Molybdenum-mediated cleavage reactions of isoxazoline rings fused in bicyclic frameworks

Article abstract of DOI:10.1021/ol026846k

(matrixpresented) The molybdenum-mediated cleavage reactions of isoxazoline rings fused in bicyclic frameworks were investigated. A tandem N-O bond cleavage-retro aldol reaction of an isoxazoline ring fused in a bicyclic framework led to the cleavage of t

Full text of DOI:10.1021/ol026846k

Supporting Information
Molybdenum-mediated Cleavage Reactions of Isoxazoline Rings Fused in Bicyclic Frameworks
Geoffrey K. Tranmer and William Tam*
Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry,
Department of Chemistry and Biochemistry, University of Guelph, Guelph, Ontario, Canada N1G 2W1
General Information: Standard column chromatography was performed on 230-400 mesh silica gel
2
6
(obtained from Silicycle) using flash column chromatography techniques.
Analytical thin-layer
chromatography (TLC) was performed on Merck pre-coated silica gel 60 F254 plates. All glassware
was flame dried under an inert atmosphere of dry nitrogen. Infrared spectra were taken on a Bomem
1
13
MB-100 FTIR spectrophotometer.
H and C NMR spectra were recorded on a Bruker-400
1
spectrometer. Chemical shifts for H NMR spectra are reported in parts per million (ppm) from
tetramethylsilane with the solvent resonance as the internal standard (chloroform: δ 7.26 ppm).
1
3
Chemical shifts for C NMR spectra are reported in parts per million (ppm) from tetramethylsilane
with the solvent as the internal standard (deuterochloroform: δ 77.0 ppm). High resolution mass
spectra were done by McMaster Regional Centre for Mass Spectrometry at McMaster University,
Hamilton, Ontario. Elemental analyses were performed by Canadian Microanalytical Service Ltd.,
British Columbia or by Quantitative Technologies Inc., New Jersey.
Reagents and Materials: Unless stated otherwise, commercial reagents were used without
2
7
2b
purification. Nitromethylbenzene 11a and cycloadducts 8a-8e were prepared in accordance to our
previously reported procedures.
2
2
6
7
Still, W. C.; Kahn, M.; Mitra, A. J. Org. Chem. 1978, 43, 2923.
a) Kornblum, N.; Larson, H. O.; Blackwood, R. K.; Mooberry, D. D.; Oliveto, E. P.; Graham, G. E. J. Am. Chem. Soc.
(
1
956, 78, 1497. (b) Baruah, A.; Kalita, B.; Barua, N. C. Synlett 2000, 1064.
1

Part I: Intermolecular 1,3-Dipolar Nitrile Oxide Cycloadditions of Bicyclic Alkenes 13 and 15a-c
Ph
C
H
H
(
BOC) O
DMAP
2
O
N
13
+
Ph
NO2
Ph
O
N
Toluene
N
H
o
1
1a
25 C
O
H
Ph
exo-14a
9%
endo-14a
1
2a
4
11%
1,3-Dipolar Nitrile Oxide Cycloaddition of Norbornadiene 13 with Nitrile Oxide 12a. A solution
of 11a (564.1 mg, 4.121 mmol) in toluene (15 mL) was added to a flame-dried flask containing
norbornadiene 13 (4.3 mL, 39.85 mmol), (BOC) O (1.4178 g, 6.496 mmol), DMAP (49.0 mg, 0.4011
2
mmol) and toluene (20 mL) via a cannula over 30 minutes. The reaction mixture was stirred at room
temperature for 18 h. The solvent was removed by rotary evaporation, and the crude reaction mixture
was purified by column chromatography (EtOAc:hexanes = 0:1, 5:95, 1:9) to give a separable mixture
of exo-14a (424.0 mg, 2.007 mmol, 49%) and endo-14a (96.1 mg, 0.455 mmol, 11%) as clear and
colourless oils which solidified upon standing to viscous semi-solids.
Cycloadduct exo-14a. R 0.23 (EtOAc:Hexanes, 1:9); IR (neat, NaCl) 3063 (m), 2982 (s), 2954 (s),
f
-1
1
2
879 (m), 1591 (m), 1561 (m), 1497 (m), 1445 (s), 1356 (s), 1325 (s) cm ; H NMR (CDCl , 400
3
MHz) δ 7.73 (m, 2H), 7.40 (m, 3H), 6.35 (dd, 1H, J = 5.7, 3.0 Hz), 6.10 (dd, 1H, J = 5.7, 3.2 Hz), 4.98
(d, 1H, J = 8.2 Hz), 3.79 (d, 1H, J = 8.2 Hz), 3.28 (s, 1H), 3.15 (s, 1H), 1.74 (d, 1H, J = 9.4 Hz), 1.62
13
(
d, 1H, J = 9.4 Hz). C NMR (CDCl , 100 MHz) δ 155.7, 140.0, 135.5, 129.8, 129.3, 128.7, 126.7,
3
2
8
89.4, 57.6, 50.0, 45.1, 43.2. This is a known compound in the literature.
Cycloadduct endo-14a. R 0.15 (EtOAc:Hexanes, 1:9); IR (neat, NaCl) 2980 (s), 2954 (s), 2876 (m),
f
-1 1
1
655 (s), 1557 (m), 1449 (s), 1345 (m), 1253 (s), 1222 (m), 1078 (m) cm ; H NMR (CDCl , 400
3
MHz) δ 7.70 (m, 2H), 7.39 (m, 3H), 6.18 (dd, 1H, J = 5.7, 2.9 Hz), 5.94 (dd, 1H, J = 5.7, 2.9 Hz), 5.40
(dd, 1H, J = 9.6, 4.1 Hz), 4.14 (dd, 1H, J = 9.6, 4.0 Hz), 3.37 (s, 2H), 1.63 (d, 1H, J = 8.9 Hz), 1.46 (d,
1
3
1
H, J = 8.9 Hz). C NMR (CDCl , 100 MHz) δ 156.5, 135.0, 134.1, 129.7, 129.5, 128.7, 126.5, 87.5,
3
2
8
57.3, 48.9, 47.9, 46.9. This is a known compound in the literature.
2
8
(
a) Ambler, P. W.; Paton, R. M.; Tout, J. M. J. Chem. Soc., Chem. Commun. 1994, 2661. (b) Sohar, P.; Bernath, G.;
Frimpong-Manso, S.; Szabo, A. E.; Stajer, G. Magn. Reson. Chem. 1990, 28, 1045.
2

CH3
H
H
(
BOC) O
DMAP
2
O
N
C
13
+
CH3
NO2
CH
3
Toluene
N
O
O
N
H
o
1
1b
25 C
H
CH
3
exo-14b
1%
endo-14b
1
2b
7
8%
1,3-Dipolar Nitrile Oxide Cycloaddition of Norbornadiene 13 with Nitrile Oxide 12b. A solution
of 11b (0.70 mL, 9.74 mmol) in toluene (10 mL) was added to a flame-dried flask containing
norbornadiene 13 (10.5 mL, 97.32 mmol), (BOC) O (3.4316 g, 15.72 mmol), DMAP (0.1390 mg,
2
1.138 mmol) and toluene (20 mL) via a cannula over 10 minutes. The reaction mixture was stirred at
room temperature for 45 h. The solvent was removed by rotary evaporation, and the crude reaction
mixture was purified by column chromatography (EtOAc:hexanes = 1:9, 15:85, 1:4) to give a separable
mixture exo-14b (1.0387 g, 6.962 mmol, 71%) as a clear pale yellow oil and endo-14b (113.8 mg,
0.7628 mmol, 8%) as a clear pale yellow oil.
Cycloadduct exo-14b. R 0.22 (EtOAc:Hexanes, 1:4); IR (neat, NaCl) 3057 (m), 2980 (s), 2954 (s),
f
-1 1
2
923 (m), 2881 (w), 1625 (w), 1433 (m), 1388 (m), 1326 (s), 1264 (s), 919 (m) cm ; H NMR (CDCl ,
3
400 MHz) δ 6.24 (dd, 1H, J = 5.7, 3.0 Hz), 6.02 (dd, 1H, J = 5.7, 3.2 Hz), 4.75 (d, 1H, J = 8.0 Hz),
3.24 (d, 1H, J = 8.0 Hz), 3.17 (s, 1H), 2.98 (s, 1H), 1.90 (s, 3H), 1.62 (d, 1H, J = 9.3 Hz), 1.58 (d, 1H, J
13
=
9.3 Hz). C NMR (CDCl , 100 MHz) δ 154.6, 139.7, 135.4, 87.7, 60.9, 49.7, 43.7, 42.9, 11.9. This
3
2
9
is a known compound in the literature.
Cycloadduct endo-14b. R 0.15 (EtOAc:Hexanes, 1:4); IR (neat, NaCl) 3067 (m), 2979 (s), 2944 (s),
f
-1 1
2
872 (m), 1620 (m), 1455 (m), 1436 (s), 1386 (s), 1334 (m), 1252 (m), 1137 (w), 985 (s) cm ; H
NMR (CDCl , 400 MHz) δ 6.17 (dd, 1H, J = 5.7, 3.0 Hz), 6.07 (dd, 1H, J = 5.7, 2.9 Hz), 5.19 (dd, 1H,
3
J = 9.4, 4.2 Hz), 3.66 (dd, 1H, J = 9.4, 4.2 Hz), 3.29 (s, 1H), 3.13 (s, 1H), 1.83 (s, 3H), 1.56 (dt, 1H, J =
1
3
8
.9, 1.7 Hz), 1.34 (d, 1H, J = 8.9 Hz). C NMR (CDCl , 100 MHz) δ 155.2, 134.6, 134.3, 85.9, 60.5,
3
2
9
48.8, 47.9, 45.4, 12.2. This is a known compound in the literature.
2
9
Krawczyk, H.; Gryff-Keller, A. J. Chem. Res. (S), 1996, 452.
3

Ph
C
(
BOC) O
DMAP
O
2
N
15a
(
98%)
Ph
NO2
Ph
Toluene
N
H
o
H
6a
1
1a
25 C
O
1
1
2a
1
,3-Dipolar Nitrile Oxide Cycloaddition of Norbornene 15a with Nitrile Oxide 12a. A solution of
1a (0.5984 mg, 4.363 mmol) in toluene (15 mL) was added to a flame-dried flask containing
1
norbornene 15a (5.0 mL, 45.3 mmol), (BOC) O (1.6482 g, 7.552 mmol), DMAP (47.6 mg, 0.3896
2
mmol) and toluene (10 mL) via a cannula over 10 minutes. The reaction mixture was stirred at room
temperature for 24 h. The solvent was removed by rotary evaporation, and the crude reaction mixture
was purified by column chromatography (EtOAc:hexanes = 0:1, 5:95, 1:9) to give 16a (0.9150 g, 4.290
mmol, 98%) as a clear and colourless oil which solidified upon standing to a viscous semi-solid.
Cycloadduct 16a. R 0.63 (EtOAc:Hexanes, 1:4); IR (neat, NaCl) 2969 (s), 2944 (s), 2871 (s), 1563
f
-1 1
(
m), 1444 (s), 1357 (s), 1315 (m), 1264 (m), 1130 (m) cm ; H NMR (CDCl , 400 MHz) δ 7.70 (m,
3
2H), 7.38 (m, 3H), 4.64 (d, 1H, J = 8.3 Hz), 3.48 (d, 1H, J = 8.3 Hz), 2.62 (s, 1H), 2.52 (s, 1H), 1.58
1
3
(
m, 2H), 1.52 (d, 1H, J = 10 Hz), 1.35 (d, 1H, J = 10 Hz), 1.17 (m, 2H). C NMR (CDCl , 100 MHz) δ
3
156.8, 129.6, 129.4, 128.6, 126.8, 87.8, 57.0, 42.9, 39.2, 32.3, 27.4, 22.7. This is a known compound
2
3,30
in the literature.
CH3
(
BOC) O
DMAP
O
2
N
C
15a
(
96%)
CH3
NO2
CH3
Toluene
N
O
H
o
H
6b
1
1b
25 C
1
1
2b
1
1
1
,3-Dipolar Nitrile Oxide Cycloaddition of Norbornene 15a with Nitrile Oxide 12b. A solution of
1b (0.75 mL, 10.44 mmol) in toluene (10 mL) was added to a flame-dried flask containing norbornene
5a (2.10 g, 22.30 mmol), (BOC) O (3.47 g, 15.90 mmol), DMAP (0.1311 g, 1.073 mmol) and toluene
2
(
10 mL) via a cannula over 10 minutes. The reaction mixture was stirred at room temperature for 18 h.
The reaction was quenched with water (15 mL) and the aqueous layer extracted with dichloromethane
4×10 mL). The combined organic layers were washed with brine (10 mL) and dried over magnesium
sulphate and filtered. The solvent was removed by rotary evaporation and the crude reaction mixture
(
3
0
(
a) Muri, D.; Bode, J. W.; Carreira, E. M. Org. Lett. 2000, 2, 539. (b) Chen, Y. J.; Li, C. N. J. Chin. Chem. Soc. 1993, 40,
2
03. (c) Fliege, W.; Huisgen, R. Just. Lie. Ann. Chem. 1973, 2038.
4

was purified by column chromatography (EtOAc:hexanes = 0:1, 1:9, 1:4) to give 16b (1.5112 g, 9.994
mmol, 96%) as a clear pale yellow oil.
Cycloadduct 16b. R 0.28 (EtOAc:Hexanes, 1:4); IR (neat, NaCl) 2959 (s), 2875 (s), 1754 (m), 1627
f
-1 1
(
m), 1455 (s), 1384 (s), 1331 (s), 1313 (m), 1256 (m), 1029 (m) cm ; H NMR (CDCl , 400 MHz) δ
3
4.38 (d, 1H, J = 8.2 Hz), 2.91 (d, 1H, J = 8.2 Hz), 2.46 (s, 1H), 2.30 (s, 1H), 1.86 (s, 3H), 1.48 (m, 2H),
1
3
1
.37 (d, 1H, J = 10.5 Hz), 1.17 (m, 1H), 1.11 (d, 1H, J = 10.5 Hz), 1.04 (m, 1H). C NMR (CDCl ,
3
100 MHz) δ 155.3, 86.0, 60.4, 42.7, 37.8, 31.9, 27.0, 22.5, 11.8. This is a known compound in the
3
1
literature.
Hexyl
H
Ph
C
(
BOC) O
DMAP
2
O
1
5b
N
(
86%)
Ph
NO2
Toluene
N
Ph
o
Hexyl
1
1a
25 C
O
1
6c
1
2a
1
,3-Dipolar Nitrile Oxide Cycloaddition of Norbornene 15b with Nitrile Oxide 12a. A solution of
1a (514.6 mg, 3.752 mmol) in toluene (15 mL) was added to a flame-dried flask containing 2-
1
3
2
hexylbicyclo[2.2.1]hept-2-ene 15b (606.2 mg, 3.400 mmol), (BOC) O (1.2219 g, 5.599 mmol),
2
DMAP (49.3 mg, 0.4035 mmol) and toluene (2 mL) via a cannula over 10 minutes. The reaction
mixture was stirred at room temperature for 23 h. The reaction was quenched with water (15 mL) and
the aqueous layer extracted with dichloromethane (4×10 mL). The combined organic layers were
washed with brine (10 mL) and dried over magnesium sulfate and filtered. The solvent was removed
by rotary evaporation, and the crude reaction mixture was purified by column chromatography
(EtOAc:hexanes = 0:1, 5:95) to give 16c (867.0 mg, 2.915 mmol, 86%) as a clear and colourless oil.
Cycloadduct 16c. R 0.16 (EtOAc:hexanes = 1:49); IR (neat) 3060 (w), 2961 (s), 2930 (s), 2872 (s),
f
2
1
1
=
858 (s), 1705 (w), 1592 (m), 1563 (m), 1464 (s), 1445 (s), 1327 (s), 1326 (m), 1310 (m), 1266 (m),
-1 1
235 (w), 1073 (w), 1025 (w) cm ; H NMR (CDCl , 400 MHz) δ 7.69 (m, 2H), 7.37 (m, 3H), 2.90 (d,
3
H, J = 1.6 Hz), 2.55 (d, 1H, J = 4.0 Hz), 2.49 (d, 1H, J = 4.3 Hz), 1.24-1.74 (m, 15H), 1.19 (dd, 1H, J
1
3
10.4, 1.5 Hz), 0.87 (t, 3H, J = 6.9 Hz); C NMR (APT, CDCl , 100 MHz) δ 157.0, 129.8, 129.4,
3
128.6, 126.6, 96.7, 61.1, 45.6, 40.8, 35.0, 34.5, 31.7, 29.7, 27.4, 24.1, 23.1, 22.6, 14.1. Anal. Calcd. for
C H NO: C, 80.76; H, 9.15. Found C, 80.88; H, 9.01.
20
27
3
3
1
2
Cunico, R. F.; Bedell, L. J. Org. Chem. 1983, 48, 2780.
Mayo, P.; Hecnar, T.; Tam, W. Tetrahedron 2001, 57, 5931.
5

Hexyl
H
CH3
(
BOC) O
DMAP
2
O
1
5b
N
C
(
70%)
CH3
NO
1b
2 Toluene
N
O
CH3
o
Hexyl
1
25 C
1
6d
12b
1
,3-Dipolar Nitrile Oxide Cycloaddition of Norbornene 15b with Nitrile Oxide 12b. A solution of
1b (333.6 mg, 4.444 mmol) in toluene (8 mL) was added to a flame-dried flask containing 2-
1
hexylbicyclo[2.2.1]hept-2-ene 15b (292.7 mg, 1.641 mmol), (BOC) O (598.7 mg, 2.743 mmol),
2
DMAP (25.0 mg, 0.2046 mmol) and toluene (8 mL) via a cannula over 15 minutes. The reaction
mixture was stirred at room temperature for 42 h. The reaction was quenched with water (15 mL) and
the aqueous layer extracted with dichloromethane (4×10 mL). The combined organic layers were
washed with brine (10 mL) and dried over magnesium sulfate and filtered. The solvent was removed
by rotary evaporation, and the crude reaction mixture was purified by column chromatography
(EtOAc:hexanes = 0:1, 1:9, 1:4) to give 16d (271.8 mg, 1.155 mmol, 70%) as a clear and colourless oil.
Cycloadduct 16d. R 0.45 (EtOAc:Hexanes, 1:4); IR (neat, NaCl) 2958 (s), 2930 (s), 2872 (s), 2858
f
-1 1
(
s), 1794 (s), 1758 (s), 1460 (m), 1385 (m), 1331 (m), 1160 (m), 907 (m) cm ; H NMR (CDCl , 400
3
MHz) δ 2.43 (d, 1H, J = 4.0 Hz), 2.35 (s, 1H), 2.30 (d, 1H, J = 4.4 Hz), 1.89 (s, 3H), 1.64 - 1.18 (m,
1
3
1
5H), 1.14 (dd, 1H, J = 10.3, 1.4 Hz), 0.87 (t, 3H, J = 6.8 Hz). C NMR (CDCl , 100 MHz) δ 155.6,
3
94.7, 64.7, 45.5, 39.5, 34.9, 34.3, 31.7, 29.7, 27.2, 24.8, 22.9, 22.6, 14.1, 12.2. HRMS calcd. for
C H NO: m/z 235.1936, found m/z 235.1927.
15
25
SiMe3
Ph
C
(
BOC) O
DMAP
2
O
1
5c
N
(
88%)
Ph
NO2
Toluene
N
Ph
5oC
SiMe3
1
1a
2
O
H
1
6e
12a
1
,3-Dipolar Nitrile Oxide Cycloaddition of Norbornene 15c with Nitrile Oxide 12a. A solution of
1a (0.4794 g, 3.496 mmol) in toluene (15 mL) was added to a flame-dried flask containing 2-
1
3
2
(
trimethylsilyl)bicyclo[2.2.1]hept-2-ene 15c (512.9 mg, 3.084 mmol), (BOC) O (1.1475 g, 5.258
2
mmol), DMAP (39.9 mg, 0.3266 mmol) and toluene (10 mL) via a cannula over 10 minutes. The
reaction mixture was stirred at room temperature for 23 h. The reaction was quenched with water (15
mL) and the aqueous layer extracted with dichloromethane (4×10 mL). The combined organic layers
6

were washed with brine (10 mL) and dried over magnesium sulfate and filtered. The solvent was
removed by rotary evaporation and the crude reaction mixture was purified by column chromatography
(EtOAc:hexanes = 0:1, 5:95) to give 16e (0.7765 g, 2.720 mmol, 88%) as a clear and colourless oil.
Cycloadduct 16e. R 0.15 (Et O:hexanes = 1:49); IR (CH Cl ) 2965 (s), 2878 (w), 1594 (w), 1445 (w),
f
2
2
2
-
1 1
1
1
1
1
351 (m), 1260 (s), 1005 (w) cm ; H NMR (CDCl , 400 MHz) δ 7.72 (m, 2H), 7.38 (m, 3H), 3.29 (s,
3
H), 2.68 (d, 1H, J = 4.4 Hz), 2.52 (d, 1H, J = 4.3 Hz), 1.62 (m, 2H), 1.48 (tt, 1H, J = 12.8, 4.7 Hz),
1
3
.37 (m, 1H), 1.26 (m, 1H), 1.19 (ddd, 1H, J = 10.4, 2.7, 1.3 Hz), 0.13 (s, 9H); C NMR (APT, CDCl ,
3
00 MHz) δ 156.6, 129.8, 129.4, 128.0, 126.8, 91.3, 59.3, 46.3, 40.8, 34.4, 26.9, 22.6, -2.8. Anal.
Calcd. for C H SiNO: C, 71.53; H, 8.12. Found C, 71.94; H, 7.84.
1
7
23
SiMe3
CH3
(
BOC) O
DMAP
2
O
1
5c
N
C
(
90%)
CH3
NO
2 Toluene
N
O
CH3
5oC
SiMe3
1
1b
2
H
1
6f
1
2b
1
,3-Dipolar Nitrile Oxide Cycloaddition of Norbornene 15c with Nitrile Oxide 12b. A solution of
1b (280.3 mg, 2.044 mmol) in toluene (8 mL) was added to a flame-dried flask containing 2-
1
3
2
(
trimethylsilyl)bicyclo[2.2.1]hept-2-ene 15c (270.0 mg, 1.623 mmol), (BOC) O (589.8 mg, 2.702
2
mmol), DMAP (23.5 mg, 0.1924 mmol) and toluene (8 mL) via a cannula over 15 minutes. The
reaction mixture was stirred at room temperature for 19 h. The reaction was quenched with water (15
mL) and the aqueous layer extracted with dichloromethane (4×10 mL). The combined organic layers
were washed with brine (10 mL) and dried over magnesium sulfate and filtered. The solvent was
removed by rotary evaporation, and the crude reaction mixture was purified by column
chromatography (EtOAc:hexanes = 0:1, 1:9, 1:4) to give 16f (326.5 mg, 1.462 mmol, 90%) as a clear
and colourless oil.
Cycloadduct 16f. R 0.43 (EtOAc:Hexanes, 1:4); IR (neat, NaCl) 2958 (s), 2899 (s), 2879 (s), 1794
f
-1 1
(
w), 1755 (m), 1456 (s), 1328 (s), 1322 (s), 1248 (s), 1166 (m), 919 (m) cm ; H NMR (CDCl , 400
3
MHz) δ 2.74 (s, 1H), 2.56 (d, 1H, J = 4.4 Hz), 2.33 (d, 1H, J = 4.4 Hz), 1.90 (s, 3H), 1.58 - 1.51 (m,
1
3
2
H), 1.41 (m, 1H), 1.28 (m, 1H), 1.14 (m, 1H), 1.09 (m, 1H), 0.08 (s, 9H). C NMR (CDCl , 100
3
MHz) δ 154.9, 88.8, 63.1, 46.1, 39.6, 34.1, 26.7, 22.5, 12.1, -2.8. HRMS calcd. for C H SiNO: m/z
1
2
21
2
23.1392, found m/z 223.1386.
7

Part II: Mo-mediated Cleavage Reactions
General procedure for the Mo-mediated tandem N–O bond cleavage–retroaldol reaction. To a
flame dried flask containing the isoxazoline (1 eq) and acetonitrile (0.08 M–0.06 M) was added
molybdenum hexacarbonyl (1 eq) and distilled water (0.08–0.2 mL, 5–12.5 mmol, 20–60 eq. (usually
40 eq.), 1–4 M). A water condenser was then attached and the flask was heated to 80 ºC for 3-16 hrs.
The solvent was then removed using rotary evaporation and the crude reaction mixture purified by
column chromatography.
O
O
N
Mo(CO)6
Ph
H
Ph CH CN/H O
3
2
o
H
O
80 C
H
1
7a
(
66%)
exo-14a
Mo-mediated cleavage reaction of cycloadduct exo-14a (Table 1, entry 1). To a flame dried flask
containing the cycloadduct exo-14a (41.1 mg, 0.1945 mmol) and acetonitrile (2.0 mL) was added
molybdenum hexacarbonyl (57.4 mg, 0.2174 mmol) and distilled water (0.2 mL, 12.5 mmol). A water
condenser was then attached and the flask was heated to 80 ºC for 12 h. The solvent was then removed
using rotary evaporation and the crude reaction mixture was purified by column chromatography
(EtOAc:hexanes = 0:1, 1:9, 1:4) to give 17a (27.5 mg, 0.1283 mmol, 66%) as a clear pale yellow oil.
Cyclopentene 17a. R 0.21 (EtOAc:Hexanes, 1:4); IR (neat, NaCl) 3063 (s), 2982 (s), 2952 (s), 2879
f
-1 1
(
m), 1591 (m), 1562 (m), 1497 (m), 1445 (m), 1356 (m), 1326 (m), 1019 (m) cm ; H NMR (CDCl ,
3
4
00 MHz) δ 9.77 (s, 1H), 7.94 (d, 2H, J = 7.2 Hz), 7.56 (t, 1H, J = 7.3 Hz), 7.46 (t, 2H, J = 7.4 Hz),
.83 (m, 1H), 3.17 (dd, 1H, J = 16.5, 5.6 Hz), 3.08 (m, 1H), 2.98 (m, 2H), 2.86 (m, 1H), 2.29 (m, 2H).
6
1
3
C NMR (CDCl , 100 MHz) δ 199.0, 189.6, 151.4, 146.7, 137.0, 133.1, 128.6, 128.0, 44.7, 40.0, 34.8,
3
3
3.2. HRMS calcd. for C H O : m/z 214.0994, found m/z 214.0980.
1
4
14
2
H
H
O
Mo(CO)6
Ph
H
O
N
CH CN/H O
3 2
o
O
8
0 C
Ph
endo-14a
1
7a
(
70%)
Mo-mediated cleavage reaction of cycloadduct endo-14a (Table 1, entry 2). To a flame dried flask
containing the cycloadduct endo-14a (30.8 mg, 0.1458 mmol) and acetonitrile (2.0 mL) was added
8

molybdenum hexacarbonyl (38.6 mg, 0.1462 mmol) and distilled water (0.2 mL, 12.5 mmol). A water
condenser was then attached and the flask was heated to 80 ºC for 12 h. The solvent was then removed
using rotary evaporation and the crude reaction mixture was purified by column chromatography
(EtOAc:hexanes = 0:1, 1:9, 1:4) to give 17a (21.9 mg, 0.1022 mmol, 70%) as a clear pale yellow oil.
Spectral data as reported above.
O
O
N
Mo(CO)6
Me
H
Me CH CN/H O
3
2
o
H
O
80 C
H
1
7b
(
61%)
exo-14b
Mo-mediated cleavage reaction of cycloadduct exo-14b (Table 1, entry 3). To a flame dried flask
containing the cycloadduct exo-14b (84.6 mg, 0.5670 mmol) and acetonitrile (2.0 mL) was added
molybdenum hexacarbonyl (156.6 mg, 0.5932 mmol) and distilled water (0.12 mL, 7.5 mmol). A
water condenser was then attached and the flask was heated to 80 ºC for 3 h. The solvent was then
removed using rotary evaporation and the crude reaction mixture was purified by column
chromatography (EtOAc:hexanes = 0:1, 1:9, 1:4) to give 17b (52.3 mg, 0.3438 mmol, 61%) as a clear
pale yellow oil.
Cyclopentene 17b. R 0.29 (EtOAc:Hexanes, 1:3); IR (neat, NaCl) 3055 (m), 2940 (s), 2834 (s), 2717
f
-1 1
(
m), 1716 (s), 1683 (s), 1616 (s), 1434 (s), 1360 (m), 1262 (m), 1189 (m), 1074 (m) cm ; H NMR
(
CDCl , 400 MHz) δ 9.74 (s, 1H), 6.79 (s, 1H), 2.83 (m, 3H), 2.62 (dd, 1H, J = 17.2, 5.7 Hz), 2.54 (dd,
3
1
3
1
H, J = 17.2, 7.3 Hz), 2.21 (m, 2H), 2.14 (s, 3H). C NMR (CDCl , 100 MHz) δ 207.7, 189.6, 151.4,
3
1
46.6, 49.7, 39.8, 34.6, 32.7, 30.2. HRMS calcd. for C H O : m/z 152.0837, found m/z 152.0825.
9
12
2
H
H
O
Mo(CO)6
Me
H
O
N
CH CN/H O
3 2
o
O
8
0 C
Me
endo-14b
17b
(
52%)
Mo-mediated cleavage reaction of cycloadduct endo-14b (Table 1, entry 4). To a flame dried flask
containing the cycloadduct endo-14b (34.0 mg, 0.2279 mmol) and acetonitrile (3.5 mL) was added
molybdenum hexacarbonyl (62.1 mg, 0.2352 mmol) and distilled water (0.2 mL, 12.5 mmol). A water
condenser was then attached and the flask was heated to 80 ºC for 12 h. The solvent was then removed
9

using rotary evaporation and the crude reaction mixture was purified by column chromatography
EtOAc:hexanes = 0:1, 1:9, 1:4) to give 17b (21.6 mg, 0.1419 mmol, 62%) as a clear pale yellow oil.
Spectral data as reported above.
(
O
O
N
Mo(CO)6
Ph
H
Ph CH CN/H O
3
2
o
H
O
8
0 C
H
1
8a
1
6a
(75%)
Mo-mediated cleavage reaction of cycloadduct 16a (Table 1, entry 5). To a flame dried flask
containing the cycloadduct 16a (50.5 mg, 0.2368 mmol) and acetonitrile (2.0 mL) was added
molybdenum hexacarbonyl (43.0 mg, 0.1629 mmol) and distilled water (~0.2 mL, 12.5 mmol). A
water condenser was then attached and the flask was heated to 80 ºC for 12 h. The solvent was then
removed using rotary evaporation and the crude reaction mixture was purified by column
chromatography (EtOAc:hexanes = 0:1, 1:9, 1:4) to give 18a (38.5 mg, 0.1780 mmol, 75%, as an
1
inseparable 50:50 mixture of cis/trans isomers, measured by H NMR) as a clear pale yellow oil.
Cyclopentane 18a. R 0.29 (EtOAc:Hexanes, 1:4); IR (neat, NaCl) 3062 (m), 2954 (s), 2871 (s), 1707
f
-1 1
(
s), 1650 (m), 1593 (m), 1444 (s), 1371 (m), 1279 (m), 1212 (m), 1001 (m) cm ; H NMR (CDCl , 400
3
MHz) δ 9.64 (d, 0.5H, J = 2.2 Hz), 9.61 (d, 0.5H, J = 2.2 Hz), 7.94 (d, 2H, J = 7.4 Hz), 7.56 (t, 1H, J =
7
1
1
2
.4 Hz), 7.46 (t, 2H, J = 7.4 Hz), 3.03 (dd, 2H, J = 9.7, 6.9 Hz), 2.84 (m, 1H), 2.49 (m, 1H), 2.23 (m,
1
3
H), 1.99 (m, 2H), 1.90 (m, 1H), 1.49 (m, 1H), 1.23 (m, 1H). C NMR (CDCl , 100 MHz) δ 203.4,
3
99.5, 199.4, 136.94, 136.88, 133.0, 128.6, 128.0, 51.2, 50.6, 44.0, 43.9, 36.0, 35.4, 32.7, 32.6, 32.1,
5.65, 25.59. HRMS calcd. for C H O : m/z 216.1150, found m/z 261.1141.
1
4
16
2
O
O
N
Mo(CO)6
Me
H
Me CH CN/H O
3
2
o
H
O
80 C
H
1
8b
1
6b
(65%)
Mo-mediated cleavage reaction of cycloadduct 16b (Table 1, entry 6). To a flame dried flask
containing the cycloadduct 16b (77.1 mg, 0.5099 mmol) and acetonitrile (2.0 mL) was added
molybdenum hexacarbonyl (140.0 mg, 0.5303 mmol) and distilled water (0.2 mL, 12.5 mmol). A
water condenser was then attached and the flask was heated to 80 ºC for 12 h. The solvent was then
removed using rotary evaporation and the crude reaction mixture was purified by column
1
0

chromatography (EtOAc:hexanes = 0:1, 1:9, 1:4) to give 18b (50.9 mg, 0.3301 mmol, 65%, as an
1
inseparable 60:40 mixture of cis/trans isomers, measured by H NMR) as a clear pale yellow oil.
Cyclopentane 18b. R 0.20 (EtOAc:Hexanes, 1:4); IR (neat, NaCl) 2959 (s), 2871 (s), 1738 (s), 1673
f
-1 1
(
s), 1455 (m), 1422 (m), 1360 (m), 1238 (m), 1184 (m) cm ; H NMR (CDCl , 400 MHz) δ 9.62 (d,
3
0
1
2
.4H, J= 2.0 Hz), 9.60 (d, 0.6H, J = 2.0 Hz), 2.80 (m, 1H), 2.47 (m, 3H), 2.26 (m, 2H), 2.13 (s, 3H),
13
.89 (m, 4H), 1.37 (m, 1H), 1.18 (m, 1H) (integration to high). C NMR (CDCl , 100 MHz) δ 208.1,
3
03.4, 51.2, 50.6, 49.2, 49.0, 35.6, 35.0, 32.5, 32.4, 31.9, 30.3, 30.1, 25.6, 25.5. HRMS calcd. for
C H O : m/z 154.0994, found m/z 154.0986.
9
14
2
O
O
N
Mo(CO)6
Ph
Hexyl
Ph
CH CN/H O
3
2
o
Hexyl
O
8
0 C
H
1
8c
1
6c
(75%)
Mo-mediated cleavage reaction of cycloadduct 16c (Table 1, entry 7). To a flame dried flask
containing the cycloadduct 16c (85.3 mg, 0.2868 mmol) and acetonitrile (3.5 mL) was added
molybdenum hexacarbonyl (76.1 mg, 0.2883 mmol) and distilled water (0.2 mL, 12.5 mmol). A water
condenser was then attached and the flask was heated to 80 ºC for 12 h. The solvent was then removed
using rotary evaporation and the crude reaction mixture was purified by column chromatography
(EtOAc:hexanes = 0:1, 1:9, 1:4) to give 18c (64.9 mg, 0.2160 mmol, 75%) as a clear pale yellow oil.
Cyclopentane 18c. R 0.49 (EtOAc:Hexanes, 1:4); IR (neat, NaCl) 3061 (w), 2954 (s), 2931 (s), 2870
f
-1
1
(
s), 1705 (s), 1682 (s), 1597 (m), 1448 (s), 1374 (s), 1275 (s), 1212 (s), 1001 (m) cm ; H NMR
(
CDCl , 400 MHz) δ 7.94 (d, 2H, J = 8.7 Hz), 7.55 (t, 1H, J = 7.4 Hz), 7.45 (t, 1H, J = 7.4 Hz), 3.04 (d,
3
2
1
1
H, J = 6.9 Hz), 2.97 (m, 1H), 2.49 (m, 1H), 2.42 (m, 2H), 2.14 (m, 1H), 1.87 (m, 3H), 1.55 (m, 2H),
13
.38 (m, 1H), 1.27 (m, 7H), 0.86 (t, 3H, J = 6.7 Hz). C NMR (CDCl , 100 MHz) δ 213.2, 199.8,
3
37.0, 132.9, 128.5, 128.0, 50.8, 44.0, 42.0, 36.2, 35.6, 32.1, 31.6, 28.9, 27.7, 23.7, 22.5, 14.0. HRMS
calcd. for C H O : m/z 300.2089, found m/z 300.2088.
2
0
28
2
1
1

O
O
N
Mo(CO)6
Me
Hexyl
Me CH CN/H O
3
2
o
Hexyl
O
8
0 C
H
18d
1
6d
(82%)
Mo-mediated cleavage reaction of cycloadduct 16d (Table 1, entry 8). To a flame dried flask
containing the cycloadduct 16d (40.0 mg, 0.1699 mmol) and acetonitrile (2.5 mL) was added
molybdenum hexacarbonyl (46.9 mg, 0.1777 mmol) and distilled water (0.2 mL, 12.5 mmol). A water
condenser was then attached and the flask was heated to 80 ºC for 7 h. The solvent was then removed
using rotary evaporation and the crude reaction mixture was purified by column chromatography
(EtOAc:hexanes = 0:1, 1:9, 1:4) to give 18d (33.1 mg, 0.1389 mmol, 82%) as a clear pale yellow oil.
Cyclopentane 18d. R 0.32 (EtOAc:Hexanes, 1:4); IR (neat, NaCl) 2954 (s), 2930 (s), 2860 (s), 1719
f
-1 1
(
s), 1467 (s), 1374 (s), 1179 (m), 1071 (m), 918 (m) cm ; H NMR (CDCl , 400 MHz) δ 2.93 (q, 1H, J
3
=
8.2 Hz), 2.49 (d, 2H, J = 7.0 Hz), 2.41 (dt, 2H, J = 7.4, 1.9 Hz), 2.30 (m, 1H), 2.11 (s, 3H), 2.05 (m,
13
1
H), 1.80 (m, 3H), 1.53 (m, 2H), 1.22 (m, 7H), 0.87 (t, 3H, J = 6.7 Hz). C NMR (CDCl , 100 MHz) δ
3
213.0, 208.3, 50.8, 49.2, 42.0, 35.8, 35.4, 31.9, 31.6, 30.3, 29.0, 27.8, 23.8, 22.5, 14.0. HRMS calcd.
for C H O : m/z 238.1933, found m/z 238.1939.
1
5
26
2
O
O
N
Mo(CO)6
Ph
Me Si
3
Ph
CH CN/H O
3
2
o
SiMe3
O
80 C
(65%)
H
1
8e
1
6e
Mo-mediated cleavage reaction of cycloadduct 16e (Table 1, entry 9). To a flame dried flask
containing the cycloadduct 16e (100.2 mg, 0.3510 mmol) and acetonitrile (3.5 mL) was added
molybdenum hexacarbonyl (95.5 mg, 0.3617 mmol) and distilled water (0.2 mL, 12.5 mmol). A water
condenser was then attached and the flask was heated to 80 ºC for 12 h. The solvent was then removed
using rotary evaporation and the crude reaction mixture was purified by column chromatography
(EtOAc:hexanes = 0:1, 1:9, 1:4) to give 18e (65.6 mg, 0.2274 mmol, 65%) as a clear pale yellow oil.
Cyclopentane 18e. R 0.51 (EtOAc:Hexanes, 1:4); IR (neat, NaCl) 3061 (w), 2956 (s), 2867 (s), 1737
f
-1 1
(
w), 1687 (s), 1636 (s), 1597 (m), 1449 (s), 1373 (m), 1249 (m) cm ; H NMR (CDCl , 400 MHz) δ
3
7.94 (m, 2H), 7.55 (m, 1H), 7.45 (m, 2H), 3.36 (m, 1H), 3.02 (dd, 2H, J = 6.8, 1.6 Hz), 2.49 (m, 1H),
1
3
2
.01 (m, 1H), 1.86 (m, 2H), 1.70 (m, 1H), 1.40 (m, 1H), 1.16 (m, 1H), 0.20 (s, 9H). C NMR (CDCl ,
3
1
2

100 MHz) δ 248.2, 199.9, 137.1, 132.9, 128.5, 128.0, 55.3, 43.9, 36.2, 33.0, 32.0, 25.9, -2.8. HRMS
calcd. for C H O Si: m/z 288.1546, found m/z 288.1538.
1
7
24
2
O
O
N
Mo(CO)6
Me
Me Si
3
Me CH CN/H O
3
2
o
SiMe3
O
80 C
(73%)
H
18f
1
6f
Mo-mediated cleavage reaction of cycloadduct 16f (Table 1, entry 10). To a flame dried flask
containing the cycloadduct 16f (70.6 mg, 0.3160 mmol) and acetonitrile (3.5 mL) was added
molybdenum hexacarbonyl (89.2 mg, 0.3617 mmol) and distilled water (0.2 mL, 12.5 mmol). A water
condenser was then attached and the flask was heated to 80 ºC for 8 h. The solvent was then removed
using rotary evaporation and the crude reaction mixture was purified by column chromatography
(EtOAc:hexanes = 0:1, 1:9, 1:4) to give 18f (65.6 mg, 0.2274 mmol, 84%) as a clear pale yellow oil.
Cyclopentane 18f. R 0.35 (EtOAc:Hexanes, 1:4); IR (neat, NaCl) 2956 (s), 2902 (s), 2867 (s), 1716
f
-1
1
(
s), 1636 (s), 1408 (m), 1372 (m), 1356 (s), 1249 (s), 1175 (m), 1154 (m), 843 (s) cm ; H NMR
(
CDCl , 400 MHz) δ 3.29 (m, 1H), 2.45 (m, 2H), 2.26 (m, 1H), 2.09 (s, 3H), 1.89 (m, 1H), 1.77 (m,
3
1
3
2
H), 1.66 (m, 1H), 1.28 (m, 1H), 1.03 (m, 1H), 0.17 (s, 9H). C NMR (CDCl , 100 MHz) δ 247.9,
3
2
08.6, 55.2, 49.0, 35.7, 32.6, 31.8, 30.3, 25.8, -2.8. HRMS calcd. for C H O Si: m/z 266.1389, found
1
2
22
2
m/z 266.1384.
O
O
O
N
Mo(CO)6
H
CH CN/H O
3
2
H
o
H
8
0 C
8
a
2
4a
(
62%)
Mo-mediated cleavage reaction of cycloadduct 8a (Table 2, entry 1). To a flame dried flask
containing the cycloadduct 8a (20.9 mg, 0.1193 mmol) and acetonitrile (2.0 mL) was added
molybdenum hexacarbonyl (33.3 mg, 0.1261 mmol) and distilled water (0.08 mL, 5 mmol). A water
condenser was then attached and the flask was heated to 80 ºC for 3 h. The solvent was then removed
using rotary evaporation and the crude reaction mixture was purified by column chromatography
(EtOAc:hexanes = 0:1, 1:9, 1:4) to give 24a (13.2 mg, 0.07406 mmol, 62%, as an inseparable 67:33
1
mixture of cis/trans isomers, measured by H NMR) as a clear pale yellow oil.
1
3

Attached-ring compound 24a. R 0.14 (EtOAc:Hexanes, 1:4); IR (neat, NaCl) 3058 (m), 2964 (s),
f
-1 1
2
881 (s), 1738 (s), 1716 (s), 1674 (m), 1455 (m), 1267 (m), 1155 (m), 1062 (m), 972 (m) cm ; H
NMR (CDCl , 400 MHz) δ 9.75 (s, 1H), 6.85 (0.67H, s), 6.80 (0.33H, s), 2.96–2.56 (m, 4H), 2.34–2.02
3
13
(
m, 6H), 1.77 (m, 1H), 1.58 (m, 1H). C NMR (CDCl , 100 MHz) δ 220.1, 189.7, 152.3, 151.3, 146.4,
3
53.3, 52.9, 38.9, 38.7, 38.5, 37.7, 36.9, 36.8, 32.9, 32.6, 27.7, 26.8, 20.50, 20.47. HRMS calcd. for
C H O : m/z 178.0994, found m/z 178.0990.
11
14
2
O
O
O
N
Mo(CO)6
H
CH CN/H O
3
2
H
o
H
8
0 C
8
b
2
4b
(
60%)
Mo-mediated cleavage reaction of cycloadduct 8b (Table 2, entry 2). To a flame dried flask
containing the cycloadduct 8b (30.9 mg, 0.1633 mmol) and acetonitrile (1.5 mL) was added
molybdenum hexacarbonyl (46.2 mg, 0.1750 mmol) and distilled water (0.08 mL, 5 mmol). A water
condenser was then attached and the flask was heated to 80 ºC for 3 h. The solvent was then removed
using rotary evaporation and the crude reaction mixture was purified by column chromatography
(EtOAc:hexanes = 0:1, 1:9, 1:4) to give 24b (18.9 mg, 0.09830 mmol, 60%, as an inseparable 60:40
1
mixture of cis/trans isomers, measured by H NMR) as a clear pale yellow oil.
Attached-ring compound 24b. R 0.21 (EtOAc:Hexanes, 1:4); IR (neat, NaCl) 2936 (s), 2861 (s),
f
-1 1
1
705 (s), 1674 (m), 1447 (m), 1311 (w), 1263 (w), 1132 (m), 1068 (m) cm ; H NMR (CDCl , 400
3
MHz) δ 9.73 (s, 1H), 6.83 (m, 0.6H), 6.80 (m, 0.4H), 6.17 (m, 0.5H), 3.60 (d, 0.25H, J = 5.2 Hz), 3.44
(d, 0.25H, J = 6.8 Hz), 3.01 (m, 0.75H), 2.91 (s, 0.25H), 2.85 (m, 0.5H), 2.77–2.52 (m, 3H), 2.42–2.28
1
3
(
m, 4H), 2.23–2.05 (m, 4H), 2.00–1.86 (m, 2H), 1.75–1.64 (m, 3H), 1.43 (m, 1H). C NMR (CDCl ,
3
1
4
2
00 MHz) δ 212.8, 212.3, 189.76, 189.72, 152.6, 151.6, 146.5, 137.1, 135.9, 81.2, 56.3, 55.5, 51.9,
8.9, 45.7, 42.4, 42.3, 39.1, 37.9, 37.7, 37.0, 36.9, 33.2, 32.4, 32.2, 31.1, 28.3, 28.0, 26.8, 25.0, 24.9,
2.4. HRMS calcd. for C H O : m/z 192.1150, found m/z 192.1161.
1
2
16
2
1
4

O
O
O
O
N
Mo(CO)6
O
H
CH CN/H O
3
8
2
H
o
H
0 C
8
c
2
4c
(
53%)
Mo-mediated cleavage reaction of cycloadduct 8c (Table 2, entry 3). To a flame dried flask
containing the cycloadduct 8c (31.3 mg, 0.1766 mmol) and acetonitrile (2.0 mL) was added
molybdenum hexacarbonyl (49.6 mg, 0.1879 mmol) and distilled water (0.12 mL, 7.5 mmol). A water
condenser was then attached and the flask was heated to 80 ºC for 3 h. The solvent was then removed
using rotary evaporation and the crude reaction mixture was purified by column chromatography
(EtOAc:hexanes = 0:1, 1:9, 1:4) to give 24c (16.9 mg, 0.09378 mmol, 53%, as an inseparable 50:50
1
mixture of cis/trans isomers, measured by H NMR) as a clear pale yellow oil.
Attached-ring compound 24c. R 0.26 (EtOAc:Hexanes, 1:3); IR (neat, NaCl) 3067 (w), 2940 (s),
f
2877 (s), 1748 (s), 1716 (s), 1674 (m), 1433 (m), 1371 (m), 1264 (m), 1174 (m), 1063 (m), 934 (m),
-1 1
7
35 (m) cm ; H NMR (CDCl , 400 MHz) δ 9.75 (s, 1H), 6.85 (m, 0.5H), 6.80 (m, 0.5H), 4.39 (t, 1H,
3
J = 9.6 Hz), 4.02 (d, 1H, J = 17.2 Hz), 3.90 (m, 1H), 3.84 (dd, 1H, J = 17.2, 11.1 Hz), 2.91 (m, 1H),
1
3
2
.69 (m, 3H), 2.43 (m, 2H). C NMR (CDCl , 100 MHz) δ 215.7, 215.5, 189.34, 189.30, 151.3, 150.4,
3
1
46.8, 146.0, 71.6, 71.5, 70.9, 70.3, 50.9, 50.4, 37.9, 37.0, 36.4, 36.0, 32.84, 32.75. HRMS calcd. for
C H O : m/z 180.0786, found m/z 180.0782.
10
12
3
O
O
O
N
Mo(CO)6
Hexyl
CH CN/H O
3
2
Hexyl
o
H
80 C
8
d
2
4d
(
73%)
Mo-mediated cleavage reaction of cycloadduct 8d (Table 2, entry 4). To a flame dried flask
containing the cycloadduct 8d (22.8 mg, 0.0879 mmol) and acetonitrile (1.5 mL) was added
molybdenum hexacarbonyl (23.1 mg, 0.0875 mmol) and distilled water (0.06 mL, 3.75 mmol). A
water condenser was then attached and the flask was heated to 80 ºC for 3 h. The solvent was then
removed using rotary evaporation and the crude reaction mixture was purified by column
chromatography (EtOAc:hexanes = 0:1, 1:9, 1:4) to give 24d (16.9 mg, 0.06441 mmol, 73%, as an
1
inseparable 60:40 mixture of cis/trans isomers, measured by H NMR) as a clear pale yellow oil.
Attached-ring compound 24d. R 0.24 (EtOAc:Hexanes, 1:4); IR (neat, NaCl) 3054 (w), 2957 (s),
f
-1 1
2
928 (s), 2861 (s), 1737 (s), 1715 (s), 1683 (m), 1470 (m), 1455 (m), 1155 (m), 1077 (m) cm ; H
1
5

NMR (CDCl , 400 MHz) δ 5.99 (m, 0.4H), 5.79 (m, 1H), 5.60 (m, 0.6H), 3.61 (m, 1H), 3.07 (m, 1H),
3
2.48 (m, 2H), 2.34 (m, 2H), 2.20–1.87 (m, 4H), 1.77–1.52 (m, 5H), 1.27 (m, 6H), 0.88 (t, 3H, J = 6.7
13
Hz). C NMR (CDCl , 100 MHz) δ 136.2, 134.8, 130.0, 128.8, 58.3, 58.1, 53.2, 53.0, 45.2, 45.1, 41.4,
3
4
1.3, 38.72, 38.67. HRMS calcd. for C H O : m/z 262.1933, found m/z 262.1938.
17 26 2
O
O
O
N
Mo(CO)6
MeO
CH CN/H O
3
2
o
H
MeO
80 C
8
e
24e
(
67%)
Mo-mediated cleavage reaction of cycloadduct 8e (Table 2, entry 5). To a flame dried flask
containing the cycloadduct 8e (20.2 mg, 0.0921 mmol) and acetonitrile (1.5 mL) was added
molybdenum hexacarbonyl (25.8 mg, 0.0977 mmol) and distilled water (0.08 mL, 5 mmol). A water
condenser was then attached and the flask was heated to 80 ºC for 3 h. The solvent was then removed
using rotary evaporation and the crude reaction mixture was purified by column chromatography
(EtOAc:hexanes = 0:1, 1:9, 1:4) to give 24e (13.7 mg, 0.06163 mmol, 67%, as an inseparable mixture
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of 4 stereoisomers, ~ 42:39:14:5, measured by C NMR) as a clear pale yellow oil.
Attached-ring compound 24e. R 0.26 (EtOAc:Hexanes, 1:3); IR (neat, NaCl) 2964 (m), 2938 (m),
f
2876 (m), 2825 (w), 1727 (vs), 1444 (m), 1402 (m), 1357 (m), 1326 (m), 1274 (w), 1202 (m), 1156
-1 1
(
m), 1103 (s), 1042 (m) cm ; H NMR (CDCl , 400 MHz) δ 6.04 (m, 0.5H), 5.75 (m, 1H), 5.63 (m,
3
1H), 4.11 (s, 2H), 3.73 (m, 1H), 3.42 (s, 3H), 3.09 (m, 1H), 2.32 (m, 2H), 2.22–1.90 (m, 5H), 1.78–1.54
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(
m, 2H). C NMR (CDCl , 100 MHz) δ 220.4, 220.3, 208.2, 208.1, 136.7, 135.4, 129.1, 127.9, 59.4,
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5
4.8, 54.6, 53.2, 53.0, 45.2, 45.0, 38.7, 38.6, 30.2, 28.3, 26.7, 26.6, 20.6. HRMS calcd. for C H O :
13 18 3
m/z 222.1256, found m/z 222.1247.
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