SPECIAL TOPIC
Platinum(II) Chloride Catalyzed Cycloisomerizations of 1,5-Enynes
2047
Anal. Calcd for C15H15NO4: C, 65.92; H, 5.53; N, 5.13. Found: C,
65.75; H, 5.39; N, 4.88.
1H NMR (400 MHz, benzene-d6): d = 7.75 (d, J = 9.1 Hz, 0.8 H and
1.2 H, Ar), 7.64 (d, J = 9.1 Hz, 0.8 H, Ar), 7.58 (d, J = 9.1 Hz,
1.2 H, Ar), 7.4–7.2 (m, 5 H, Ar), 5.71 [m, 0.6 H, CHOC(O)], 5.51
(m, 0.4 H, CHOC(O)], 5.34 (m, 1 H, CH2CH=), 5.11 [m, 1 H,
(CH3)2CCH=], 4.35 (s, 1.2 H, OCH2Ar), 4.31 (s, 0.8 H, OCH2Ar),
3.18 (m, 2 H, CHCH2O), 2.60 (m, 1 H, CHHCH=), 2.2–1.5 (m,
8 H), 1.23 (s, 1.2 H, CH3), 1.19 (s, 1.8 H, CH3), 0.91 (s, 1.8 H, CH3),
0.89 (s, 1.2 H, CH3).
cis-anti-cis-Tricyclo[4.4.0.0.1,7]decan-9-one (6h)
Yield: 85%; yellow solid; mp 161–163 °C.
IR (neat): 3120, 3090, 3070, 1730, 1649, 1605, 1268, 1253 cm–1.
1H NMR (400 MHz, CDCl3): d = 8.27 (m, 4 H, Ar), 5.16 (m, 1 H,
CH=), 2.48 (dt, J = 17.2, 2.8 Hz, 1 H, CH3bHCH=), 2.40 (d,
J = 17.2 Hz, 1 H, CHH3aCH=), 1.97 (m, 2 H, CHHCCH2 and CHH-
CHCH), 1.83 (m, 1 H, CHHCCH2), 1.60 (m, 2 H, CHC= and CHH-
CHCH), 1.44 (m, 1 H, CHHCH2CHCH), 1.25 (m, 2 H, CH2CH2C),
1.13 (m, 1 H, CHHCH2CHCH), 0.90 (dt, J = 7.6, 2.3 Hz, 1 H,
CH2CHCH).
13C NMR (100 MHz, CDCl3): d (major diastereomer) = 164.1,
151.1, 139.8, 138.1, 135.9, 131.2, 129.9, 129.2, 128.4, 126.2, 124.0,
87.2, 80.2, 73.9, 73.5, 67.7, 40.0, 39.2, 33.8, 32.0, 30.2, 28.2, 24.0,
22.0.
13C NMR (100 MHz, CDCl3): d (minor diastereomer) = 164.1,
151.1, 139.9, 138.1, 136.0, 131.3, 130.1, 129.3, 129.1, 126.2, 124.0,
87.2, 80.3, 73.8, 73.2, 67.8, 40.1, 39.3, 33.9, 31.9, 30.2, 28.0, 24.0,
22.0.
13C NMR (100 MHz, CDCl3): d = 162.3, 153.9, 150.6, 135.1, 131.0,
123.6, 108.8, 39.0, 31.9, 28.2, 28.1, 26.3, 24.2, 22.2, 21.9.
Anal. Calcd for C17H17NO4: C, 68.21; H, 5.72; N, 4.68. Found: C,
68.52; H, 5.69; N, 4.46.
HRMS (ESI): m/z [M + Na]+ Calcd for C28H31NO5Na: 484.2100;
found: 484.2119.
Synthesis of Sabinaketone (10) via Basic Hydrolysis
(6Z)-5,5-Dimethyl-9-benzyloxymethyl-12-(tert-butyldiphenyl-
silyloxy)dodec-6-en-2-yn-1-yl p-Nitrobenzoate (20)
Pale-yellow paste.
NaOH (2 N, 20 mL) was added to compound 6d (200 mg, 0.70
mmol, 1.0 equiv) at r.t. and the resulting mixture was vigorously
stirred. After the reaction was complete, the product was extracted
with Et2O (3 × 50 mL) and the combined organic layers were
washed with brine (75 mL), dried over Na2SO4 and evaporated in
vacuo. Purification by flash chromatography on silica gel (PE–
Et2O, gradient) afforded pure sabinaketone 10.
IR (neat): 3069, 3051, 3029, 2999, 2233, 1730, 1607, 1529, 700 (br)
cm–1.
1H NMR (400 MHz, benzene-d6): d = 8.29 (d, J = 8.8 Hz, 2 H, Ar),
8.23 (d, J = 8.8 Hz, 2 H, Ar), 7.67 (m, 4 H, Ar), 7.35 (m, 11 H, Ar),
5.38 [d, J = 12.1 Hz, 1 H, (CH3)2CCH=], 5.26 (dt, J = 12.1, 6.9 Hz,
1 H, CH2CH=), 4.98 [m, 2 H, CH2OC(O)], 4.48 (s, 2 H, OCH2Ar),
3.65 (t, J = 6.3 Hz, 2 H, CH2CH2OSi), 3.36 (m, 2 H, OCH2CH),
2.32 (m, 2 H and 1 H, CH2C(CH3)2 and CHHCH=), 2.18 (m, 1 H,
CHHCH=), 1.8–1.4 (m, 5 H, CHCH2CH2), 1.21 (s, 6 H, CH3), 1.05
[s, 9 H, C(CH3)3].
Spectroscopic data were consistent with those reported in the liter-
ature.29
Yield: 91 mg (95%); calculated yield from 1,5-enyne 5d is 79% for
two steps.
IR (neat): 1725 cm–1.
1H NMR (400 MHz, CDCl3): d = 2.07 (m, 2 H), 1.93 (m, 2 H), 1.62
(dd, J = 9.2, 3.2 Hz, 1 H), 1.53 (hept, J = 6.8 Hz, 1 H), 1.15 (dd,
J = 9.2, 4.5 Hz, 1 H), 1.03 (dd, J = 4.5, 3.2 Hz, 1 H), 0.94 (d, J = 6.8
Hz, 3 H), 0.90 (d, J = 6.8 Hz, 3 H).
13C NMR (100 MHz, CDCl3): d = 215.3, 39.7, 33.9, 33.3, 32.4, 23.7,
19.7, 19.5, 19.3.
13C NMR (100 MHz, CDCl3): d = 164.3, 150.8, 138.9, 138.1, 135.8,
135.3, 134.2, 131.1, 129.7, 128.9, 128.5, 127.8, 127.7, 127.6, 123.7,
86.9, 75.0, 73.2, 73.0, 64.3, 54.5, 39.4, 36.3, 33.9, 30.6, 30.3, 28.4,
28.3, 27.6, 27.1, 19.4.
Anal. Calcd for C45H53NO6Si: C, 73.84; H, 7.30; N, 1.91. Found: C,
73.88; H, 7.25; N, 1.81.
Basic Hydrolysis of Regioisomers 6f/6f¢
Basic hydrolysis of a mixture of 6f/6f¢ (10:8 ratio) as described for
the synthesis of 10, afforded ketones 7f30 and 7f¢31 in the same 10:8
ratio.
cis-syn-anti-4-Nitrobenzoic Acid {6-[2-Benzyloxymethyl-5-(tert-
butyldiphenylsilyloxy)pent-1-yl]bicyclo[3.1.0]hex-2-en-4,4-
dimethyl-1-yl}methyl Ester (21)
Yield: 191 mg (74%); 1:1 mixture of diastereomers; pale-yellow
paste.
6,6-Dimethylbicyclo[3.1.0]hexan-2-one (7f)
Spectroscopic data were consistent with those reported in the liter-
ature.28
IR (neat): 3134, 3111, 3087, 3070, 3049, 1722, 1606, 1528, 1268,
1100 (br), 700 (br) cm–1.
1H NMR (400 MHz, CDCl3): d = 8.23 (m, 4 H, Ar), 7.70 (m, 4 H,
Ar), 7.34 (m, 11 H, Ar), 5.48 (m, 1 H and 1 H, CH=), 4.63 [d,
J = 11.8 Hz, 0.5 H, CHHOC(O)], 4.62 [d, J = 11.8 Hz, 0.5 H,
CHHOC(O)], 4.47 (s, 2 H, ArCH2O), 4.32 [d, J = 11.8 Hz, 0.5 H,
CHHOC(O)], 4.29 [d, J = 11.8 Hz, 0.5 H, CHHOC(O)], 3.66 (m,
2 H, CH2OSi), 3.40 (m, 3 × 0.5 H, OCHHCH), 3.32 (dd, J = 9.1, 6.0
Hz, 0.5 H, OCHHCH), 1.7–1.1 (m, 9 H), 1.09 (s, 6 H, 2 × CH3),
1.08 [s, 4.5 H, C(CH3)3], 1.07 [s, 4.5 H, C(CH3)3].
13C NMR (100 MHz, CDCl3): d = (165.0 and 164.9), 150.6, 142.2,
138.8, (136.1 and 136.0), 135.7, 134.2, 130.8, 129.7, 128.5, 127.8,
(127.7 and 127.6), (126.6 and 126.4), 123.7, (73.2 and 73.1), 72.8,
(70.8 and70.7), (65.5 and 65.4), (45.8 and 45.7), (39.5 and 39.4),
(39.0 and 38.8), (34.7 and 34.4), 32.9, 32.7, (30.2 and 30.0), (28.7
and 28.6), (27.8 and 27.5), 27.1, 25.3, 21.3, 19.4.
1H NMR (200 MHz, CDCl3): d = 2.26–1.86 (m, 5 H), 1.63 (m, 1 H),
1.14 (s, 3 H, CH3), 1.10 (s, 3 H, CH3).
6,6-Dimethylbicyclo[3.1.0]hexan-3-one (7f¢)
Spectroscopic data were consistent with those reported in the liter-
ature.29
1H NMR (200 MHz, CDCl3): d = 2.57–1.86 (m, 4 H), 1.28 (m, 2 H),
1.06 (s, 3 H, CH3), 0.85 (s, 3 H, CH3).
(6Z)-4-Benzyloxymethyl-8,8-dimethylcycloundec-6-en-10-yn-1-
yl p-Nitrobenzoate (19)
Obtained as a 6:4 mixture of diastereomers; yellow paste.
IR (neat): 3120, 3109, 3085, 3028, 2999, 2242, 1725, 1606, 1527
cm–1.
Anal. Calcd for C45H53NO6Si: C, 73.84; H, 7.30; N, 1.91. Found: C,
73.72; H, 7.35; N, 1.81.
Synthesis 2007, No. 13, 2037–2049 © Thieme Stuttgart · New York