Synthesis and Thermolysis of Enediynyl Ethyl Ethers
J . Org. Chem., Vol. 62, No. 25, 1997 8847
ferred via cannula to the flask containing 15a at rt. After 5
min, the reaction mixture was heated to reflux for 2 h before
it was allowed to cool to 0 °C followed by sequential treatment
with 14 mL of a 6 N NaOH solution and 7.60 g of iodine (30.0
mmol) in 40 mL of Et2O. After 1 h of stirring at rt, a saturated
Na2S2O3 solution was introduced to reduce excess iodine. An
additional 60 mL of Et2O was added and the organic layer was
then separated. The aqueous layer was extracted with Et2O
(3 × 40 mL). The combined organic layers were dried over
MgSO4 and concentrated. The residue was purified by column
chromatography (neutral alumina/50% diethyl ether in hex-
anes) to furnish 1.28 g of 16a (52%, Z:E ) 1.9:1) as an orange
oil: IR (neat) 2207, 1029 cm-1; 1H (Z-isomer) 6.35 (1 H, q, J
) 1.4 Hz), 3.45 (2 H, s), 2.37 (6 H, s), 1.99 (3 H, d, J ) 1.6 Hz);
(E-isomer) 6.62 (1 H, q, J ) 1.2 Hz), 3.33 (2 H, s), 2.29 (6 H,
s), 1.97 (3 H, d, J ) 1.2 Hz); 13C (Z-isomer) 131.88, 90.64,
87.76, 82.95, 48.48, 44.10, 24.95; (E-isomer) 129.26, 86.76,
85.21, 84.62, 48.39, 44.15, 24.86; MS m/e 249 (M+), 122, 107.
Th er m olysis of En ed iyn yl Eth yl Eth er 14a . The fol-
lowing procedure is representative for the thermolysis of
enediynyl ethyl ethers. Enediynyl ethyl ether 14a (0.056 g,
0.227 mmol) was dissolved in 114 mL of anhydrous chloroben-
zene, and the resulting solution was degassed by three cycles
of freeze-thaw and then heated to reflux. After 3 h, the
solution was cooled to rt, and chlorobenzene was evaporated
in vacuo. The residue was purified by column chromatography
(silica gel/8%-50% of diethyl ether in hexanes) to afford 0.0194
g of the chromanol 21 (39%), 0.0041 g of the phenol 22 (8%),
0.0034 g of the bicyclic phenol 23 (7%), and 0.0063 g of the
Diels-Alder adduct 24 (14%).
Th e Diels-Ald er Ad d u ct 24: IR (neat) 1664, 800 cm-1
1H 6.75 (1 H, s), 6.65 (1 H, s), 5.76 (1 H, t, J ) 1.5 Hz), 2.9-
1.8 (17 H, m), 1.66-1.2 (8 H, m), 1.15 (3 H, t, J ) 7.5 Hz),
1.10 (3 H, t, J ) 7.3 Hz), 0.93 (3 H, t, J ) 7.3 Hz), 0.81 (3 H,
;
t, J ) 7 Hz); 13C
201.37, 169.57, 151.54, 139.95, 133.85,
128.42 (CH), 124.35 (CH), 118.13, 116.41 (CH), 79.76, 51.75,
42.37 (CH), 33.51, 33.20, 32.75, 32.05, 29.88, 29.21, 28.92,
24.61, 24.34, 22.74, 22.41, 16.06, 15.45 (CH3), 14.02 (CH3),
13.82 (CH3), 7.85 (CH3); MS m/e 408 (M+), 380, 218, 217, 203,
191, 190, 189, 175, 161; HRMS calcd for C28H40O2 408.3028,
found 408.3031.
Th er m olysis of En ed iyn yl Eth yl Eth er 14c. The same
procedure was repeated as described for the thermolysis of 14a
except that 0.133 g of 14c (0.535 mmol) was used to afford
0.034 g of the trimer 40 (34%) and 0.005 g of 41 (4%).
Th e Tr im er 40: viscous yellow oil; IR (neat) 1680, 1098
cm-1; 1H 6.81 (1 H, s), 6.79 (1 H, s), 6.74 (1 H, s), 6.63 (1 H,
s), 5.91 (1 H, t, J ) 1 Hz), 3.03-2.87 (2 H, m), 2.82-2.68 (3 H,
m), 2.6-2.48 (10 H, m), 2.45-2.35 (1 H, m), 2.35-2.27 (1 H,
m), 2.25-2.14 (1 H, m), 1.91 (1 H, dq, J ) 14.6 and 7.0 Hz),
1.62-1.46 (6 H, m), 1.45-1.28 (6 H, m), 1.18 (3 H, t, J ) 7.5
Hz), 1.15 (3 H, t, J ) 7.5 Hz), 1.11 (3 H, t, J ) 7.3 Hz), 0.95 (3
H, t, J ) 7.3 Hz), 0.93 (3 H, t, J ) 7.1 Hz), 0.85 (3 H, t, J ) 7.1
Hz); 13C
196.19, 169.25, 151.11, 151.04, 139.96, 139.85,
134.07, 133.94, 128.34 (CH), 128.31 (CH), 123.85 (CH), 118.81,
118.09, 117.07 (CH), 115.99 (CH), 80.83, 80.25, 40.64 (CH),
33.54, 33.24, 33.16, 32.07, 32.05, 29.99, 29.50, 28.89, 24.67 (2
carbons), 24.65, 22.74, 22.72, 22.43, 21.43, 15.48 (2 methyls),
14.04 (CH3), 13.99 (CH3), 13.81 (CH3), 8.05 (CH3); MS m/e 570
(M+), 541, 483, 468, 423, 392, 380; HRMS calcd for C39H54O3
570.4073, found 570.4081.
1-(3-Bu ten yl)-5-eth oxy-2-eth yl-4-(m eth oxym eth yl)ben -
zen e (41): 1H 7.13 (1 H, s), 6.66 (1 H, s), 5.89 (1 H, ddt, J
) 17.1, 10.4, and 6.5 Hz), 5.07 (1 H, dq, J ) 17.2 and 1.7 Hz),
4.99 (1 H, ddt, J ) 10.1, 1.8, and 1 Hz), 4.47 (2 H, s), 4.03 (2
H, q, J ) 7.0 Hz), 3.43 (3 H, s), 2.68 (2 H, t, J ) 7.7 Hz), 2.59
(2 H, q, J ) 7.5 Hz), 2.32 (2 H, q, J ) 7.6 Hz), 1.40 (3 H, t, J
) 6.9 Hz), 1.19 (3 H, t, J ) 7.5 Hz); 13C 154.59, 139.69,
138.27, 133.64, 129.32, 124.33, 114.78, 112.48, 69.39, 63.80,
58.36, 35.36, 32.28, 24.83, 15.73, 14.98; MS m/e 248 (M+), 233,
219, 217, 207, 175, 147.
7-Bu tyl-3,4-d ih yd r o-6-eth yl-2H-1-ben zop yr a n (21): yel-
low oil; IR (neat) 1625, 1574, 1498, 1102 cm-1; 1H 6.82 (1 H,
s), 6.60 (1 H, s), 4.15 (2 H, t, J ) 5.1 Hz), 2.74 (2 H, t, J ) 6.4
Hz), 2.55 (2 H, q, J ) 7.5 Hz), 2.52 (2 H, t, J ) 7.8 Hz), 1.98
(2 H, m), 1.63-1.48 (2 H, m), 1.39 (2 H, sextet, J ) 7.2 Hz),
1.18 (3 H, t, J ) 7.5 Hz), 0.93 (3 H, t, J ) 7.2 Hz); 13
C
152.67,
139.62, 133.61, 129.39, 119.39, 116.77, 66.36, 33.27, 32.00,
24.68, 24.51, 22.76, 22.66, 15.62, 14.01; MS m/e 218 (M+), 203,
176, 175, 161; HRMS calcd for C15H22O 218.1671, found
218.1676.
1
5-Bu tyl-4-eth yl-2-(2-p r op en yl)p h en ol (22): H 6.87 (1
H, s), 6.62 (1 H, s), 6.02 (1 H, ddt, J ) 17.0, 10.1, and 6.4 Hz),
5.17 (1 H, dq, J ) 17 and 1.7 Hz), 5.14 (1 H, dq, J ) 10 and
1.6 Hz), 4.77 (1 H, br OH), 3.37 (2 H, dt, J ) 6.4 and 1 Hz),
2.55 (2 H, q, J ) 7.5 Hz), 2.53 (2 H, t, J ) 7.8 Hz), 1.6-1.48
(2 H, m), 1.39 (2 H, sextet, J ) 7.2 Hz), 1.17 (3 H, t, J ) 7.6
Hz), 0.93 (3 H, t, J ) 7.1 Hz); 13C 152.00, 140.25, 136.91,
134.33, 130.32, 122.40, 116.42, 116.28, 35.13, 33.35, 32.07,
24.82, 22.87, 15.76, 14.10; MS m/e 218 (M+), 203, 189, 175,
161, 147.
Ack n ow led gm en t. The financial support of the
National Science Foundation (CHE-9618676) is grate-
fully acknowledged. We thank Mr. Chongsheng Shi for
preparing compounds 15a , 15b, and 16b.
Su p p or tin g In for m a tion Ava ila ble: Experimental pro-
cedures and spectroscopic data for 13c-e, 14b-e, 15b, 16b,
17a ,b, 32-36, 48, 51, 54, 58, and 59 and 1H and 13C NMR
spectra of 13a ,c-e, 14a -e, 15a ,b, 16a ,b, 17a ,b, 21-24, 32-
34, 40, 41, 48, 51, 54, 58, and 59 (61 pages). This material is
contained in libraries on microfiche, immediately follows this
article in the microfilm version of the journal, and can be
ordered from the ACS; see any current masthead page for
ordering information.
6-Bu tyl-2,3-d ih yd r o-7-eth yl-1H-in d en -4-ol (23): 1H
6.48 (1 H, s), 2.89 (2 H, t, J ) 7.5 Hz), 2.83 (2 H, t, J ) 7.5
Hz), 2.55 (2 H, q, J ) 7.7 Hz), 2.54 (2 H, t, J ) 7.7 Hz), 2.10
(2 H, quintet, J ) 7.5 Hz), 1.6-1.5 (2 H, m), 1.45-1.3 (2 H,
m), 1.09 (3 H, t, J ) 7.5 Hz), 0.94 (3 H, t, J ) 7.1 Hz); 13C
149.53, 145.10, 140.26, 130.32, 126.51, 113.79, 34.05, 32.05,
31.84, 28.76, 24.90, 22.86, 22.59, 14.81, 14.04; MS m/e 218
(M+), 203, 189, 175, 161, 147.
J O971391B