3430
M. Venugopal et al. / Tetrahedron: Asymmetry 15 (2004) 3427–3431
+
to room temperature and stirred for 12h during which
time the reaction was completed as shown by TLC.
The reaction mixture was then diluted with CH Cl
3460 (–OH), 2361, 1337, 667; MS m/e (%) 449 (M
100) 368 (80), 290 (30), 263 (82), 248 (28), 184 (75),
145 (40), 124 (45), 77 (10); HRMS calcd for
C H Br O 447.9657. Found 447.9673.
2
2
(
NaHSO solution to remove excess bromine, followed
25mL) and the organic layer washed with aqueous
2
0
18
2
2
3
0 0 0
3.7. Resolution of 7,7 -dihydroxy-4,4 -dibromo-2,2 -cyclo-
by dilute HCl. It was then dried over magnesium sulfate
and removing solvent to get the product 6 as yellow
0 0
hexyl-1,1 -biindane (CHEXDBSPINOL) and 7,7 -bis-(L-
menthyloxy-carbonyloxy)-4,4 -dibromo-2,2 -cyclohexyl-
1
0
0
solid (3.98g). Mp 167–168ꢁC. H NMR: (CDCl3 d)
0
2
.024–2.062 (m, 2H), 2.558 (dd, 2H, J = 13.8Hz,
1,1 -biindane 8a and 8b
J = 8Hz), 2.66–2.69 (m, 2H), 2.65 (dd, 2H, J = 16.Hz,
J = 5.2Hz), 6.603 (dd, 2H, J = 8.8Hz, J = 3.2Hz),
A racemic mixture of CHEXDBSPINOL (1.575g,
3.5mmol) was taken in aqueous solution of sodium
hydroxide (0.6g in 10mL of H O, 15mmol) and to this
1
3
6
.776 (d, 2H, J = 3.2Hz), 7.36 (d, 2H, J = 8.8Hz).
NMR: (CDCl3 d) 25.34, 34.92, 35.53, 52.81, 55.13,
11.14, 114.93, 121.21, 142.25, 159.55, 212.74. IR (KBr
C
2
1
added a solution of chloroform (10mL) containing
0.50g (1.56mmol) of tetrabutylammonium bromide
after which (ꢀ)-menthyl chloroformate 3.47g
(11.1mmol, 70% w/w) was added under rapid stirring.
After the solution had been stirred at room temperature
for 10min, the two phases were separated. The aqueous
phase was extracted two times with CH Cl . The com-
ꢀ
1
pellet, cm ): 602, 1240, 1697 (C@O); MS m/e (%):
+
4
(
94 (M 9), 414 (100), 336 (95), 278 (15), 198 (85), 161
20), 137 (80), 91 (10); HRMS calcd C H Br O
3
2
2
24
2
4
94.0092. Found 494.0116.
0 0 0 0
.5. 7,7 -Dimethoxy-4,4 -dibromo-2,2 -cyclohexyl-1,1 -
biindane 7
3
2
2
bined organic phase was dried over MgSO and evapo-
4
ration of the solvent in a rotary evaporator afforded a
crude product, which was passed through a column
packed in hexane to collect the two diastereomers. The
mixture was then dissolved in hot hexane (30mL) and
allowed to cool to room temperature slowly wherein
one of the diastereomers crystallized out. The mother
liquid was decanted and left out at room temperature
overnight to afford a second crop of crystals. The com-
bined white crystals were washed with hexane (2 · 2mL)
and dried in vacuo (1.15, 81% yield). (S)-(+)-menthyl
Compound 6 (3.98g) was stirred with polyphosphoric
acid (30g) at 105ꢁC for 6h. The mixture was poured
into water (more dilution with 300mL of water was
needed in order to prevent the formation of emulsion
during extraction) and extracted with methylene chlo-
ride (2 · 100mL). The organic layer was washed with
water, dried, and concentrated. The crude product was
purified by column chromatography with EA/Hex
(
2:98) as eluent to give product 7 (2.83g, 67% yield for
1
two steps). Mp 168–170.4ꢁC. H NMR: (CDCl3 d)
.42–1.46 (m, 2H), 1.52–1.54 (m, 4H), 2.715 (dd, 2H,
J = 15.8Hz, J = 6.6Hz), 2.87–2.90 (m, 2H), 3.068 (dd,
H, J = 15.8Hz, J = 7.8Hz), 3.44 (s, 6H), 6.49
CHEXDBSPINOL. Mp 142.8–143.7ꢁC; [a] = +33.1
D
1
1
(c 2, CHCl ). H NMR: (CDCl d) 0.64 (d, 6H,
3
3
J = 7.2Hz), 0.83–1.0 (m, 14H), 1.28–1.69 (m, 20H),
1.84–1.88 (m, 2H), 2.74–2.82 (m, 4H), 3.09–3.12 (m,
2H), 4.31–4.37 (m, 2H), 6.83 (d, 2H, J = 8.4Hz), 7.30
2
1
3
(
d, 2H, J = 8Hz), 7.23 (d, 2H, J = 8Hz). C NMR:
1
3
(
CDCl3 d) 17.92, 26.21, 39.50, 41.98, 55.58, 111.15,
(d, 2H, J = 8.8Hz). C NMR: (CDCl d) 16.22, 17.67,
3
1
11.54, 130.35, 136.79, 145.96, 156.32. IR (KBr pellet,
20.75, 21.95, 23.21, 26.12, 26.24, 31.22, 31.58, 34.03,
40.17, 42.91, 46.75, 63.75, 79.15, 116.85, 122.59,
131.22, 138.94, 146.42, 147.26, 152.27. IR (KBr pellet,
ꢀ
1
+
cm ): 669, 2361; MS m/e (%) 476 (M 60), 399 (80),
55 (10), 318 (25), 276 (80), 239 (15), 198 (58), 159
34), 138 (33), 101 (12); HRMS calcd for C H Br O
3
(
ꢀ
1
cm ): 1755, 1258, 1230.
2
2
22
2
2
4
75.9986. Found 475.9971.
The mother liquid was evaporated to dryness and the
residue passed through a short column of silica gel
packed in hexane to afford the other diastereomer of
0 0 0 0
.6. rac-7,7 -Dihydroxy-4,4 -dibromo-2,2 -cyclohexyl-1,1 -
biindane 3
3
(
R)-(ꢀ)-menthyl CHEXDBSPINOL (1.18g, 83% yield).
1
Compound 7 (2.38g, 5mmol) was dissolved in dry meth-
ylene chloride (25mL) in a flame-dried flask under an
argon atmosphere. The solution was then cooled down
to ꢀ75ꢁC and treated with 1M BBr CH Cl solution
Mp 61–62.5ꢁC. H NMR: (CDCl d) 0.75 (d, 6H,
3
J = 6.8Hz), 0.84–0.91 (m, 12H), 0.91–1.00 (m, 2H),
1.28–1.64 (m, 18H), 1.70–1.73 (m, 2H), 1.84–1.88 (m,
2H), 2.74–2.82 (m, 4H), 3.09–3.14 (m, 2H), 4.31–4.37
(m, 2H), 6.82 (d, 2H, J = 8.4Hz), 7.29 (d, 2H,
3
2
2
(
11.5mL, 2.3equiv). Upon completing the addition,
1
3
the reaction mixture was allowed to warm up to room
temperature and stirred overnight. The reaction mixture
was diluted with CH Cl (25mL) and washed with water
J = 8.8Hz). C NMR: (CDCl d) 16.22, 17.66, 20.75,
3
21.96, 23.20, 26.12, 26.22, 31.28, 34.03, 39.19, 40.17,
42.91, 46.75, 63.74, 79.16, 116.86, 122.60, 131.22,
2
2
ꢀ1
until the washings were neutral. The organic layer was
dried and concentrated and the crude product obtained,
crystallized from hexane to yield compound 3 (2.02g,
138.94, 146.42, 147.26, 152.28. IR (KBr pellet, cm ):
1758, 1734, 1260, 1230.
1
9
1
4
0% yield). Mp 187–192.4ꢁC. H NMR: (CDCl3 d)
.53–1.55 (m, 8H), 1.60–1.68 (m, 2H), 2.75–2.85 (m,
H), 2.95–3.03 (m, 2H), 4.47 (b, 2H), 6.47 (d, 2H,
3.8. Hydrolysis of menthyl esters 8a and 8b
To a solution of KOH (8.7g, 155mmol) in 10% degassed
water/ethanol (10mL) was added 1.06g of 8a (1.3mmol)
and the mixture refluxed for 1h after which time no 7a
remained (TLC). The reaction mixture was then cooled
1
3
J = 8Hz), 7.21 (d, 2H, J = 8Hz). C NMR: (CDCl d)
3
1
1
6.10, 22.99, 38.50, 42.68, 62.80, 111.36, 116.94,
32.20, 132.25, 145.43, 152.52. IR (KBr pellet, cm ):
ꢀ
1