872
J. Am. Chem. Soc. 1999, 121, 872-873
Table 1. Enantioselective Propargylic Hydroxylation Catalyzed
Highly Enantioselective Propargylic Hydroxylations
Catalyzed by Chloroperoxidase
by CPOa
entry
R
R′
CH3
CH3
CH3
ee (%) yieldf (%) configh
7g
26
30
8
15
52
65
26
25
8
R
R
R
Shanghui Hu and Lowell P. Hager
1
2
3
4
5
6
7
8
9
CH3
57
CH2CH3
CH2 CH2CH3
CH2(CH2)2CH3 CH3
91b
87c
78c
86c
95c,d
94e
83c
94d,e
87d
Department of Biochemistry
UniVersity of Illinois, Urbana, Illinois 61801
R
Ph
CH3
CH3
CH3
CH3
CH3
CH2CH3
CH3
Ri
R
ReceiVed October 14, 1998
CH2OAc
CH2Br
CH2CH2OAc
CH2CH2Br
CH2OAc
COCH3
R
R
Chiral propargylic alcohols are important building blocks for
the enantioselective synthesis of complex molecules, in particular,
biologically active compounds.1 There are two general strategies
for the asymmetric synthesis of propargylic alcohols: (a) enan-
tioselective alkynylation of aldehydes2 and (b) stoichiometric or
catalytic reduction of acetylenic ketones.3 However, the most
direct procedure for the preparation of optically pure propargylic
alcohols would be the asymmetric hydroxylation of alkynes. Until
now an effective and versatile catalyst for this approach has not
been available.4
Chloroperoxidase (CPO) is the most versatile and efficient
oxidation catalyst in the heme enzyme family.5 Since the discovery
of CPO more than three decades ago,6 a large number of CPO-
catalyzed reactions have been described. CPO catalyzes halogena-
tion,6,7 the oxidation of alcohols to aldehydes,8 aldehydes to acids,9
dealkylations of alkylamines,10 dimerization of phenols,11 and
oxidation of amines to nitroso compounds.12 In particular, CPO
R
10
11
N.D.j
no reaction
a Hydrogen peroxide as the terminal oxidant. b Determined by GLC
on a â-CDX column. c Determined by conversion to corresponding
trifluoroacetate and GLC analysis using a chiral G-TA column.
d Determined by 1H NMR analysis of the corresponding Mosher
f
(MTPA) ester. e Determined by GLC on a chiral G-TA column. Unless
otherwise specified, the isolated yields are after flash chromatography
and are not optimized. g Determined by GLC analysis. h Determined
by hydrogenation (Pd/C, MeOH) followed by correlation to (R)-mono
or diols commercially available (Aldrich) or previously reported.
i Determined by comparison of the optical rotation with the known
compound. j Not determined.
catalyzes several enantioselective oxidation reactions: epoxidation
of alkenes,13 allylic and benzylic hydroxylations,9 and sulfoxi-
dations.14 There are very few reports concerning the enzymatic
oxidation of acetylenes.15 We now report a new oxidation reaction
catalyzed by CPO, stereoselective propargylic hydroxylations.
Under appropriate conditions16 CPO catalyzes the enantiose-
lective hydroxylation of a variety of unfunctionalized and
functionalized alkynes yielding chiral propargylic alcohols. Both
hydrogen peroxide and tert-butyl hydroperoxide (TBHP) can serve
as the terminal oxidant in this reaction. When hydrogen peroxide
is used as the oxidant, it is added slowly to the reaction mixture
to minimize the potent catalase activity of CPO. When TBHP is
used, the oxidation is started by adding 2 equiv of TBHP directly
to the reaction medium.
Table 1 records the results obtained with a variety of alkynes.
To assess the relative utilization of the different alkynes, all of
the reactions contained 1 equiv of alkyne, 2 equiv of oxidant,
and identical amounts of enzyme. All product yields and ee’s
are reported for 2-h reaction periods. The extent of the conversion
of an alkyne to product in a 2-h reaction is controlled by the rate
(1) For selected examples: (a) Helai, C. J.; Magriotis, P. A.; Corey, E. J.
J. Am. Chem. Soc. 1996, 118, 10938-10939. (b) Matsummura, K.; Hashiguchi,
S.; Ikariya, T.; Noyori, R. J. J. Am. Chem. Soc. 1997, 119, 8738-8739 and
references therein.
(2) (a) Mukaiyama, T.; Suzuki, K.; Soai, K.: Sato, T. Chem. Lett. 1979,
447-448. (b) Mukaiyama, T.; Suzuki, K. Chem. Lett. 1980, 255-256. (c)
Tombo, G. M. R.; Didier, E.; Loubinoux, B. Synlett 1990, 547-548. (d) Niwa,
S.; Soai, K. J. Chem. Soc., Perkin Trans. 1 1990, 937-943. (e) Corey, E. J.;
Cimprich, K. A. J. Am. Chem. Soc. 1994, 116, 3151-3152.
(3) (a) Brinkmeyer, R. S.; Kapoor, V. M. J. Am. Chem. Soc. 1977, 95,
8339-8341. (b) Noyori, R.; Tomino, I.; Yamada, M.; Nishizawa, M. J. Am.
Chem. Soc. 1984, 106, 6717-6725. (c) Midland, M. M.; Tramontano, A.;
Kazubski, A.; Graham, R. S.; Tsai, D. J. S.; Cardin, D. B. Tetrahedron 1984,
40, 1371-1380. (d) Ramachandran, P. V.; Teodorovic, A. V.; Rangaishenvi,
M. V.; Brown, H. C. J. Org. Chem. 1992, 57, 2379-2386. (e) Bach, J.;
Berenguer, R.; Garcia, J.; Loscertales, T.; Vilarrasa, J. J. Org. Chem. 1996,
61, 9021-9025. (f) Helai, C. J.; Magriotis, P. A.; Corey, E. J. J. Am. Chem.
Soc. 1996, 118, 10938-10939. (g) Matsumura, K.; Hashiguchi, S.; Ikariya,
T.; Noyori, R. J. Am. Chem. Soc. 1997, 119, 8738-8739.
(4) Clark, J. S.; Tolhurst, K. F.; Taylor, M.; Swallow, S. Tetrahedron Lett.
1998, 39, 4913-4916.
(5) (a) Continuous flow reactors have been developed which produce CPO
titers greater than 600 mg/L in Chirazyme Lab. (Urbana, IL). See: Blanke,
S. R.; Yi, S.; Hager, L. P. Biotechnol. Lett. 1989, 11, 769-774. (b) Franssen,
M. C. R.; van der Plas, H. C. AdV. Appl. Microbiol. 1992, 37, 41-98. (c)
Van Deurzen, M. P. J.; van Rantwijk, F.; Sheldon, R. A. Tetrahedron. 1997,
53, 13183-13220.
(13) (a) Allain, E. J.; Hager, L. P.; Deng, L.; Jacobsen, E. J. J. Am. Chem.
Soc. 1993, 115, 4415-4416. (b) Dexter, A. F.; Lakner, F. J.; Campbell, R.
A.; Hager, L. P. J. Am. Chem. Soc. 1995, 117, 6412-6413. (c) Lakner, F. J.;
Hager, L. P. J. Org. Chem. 1996, 61, 3923-3925. (d) Lakner, F. J.; Hager,
L. P. Tetrahedron: Asymmetry. 1997, 8, 3547-3550
(6) (a) Shaw, P. D.; Hager, L. P. J. Biol. Chem. 1961, 236, 1626-1630.
(b) Hager, L. P.; Morris, D. R.; Brown, F. S.; Eberwein, H. J. Biol. Chem.
1966, 241, 1769-1777. (c) Morris, D. R.; Hager, L. P. J. Biol. Chem. 1966,
241, 1763-1768.
(14) (a) Kobayashi, S.; Nakano, M.; Goto, T.; Kimura, T.; Schapp, A. P.
Biochem. Biophys. Res. Commun. 1986, 135, 166-171. (b) Colonna, S.;
Gaggero, N.; Manfred, A.; Casella, L.; Gulotti, M.; Carrea, G.; Pasta, P.
Biochemistry 1990, 29, 10465-10468. (c) Colonna, S.; Gaggero, N,; Casella,
L.; Carrea, G.; Pasta, P. Tetrahedron: Asymmetry 1992, 3, 95-106. (d) Van
Deurzen, M. P. J.; Groen, B. W.; Van Rantwijk, F.; Sheldon, R. A. Biocatalysis
1994, 10, 247-255. (e) Allenmark, S. G.; Andersson, M. A. Tetrahedron:
Asymmetry 1996, 7, 1089-1094.
(7) (a) Morrison, S. L.; Schonbaum, G. R. Annu. ReV. Biochem. 1976, 45,
861-889. (b) Neidelman, S. L.; Geigert, J. Biochem. Soc. Symp. 1981, 48,
39-52. (c) Libby, R. D.; Thomas, J. A.; Hager, L. P. J. Biol. Chem. 1982,
257, 5030-5037. (d) Fu, H.; Kondo, H.; Ichikawa, Y.; Look, G. C.; Wong,
C.-H. J. Org. Chem. 1992, 57, 7265-7270. (e) Libby, R. D.; Beachy, T. M.;
Phipps, A. K. J. Biol. Chem. 1996, 271, 21820-21827.
(8) (a) Geigert, J.; Dalietos, D. J.; Neidelman, S. L.; Lee, T. D.; Wadsworth,
J. Biochem. Biophys. Res. Commun. 1983, 114, 1104-1108. (b) Miller, V.
P.; Tschirret-Guth, R. A.; Ortiz de Montillano, P. R. Arch. Biochem. Biophys.
1995, 319, 333-340.
(15) Helvig, C. H.; Alayrac, C.; Mioskowski, C.; Koop, D.; Poullain, D.;
Durst, F.; Salau¨n, J. P. J. Biol. Chem. 1997, 272, 414-421.
(16) General procedure: A mixture of alkyne (1.0 mmol) and CPO (1.1 ×
10-3 mmol) was stirred vigorously in 10.0 mL of 10 mM Na citrate buffer
adjusted to pH 5.5. H2O2 was provided to the system via a syringe pump in
a continuous and slow addition fashion (1.7 M, 10 µL/min.). When t-BuOOH
served as the terminal oxidant, it was directly added to the reaction medium
(2 mmol). The reaction vial was capped, and the reaction was stirred for 2 h
at room temperature, after which Na2S2O3 was added and the mixture was
extracted twice with CH2Cl2. The combined organic extracts were dried over
MgSO4, and the products were purified by flash chromatography using pentane/
ether as eluent. Quantitative gas chromatography was carried out with decane
or dodecane as an internal standard. For further details, see the Supporting
Information.
(9) Zaks, A.; Dodds, D. R. J. Am. Chem. Soc. 1995, 117, 10419-10424.
(10) (a) Ketters, G. L.; Hollenberg, P. F. Arch. Biochem. Biophys. 1984,
233, 315-321. (b) Okazaki, O.; Guengerich, F. P. J. Biol. Chem. 1993, 268,
1546-1552.
(11) (a) McCarthy, M. B.; White, R. E. J. Biol. Chem. 1983, 258, 9153-
9158. (b) Casella, L.; Poli, S.; Gullotti, M.; Selvaggini, C.; Beringhelli, T.
Biochemistry 1994, 33, 6377-6386.
(12) (a) Corbett, M. D.; Chipko, B. R.; Batchelor, A. O. Biochem. J. 1980,
187, 893-903. (b) Doerge, D. R.; Corbett, M. D. Chem. Res. Toxicol. 1991,
4, 556-560.
10.1021/ja983612g CCC: $18.00 © 1999 American Chemical Society
Published on Web 01/13/1999