonium chloride and extracted with ether. The
ether extract was washed with water, dried over anhydrous
magnesium sulfate and evaporated in vacuo to give an oil. The
oil was dissolved in ether, filtered to remove the insoluble
hexaphenylditin by-product, and the filtrate evaporated. The
resultant oil was chromatographed on silica preparatory plates
[eluent 5–10% ethyl acetate–light petroleum (bp 60–80 ЊC)]. The
top band on the plates was collected as an oil and was crystal-
lised from chloroform and ethanol (1:5) as colourless plates
(1.46 g, 29%), mp 88–90 ЊC (lit.,29 mp 85–91 ЊC) (Found: C,
75.3; H, 8.7%. C45H60Sn requires C, 75.1; H, 8.4%).
A similar reaction of 15 with Ph3SnLi also produced 1. The
1H and 13C NMR spectra of compound 1 were assigned (see
Table 2) using HMQC32 and HMBC33 NMR spectra, as well as
3â-(Iododiphenyl)stannylcholest-5-ene (11). From 2 (0.101 g,
0.14 mmol) and I2 (0.0389 g, 0.15 mmol), was recrystallised
3662
J. Chem. Soc., Perkin Trans. 1, 1997
Buchanan, Heather J.
