Ryanodine Cyclohexane Substituents
J ournal of Medicinal Chemistry, 1996, Vol. 39, No. 12 2345
Hz) and 1.97 (d, J ) 13.9 Hz) AB H2-14; 13C NMR (CD3OD) δ
21.1 and 28.4 (C-7 and -8), 66.8 (C-9), 72.7 (C-10), 87.0 (C-11),
8.0 and 6.7 (br) (EtBO2). Methanolysis of the boronate was
carried out by slow distillation with methanol containing
initially 5% MeNH2 (40%) during 4h. Chromatography on
silica (0.5 g) and elution with CHCl3/MeOH (9:1) containing
1% NH3 gave diol 24 (8 mg): 1H NMR (CD3OD) as for ketol
23 except δ 4.19 (d, J ) 3.9 Hz, H-10), 3.92 (m, H-9), 2.15 (dt,
J ) 13, 13, and 4.2 Hz, H-7ax), 1.27 (ddd, J ) 13.5, 3.0, and
1.0 Hz, H-7eq), 2.01 (m, H-8ax), 1.78 (m, H-8eq), 1.42 (s, H3-17);
13C NMR (CD3OD) 88.8 and 85.9 (C-6 and -11), 25.4 and 28.8
(C-7 and -8), 67.1 (C-9), 73.0 (C-10), 97.2 (C-12); HRMS (FAB)
m/z C24H33NO10Na+ 518.2002, found 518.1988.
ethylboronate with NaBH4 in MeOH at -20 °C and then
deboronation with MeOH/MeNH2 gave a similar mixture of
28 and 29.
10-Deoxy-2 (30). Ketone 27 (10 mg, 0.021 mmol) in THF
(0.2 mL) and toluene (0.5 mL) was treated with Tebbe reagent
(0.5 M in toluene) (0.2 mL, 0.10 mmol). After 15 min 0.25 M
NaOH (1 mL) and ether were added. After 15 min the pH
was adjusted to 10, and the ether extract was washed with
saturated NaHCO3, evaporated, and left for 12 h. The product
was separated from inorganic material by extraction into ether
and purified twice by TLC (2 × 0.5 mm plates) with CHCl3/
MeOH (9:1) solution to give 30 (6.4 mg, 63%): 1H NMR (CD3-
OD/CDCl3) δ 6.99 (m, H-26), 6.87 (m, H-24), 6.21 (m, H-25),
5.46 (s, H-3), 4.71 (q, J ) 1.9 Hz) and 4.64 (q, J ) 1.9 Hz)
(H2-21), 2.71 (br d, J ) 12.4 Hz, H-10ax), 2.43 (d, J ) 13.8 Hz)
and 1.82 (d, J ) 13.8 Hz) AB H2-14, 2.40 (br t, H-8ax), 2.20 (m,
H-13), 2.13 (m, H-8eq), 2.10 (br d, J ) 12.5 Hz, H-10eq), 2.05
(m, obsc, H-7ax), 1.36 (br dd, J ) 12.2 and 4.0 Hz, H-7eq), 1.29
(s, H3-17), 1.03 (d, J ) 6.7 Hz) and 0.75 (d, J ) 6.3 Hz) (H3-18
and -19), 0.85 (s, H3-20); 13C NMR (CD3OD) δ 64.9 (C-1), 83.0
(C-2), 91.3 (C-3), 91.4 (C-4), 48.3 (C-5), 86.0 (C-6), 27.5 and
29.6 (C-7 and -8), 149.5 (C-9), 35.2 (C-10), 83.8 (C-11), 94.4
(C-12), 29.8 (C-13), 40.8 (C-14), 101.5 (C-15), 10.5 (C-17), 18.3
and 18.8 (C-18 and -19), 12.3 (C-20), 110.7 and 110.6 (C-21
and -22), 122.0 (C-23), 116.8 (C-24), 110.6 (C-25), 125.1 (C-
26); HRMS (FAB) m/z C25H33NO8Na+ 498.2104, found 498.2120.
30 was also obtained in 25% yield by using CH2I2/Zn/TiCl4.30
30 was not available by treatment of 27 with the Wittig
reagent in DMSO.18
21-Nor -9eq-h yd r oxy-1 (25), 21-Nor -9-oxo-10-a cetoxy-1
(26), a n d 21-Nor -10-d eoxy-9-oxo-1 (27). The ketol 23 (58
mg, 0.12 mmol) was dissolved in acetic anhydride (0.5 mL, 0.53
mmol) and pyridine (0.05 mL). Monoacetylation was complete
in 70 min at ambient temperature. Excess acetic anhydride
was hydrolyzed by gradual addition of MeOH (1.5 mL) at 25
°C. The product isolated after acidification (HCl) and extrac-
tion with ethyl acetate was washed with saturated NaHCO3
solution and chromatographed on silica (5.0 g). Elution with
CHCl3/MeOH (97:3) gave the crystalline acetate 26 (54 mg,
84%): NMR (CD3OD) as for the ketol 23 except 1H δ 5.42 (s,
H-3), 5.85 (br s, H-10), 2.67 (d, J ) 14.1 Hz) and 1.89 (d, J )
14.5 Hz) AB H2-14, 2.70 (m, H-8ax), 2.35 (m, H-8eq), 1.49 (s,
H3-17), 0.90 (s, H3-20); 13C NMR (CD3OD) δ 47.7 (C-5), 85.0
and 88.9 (C-6 and -11), 26.2 and 35.2 (C-7 and -8), 205.0 (C-
9), 74.0 (C-10), 20.7 and 170.8 (acetate). The acetate 26 (16
mg, 0.030 mmol) in THF/MeOH (4:1, 5 mL) was treated
gradually at -60 °C under argon with 0.1 M SmI2 in THF (1
ml, 0.1 mmol). Reduction was fast, and the reaction was
repeated twice. Workup with saturated K2CO3 (2 mL) and
NaHSO3 (2 mL) solutions, extraction with ethyl acetate,
evaporation of the solvents, and separation from salts with
ethyl acetate gave the crude ketone. Purification was effected
by chromatography on silica (3.5 g). Elution with CHCl3/
MeOH (9:1) gave the ketone 27 (38 mg, 89%): NMR (CD3OD)
21-Nor -10-d eoxy-1 (31). Ketone 27 (3.8 mg, 0.0079 mmol)
in ether (2 mL) was treated with 1,2-ethanedithiol (0.075 mL,
0.80 mmol) and BF3‚Et2O (0.1 mL, 0.77 mmol). After 15 min
water was added, and the product was extracted with ether
and washed with saturated NaHCO3. The ether extract was
deborated by slow distillation (1 h) with MeOH/MeNH2 as
described above for 24 and stirred with Ni (∼100 mg) in EtOH
(2 mL) for 2 h. Addition of water, acidification (HCl), extrac-
tion with ethyl acetate, separation from Ni, and purification
by TLC with CHCl3/MeOH (9:1) gave 31 (2.4 mg, 66%): 1H
NMR (CD3OD/CDCl3) δ 6.97 (m, H-26), 6.85 (m, H-24), 6.21
(m, H-25), 5.46 (s, H-3), 2.43 (d, J ) 13.8 Hz) and 1.86 (d, J )
13.5 Hz) AB H2-14, 2.20 (m, H-13), 1.28 (s, H3-17), 1.02 (d, J
) 6.6 Hz) and 0.75 (d, J ) 6.3 Hz) (H3-18 and -19), 0.82 (s,
H3-20); 13C NMR (CD3OD/CDCl3) as for 30 except 25.1 and
26.7 (C-7 and -10), 19.3 and 20.6 (C-8 and -9), 83.6 (C-11), 94.7
(C-12); HRMS (FAB) m/z C24H33NO8Na+ 486.2104, found
486.2095. The sequence of these steps is important since the
borate complexes with Ni. Longer exposure to Ni gives a poor
yield of 31.
1
as for diol 24 except H δ 2.98 (d, J ) 15.3 Hz) and 2.23 (obsc)
H-10, 2.47 (d, J ) 14.1 Hz) and 1.90 (d, J ) 14.5 Hz) AB H2-
14, 2.33 (m, H-7ax), 1.89 (m, H-7eq), 2.55 (m, H-8ax), 2.35 (m,
H-7ax), 1.49 (s, H3-17); 13C NMR (CD3OD) δ 29.7 (C-8), 212.6
(C-9), 43.0 (C-10), 87.6 (C-11), 93.9 (C-12). Reduction of the
ketol (23, 48 mg, 0.097 mmol) as described above and TLC
using first CHCl3/MeOH (85:15) and then 8:2 gave the ketone
27 (10.5 mg, 23%), unreacted ketol (12 mg, 25%), and diol 25
(7 mg, 15%): NMR (CD3OD) as for ketol 23 except 1H δ 4.00
(d, J ) 8.9 Hz, Heq-10), 3.80 (m, Heq-9), 2.09 (dt, J ) 12.5, 12.5,
and 4.5 Hz, H-7ax), 0.89 (s, H3-20); 13C NMR (CD3OD) 86.0 and
88.0 (C-6 and -11), 25.6 and 26.8 (C-7 and -8), 72.5 and 73.0
(C-9 and -10); HRMS (FAB) m/z C24H33NO10Na+ 518.2002,
found 518.1988. Similarly acetylation of 21-nor-9-oxo-1(EtB)
(21) and reduction as above for 26 gave 21-nor-10-deoxy-9-
oxo-1(EtB) in 80% yield (reduced to 30% without the acetyla-
tion step).
21-Nor -10-d eoxy-6,9-oxid o-1 (32) a n d 21-Nor -10-d eoxy-
∆8/∆9-1 (33). The axial alcohol 28 (16 mg, 0.033 mmol) in
pyridine (2.0 mL) was treated dropwise with phosphoryl
chloride (0.2 mL, 2.1 mmol) at -20 °C. The solution was
warmed to ambient temperature (15 min) and the crude
product isolated by addition to water, acidification (HCl),
extraction with ethyl acetate and TLC with CHCl3/MeOH (19:
1) to give the ether 32 (5.8 mg, 38%): 1H NMR (CD3OD) as
for 30 except δ 4.50 (t, J ) 4.5 Hz, H-9), 2.44 (ddd, J ) 13.1,
4.0, and 2.0 Hz, H-10exo), 1.28 (m, H-10endo), 2.54 (d, J ) 13.8
Hz) and 1.77 (d, J ) 13.8 Hz) AB H2-14, 2.25 (obsc, H-7endo),
1.53 (ddd, J ) 12, 8, and 4 Hz, H-7exo), 1.62-1.75 (obsc, H2-8),
1.24 (s, H3-17); 13C NMR (CD3OD) δ 46.3 (C-5), 94.6 (C-6), 22.4
(C-7), 31.3 and 34.3 (C-8 and -10), 88.6 (C-11); HRMS (FAB)
m/z C24H31NO8Na+ 484.1947, found 484.1956. A less mobile
fraction (2.7 mg) appeared to be a mixture of 8- and 9-enes
(4:1) (33). Major component: 1H NMR (CD3OD) δ 5.64 (s, H-3),
5.55 (br m) and 5.65 (br m) H-8 and -9, 2.65 (d, J ) 13.8 Hz)
and 2.01 (d, J ) 13.5 Hz) AB H2-14, 2.69 (br m) H2-7 and H2-
10, 2.23 (m, H-13), 1.30 (s, H3-17), 1.08 (d, J ) 6.8 Hz) and
0.74 (d, J ) 7.0 Hz) H3-18 and -19, 0.94 (s, H3-20). Minor
component: 1H NMR (CD3OD) δ 6.0 (br m), 5.85 (br m), 5.63
(s), 1.32 (s), 0.96 (s); 13C NMR (CD3OD) 86.2 and 89.4 (C-6
and -11), 28.6 and 29.7 (C-7 and -10), 124.8 and 123.6 (C-8
and -9), 97.0 (C-12); HRMS (FAB) m/z C24H31NO8Na+ 484.1947,
found 484.1950.
21-Nor -10-d eoxy-9a x- a n d -9eq-h yd r oxy-1 (28 a n d 29).
Ketone 27 (28 mg, 0.058 mmol) in THF (2 mL) was treated
with ∼1 M LiAlH4 in ether (1.5 mL, ∼1.5 mmol). After 5 min
the product was isolated by addition of water, acidification
(HCl), and separation by TLC with CHCl3/MeOH (85:15) to
give the less polar 28 (Rf 0.43, 16 mg, 55%): NMR (CD3OD)
as for ketol 23 except 1H δ 4.0 (br m, W1/2h ) 9 Hz, H-9), 2.23
(m, H-13), 2.25 (dt, J ) 13, 13, and 5.0 Hz, H-7ax), 1.30 (m,
H-7eq), 1.95 (m, H-8ax), 1.70 (m, H-8eq), 1.32 (s, H3-17); 13C NMR
(CD3OD) 83.8 and 87.2 (C-6 and -11), 23.6 and 29.1 (C-7 and
-8), 68.2 (C-9), 32.3 (C-10), 11.2 (C-17); HRMS (FAB) m/z
C
24H33NO9Na+ 502.2053, found 502.2054. The more polar
fraction was the equatorial alcohol 29 (Rf 0.18, 7 mg, 15%):
1H NMR as for ketol 23 except δ 4.0 (tt, J ) 5.4 and 10.7 Hz,
H-9), 2.11 (dt, H-7ax), 1.33 (br d, J ) 12 Hz, H-7eq), 1.95-1.65
(m, H2-10 and H2-8), 0.89 (s, H3-20); 13C NMR (CD3OD) 92.5
(C-4), 83.3 and 87.4 (C-6 and -11), 26.1 and 29.8 (C-7 and -8),
68.3 (C-9), 35.2 (C-10), 11.2 (C-17); HRMS (FAB) m/z C24H33
-
NO9Na+ 502.2053, found 502.2064. Reduction of 27 as the