Notes
4-Ch lor o-2-m eth yl-2-bu ten -1-a l, Neop en tyl Aceta l (7). To
J . Org. Chem., Vol. 64, No. 21, 1999 8053
d, J ) 7.7 Hz), 4.76 (2H, s). 5.79 (2H, t, J ) 7.7 Hz); 13C NMR
a stirred solution of 4-chloro-2-methyl-2-buten-1-al (5) (15.8 g,
0.134 mol) in benzene (100 mL) were added neopentyl glycol
(16.7 g, 0.161 mol) and p-TsOH (190.2 mg, 6.7 mol). The mixture
was heated to reflux for 3 h and cooled to room temperature.
The mixture was diluted with ether and washed with H2O. The
organic phase was dried over anhydrous Na2SO4, filtered, and
concentrated under reduced pressure. The crude product was
purified by flash chromatography over silica gel to give acetal 7
(20.6 g, 0.100 mol) in 75% yield. Data for 7: 1H NMR δ 0.73
(3H, s), 1.20 (3H, s), 1.79 (3H, s), 3.47 (2H, A of ABq, J ) 11.0
Hz), 3.62 (2H, B of ABq, J ) 11.0 Hz), 4.09 (2H, d, J ) 7.9 Hz),
4.72 (1H, s), 5.85 (1H, t, J ) 7.2 Hz); 13C NMR 11.3, 21.7, 22.8,
30.1, 39.4, 77.1, 103.4, 124.2, 138.1 ppm; IR (neat) 1467, 1392
cm-1; MS (EI, 70 eV) 205 [(M + 2)+], 203 (M+); HRMS (CI, H+)
calcd for C10H18O2Cl 205.0995, found 205.0989.
Bis(3-for m yl-3-m eth yl-2-p r op en yl) Su lfid e, Din eop en tyl
Dia ceta l (6d ). The above acetal 7 (20.6 g, 0.100 mmol) was
dissolved in MeOH (100 mL), and Na2S‚9H2O (12.0 g, 50 mmol)
was added. The resulting mixture was stirred at room temper-
ature for 10 h, and most of solvent was removed under reduced
pressure. The crude oil was dissolved in ether and washed with
H2O, dried over anhydrous Na2SO4, filtered, and concentrated
under reduced pressure. The crude product was purified by flash
chromatography over silica gel to give bis(3-formyl-3-methyl-2-
propenyl) sulfide, dineopentyl diacetal (6d ) (17.6 g, 47.5 mmol)
in 95% yield. Data for 6d : 1H NMR δ 0.68 (6H, s), 1.15 (6H, s),
1.68 (6H, s), 3.09 (4H, d, J ) 7.5 Hz), 3.43 (4H, A of ABq, J )
11.1 Hz), 3.58 (4H, B of ABq, J ) 11.1 Hz), 4.66 (2H, s), 5.63
(2H, t, J ) 7.5 Hz); 13C NMR 11.2, 21.8, 22.9, 28.0, 30.1, 77.1,
104.4, 125.4, 135.8 ppm; IR (neat) 1463, 1395, 1304 cm-1; HRMS
(CI, H+) calcd for C20H35SO4 371.2256, found 371.2264.
Bis(11-b en zen esu lfon yl-11,12-d ih yd r or et in yl) Su lfon e
(8c). The mixture of UHP (urea-hydrogen peroxide)10 (6.88 g,
73.1 mmol) and phthalic anhydride (5.41 g, 36.5 mmol) in CH3-
CN (70 mL) was stirred vigorously at room temperature for 2 h
to give a clear solution. This solution was added slowly for a 3
h period through a dropping funnel to a stirred solution of bis-
(11-benzenesulfonyl-11,12-dihydroretinyl) sulfide (6c) (10.8 g,
12.2 mmol) in CH3CN (30 mL), which was placed in an ice bath.
The reaction mixture was stirred at 0 °C for 1 h after addition.
The mixture was then diluted with ether, washed with 1 M HCl,
dried over anhydrous Na2SO4, filtered, and concentrated under
reduced pressure to give a white solid. This crude solid was
dissolved in CHCl3, and the undissolved solid was filtered. The
filtrate was concentrated under reduced pressure. The crude
product was purified by flash chromatography over silica gel to
give bis(11-benzenesulfonyl-11,12-dihydroretinyl) sulfone (8c)
(8.06 g, 8.77 mmol) in 72% yield. At least two stereoisomers were
confirmed by 1H NMR spectroscopy, one of which was crystal-
lized during chromatographic separation. The data of the pure
isomer 8c: 1H NMR δ 0.91 (6H, s), 0.96 (6H, s), 1.22 (6H, s),
1.37-1.49 (4H, m), 1.55-1.67 (4H, m), 1.62 (6H, s), 1.65 (6H,
s), 1.99 (4H, t, J ) 5.9 Hz), 2.47 (2H, dd, J ) 13.0, 11.3 Hz),
3.05 (2H, d, J ) 13.0 Hz), 3.47 (4H, d, J ) 4.5 Hz), 4.06 (2H, dt,
J d ) 3.1, J t ) 10.8 Hz), 5.07 (2H, d, J ) 10.5 Hz), 5.24 (2H, t, J
) 7.4 Hz), 5.92 (2H, A of ABq, J ) 16.4 Hz), 5.97 (2H, B of ABq,
J ) 16.4 Hz), 7.40-7.55 (4H, m), 7.55-7.70 (2H, m), 7.75-7.90
(4H, m); 13C NMR 12.3, 17.0, 19.1, 21.5, 28.7, 28.8, 32.8, 34.0,
37.3, 39.3, 51.0, 63.4, 114.1, 121.0, 128.8, 129.0, 129.3, 129.7,
133.7, 135.5, 137.1, 137.2, 140.8, 142.8 ppm. IR (KBr) 1630, 1465,
1397 cm-1; HRMS (FAB+) calcd for C52H71S3O6 - (C6H6SO2)
745.4324, found 745.4346.
12.3, 21.8, 22.9, 30.1, 51.3, 77.1, 103.1, 114.5, 142.3 ppm; IR
(KBr) 1686, 1466, 1391 cm-1; HRMS (CI, H+) calcd for C20H35
SO6 403.2154, found 403.2147.
-
11,20-Diben zen esu lfon yl-11,12,19,20-tetr a h yd r o-â-ca r o-
ten e (9c). To a stirred solution of bis(11-benzenesulfonyl-11,-
12-dihydroretinyl) sulfone (8c) (1.51 g, 1.64 mmol) in t-BuOH
(20 mL) and CCl4 (20 mL) was added pulverized KOH (1.85 g,
32.9 mmol). The mixture was stirred vigorously at room tem-
perature for 5 h under Ar atmosphere, and then most of solvent
was removed under reduced pressure. The crude product was
dissolved in CH2Cl2 and washed with 1 M HCl. The organic
phase was dried over anhydrous Na2SO4, filtered, and concen-
trated. The crude product was purified by flash chromatography
over silica gel to give 11,20-dibenzenesulfonyl-11,12,19,20-
tetrahydro-â-carotene (9c) (932 mg, 1.13 mmol) in 69% yield.
Data for 9c: 1H NMR δ 0.93 (6H, s), 0.96 (6H, s), 1.20 (6H, s),
1.37-1.50 (4H, m), 1.53-1.65 (4H, m), 1.63 (6H, s), 1.68 (6H,
s), 1.98 (4H, br s), 2.45 (2H, dd, J ) 13.0, 11.6 Hz), 3.04 (2H, d,
J ) 14.2 Hz), 4.05 (2H, dt, J d ) 3.0, J t ) 10.9 Hz), 5.82-5.98
(2H, m), 5.92 (4H, s), 6.15-6.28 (2H, m), 7.40-7.54 (4H, m),
7.56-7.67 (2H, m), 7.76-7.90 (4H, m); 13C NMR 12.3, 12.3, 16.7,
16.8, 19.1, 21.5, 28.8, 32.8, 34.1, 39.4, 64.2, 121.4, 127.8, 128.1,
128.7, 129.0, 129.3, 129.5, 132.9, 133.5, 136.0, 137.2, 137.6, 142.1
ppm; IR (CH2Cl2) 1723, 1603, 1465, 1376 cm-1; HRMS (FAB+)
calcd for C52H69S2O4 - (C6H6SO2) 679.4541, found 679.4549.
2,7-Dim eth yl-2,4,6-octa tr ien e-1,8-d ia l, Din eop en tyl Di-
a ceta l (9d ). The bis-allylic sulfone 8d (3.00 g, 7.45 mmol) in
t-BuOH (30 mL) and CCl4 (30 mL) was treated with pulverized
KOH (4.18 g, 74.5 mmol) to give the Ramberg-Ba¨cklund
reaction product 9d (2.04 g, 6.07 mmol) in 82% yield according
to the above procedure (see the preparation of 9c). Data for 9d :
1H NMR δ 0.73 (6H, s), 1.22 (6H, s), 1.85 (6H, s), 3.51 (4H, A of
ABq, J ) 9.8 Hz), 3.66 (4H, B of ABq, J ) 9.8 Hz), 4.75 (2H, s),
6.30 (2H, d, J ) 8.1 Hz), 6.50 (2H, dd, J ) 7.7, 2.8 Hz); 13C NMR
d 11.7, 21.4, 22.6, 29.8, 76.8, 103.9, 127.6, 129.1, 134.2 ppm; IR
(KBr) 1471, 1380 cm-1; HRMS (CI, H+) calcd for C20H32O4
337.2379, found 337.2383.
â-Ca r oten e (1a ). Na (674 mg, 29.3 mmol) was added to a
stirred solution of 11,20-bis(benzenesulfonyl)-11,12,19,20-tet-
rahydro-â-carotene (9c) (602 mg, 0.73 mmol) in EtOH (20 mL)
under Ar atmosphere. The reaction mixture was heated to reflux
for 10 h and cooled to room temperature. Most of the solvent
was removed under reduced pressure, and the resulting crude
oil was dissolved in toluene, washed with 1 M HCl, dried over
anhydrous Na2SO4, filtered, and concentrated under reduced
pressure. The crude product was purified by flash chromatog-
raphy over silica gel to give exclusively trans-â-carotene (1a ) (295
mg, 0.55 mmol) in 75% yield. The 1H NMR spectrum of the
synthetic sample was identical with that of the authentic sample.
2,7-Dim eth yl-2,4,6-octa tr ien e-1,8-d ia l (10). The triene 9d
(267 mg, 0.82 mmol) was dissolved in THF (12 mL), and 1 M
HCl (15 mL) was added. The resulting mixture was stirred at
room temperature for 2 h and extracted with ether. The
combined ether extract was dried over anhydrous Na2SO4,
filtered, and concentrated under reduced pressure. The crude
product was purified by flash chromatography over silica gel to
give 2,7-dimethyl-2,4,6-octatriene-1,8-dial (10) (127 mg, 0.77
mmol) in 94% yield. Data for 10: 1H NMR δ 1.96 (6H, s), 7.00-
7.15 (4H, m), 9.56 (2H, s); 13C NMR 9.7, 134.3, 140.8, 146.1, 194.4
ppm; IR (KBr) 1662, 1614, 1414 cm-1; HRMS (CI, H+) calcd for
C
10H13O2 165.0916, found 165.0916.
Bis(3-for m yl-3-m eth yl-2-p r op en yl) Su lfon e, Din eop en tyl
Dia ceta l (8d ). Bis(3-formyl-3-methyl-2-propenyl) sulfide, dineo-
pentyl diacetal (6d ) (3.39 g, 9.15 mmol) in CH3CN (20 mL) was
oxidized by perphthalic acid, which was prepared by UHP
(urea-hydrogen peroxide)10 (5.17 g, 54.9 mmol) and phthalic
anhydride (4.07 g, 27.5 mmol) in CH3CN (30 mL), to give bis-
allylic sulfone 8d (2.94 g, 7.3 mmol) in 80% yield according to
the above procedure (see the preparation of 8c). Data for 8d :
1H NMR δ 0.75 (6H, s), 1.20 (6H, s), 1.79 (6H, s), 3.50 (4H, A of
ABq, J ) 10.9 Hz), 3.66 (4H, B of ABq, J ) 10.9 Hz), 3.72 (4H,
Ack n ow led gm en t. This work was supported by the
RRC program of MOST and KOSEF.
Su p p or tin g In for m a tion Ava ila ble: 1H NMR spectra of
1a , 5, 6a -d , 7, 8c,d , 9c,d , and 10. This material is available
J O990987R