Catalytic Asymmetric Dihydroxylation of Aliphatic Olefins with Reusable Resin-Osmium Tetroxide

Article abstract of DOI:10.1002/adsc.200303114

Asymmetric dihydroxylation of aliphatic olefins to chiral diols with good yields and ees by a heterogeneous Resin-OsO₄ catalyst using ferricyanide as cooxidant is disclosed for the first time. The catalyst was recovered quantitatively by simple filtration and reused for several times without significant loss of activity.

Full text of DOI:10.1002/adsc.200303114

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Catalytic Asymmetric Dihydroxylation of Aliphatic Olefins with
Reusable Resin-Osmium Tetroxide
Boyapati M. Choudary,* Karangula Jyothi, Sateesh Madhi, M. Lakshmi Kantam
Indian Institute of Chemical Technology, Hyderabad À 500 007, India
Fax: ( ‡ 91)-40-27160921; e-mail: choudary@iict.res.in, bmchoudary@yahoo.com
Received: June 25, 2003; Accepted: September 5, 2003
tions catalyzed by OsO4 could be applied tothe synthesis
Abstract: Asymmetric dihydroxylation of aliphatic
olefins to chiral diols with good yields and ees by a
heterogeneous Resin-OsO4 catalyst using ferricya-
nide as cooxidant is disclosed for the first time. The
catalyst was recovered quantitatively by simple
filtration and reused for several times without
significant loss of activity.
of pharmaceuticals, fine chemicals, etc., the high cost,
and possible contamination of toxic osmium in the
product restricts its use in industry. To overcome the
above problems, heterogenization of the ligands on a
polymer or silica gel support and eventual complexation
with osmium, a possible solution to address this issue
attempted by several groups, failed to recover and reuse
the osmium since the coordination of anchored ligands
and osmium tetroxide is in equilibrium.[4 6] When
microencapsulated (MC) polymer-supported osmium
catalysts are employed in AD of aliphatic olefins using
NMO as cooxidant,[7] moderate ees are obtained. On the
other hand, a lower yield is reported in the AD of 5-
decene despite slow addition of ferricyanide.[8] There-
fore, we felt that there is a strong need to develop a
Keywords: aliphatic olefins; asymmetric dihydroxy-
lation; chiral diols; immobilization; supported cata-
lysts; resin-osmium tetroxide
Osmium-catalyzed asymmetric dihydroxylation (AD) is robust heterogeneous catalytic system to withstand the
an efficient method for the transformation of unfunc- vagaries of the reaction conditions induced by various
tionalized olefins to chiral diols.[1] Aliphatic olefins, cooxidants for the AD of aliphatic olefins. Recently, we
especially terminal ones provide the most useful chiral designed and developed an ion-exchange technique for
diols in AD reaction.[2] Various cooxidants such as N- a recoverable and reusable osmium catalyst immobi-
methylmorpholine N-oxide (NMO), potassium ferri- lized on layered double hydroxides (LDH-OsO4) and
cyanide [K3Fe(CN)6] and very recently molecular oxy- quaternary ammonium salts covalently bound to resin
gen[3] are effectively used to facilitate the Os(VI)/ (Resin-OsO4) (Scheme 1) for the AD of aromatic
Os(VIII) catalytic cycle that allows the use of catalytic olefins using various cooxidants.[9] In view of the
amounts of osmium tetroxide in the dihydroxylation importance of aliphatic terminal chiral diols and the
reaction. K3Fe(CN)6 is found to be an efficient oxidant necessity to have a recyclable heterogenized OsO4
to afford high yields and ees in the homogeneous AD catalyst, we undertook studies on the AD of aliphatic
reactions of aliphatic olefins. Although the AD reac- olefins.[3] We herein report the AD of aliphatic olefins
Scheme 1. Schematic representation of Resin-OsO4 catalyst preparation.
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DOI: 10.1002/adsc.200303114
Adv. Synth. Catal. 2003, 345, 1190 1192

Catalytic Asymmetric Dihydroxylation of Aliphatic Olefins
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Table 1. Asymmetric dihydroxylation of olefins with Resin-
OsO4
Table 2. Reuse of Resin-OsO4 catalyst in the AD of 2-
methyl-1-heptene.
Entry Olefin
Yield [%] ee [%][a] Diol config.[b]
1
85
83
82 (86)[c]
80
R
R
2[b]
3
4
80
80
74
R
R
70[e]
5
85
90
84
R
easily recovered from reaction mixture by simple
filtration after completion of the reaction. The high
binding ability of the heterogeneous osmium catalyst
enables the use of an equimolar ratio of ligand to
osmium to give good enantioselectives in asymmetric
dihydroxylation of aliphatic olefins.
6[f]
75[e]
S, S
[a]
The ee is determined by HPLC analysis.
[b]
The absolute configuration was determined by comparison
of specific rotation with literature value.
ee with 3 mol % ligand.
[c]
[d]
[e]
Results after 5th cycle.
Determined by comparison of specific rotation with
literature value.
1 mmol of CH3SO2NH2 was added.
Experimental Section
[f]
Preparation of the Resin-OsO4 Catalyst
Modified resin was obtained by quaternization of triethyl-
amine (2.1 mL, 21 mmol) with 1 g of chloromethylated styr-
ene-divinylbenzene copolymer (Merrifield resin, capacity
ꢀ 2.1 mequiv/g) in chloroform (20 mL) under reflux for 24 h.
1 g of quaternary ammonium resin was suspended in 100 mL of
0.8 mmol aqueous potassium osmate solution and stirred at
258C for 12 h under a nitrogen atmosphere. The solid catalyst
was filtered, washed thoroughly with 300 mL of water and
vacuum dried to obtain the resin-OsO4 (0.641 mmol of Os per
g, 12.19%) as determined by scanning electron microscopy-
energy dispersive X-ray analysis (SEM-EDX). This result was
revalidated by quantitative estimation of the potassium halide
formed in the ion-exchange process using 0.1 N silver nitrate
solution as titrant in the presence of potassium chromate.
affording good ees and yields using a heterogeneous
resin-OsO4 with 1,4-bis(dihydroquininyl)-anthraqui-
none [(DHQD)2AQN] ligand for the first time.
We performed AD of various aliphatic olefins by
taking an olefin (1 mmol), resin-OsO4 (1 mol %),
(DHQD)2AQN (1 mol %), K3Fe(CN)6, and K2CO3
(3.0 equivs.) in t-BuOH-H2O system (1:1, 10 mL) at
108C. All the olefins investigated gave good yields
ranging from 80 90% and ees (Table 1). When the
reaction is conducted with the (DHQD)2PHAL ligand
under similar reaction conditions, a lower ee is observed.
Higher concentrations of the ligand (3 mol %), did show
a small improvement in ees (4%), Table 1, entry 1.
The Resin-OsO4 was recovered quantitatively by
simple filtration. The recovered catalyst along with the
replenished chiral ligand (to make up 1 mol %) was
reused and a marginal decrease in activity was noticed
Typical Procedure for Asymmetric Dihydroxylation of
Aliphatic Olefins with Resin-OsO4 using K3Fe(CN)6 as
the Cooxidant
during 5th 7th cycles (Table 2). When the reaction was Resin-OsO4 (15.6 mg, 1 mol %), (DHQD)2AQN (8.6 mg,
1 mol %), K3Fe(CN)6 (990 mg, 3.0 equivs.) and K2CO3
(420 mg, 3 equivs.) and t-BuOH-H2O (1:1, 10 mL) were placed
in a round-bottomed flask and stirred at room temperature for
5 min. For 1,2-disubstitued and trisubstituted olefins
CH3SO2NH2 (95 mg, 1 mmol) was added. The solution was
cooled to 108C and then an olefin was added. The reaction
mixture was stirred at 108C for 12 15 h, and then to this
Na2SO3 (0.8 g) was added and the suspension was brought up to
room temperature with vigorous stirring. Resin-OsO4 catalyst
was filtered and washed with ethyl acetate. The aqueous layer
conducted with the filtrate obtained by treatment of the
catalyst in a solvent system for prolonged time no
product formation was observed. The absence of
osmium in the filtrate is further reconfirmed using the
iodometry test.[7b]
In conclusion, we have successfully applied the
heterogeneous Resin-OsO4 catalyst for the AD of
aliphatic olefins affording chiral diols without slow
addition of cooxidant for the first time with good yields
and ees, having consistency for five cycles. The catalyst is was further extracted with ethyl acetate. The combined organic
Adv. Synth. Catal. 2003, 345, 1190 1192
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Boyapati M. Choudary et al.
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layers were washed with 2 M aqueous NaOHsolution, if
CH3SO2NH2 was used. After removing the solvent, the crude
material was chromatographed on silica gel with EtOAc/
hexane to afford the corresponding cis-diol. The ee values of
the derivatized diols were determined by HPLC analysis using
Chiralcel OD-Hcolumn.
[3] a) C. Dobler, G. Mehltretter, M. Beller, Angew. Chem.
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[4] Review: a) C. Bolm, A. Gerlach, Eur. J. Org. Chem. 1998,
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1181 1190.
[5] For polymer supported chiral ligands see: a) B. M. Kim,
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Acknowledgements
K. Jyothi thanks the Indian Institute of Chemical Technology,
India for the award of a research fellowship and S. M. thanks the
Council of Scientific and Industrial Research, India for the
award of a senior research fellowship.
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