A new resolution of (1α,2β,3α,4β)-2,3-dibromocyclohex-5-en-1,4-diol by lipase from Mucor miehei

Article abstract of DOI:10.1016/S0957-4166(00)00038-0

An efficient resolution of 2,3-dibromocyclohex-5-en-1,4-diol has been carried out, using Mucor miehei lipase operating in an organic solvent. The enantioforms obtained may find application in the preparation of chiral conduritols. Copyright (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0957-4166(00)00038-0

Tetrahedron: Asymmetry 11 (2000) 1043±1045
A new resolution of (1a,2b,3a,4b)-2,3-dibromocyclohex-5-en-
1
,4-diol by lipase from Mucor miehei
Claudia San®lippo, Angela Patti and Giovanni Nicolosi*
Istituto CNR per lo Studio delle Sostanze Naturali di Interesse Alimentare e Chimico-Farmaceutico, Via del Santuario 110,
I-95028 Valverde CT, Italy
Received 11 December 1999; accepted 19 January 2000
Abstract
An ecient resolution of 2,3-dibromocyclohex-5-en-1,4-diol has been carried out, using Mucor miehei
lipase operating in an organic solvent. The enantioforms obtained may ®nd application in the preparation
of chiral conduritols. # 2000 Elsevier Science Ltd. All rights reserved.
1
Conduritols, 1,2,3,4-tetrahydroxycylohexenes, represent an important class of cyclitols due to
their biological properties and synthetic role as starting material in the preparation of bioactive
2
molecules, such as glycosidase inhibitors. Ten di€erent stereoforms of conduritol are possible,
from which conduritols A and D are meso forms, while B, C, E and F exist as pairs of enantio-
mers. Considering the crucial role that stereoselectivity plays in the chemical recognition regula-
tion of the biological process, to have access to these cyclitols in enantiopure forms is particularly
attractive and of synthetic interest. In the context of our research programme regarding the prep-
aration of cyclitols in enantiopure forms by biocatalytic procedures, we have focused our atten-
tion on (1a,2b,3a,4b)-2,3-dibromocyclohex-5-en-1,4-diol, (‹)-1, having C symmetry, easily
2
3
prepared by bromination/reduction of commercially available p-benzoquinone, and which is
known to be a starting material for access to six chiral conduritols, (+)- and (� )-conduritols B, C
and E.4
Resolution of (‹)-1 has already been achieved by enantioselective hydrolysis of ester (‹)-2 in
5
the presence of Pseudomonas cepacia lipase. However, the concomitant spontaneous hydrolysis
occurring in water has a detrimental e€ect on the enantiomeric purity of the products, making
this unsuitable for preparative purposes. We thought this disadvantage could be avoided by the
use of biocatalytic procedures, alcoholysis and esteri®cation, operating in an organic solvent, and
thus provide an ecient way of accessing enantiopure dialcohol 1.
*
Corresponding author. Fax: 39-0957212141; e-mail: nicolosi@issn.ct.cnr.it
0957-4166/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(00)00038-0

1
044
C. San®lippo et al. / Tetrahedron: Asymmetry 11 (2000) 1043±1045
In this context, we ®rst tried alcoholysis of (‹)-2 in tert-butyl methyl ether (TBME), using four
6
di€erent lipases whose e€ectiveness was proven in previous resolutions of cyclitols (Scheme 1).
1
Of these, after 24 h reaction, only Mucor miehei lipase on polymeric resin (Lipozyme , Novo
Nordisk) showed satisfactory activity in terms of the reaction rate and it was thus selected for
further investigation.
ꢀ
Scheme 1. Substrate 10 mg/ml, lipase 20 mg/ml, n-BuOH or AcV 5 equiv., TBME, 45 C, 300 rpm
The alcoholysis of (‹)-2 in the presence of Lipozyme occurs with the recognition of the 1R
enantiomer giving, at ®rst, monoester (+)-3, the concentration of which, nevertheless, does not
exceed 15% because it is itself quickly transformed into dialcohol (+)-1. The enantiopure nature
of monoester and, consequently, of diol (+)-1, determined by chiral GC analysis, established the
high enantioselectivity (E >200) for M. miehei lipase. Under the reaction conditions adopted no
spontaneous hydrolysis of the products occurs so that after 72 h the alcoholysis reached 50%
2
D
5
5
conversion and allowed enantiopure (+)-2 (‰ꢀŠ +12.0, c 0.4, CH Cl ; lit. [ꢀ] +11.7) and (+)-
2
2
D
2
5
5
1
(‰ꢀŠ +42.0, c 2.0, acetone; lit. [ꢀ] +45.8) to be obtained.
D
When we tried the resolution of (‹)-1 by direct esteri®cation with vinyl acetate in TBME using
D
Lipozyme as the catalyst, the sequential esteri®cation of the hydroxyl groups in the recognised
enantiomer occurred with di€erent rates. Thus, fast formation of monoester (+)-3 in enantiopure
form was observed, whose concentration rose to 40% in 4 h, followed by a further slow ester-
i®cation step to give diester (� )-2. Following this procedure, on a preparative scale, 2 g of (‹)-1
in 6 h (50% conv.) furnished 0.96 g of (� )-1 (yield 48%, ee >98%), 0.85 g of (+)-3 (yield 37%,
ee >98%) and 0.26 g of (� )-2 (yield 10%, ee >98). Hydrolysis with NH OH:MeOH, 1:9, of
4
these esters a€orded the homochiral dialcohol (+)-1 in a 42% overall yield.7
In conclusion, the enzymatic method described here o€ers a convenient route to gain access to
bromoconduritols, (+)- and (� )-1, of synthetic interest in excellent ee and good yield.
Acknowledgements
Financial support from the CNR Target Project on `Biotechnology' is gratefully acknow-
ledged. Thanks are also due to Novo Nordisk for kindly providing lipase from Mucor miehei.

C. San®lippo et al. / Tetrahedron: Asymmetry 11 (2000) 1043±1045
1045
References
1
2
3
4
È
. Balci, M.; Sutbeyaz, Y.; SecË en, H. Tetrahedron 1990, 46, 3715±3742.
. Balci, M. Pure Appl. Chem. 1997, 69, 97±104.
. Altenbach, H. J.; Stegelmeier, H.; Vogel, E. Tetrahedron Lett. 1978, 3333±3337.
. Guo, Z.-H; Haines, A. H.; Pyke, S. M.; Pyke, S. G.; Taylor, R. J. K. Carbohydr. Res. 1994, 264, 147±153. Sec
H.; Mara, A.; Sutbeyaz, Y.; Balci, M. Synth. Commun. 1992, 22, 2613±2619.
. Johnson, C. R.; Miller, M. W. J. Org. Chem. 1995, 60, 6674±6675.
Ë en,
È
5
6
. The following lipases have been investigated: from Candida cylindracea, C. antarctica, Pseudomonas cepacia and
Mucor miehei. San®lippo, C.; Patti, A.; Nicolosi, G. Tetrahedron: Asymmetry 1999, 10, 3273±3276. San®lippo, C.;
Patti, A.; Piattelli, M.; Nicolosi, G. Tetrahedron: Asymmetry 1998, 9, 2809±2817. San®lippo, C.; Patti, A.; Piattelli,
M.; Nicolosi, G. Tetrahedron: Asymmetry 1997, 8, 1569±1573. Ling, L.; Ozaki, S. Tetrahedron Lett. 1993, 34,
2
501±2504. Ling, L.; Watanabe, Y.; Akiyama, T.; Ozaki, S. Tetrahedron Lett. 1992, 33, 1911±1914.
7
. The enantiomeric excesses of 1 and 2 were determined by chiral GC analysis on Megadex DMP b-dimethylpentyl
bCDX OV1701 capillary column. For (+)-3, (+)-(1R,2S,3S,4R)-1-acetyloxy-2,3-dibromo-4-hydroxycyclohex-5-
ene: white crystals, (from EtOAc/hexane), mp 147±148 C; ee >98% (determined by chiral GC analysis after
ꢀ
2
5
1
exhaustive chemical acetylation); ‰ꢀŠ +25.0 (c 1.6, CHCl ); H NMR (CDCl /TMS, 250.13 MHz): ꢁ (ppm) 2.15
D
3
3
(
1
s, 3H), 2.83 (d, J=4.5 Hz, 1H), 4.26 (m, 2H), 4.56 (m, 1H), 5.67±5.75 (m, 2H), 5.92 (ddd, J=2.2, 4.5, 10.5 Hz,
H); 13C NMR (CDCl
/TMS, 62.9 MHz): ꢁ (ppm) 20.9, 52.9, 59.9, 73.1, 74.2, 126.8, 130.9, 169.0.
3