Cyclization Reactions of Rhodium Carbene Complexes
J . Org. Chem., Vol. 62, No. 6, 1997 1651
1.46 (m, 2H), 2.10 (s, 3H), 2.45 (t, 2H, J ) 7.4 Hz), 3.15 (s,
3H), 7.45-7.50 (m, 3H), and 8.00 (m, 2H); 13C NMR (75 MHz,
CDCl3) δ 9.7, 13.7, 20.4, 26.4, 27.8, 31.0, 100.8, 105.6, 127.7,
128.1, 131.9, 138.8, and 204.4. Anal. Calcd for C16H20O: C,
84.15; H, 8.83. Found: C, 84.03; H, 8.72.
75 MHz) δ 13.6, 20.3, 24.6, 36.7, 54.4, 77.7, 84.8, 125.6, 128.2,
128.5, 128.7, 130.4, 133.3, 137.7, 138.5, and 198.8; HRMS calcd
for C18H20O2 268.1463, found 268.1462.
Rh od iu m (I)-Ca ta lyzed Rea ction of 3-Ben zoyl-1-p r o-
p ylcyclop r op en e (41) w ith 1-Hexyn e. A solution contain-
ing 150 mg (0.81 mmol) of 41 and 1.40 mL (12 mmol) of
1-hexyne in 5 mL of CH2Cl2 under Ar was treated with 22 mg
(0.06 mmol) of [ClRh(CO)2]2. The resulting mixture was
stirred at 25 °C for 30 min and concentrated under reduced
pressure, and the residue was chromatographed on silica gel
to give 135 mg (62%) of 2-butyl-7-phenyl-4-propyloxepin (53)
along with 18 mg (8%) of 2-butyl-6-phenyl-3-propylphenol (54).
Oxepin 53 exhibited the following spectral properties: IR
Rh od iu m (II)-Ca ta lyzed Rea ction of 3-Ben zoyl-1-p r o-
p ylcyclop r op en e (41). To a solution of 2.9 mL (25 mmol) of
benzoyl chloride in 25 mL of THF at 0 °C was added an
ethereal solution of diazomethane (100 mmol). The resulting
mixture was allowed to warm to 25 °C, stirred for an additional
30 min, and worked up by washing with 15 mL of water.
Concentration of the solution under reduced pressure left a
yellow oil which was chromatographed on silica gel to give 2.8
g (77%) of R-diazoacetophenone as a yellow solid: IR (CHCl3)
(neat) 2873, 1654, 1447, 1142, and 760 cm-1 1H NMR (300
;
1
2107, 1575, and 1364 cm-1; H NMR (90 MHz, CDCl3) δ 5.90
MHz, CDCl3) δ 0.87 (t, 3H, J ) 7.3 Hz), 0.94 (t, 3H, J ) 7.3
Hz), 1.34 (sex, 2H, J ) 7.5 Hz), 1.50-1.61 (m, 4H), 2.13-2.20
(m, 4H), 5.45 (s, 1H), 6.05 (d, 1H, J ) 6.1 Hz), 6.27 (d, 1H, J
) 6.1 Hz), 7.25-7.37 (m, 3H), and 7.65 (d, 2H, J ) 7.4 Hz);
13C NMR (75 MHz, CDCl3) δ 13.8, 13.8, 22.1, 22.7, 28.9, 34.4,
40.1, 111.7, 114.4, 123.7, 125.3, 127.9, 128.2, 135.3, 143.0,
147.5, and 154.9. Anal. Calcd for C19H24O: C, 85.02; H, 9.02.
Found: C, 84.96; H, 8.84.
Phenol 54 exhibited the following spectral properties: 1H
NMR (300 MHz, CDCl3) δ 0.96 (t, 3H, J ) 7.6 Hz), 1.03 (t, 3H,
J ) 7.6 Hz), 1.43-1.70 (m, 6H), 2.60-2.73 (m, 4H), 5.23 (s,
1H), 6.80 (d, 1H, J ) 7.8 Hz), 7.00 (d, 1H, J ) 7.8 Hz), and
7.34-7.50 (m, 5H). Anal. Calcd for C19H24O: C, 85.02; H,
9.02. Found: C, 84.87; H, 8.96.
(s, 1H), 7.42-7.54 (m, 3H), and 7.74-7.77 (m, 2H).
To a solution containing 6.8 mL of 1-pentyne and a catalytic
amount of rhodium(II) acetate dimer in 10 mL of distilled CH2-
Cl2 was added a solution of 1.0 g of the above diazo ketone in
10 mL of CH2Cl2. The resulting solution was stirred at 25 °C
for 20 min, concentrated under reduced pressure, and chro-
matographed on silica gel to give 1.0 g (79%) of cyclopropene
41 as a pale yellow oil: IR (neat) 2964, 1802, 1671, 1598, 1449,
and 1225 cm-1; 1H NMR (300 MHz, CDCl3) δ 0.97 (t, 3H, J )
7.5 Hz), 1.58-1.63 (m, 2H), 2.51 (t, 2H, J ) 7.5 Hz), 3.20 (s,
1H), 6.33 (s, 1H), 7.26-7.55 (m, 3H), and 8.01-8.04 (m, 1H);
13C NMR (75 MHz, CDCl3) δ 13.6, 20.2, 24.3, 26.9, 92.9, 114.4,
127.9, 128.2, 132.2, 138.3, and 203.8. Anal. Calcd for
C13H14O: C, 83.82; H, 7.58. Found: C, 83.67; H, 7.41.
A solution containing 480 mg of cyclopropene 41 in 25 mL
of benzene under Ar was treated with 3 mg of rhodium(II)
acetate dimer. The mixture was heated at reflux for 48 h,
concentrated under reduced pressure, and chromatographed
on silica gel to give 249 mg of the bicyclic compound 44 as
well as 30 mg of a 3:1 mixture of furans 42 and 43. 2-Phenyl-
4-propylfuran (42) exhibited the following spectral proper-
ties: 1H NMR (300 MHz, CDCl3) δ 0.96 (t, 3H, J ) 7.5 Hz),
1.62 (m, 2H), 2.42 (t, 2H, J ) 7.5 Hz), 6.54 (s, 1H), 7.20-7.23
(m, 1H), 7.25 (s, 1H), 7.30-7.36 (m, 2H), and 7.60-7.70 (m,
2H); 13C NMR (75 MHz, CDCl3) δ 13.8, 23.1, 27.0, 106.6, 123.6,
127.1, 127.3, 131.1, and 138.4. Anal. Calcd for C13H14O: C,
83.82; H, 7.58. Found: C, 83.75; H, 7.49.
To a solution containing 100 mg (0.37 mmol) of oxepin 53
in 10 mL of CH2Cl2 was added 1 drop of 1 N HCl. The
resulting solution was heated at reflux for 2 h, concentrated
under reduced pressure, and chromatographed on silica gel
to give 95 mg (95%) of 2-butyl-6-phenyl-4-propylphenol (55):
IR (neat) 2873, 1470, 1217, and 704 cm-1; 1H NMR (300 MHz,
CDCl3) δ 0.95 (t, 6H, J ) 7.3 Hz), 1.42 (sex, 2H, J ) 7.8 Hz),
1.57-1.69 (m, 4H), 2.53 (t, 2H, J ) 7.4 Hz), 2.65 (t, 2H, J )
7.6 Hz), 5.08 (s, 1 H), 6.89 (d, 1H, J ) 2.1 Hz), 6.95 (d, 1H, J
) 2.0 Hz), and 7.35-7.53 (m, 5H); 13C NMR (75 MHz, CDCl3)
δ 13.9, 14.0, 22.8, 24.8, 30.1, 32.1, 37.3, 127.5, 127.7, 129.0,
129.2, 129.2, 129.7, 134.3, 137.7, and 148.1. Anal. Calcd for
C19H24O: C, 85.02; H, 9.02. Found: C, 84.96; H, 8.84.
Rh od iu m (I)-Ca ta lyzed Rea ction of 3-Ben zoyl-1-p r o-
p ylcyclop r op en e (41) w ith Meth yl P r op a r gyl Eth er .
Using a procedure analagous to that described above, 150 mg
(0.81 mmol) of cyclopropene 41 was converted into 138 mg
(54%) of 2-(methoxymethyl)-7-phenyl-4-propyloxepin (56) to-
gether with 14 mg (7%) of 2-(methoxymethyl)-6-phenyl-3-
propylphenol (57). Oxepin 56 exhibited the following spectral
properties: IR (neat) 2931, 1661, 1493, 1447, 1192, and 1117
2-Phenyl-5-propylfuran (43) exhibited the following spectral
properties: IR (neat) 2935, 1596, 1548, 1488, and 962 cm-1
;
1H NMR (300 MHz, CDCl3) δ 0.97 (t, 3H, J ) 7.5 Hz), 1.70
(m, 2H), 2.63 (t, 2H, J ) 7.5 Hz), 6.03 (d, 1H, J ) 3.0 Hz),
6.51 (d, 1H, J ) 3.0 Hz), 7.17-7.19 (m, 1H), 7.29-7.34 (m,
2H), and 7.60-7.62 (m, 2H); 13C NMR (75 MHz, CDCl3) δ 13.7,
21.4, 30.2, 105.6, 106.9, 123.3, 126.6, 128.5, 131.2, 152.1, and
156.2. Anal. Calcd for C13H14O: C, 83.82; H, 7.58. Found:
C, 83.73; H, 7.56.
1
cm-1; H NMR (300 MHz, CDCl3) δ 0.94 (t, 3H, J ) 7.3 Hz),
1.55 (sex, 2H, J ) 7.4 Hz), 2.22 (t, 2H, J ) 7.3 Hz), 3.36 (s,
3H), 3.91 (s, 2H), 5.74 (s, 1H), 6.13 (d, 1H, J ) 6.3 Hz), 6.31
(d, 1H, J ) 6.2 Hz), 7.27-7.40 (m, 2H), and 7.66-7.68 (m, 2H);
13C NMR (75 MHz, CDCl3) δ 13.7, 22.6, 39.8, 57.9, 71.9, 111.2,
116.2, 125.0, 125.2, 128.1, 128.3, 134.8, 142.3, 147.6, and 148.4.
Anal. Calcd for C17H20O2: C, 79.64; H, 7.87. Found: C, 79.51;
H, 7.75.
4-Benzoyl-3,7-di-n-propyl-5-phenyl-8-oxabicyclo[3.2.1]octa-
2,6-diene (44) exhibited the following spectral properties: IR
1
(neat) 2960, 2933, 1671, 1449, and 1202 cm-1; H NMR (300
MHz, CDCl3) δ 0.79 (t, 3H, J ) 7.3 Hz), 1.01 (t, 3H, J ) 7.3
Hz), 1.29-1.40 (m, 2H), 1.57-1.68 (m, 2H), 1.70-1.87 (m, 2H),
2.29 (t, 2H, J ) 7.3 Hz), 4.63 (s, 1H), 4.77 (d, 1H, J ) 4.4 Hz),
4.90 (s, 1H), 6.18-6.24 (m, 1H), 7.14-7.22 (m, 5H), and 7.27-
7.46 (m, 5H); 13C NMR (75 MHz, CDCl3) δ 13.6, 13.9, 20.2,
20.8, 30.0, 36.8, 56.5, 79.9, 89.5, 120.4, 125.2, 125.2, 127.5,
128.1, 128.2, 128.3, 132.6, 138.5, 138.9, 141.8, 155.2, and 199.2.
Anal. Calcd for C26H28O2: C, 83.82; H, 7.58. Found: C, 83.94;
H, 7.62.
Phenol 57 exhibited the following spectral properties: 1H
NMR (300 MHz, CDCl3) δ 1.00 (t, 3H, J ) 7.5 Hz), 1.50-1.62
(m, 2H), 2.60 (t, 2H, J ) 7.5 Hz), 3.39 (s, 3H), 3.94 (s, 2H),
6.80 (d, 1H, J ) 7.4 Hz), 7.20 (d, 1H, J ) 7.4 Hz), and 7.35-
7.70 (m, 5H). Anal. Calcd for C17H20O2: C, 79.64; H, 7.87.
Found: C, 79.51; H, 7.73.
A sample containing 100 mg of 56 was converted into 93
mg (93%) of 58 in a manner similar to that described above.
Phenol 58 exhibited the following spectral properties: IR (neat)
2960, 1478, 1233, and 1088 cm-1; 1H NMR (300 MHz, CDCl3)
δ 0.94 (t, 3H, J ) 7.5 Hz), 1.62 (sex, 2H, J ) 7.5 Hz), 2.53 (t,
2H, J ) 7.5 Hz), 3.45 (s, 3H), 4.67 (s, 2H), 6.89 (d, 1H, J ) 1.5
Hz), 7.09 (d, 1H, J ) 1.7 Hz), 7.25 (s, 1H), 7.30-7.36 (m, 1H),
7.40-7.46 (m, 2H), and 7.55-7.59 (m, 2H); 13C NMR (75 MHz,
CDCl3) δ 13.8, 24.7, 37.1, 58.1, 73.7, 122.4, 127.0, 127.7, 128.2,
128.8, 129.3, 130.4, 138.1, and 150.6. Anal. Calcd for
C17H20O2: C, 79.64; H, 7.87. Found: C, 79.46; H, 7.92.
R h od iu m (I)-Ca t a lyzed R ea ct ion of 3-Ben zoyl-1-(5-
h exyn yl)cyclop r op en e (68). A sample of 200 mg (1.4 mmol)
of R-diazoacetophenone was converted in the normal manner
Rh od iu m (II)-Ca ta lyzed Rea ction of 3-Ben zoyl-1-p r o-
p ylcyclop r op en e (41) w ith 2-Meth ylfu r a n . A solution
containing 130 mg (0.7 mmol) of cyclopropene 33 and 0.3 g
(5.0 mmol) of 2-methylfuran in 15 mL of benzene was treated
with 5 mg of rhodium(II) acetate dimer. The reaction mixture
was heated at reflux for 24 h, concentrated under reduced
pressure, and chromatographed on silica gel to give a 4:1
mixture of furans 42 and 43 in 28% yield together with 68 mg
(37%) of 4-benzoyl-5-methyl-3-propyl-8-oxabicyclo[3.2.1]octa-
2,6-diene (47): IR (neat) 2931, 1673, 1596, and 1450 cm-1; 1H
NMR (CDCl3, 300 MHz) δ 0.77 (t, 3H, J ) 7.3 Hz), 1.44 (m,
2H), 1.47 (s, 3H), 1.70-1.82 (m, 2H), 4.52 (s, 1H), 4.79 (m, 1H),
5.63 (d, 1H, J ) 5.8 Hz), 6.07 (m, 1H), 7.40-7.52 (m, 2H),
7.55-7.60 (m, 1H), and 7.75-7.80 (m, 2H); 13C NMR (CDCl3,