Crombie et al.
silica gel (compound adsorbed on 8 g of silica gel, elution with
20% ethyl acetate-hexanes) to afford 1.96 g (60% overall yield
from 2-methyl-3-phenylpropionic acid) of 4-bromo-1-diazo-3-
methyl-4-phenyl-2-butanone (67) (mixture of diastereomers)
as a yellow solid: mp 51.0-61.0 °C; IR (CCl4) 2890, 2080, 1635,
and 1535 cm-1; 1H NMR (300 MHz, CDCl3) δ 7.22-7.39 (m, 5
H), 5.42 (br s, 1 H, minor isomer), 5.14 (app t, J ) 8.8, 10.3
Hz, 1 H), 5.06 (br s, 1 H, major isomer), 3.03-3.11 (m, 1 H),
1.47 (d, J ) 7.1 Hz, 3 H, major isomer), 0.92 (d, J ) 7.0 Hz, 3
H, minor isomer); 13C NMR (75 MHz, CDCl3) δ 195.4, 194.3,
140.5, 139.4, 128.8, 128.4, 127.8, 127.6, 57.5, 55.1, 55.0, 54.1,
52.8, 17.7, 17.0; UV (CH3CN) λmax (ꢀ) 247 (20 145), 192 (35 500)
nm; HRMS (EI) m/z calcd for C11H11BrN2O 266.0055, found
266.0048.
(22 260) nm. Anal. Calcd for C12H9IO2: C, 46.18; H, 2.91.
Found: C, 46.08; H, 2.83.
1-Acetoxy-5-isopropylazulene (70). Application of the
general procedure (except that Et2O was employed as solvent
in place of dichloromethane) gave 0.151 g (54%) of 70 as a blue
1
oil. IR (thin film) 2960, 2920, 2860, 1755, and 1580 cm-1; H
NMR (300 MHz, CDCl3) δ 8.20 (d, J ) 1.8 Hz, 1H), 8.08 (d, J
) 10.0 Hz, 1H), 7.75 (d, J ) 4.3 Hz, 1H), 7.49 (d, J ) 9.5 Hz,
1H), 7.17 (d, J ) 4.3 Hz, 1H), 7.01 (app t, J ) 9.5, 10.0 Hz,
1H), 3.03 (sept, J ) 6.9 Hz, 1H), 2.40 (s, 3H), and 1.33 (d, J )
6.9 Hz, 6H); 13C NMR (75 MHz, CDCl3) δ 169.4, 142.7, 138.1,
137.0, 135.7, 130.6, 127.9, 125.6, 121.6, 121.5, 112.9, 38.4, 24.4,
and 21.0; UV-vis max (hexane) λmax (ꢀ) 614 (119), 352 (2170),
279 (21 570), and 225 (67 000) nm. Anal. Calcd for C15H16O2:
C, 78.92; H, 7.06. Found: C, 79.14; H, 6.87.
General Procedure for the Synthesis of Acetoxyazu-
lenes: 1-Acetoxyazulene (20). A 500-mL, three-necked,
round-bottomed flask equipped with a rubber septum, 125-
mL pressure-equalizing addition funnel, and an argon inlet
adapter was charged with rhodium pivalate75 (0.022 g, 0.040
mmol) and 120 mL of dichloromethane. The addition funnel
was charged with 4-bromo-1-diazo-4-phenyl-2-butanone (19)
(2.00 g, 7.89 mmol) and 75 mL of dichloromethane. The
solution of the diazo ketone was added dropwise over 1.5 h to
the rapidly stirred solution of the catalyst. After 5 min, acetic
anhydride (4.02 g, 3.70 mL, 39.5 mmol) was added in one
portion via syringe, and then 4-DMAP (2.89 g, 23.7 mmol) was
immediately added in one portion. The resulting deep blue
solution was stirred for 5 min and then treated with 10 mL of
methanol. After stirring an additional 10 min, the reaction
mixture was poured into 100 mL of dichloromethane and 200
mL of 3% HCl solution. The organic phase was separated,
washed with 150 mL of 3% HCl solution and 200 mL of brine,
dried over MgSO4, filtered, and concentrated to provide 1.40
g of a blue oil. Column chromatography on 50 g of silica gel
(elution with 5% ethyl acetate-hexanes) afforded 0.948 g (64%)
of 1-acetoxyazulene as blue needles: mp 53.5-54.5 °C (lit.28
mp 47.5-50.2 °C); IR (CCl4) 3030, 2810, 1765, 1580, 1545, and
1-Acetoxy-5-bromoazulene (71). Application of the gen-
eral procedure gave 0.109 g (39%) of 71 as an olive green solid,
mp 60.5-61.5 °C. IR (CCl4) 2900, 1765, 1580, and 1545 cm-1
;
1H NMR (300 MHz, CDCl3) δ 8.49 (d, J ) 2.1 Hz, 1 H), 8.13
(d, J ) 9.8 Hz, 1 H), 7.90-7.84 (m, 2 H), 7.24 (d, J ) 4.3 Hz,
1 H), 6.83 (app t, J ) 9.9 Hz, 1 H), 2.42 (s, 3 H); 13C NMR (75
MHz, CDCl3) δ 168.9, 141.0, 140.9, 138.6, 133.6, 131.3, 129.9,
126.2, 120.7, 117.4, 114.7, 21.0; UV-vis (hexane) λmax (ꢀ) 690
(273), 632 (302), 601 (250), 371 (3230), 362 (2440), 351 (3980),
347 (2860), 337 (2070), 278 (28 900) nm. Anal. Calcd for C12H9-
BrO2: C, 54.37; H, 3.42. Found: C, 54.59; H, 3.29.
1-Acetoxy-5-(trifluoromethyl)azulene (72). Application
of the general procedure gave 0.109 g (40%) of 72 as a blue
solid, mp 43.5-44.5 °C. IR (CCl4) 2920, 2840, 1770, 1580, and
1
1500 cm-1; H NMR (300 MHz, CDCl3) δ 8.45 (d, J ) 1.4 Hz,
1 H), 8.29 (d, J ) 9.5 Hz, 1 H), 7.92 (d, J ) 4.3 Hz, 1 H), 7.83
(d, J ) 4.3 Hz, 1 H), 7.47 (d, J ) 4.3 Hz, 1 H), 7.09 (app t, J
) 9.8 Hz, 1 H), 2.43 (s, 3 H); 13C NMR (75 MHz, CDCl3) δ
168.8, 140.5, 134.8, 134.7, 134.4, 134.1, 134.0, 133.3, 129.4,
126.2, 120.5, 118.6, 21.0; UV-vis (hexane) λmax (ꢀ) 608 (255),
583 (221), 352 (8474), 278 (61 858), 215 (11 863) nm. Anal.
Calcd for C13H9F3O2: C, 61.42; H, 3.56. Found: C, 61.43; H,
3.63.
1
1500 cm-1; H NMR (300 MHz, CDCl3) δ 8.25 (d, J ) 9.3 Hz,
1 H), 8.21 (d, J ) 10.0 Hz, 1 H), 7.80 (d, J ) 4.2 Hz, 1 H), 7.58
(app t, J ) 9.8 Hz, 1 H), 7.27 (d, J ) 4.2 Hz, 1 H), 7.09 (dt, J
) 4.2, 10.0 Hz, 2 H), 2.43 (s, 3 H); 13C NMR (75 MHz, CDCl3)
δ 169.2, 138.5, 138.1, 137.8, 135.5, 132.1, 127.8, 126.1, 122.6,
121.7, 113.8, 20.9; UV-vis (hexane) λmax (ꢀ) 732 (101), 663
(258), 608 (292), 586 (252), 347 (2933), 277 (30 166), 238 (8845),
213 (3352) nm.
1-Acetoxy-6-methylazulene (73). Application of the gen-
eral procedure gave 0.076 g (22% overall from 4-methyl-
cinnamic acid 27, estimated 47% yield for ring expansion-
annulation step) of 73 as a blue solid, mp 67.0-67.5 °C. IR
1
(CCl4) 3030, 2920, 2880, 1765, and 1580 cm-1; H NMR (300
MHz, CDCl3) δ 8.08 (d, J ) 9.4 Hz, 1 H), 8.04 (d, J ) 10.2 Hz,
1 H), 7.67 (d, J ) 4.3 Hz, 1 H), 7.21 (d, J ) 4.3 Hz, 1 H), 6.99
(d, J ) 9.4 Hz, 1 H), 6.98 (d, J ) 10.2 Hz, 1 H), 2.60 (s, 3 H),
2.41 (s, 3 H); 13C NMR (75 MHz, CDCl3) δ 169.4, 150.5, 138.1,
137.3, 134.1, 131.1, 126.4, 125.0, 123.9, 123.6, 114.0, 28.3, 21.1;
UV-vis (CH3CN) λmax (ꢀ) 714 (105), 645 (270), 596 (300), 368
(3000), 352 (5700), 349 (5890), 335 (4390), 281 (72 290), 234
(18 120) nm. Anal. Calcd for C13H12O2: C, 77.98; H, 6.04.
Found: C, 77.84; H, 6.04.
1-Acetoxy-4-chloroazulene (68). Application of the gen-
eral procedure gave 0.157 g (58%) of 68 as a blue-gray solid,
mp 55.5-56.5 °C. IR (CCl4) 3020, 1760, 1585, and 1550 cm-1
;
1H NMR (300 MHz, CDCl3) δ 8.22 (d, J ) 9.7 Hz, 1 H), 7.80
(d, J ) 4.2 Hz, 1 H), 7.52 (d, J ) 4.2 Hz, 1 H), 7.44 (app t, J
) 10.2 Hz, 1 H), 7.29 (d, J ) 10.8 Hz, 1 H), 7.06 (app t, J )
9.6 Hz, 1 H), 2.41 (s, 3 H); 13C NMR (75 MHz, CDCl3) δ 169.1,
144.0, 139.4, 136.0, 132.4, 130.1, 128.0, 126.3, 124.5, 121.1,
114.3, 21.0; UV-vis (hexane) λmax (ꢀ) 657 (267), 605 (311), 520
(114), 351 (4130), 337 (2970), 284 (35 440), 245 (23 670), 219
(8960) nm. Anal. Calcd for C12H9ClO2: C, 65.32; H, 4.11.
Found: C, 65.31; H, 3.99.
1-Acetoxy-6-chloroazulene (74). Application of the gen-
eral procedure gave 0.569 g (61%) of 74 as metallic blue flakes,
mp 66.5-67.0 °C. IR (CCl4) 2880, 1750, 1565, and 1510 cm-1
;
1H NMR (300 MHz, CDCl3) δ 8.01 (d, J ) 10.2 Hz, 1 H), 8.00
(d, J ) 10.6 Hz, 1 H), 7.77 (d, J ) 4.3 Hz, 1 H), 7.27 (d, J )
4.3 Hz, 1 H), 7.23-7.16 (m, 2 H), 2.42 (s, 3 H); 13C NMR (75
MHz, CDCl3) δ 169.0, 145.6, 139.6, 135.8, 133.9, 130.3, 128.0,
124.7, 122.8, 122.3, 116.1, 21.0; UV-vis (hexane) λmax (ꢀ) 777
(100), 664 (252), 606 (290), 582 (250), 561 (212), 304 (6730),
283 (61 500), 237 (9270), 217 (10 205) nm. Anal. Calcd for
C12H9ClO2: C, 65.32; H, 4.11; Cl, 16.07. Found: C, 65.16; H,
4.17; Cl, 15.88.
1-Acetoxy-4-iodoazulene (69). Application of the general
procedure gave 0.792 g (73%) of 69 as a metallic blue solid,
mp 76.0-77.0 °C. IR (CCl4) 2950, 2920, 1754, and 1550 cm-1
;
1H NMR (500 MHz, CDCl3) δ 8.18 (d, J ) 9.5 Hz, 1 H), 7.87-
7.89 (m, 2 H), 7.39 (d, J ) 4.3 Hz, 1 H), 7.20 (app t, J ) 10.1
Hz, 1 H), 7.13 (app t, J ) 9.6 Hz, 1 H), and 2.45 (s, 3 H); 13C
NMR (125 MHz, CDCl3) δ 169.3, 140.4, 136.6 (2 C), 135.0,
132.2, 129.2, 125.7, 123.0, 121.9, 117.2, and 21.3; UV-vis
(hexane) λmax (ꢀ) 611 (380), 352 (7075), 316 (15 710), 296
(53 475), 279 (47 230), 261 (61 175), 231 (15 810), and 192
1-Acetoxy-5,6-dichloroazulene (75). Application of the
general procedure gave 0.054 g (19%) of 75 as a green solid,
mp 73.0-76.0 °C. IR (CCl4) 3020, 2920, 1770, 1570, and 1505
1
cm-1; H NMR (300 MHz, CDCl3) δ 8.37 (s, 1H), 7.89 (d, J )
(75) Rhodium(II) pivalate was prepared by reaction of rhodium(III)
chloride with 5.0 equiv of trimethylacetic acid and 2.0 equiv of
trimethylacetic acid sodium salt in EtOH (reflux, 3 h) according to the
procedure of: Legzdins, P.; Mitchell, R. W.; Rempel, G. L.; Ruddick,
J. D.; Wilkinson, G. J. Chem. Soc. 1970, 3322.
11.0 Hz, 1H), 7.82 (d, J ) 4.4 Hz, 1H), 7.27 (d, J ) 11.0 Hz,
1H), 7.22 (d, J ) 4.4 Hz, 1H), and 2.41 (s, 3H); 13C NMR (75
MHz, CDCl3) δ 168.6, 142.7, 140.0, 137.3, 132.5, 130.3, 128.1,
126.6, 125.5, 121.8, 116.4, and 21.1; UV-vis max (hexane) λmax
8662 J. Org. Chem., Vol. 69, No. 25, 2004