FULL PAPERS
B. M. Choudary et al.
the metal after the first cycle was determined by AAS General Procedure for the Synthesis of (R,R)-1
and it was found to be 33% in silica-(R,R)-1 and was neg-
(
a) Synthesis of disodium 3-tert-butyl-salicylaldehyde 5-sul-
[14]
ligble in LDH-(R,R)-1 and resin-(R,R)-1. The insignifi-
cant leaching of the Mn into solution is attributed to
the strong ionic bond between the complex and support.
fonate (3): 2-tert-Butylsalicylaldehyde (1; 33.7 mmol) was
charged in a 100-mL round-bottomed flask containing aniline
(
33.7 mmol) in dry ethanol (40 mL) and the mixture stirred
The homogeneous catalyst (R,R)-1 produces chiral at reflux temperature for 20 h. Thereafter, the reaction mixture
epoxides in quantitative yields and the ees are 89% for was allowed to cool to 08C for 1 h. Then, the solvent was re-
6
-cyanochromene, 18% for trans-stilbene and 25% for moved under reduced pressure to obtain protected aldehyde
2
as a brownish yellow oil; yield: 8.5 g (>99%).
styrene. Immobilisation of the catalyst (R,R)-1 on silica,
LDH and resin results in similar yields but the ee values
are higher than for the homogeneous counterparts. This
increase in ee values is due to the spatial constraints im-
This compound was charged in a 100-mL round-bottomed
flask containing five times its weight of concentrated sulfuric
acid, which gave upon stirring a clear orange solution. This sol-
ution was heated for 2 h at 105–1108C. Then the reaction mix-
ture was allowed to cool at 08C for 30 min, then ice-pieces were
added to induce crystallisation of N-phenyl-3-tert-butylsalicy-
laldimine-5-sulfonic acid, which was then filtered, washed
with small quantities of ice-water to remove excess sulfuric
acid and then dried under vacuum to afford the sulfonated al-
dehyde product as yellow powder; yield: 8.0 g (73%).
[
12]
posed by the immobilisation.
Conclusion
The deprotection was executed by a simple base hydrolysis
by dissolving the compound in boiling distilled water
to immobilise a chiral Mn(salen) complex on silica, (200 mL), and then anhydrous sodium carbonate was added
LDH, and resin for AE of unfunctionalised olefins. We in small portions until the evolution of carbon dioxide ceased.
have successfully prepared LDH-(R,R)-1 and resin- This mixture was then heated to boiling and nitrogen gas was
passed continuously to remove aniline. This process was re-
In summary, an inorganic ÀSO Na group has been used
3
(
R,R)-1 catalysts to overcome the leaching problem as-
peated several times until the water vapour showed no alkaline
response to pH paper while maintaining the volume of the wa-
ter constant by adding more water if and when needed. Then,
the aqueous solution was evaporated to dryness under reduced
pressure, and the residue washed with chloroform (300 mL) to
remove organic impurities. Then the crude compound was re-
dissolved in a small amount of boiling water and precipitated
with THF as yellow powder. This bright yellow coloured diso-
dium 3-tert-butyl-salicylaldehyde-5-sulfonate (3) (7.5 g; yield:
sociated with silica-(R,R)-1. We found that resin-
R,R)-1 is an efficient catalyst and can be reused for 5 cy-
cles with consistent ees.
(
Experimental Section
All chemicals were purchased from Aldrich and were used as
received. 2-tert-Butylsalicylaldehyde was prepared by follow-
ing a reported literature procedure starting from 2-tert-butyl-
97%) was dried under vacuum and used without further purifi-
1
cation. H NMR (400 MHz, D O): d¼9.95 (s, 1H), 7.66 (d, 1H,
2
J¼2.3 Hz), 7.55 (d, 1H, J¼2.3 Hz), 1.22 (s, 9H); ES-MS:
[13]
À
phenol. All solvents used were analytical grade and used
as received from Merck India Pvt. Ltd. Commercial column
chromatography grade silica gel (60–120 mesh) was first cal-
cined at 2008C for 6 h prior to use. No high purity nitrogen
was used and all reactions were conducted at À208C in aceto-
(negative): m/z¼257 [(MÀ2 Na)þH] ; anal. calcd. for
C H SO Na : C 43.7, H 3.9, S 10; found: C 43.5, H 3.85, S 9.1.
1
1
12
5
2
(b) Synthesis of chiral ligand 4: The compound 3 (2.6 mmol)
was charged in a round-bottomed flask containing methanol
(50 mL). To the reaction mixture (1R,2R)-(þ)-diaminocyclo-
hexane l-tartarate (1.6 mmol) and triethylamine (5 mL) were
added and the mixture stirred at room temperature for 17 h.
Then, the reaction mixture was filtered to remove the triethyl-
amine salt of tartaric acid. Then the filtrate was concentrated
under reduced pressure and washed with chloroform to obtain
1
nitrile. The H NMR spectra of samples were recorded on Var-
ian-Unity 400 MHz, and Bruker-Avance-300 MHz spectrome-
ters using TMS as an internal standard in CDCl . IR spectra
3
were recorded on a Perkin Elmer instrument. The positive
and negative ion electrospray mass spectra (ES-MS) were re-
corded on a Quattro LC triple quadrupole mass spectrometer
1
the bright yellow-coloured product 4; yield: 550 mg (81%). H
(
(
Micromass, Manchester, UK). X-ray powder diffraction
PXRD) data were collected on a Siemens/D-5000 diffractom-
NMR (300 MHz, D O): d¼8.49 (s, 1H), 8.58 (s, 1H), 7.86 (d,
2
1H, J¼2.1 Hz), 7.64 (d, 1H, J¼2.1 Hz), 7.78 (d, 1H, J¼
3.4 Hz), 7.75 (d, 1H, J¼3.4 Hz), 2.9–3.1 (m,1H), 2.75–2.91
eter using Cu-Ka radiation (l¼1.5405 ). High performance
liquid chromatography (HPLC) was performed using an Agi-
lent-1100 series liquid chromatograph equipped with a single
pump and UV detector (fixed at 216 nm) using a CHIRA-
CEL-OD-H capillary column with 2-propanol/hexane as elut-
ing agent. For these studies, only crude reaction products were
used, as the reactions were quantitative in all substrates. Opti-
cal rotations were obtained on an automated JASCO P-1020
1
3
(m,1H), 1.1–2.1 (m, 8H), 1.45 (s, 9H), 1.41 (s, 9H); C NMR
(300 MHz, D O, dioxane as internal standard): d¼169.23,
2
165.44, 167.11, 167.01, 140.74, 140.47, 134.04, 133.75, 130.09,
129.09, 118.89, 118.48, 70.75, 70.26, 68.21, 36.20, 33.34, 33.34,
À1
30.45, 25.42; IR (KBr): n¼1626, 1540,1118, 1039 cm ; ES-
2
5
MS (negative): m/z ¼ 651, 593, 353, 296; [a] : À165.2 (c 0.01,
D
H O); anal. calcd. for C H N O Na S ·2 H O: C 46.79, H
2
28 34
2
8
4
2
2
Polarimeter, and the values were reported in absolute rota-
5.29, N 3.89; found: C 46.62, H 5.13, N 3.80.
temperature
tions: [a]D
[concentration c in g/100 mL of solvent]. El-
(c) Synthesis of (R,R)-1: The compound 4 (0.450 g) was
emental analysis was carried out on an ELEMENTAR
VARIO-EL CHNS analyzer.
charged in a 100-mL round-bottomed flask containing metha-
nol (15 mL) and Mn(acac) (0.230 g) and the mixture stirred at
3
496
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ꢁ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2006, 348, 493 – 498