Pentacarbonyl(acyloxyalkylidene)chromium(0) Complexes
J . Org. Chem., Vol. 62, No. 17, 1997 5951
Hz, 2 H), 4.98 (td, J ) 7.6, 6.4 Hz, 1 H), 3.87 (s, 3 H), 2.26 (q,
J ) 6.6 Hz, 2 H), 1.47 (sextet, J ) 6.9 Hz, 2 H), 0.96 (t, J )
7.2 Hz, 3 H); 13C NMR (22.5 MHz) δ 163.7, 163.4, 134.4, 132.0
(2C), 121.8, 114.1, 113.8 (2C), 55.5, 26.7, 22.4, 13.7; MS (EI)
m/ z 220 (M+). Anal. Calcd for C13H16O3: C, 70.88; H, 7.32.
Found: C, 71.22; H, 7.61.43
7.7 Hz, 3 H); 13C NMR (22.5 MHz) δ 175.7, 129.9, 123.5, 38.8,
27.1 (3C), 22.7, 13.4, 12.0.
1
E-17: H NMR (90 MHz) δ 6.81 (m, 1 H), 2.14 (q, J ) 7.4
Hz, 2 H), 1.63 (d, J ) 1.5 Hz, 3 H), 1.25 (s, 9 H), 1.00 (t, J )
7.4 Hz, 3 H); 13C NMR (22.5 MHz) δ 175.6, 129.5, 123.4, 38.8,
26.5 (3C), 22.3, 17.0, 11.4.
2-Meth yl-1-bu ten -1-yl Aceta te (18). To a -40 °C cold
solution of tetramethylammonium pentacarbonyl(1-oxo-2-
methylbutyl)chromate(1-) (6) (1.404 g, 4.00 mmol) in CH2Cl2
(60 mL) was added acetyl chloride (284 µL, 4.00 mmol), as
described above, and the mixture gave, after evaporation and
column chromatography (ethanol), 18 (110 mg, 0.86 mmol,
21%, Z/ E ) 5:3) as a colorless oil.25a,46
(Z)-3-P h en yl-1-p r op en -1-yl Aceta te (19). Reaction of
tetramethylammonium pentacarbonyl(1-oxo-3-phenylpropyl)-
chromate(1-) (7)47 (798 mg, 2.00 mmol) with acetyl bromide
(142 µL, 2.00 mmol) in CH2Cl2 (40 mL) at -40 °C to ambient
temperature (20 h), as described above, gave, after solvent
removal at water aspirator pressure (0 °C) and chromatogra-
phy (pentane-Et2O, 8:2), 19 (92 mg, 0.52 mmol, 26%, Z/ E )
17:1) as a faint yellow oil.48
Reaction of 7 (399 mg, 1.00 mmol) with acetyl chloride (71
µL, 1.00 mmol) and pyridine (81 µL, 1.00 mmol) in CH2Cl2 (25
mL) at -40 °C to ambient temperature (20 h), as described
above, gave, after solvent removal at water aspirator pressure
(0 °C) and chromatography (pentane-Et2O, 9:1), 19 (69 mg,
0.40 mmol, 40%, Z/E ) 40:1) as a faint yellow oil followed by
(CO)5CrC5H5N (101 mg, 0.38 mmol, 38%) as yellow crystals.
(Z)-Hexen -1-yl Aceta te (20). Reaction of tetramethylam-
monium pentacarbonyl(1-oxohexyl)chromate(1-) (8) (730 mg,
2.00 mmol) with acetyl chloride (142 µL, 2.00 mmol) in
CH2Cl2 (50 mL) at -40 °C to ambient temperature (24 h), as
described above, gave, after solvent removal at water aspirator
pressure (0 °C) and chromatography (pentane-Et2O, 9:1), 20
(88 mg, 0.62 mmol, 31%, Z/ E ) 19:1) as a faint yellow oil.18
(Z)-Hexen -1-yl p en ta n oa te (21). Reaction of tetrameth-
ylammonium pentacarbonyl(1-oxohexyl)chromate(1-) (8) (730
mg, 2.00 mmol) with pentanoyl chloride (261 µL, 2.20 mmol)
in CH2Cl2 (50 mL) at -40 °C to ambient temperature (24 h),
as described above, gave, after solvent removal at water
aspirator pressure (0 °C) and chromatography (pentane-Et2O,
19:1), 21 (199 mg, 1.08 mmol, 54%, Z/ E ) 13:1) as a faint
yellow oil.18
Reaction of 8 (365 mg, 1.00 mmol) with pentanoyl chloride
(120 µL, 1.00 mmol) and pyridine (81 µL, 1.00 mmol) in CH2Cl2
(20 mL) at -40 °C to ambient temperature (20 h), as described
above, gave, after solvent removal at water aspirator pressure
(0 °C) and chromatography (pentane-Et2O, 19:1), 21 (152 mg,
0.83 mmol, 83%, Z/ E > 20:1) as a faint yellow oil followed by
(CO)5CrC5H5N (120 mg, 0.45 mmol, 45%) as yellow crystals.
Cycloh exylid en em eth a n ol Aceta te (22). Reaction of
tetramethylammonium pentacarbonyl(cyclohexylcarbonyl)-
chromate(1-) (9) (1.51 g, 4.00 mmol) with acetyl chloride (285
µL, 4.00 mmol) in CH2Cl2 (40 mL) at -40 °C to ambient
temperature (14 h), as described above, gave, after solvent
removal at water aspirator pressure (0 °C) and chromatogra-
phy (pentane-Et2O, 19:1), 22 (402 mg, 2.61 mmol, 65%) as a
colorless oil.49
A solution of tetramethylammonium pentacarbonyl(1-oxo-
pentyl)tungstate(1-)44 (5-W) (483 mg, 1.00 mmol) and pyridine
(81 µL, 1.00 mmol) in CH2Cl2 (10 mL) was reacted, at -40 °C,
with 4-methoxybenzoyl chloride (141 µL, 1.04 mmol) as
described above, affording 15 (32 mg, 0.14 mmol, 14%) as a
colorless oil.
n-Butyllithium (1.6 M in hexanes, 1.88 mL, 3.00 mmol) was
added to a slurry of Cr(CO)6 (660 mg, 3.00 mmol) in Et2O (500
mL) via syringe. The reaction mixture was stirred (1 h)
followed by solvent removal. The obtained residue was
treated, at -40 °C, with, in sequence, CH2Cl2 (50 mL), NMe4-
Cl (508 mg, 4.64 mmol), and 4-methoxybenzoyl chloride (465
µL, 3.44 mmol). After stirring (18 h), the solvent was removed,
and hexanes-EtOAc (1:1, 50 mL) was added to the resulting
brown solid residue. The open flask was put outside the
chemistry building, and the slurry was oxidized in the
sunlight, “air-oxidation”, for 3 h. The colorless solution with
a brown solid residue was filtered (Celite), and the solvents
were removed. The crude product was purified by chroma-
tography (hexanes-EtOAc, 19:1), affording 15 (112 mg, 0.51
mmol, 17%) as a colorless oil.
(Z)-1-P en ten -1-yl 2,2-Dim eth ylp r op a n oa te (16). Reac-
tion of tetramethylammonium pentacarbonyl(1-oxopentyl)-
chromate(1-) (5) (351 mg, 1.00 mmol) with 2,2-dimethylpro-
panoyl chloride (123 µL, 1.00 mmol) in CH2Cl2 (10 mL) at -40
°C, as described above, gave, after evaporation and short
column chromatography (ethanol), 16 (83 mg, 0.49 mmol, 49%,
Z/ E ) 6:1) as a colorless oil: IR (film) 2960, 2920, 2870, 1740
(CO), 1475, 1455, 1395, 1370, 1275, 1140 cm-1; MS (EI) m/ z
170 (M+). Anal. Calcd for C10H18O2: C, 70.55; H, 10.66.
Found: C, 70.89; H, 10.35.
Z-16: from a 11:2 (Z/ E) mixture; 1H NMR (90 MHz) δ 7.01
(d, J ) 7.2 Hz, 1 H), 4.89 (q, J ) 7.3 Hz, 1 H), 2.13 (q, J ) 7.4
Hz, 2 H), 1.41 (m, J ) 7.7 Hz, 2 H), 1.26 (s, 9 H), 0.91 (t, J )
6.9 Hz, 3 H); 13C NMR (22.5 MHz) δ 175.5, 134.4, 113.9, 38.8,
26.9 (3C), 22.2, 18.2, 13.5.
1
E-16: partial spectra from a 11:2 (Z/ E) mixture; H NMR
(90 MHz) δ 6.42 (dt, J ) 12.5, 7.1 Hz, 1 H), 1.24 (s, 9 H); 13C
NMR (22.5 MHz) δ 135.7, 114.5, 26.3 (3C), 22.6.
Reaction of 5 (351 mg, 1.00 mmol) with 2,2-dimethylpro-
panoyl chloride (123 µL, 1.00 mmol) in CH2Cl2 (10 mL) at
ambient temperature for 21 h, as described above, gave, after
chromatography (pentane-Et2O, 9:1), 16 (93 mg, 0.55 mmol,
55%, Z/ E ) 7.6:1) as a colorless oil.
Reaction of 5 (352 mg, 1.00 mmol) with 2,2-dimethylpro-
panoyl chloride (123 µL, 1.00 mmol) in CH2Cl2 (10 mL) at -40
°C in the presence of pyridine (81 µL, 1.00 mmol) gave, after
evaporation and column chromatography (pentane), 16 (68 mg,
0.40 mmol, 40%, Z/ E ) 10:1) as a colorless oil.
2-Meth yl-1-bu ten -1-yl 2,2-Dim eth ylp r op a n oa te (17).
Reaction of tetramethylammonium pentacarbonyl(1-oxo-2-
methylbutyl)chromate(1-) (6)45 (1.404 g, 4.00 mmol) with 2,2-
dimethylpropanoyl chloride (493 µL, 4.00 mmol) in CH2Cl2 (60
mL) at -40 °C, as described above, gave, after evaporation
and short column chromatography (ethanol), 17 (310 mg, 1.84
mmol, 46%, Z/ E ) 5:3) as a colorless oil. Spectral data from
a 3:2 (Z/ E) mixture: IR (neat) 2970, 2930, 2875, 1730, 1695,
1475, 1455, 1395, 1275, 1145, 1040, 1005 cm-1; MS (EI) m/ z
170 (M+).
(Z)-4-Ch lor o-1-bu ten -1-yl 4-Meth oxyben zoa te (23). Re-
action of tetramethylammonium pentacarbonyl(cyclopropyl-
carbonyl)chromate(1-) (10)20,24 (670 mg, 2.00 mmol) with
4-methoxybenzoyl chloride (272 µL, 2.01 mmol) in CH2Cl2 (20
mL) at -40 °C to ambient temperature, as described above
(24 h), gave, after air-oxidation (16 h) and chromatography
(pentane-Et2O, 8:2) 23 (187 mg, 0.78 mmol, 39%, Z/ E > 15:
1) as a colorless oil:50 IR (neat) 1721 cm-1; 1H NMR (90 MHz)
δ 8.05 (d, J ) 9.1 Hz, 2 H), 7.38 (d with further fine splitting,
J ) 6.4 Hz, 1 H), 6.96 (d, J ) 9.1 Hz, 2 H), 5.04 (q, J ) 6.6 Hz,
Z-17: 1H NMR (90 MHz) δ 6.89 (br s, 1 H), 2.01 (q, J ) 7.8
Hz, 2 H), 1.68 (d, J ) 1.0 Hz, 3 H), 1.25 (s, 9 H), 1.02 (t, J )
(46) Z-Isomer: Commercon, A.; Normant, J .; Villeras, J . J . Orga-
nomet. Chem. 1975, 93, 415.
(43) The minor E-isomer could not be seen in the 1H NMR spectra,
but some of the 13C NMR peaks were recorded: δ 134.0, 121.8, 114.3,
55.7, 29.5, 22.8.
(44) Nakamura, T.; Matsuyama, H.; Iyoda, M. Chem. Lett. 1994,
1537.
(47) So¨derberg, B. C.; Odens, H. H. Organometallics 1996, 15, 5080.
(48) Taguchi, T.; Morikawa, T.; Takigawa, T.; Yoshizawa, A.;
Tawara, Y.; Kobayashi, Y. Nippon Kagaku Kaishi 1985, 11, 2177.
(49) Hurst, J . R.; Wilson, S. L.; Schuster, G. B. Tetrahedron 1985,
41, 2191.
(45) Montgomery, J .; Wieber, G. M.; Hegedus, L. S. J . Am. Chem.
Soc. 1990, 112, 6255.
(50) The E-isomer was not observed by 1H or 13C NMR.