Synthetic studies on d-biotin, part 9.1) An improved asymmetric synthetic route to d-biotin via Hoffmann-Roche lactone-thiolactone approach

Article abstract of DOI:10.1248/cpb.53.743

An efficient and highly stereoselective total synthesis of d-biotin has been achieved starting from cis-1,3-dibenzyl-2-imidazolidone-4,5-dicarboxylic acid (2) with an overall yield of 33%. Polymer-supported oxazaborolidine- catalyzed asymmetric reduction of meso-cyclic imide 4 constitutes the key synthetic step in introducing stereogenic centers into the d-biotin molecule.

Full text of DOI:10.1248/cpb.53.743

July 2005
Chem. Pharm. Bull. 53(7) 743—746 (2005)
743
Synthetic Studies on d-Biotin, Part 9.1) An Improved Asymmetric
Synthetic Route to d-Biotin via Hoffmann–Roche Lactone–Thiolactone
Approach
Fen-Er CHEN, ,a Hui-Qing JIA,a Xu-Xiang CHEN,b Hui-Fang DAI,a Bin XIE,a Yun-Yan KUANG,a and
*
a
Jian-Feng ZHAO
a Department of Chemistry, Fudan University; Shanghai, 200433, People’s Republic of China: and b School of
Pharmaceutical Engineering, Shenyang Pharmaceutical University; 110016, People’s Republic of China.
Received November 8, 2004; accepted February 28, 2005
An efficient and highly stereoselective total synthesis of d-biotin has been achieved starting from cis-1,3-
dibenzyl-2-imidazolidone-4,5-dicarboxylic acid (2) with an overall yield of 33%. Polymer-supported oxazaboroli-
dine-catalyzed asymmetric reduction of meso-cyclic imide 4 constitutes the key synthetic step in introducing
stereogenic centers into the d-biotin molecule.
Key words d-biotin; vitamin H; polymer-supported oxazaborolidine; asymmetric reduction; Wittig reaction; desymmetrization
The development of efficient processes for the total syn-
Next, we embarked upon the development of an efficient
thesis of d-biotin (1), continues to be an attractive goal in and convenient strategy for the large-scale asymmetric bo-
synthetic organic chemistry, because of its unique structural rane reduction of 4 into (3aS,6R,6aR)-hydroxylactam 5 using
features, significant biological properties and commercial a chiral polymer-supported oxazaborolidine derived from
importance.2—8) Despite great advances9—21) in total synthesis polymer-supported ligand 1025) (containing 0.39 mmol of di-
over the past 55 years, large-scale preparation of this vitamin aryprolinol function units/g of polymer by elemental analy-
employing the F. Hoffmann–La Roche lactone–thiolactone sis) with in situ generated borane from cheap and convenient
approach, developed by Goldberg and Sternbach in 1949, hydritic reagents and boron halide etherates. Thus, the meso-
still retains technically and economic advantages.22) How- cyclic imide 4 was treated with 80% NaH and BF3·Et2O in
ever, a long-standing problem in this synthesis has been the the presence of 10 under reflux in anhydrous THF to afford 5
lack of an efficient and convenient procedure for the desym- in 82% yield. The enantiomeric excess of 5 was measured to
metrization of dicarboxylic acid 2 to form (3aS,6aR)-lactone be ꢀ98% by HPLC analysis using a Chiralcel OD column
(6). Our recent strategy, using a polymer-supported oxaz- (eluent : hexane/2-propanol, 6 : 4, 0.7 ml/min).
aborolidine catalyzed enantioselective reduction of meso-
As pointed out in a number of studies,26—32) one of the
cyclic imide approach, allowed us to prepare (3aS,6R,6aR)- major advantages of a polymer reagent is the ease with which
hydroxylactam 5 from 2 in high yield and excellent enan- it can be worked up and recycled. The polymer-supported
tiomeric excess.23) However, this procedure is impractical for ligand 10 could be conveniently recovered from the reaction
large-scale synthesis due to the use of expensive and toxic mixture by simple filtration followed by washing with hot
BF3·Me2S as the reducing agent which requires a lot of pre- H2O, and EtOH after the reduction was completed. To
cautions, and lack of a stable polymer-supported chiral lig- demonstrate that the ligand 10 can be recycled a number of
and.24) These obstacles prompted us, as part of our strategy to times, the enantioselective reduction of 4 was repeated four-
develop a new oxazaborolidine-catalyzed reducing system teen times under the same reaction conditions. As shown in
that can easily be employed and that gives high enantiomeric Table 1, the reached enantioselectivities remained around
excess for a large-scale conversion of 4 into 5 as a precursor 98% ee, clearly illustrating the reusability of the polymer-
for the formation of 6, to complete the asymmetric synthesis supported ligand 10.
of 1.
The reduction of 5 by NaBH4 in EtOH at 50 °C for 4 h and
In the present paper, we describe an efficient and practical subsequent hydrolysis with 2N aq. H2SO4 at 80 °C for 1 h af-
asymmetric total synthesis of 1 starting from commercially forded the (3aS,6aR)-lactone 6 in 90% yield. Comparison of
available dicarboxylic acid 2 through an improved enantiose- its specific optical rotation {[a]D20 ꢁ57.3° (cꢂ2.0, CHCl3)}
lective reduction of meso-cyclic imide 4 with the use of re- with the literature value {[a]D20 ꢁ59.8° (cꢂ2, CHCl3)}33) for
coverable chiral polymer-supported oxazaborolidine as a cat- 6 implied an enantiomeric purity of 95.8%, which was then
alyst.
upgraded to 98.6% ee by recrystallization from EtOH. Treat-
ment of with potassium butylthioxanthogenate (n-
BuSC(S)SK) in DMA at 125 °C for 6 h effected the thiolac-
6
Results and Discussion
The asymmetric synthesis of 1 is presented in Chart 1. The tonization to form the (3aS,6aR)-thiolactone 7 in 82% yield.
known meso-cyclic-1,2-dicarboxylic anhydride 3 was pre- From a practical point of view, a one-step introduction of
pared in almost quantitative yield by heating 2 in xylene with the carboxybutyl chain to 7 based on a Wittig reaction to
a catalytic amount of Ac2O with azeotropic removal of H2O form (Z)-configurated unsaturated acid 8 seemed to be very
for 13 h. Treatment of 3 with benzylamine in toluene under attractive. Following the published conditions,34) Wittig olefi-
reflux for 6 h afforded the meso-cyclic imide 4 in a 90% nation of 7 with the ylide, derived from 4-carboxybutyltri-
yield.
phenylphosphonium bromide (BrPh3PCH2CH2CH2CH2CO2H)
∗ To whom correspondence should be addressed. e-mail: rfchen@fudan.edu.cn
© 2005 Pharmaceutical Society of Japan

744
Vol. 53, No. 7
Chart 1. Synthetic Route to d-Biotin (1)
Table 1. Recycling of the Chiral Polymer-Supported Ligand 10 in the
Asymmetric Reduction of 4 in THF Under Reflux
Entry
Yield (%)a)
ee (%)b)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
80.5
81
80
81
81
80.5
80.7
81
87
81
97.8
98.1
98.2
97.6
98.09
98
Fig. 1. 1H-NMR Studies of NOE for Compound 8
Conclusion
We have developed a very efficient route for the highly
stereoselective synthesis of d-biotin in a 33% overall yield
starting from readily accessible cis-1,3-dibenzyl-2-imidazo-
lidione-4,5-dicarboxylic acid (2), via Hoffmann–Roche’s lac-
tone–thiolactone approach. The short steps, high yield, sim-
ple work-up, and ready availability of the reagents should
provide a practical means with which to obtain d-biotin.
98
98.2
98.1
98.3
98.3
98
79.5
80
81.3
80.5
98.1
98.1
Experimental
a) Yields of isolated pure products. b) Determined by chiral HPLC analysis.
General Procedure Melting points (mp) were measured using a WRS-
1B digital melting point apparatus and are uncorrected. 1H-NMR was
recorded on Bruker DMX500 (500 MHz) spectrometer. Chemical shifts (d)
are expressed in ppm with TMS as an internal standard. Optical rotations
were measured on a WZZ-2S digital automatic polarimeter. IR spetra were
measured using a Nicolet FI-IR 360 Spectrometer. Mass spectra (MS) were
recorded on HP-5988 Å mass spectrometer. THF was distilled from sodium
benzo phenone ketyl and DMA was distilled from CaH2 before use. Routine
monitoring of reaction was carried out using Merck 60 GF254 silica gel,
glass-supported plates (TLC). Polymer-supported chiral ligand 10 was pre-
pared according to a literature method.25)
provided the (Z)-configurated unsaturated acid 8 with low
yield (max. 40%). Attempts to treat 4-carboxybutyltriphenyl-
phosphonium bromide with freshly sublimed t-BuOK with 7
at reflux in anhydrous toluene failed completely. However,
heating a toluene solution of these compounds at 135 °C in a
sealed vessel for 7 h gave the desired 8 exclusively as a single
(Z)-isomer in 81% yield. The (Z)-configuration of 8 was un-
equivocally ascertained by NOE experiments (Fig. 1). A
10.1% enhancement of the signal of H-C3a at dꢂ4.62 was
observed on irradiation of the signal at dꢂ5.53, which be-
longs to the olefinic H-atom of the side chain.
cis-1,3-Dibenzyl-tetrahydro-2H-furo[3,4-d]imidazole-2,4,6-trione (3)
A mixture of 2 (17.7 g, 50 mmol), acetic anhydride (0.94 ml, 0.01 mol), and
xylene (100 ml) was stirred under reflux for 13 h and fixed with a Dean-
Stark apparatus. The solid precipitate was cooled to r.t., filtered and washed
Stereospecific hydrogenation of 8 was carried out under 4 with H2O (100 ml) until acid-free. The solid product was dried to give 3 as a
white solid (16.5 g, 98%), mp 237—239 °C (lit.35): mp 236—238 °C). IR
atm of H2 in the presence of Pd(OH)2 over charcoal to give
the N,N-dibenzylbiotin 9 in 95% yield. Removal of the N-
benzyl group was conducted with CH3SO3H–AcOH–H2O
(1.5 : 1.5 : 1) under reflux for 10 h to afford d-biotin (1) in
80% yield.
(KBr) nmax 1800, 1738, 1686, 1226 cmꢃ1; 1H-NMR (CDCl3) d: 4.20 (s, 2H),
4.18 (2H, d, Jꢂ15.0 Hz), 5.10 (2H, d, Jꢂ15.0 Hz), 7.24—7.37 (10H, m); EI-
MS m/z: 336 (14Mꢁ), 264 (16), 173 (6), 132 (112), 91 (100).
N-Benzyl-cis-1,3-dibenzyl-2-imidazolidone-4,5-dicarboximide (4)
A
stirred mixture of 3 (60 g, 0.178 mol), benzylamine (19.2 g, 0.18 mol), and

July 2005
745
1662, 1485, 1452 cmꢃ1; H-NMR (CDCl3) d: 1.39—1.93 (4H, m, 2ꢄCH2),
2.00 (2H, t, Jꢂ7.4 Hz), 2.81 (1H, dd, Jꢂ5.5, 12.1 Hz), 2.95 (1H, d,
Jꢂ12.3 Hz), 4.16 (1H, m), 4.62 (1H, d, Jꢂ7.9 Hz), 4.05, 4.34, 4.52, 4.97
(4H, 4d, Jꢂ15.5, 16.8 Hz), 5.53 (1H, t, Jꢂ7.8 Hz), 7.24—7.40 (10H, m); EI-
MS m/z: 422 (6, Mꢁ), 311 (6), 289 (20), 238 (12), 106 (48), 91 (100).
(3aS,4S,6aR)-1,3-Dibenzyl-tetrahydro-1H-thieno[3,4-d]imidazol-
2(3H)-one-4-yl-pentanoic Acid (9) A suspension of Pd(OH)2/C (1.7 g) in
EtOAc (70 ml) was preactivated for 1 h under a H2 pressure of 4 atm. A solu-
tion of 8 (21.1 g, 50 mmol) in EtOAc (130 ml) was added. The reaction mix-
ture was shaken at r.t. under an atmosphere of H2 (4 atm) for 4 h. The mix-
ture was filtered through a pad of Celite. The filtrate was evaporated under
reduced pressure to give the crude product, which was recrystallized from
iso-PrOH/hexane to afford 9 as a white solid (20.2 g, 95%), mp 91—93 °C,
[a]D23 ꢃ26.6° (cꢂ1.0, CH3OH) {lit.39): mp 91—92 °C, [a]D23 ꢃ26.7° (cꢂ1.0,
1
toluene (280 ml) was heated under reflux for 5 h. The reaction mixture was
cooled to r.t. and the precipitate was filtered, and dried to afford 4 as a white
solid (68 g, 90%), mp 115—117 °C (lit.23): mp 114—116 °C). IR (KBr) nmax
3435, 1712, 1688, 1647 cmꢃ1; 1H-NMR (CDCl3) d: 4.24 (s, 2H), 4.27, 4.28,
4.71, 4.79 (4H, 4d, Jꢂ15.38, 15.42 Hz), 4.54 (2H, s), 7.20—7.38 (15H, m);
EI-MS m/z: 425 (28, Mꢁ), 334 (6), 237 (6), 132 (11), 91 (100).
(3aS,6R,6aR)-1,3,5-Tribenzyl-6-hydroxy-tetrahedro-4H-pyrolo[3,4-
d]imidazole-2,4(1H)-dione (5) BF3·Et2O (35.7 ml, 0.28 mol) was added
dropwise to a suspension of 80% NaH (5.85 g, 0.2 mol) in THF (45 ml) and
the suspension was stirred at r.t for 25 min under N2. Polymer-supported lig-
and 10 (15 g) was added, and the reaction mixture was heated at reflux for an
additional 25 min. A solution of 4 (27.4 g, 60 mmol) in THF (185 ml) was
added dropwise over 2.5 h. Stirring was continued under reflux until the
TLC showed complete disappearance of compound 4 (3 h). After cooling to
r.t., the mixture was filtered, and the polymer-supported catalyst was washed
with EtOAc (3ꢄ50 ml) and H2O (3ꢄ40 ml). The organic layers were sepa-
rated, and the aqueous layers were extracted with EtOAc (3ꢄ50 ml). The
combined organic layers were washed with sat. aq. NaHCO3 (3ꢄ30 ml),
H2O (3ꢄ40 ml), and sat. aq. NaCl (3ꢄ30 ml), and dried over Na2SO4. The
solvent was evaporated under reduced pressure. The residue was purified by
CC (silica gel, hexane/EtOAc 2 : 1) to afford 5 as a white solid (21 g, 82%),
mp 127—130 °C, [a]D20 ꢁ69.1° (cꢂ0.1, CH2Cl2) {lit.23): mp 128—131 °C,
[a]D20 ꢁ69.2° (cꢂ0.1, CH2Cl2)}. IR (KBr) nmax 3315, 2930, 1703, 1451,
CH3OH)}. IR (KBr) nmax 2926, 1097, 1451, 1238, 703 cmꢃ1 1H-NMR
;
(CDCl3) d: 1.39—1.69 (6H, m), 2.20 (2H, t, Jꢂ6.6 Hz), 2.70 (2H, 4d,
Jꢂ2.35, 4.4 Hz), 3.08 (m, 1H), 3.90 (1H, dd, Jꢂ5.56 Hz), 3.97 (1H, m),
4.04, 4.16, 4.74, 5.02 (4H, 4d, Jꢂ15.1, 15 Hz), 7.22—7.37 (10H, m); EI-MS
m/z: 423 (37, Mꢁ), 289 (18), 238 (11), 106 (49), 91 (100).
d-Biotin (1) A mixture of 9 (42.4 g, 0.1 mol), methanesulfonic acid
(100 ml), AcOH (100 ml), and H2O (50 ml) was stirred in xylene (200 ml)
until all of compound 9 had been consumed (10 h, confirmed by TLC). After
cooling to r.t., H2O (200 ml) was added. The organic layer separated off the
aqueous layer and was concentrated under reduced pressure to an approxi-
mate volume of 100 ml. The precipitated product was collected by filtration,
and recrystallized from H2O to afford 1 as a white crystalline powder
1235, 1079, 739, 700 cmꢃ1 1H-NMR (DMSO-d6) d: 3.76—3.78 (m, 2H),
;
4.11, 4.40, 5.03, 5.10 (4H, 4d, Jꢂ14.9 Hz), 4.20, 4.93 (2H, 2d, Jꢂ13.7 Hz),
4.91 (1H, dd, Jꢅ1, 5.1 Hz), 7.21—7.40 (15H, m), EI-MS m/z: 427 (13, Mꢁ),
264 (21), 106 (6), 91 (100).
(19.6 g, 80%), mp 231—232 °C, [a]D22 ꢁ91° (cꢂ1.0, 0.1 N NaOH) {lit.23)
mp 232—233 °C, [a]D22 ꢁ91.2° (cꢂ1.0, 0.1 N NaOH)}. IR (KBr) nmax 3311,
2933, 1705, 1665 cmꢃ1 1H-NMR d: 1.31—1.62 (6H, m), 2.18 (2H, t,
:
(3aS,6aR)-1,3-Dibenzyl-tetrahydro-4H-furo[3,4-d]imidazole-2.4(1H)-
dione (6) Compound 5 (128.25 g, 0.30 mol) in anhydrous EtOH (460 ml)
was added dropwise at 0—5 °C to a stirred mixture of NaBH4 (22.7 g,
0.60 mol) and anhydrous EtOH (100 ml). After stirring at 50 °C for 4 h. 2 N
H2SO4 (245 ml) was added dropwise to the reaction mixture. The reaction
mixture was allowed to warm to 80 °C and stirring for a further 1 h. After
cooling to r.t., the mixture was extracted with EtOAc (4ꢄ80 ml). The com-
bined org. layers were washed successively with sat. aq. NaCl (3ꢄ35 ml)
and H2O (3ꢄ40 ml), and dried over Na2SO4. The solvent was evaporated
under reduced pressure to give the crude product, which was recrystallized
from EtOH to afford 6 as a white solid (86.9 g, 90%), mp 118—120 °C,
[a]D25 ꢁ61.5° (cꢂ2, CHCl3) {lit.36): mp 120—121 °C, [a]D25 ꢁ61.4° (cꢂ2,
;
Jꢂ7.3 Hz), 2.57 (1H, dd, Jꢂ1.7, 12.5 Hz), 2.79 (1H, dd, Jꢂ4.7, 12.5 Hz),
3.15 (1H, m), 4.16 (1H, m), 4.36 (1H, m), 6.37 (1H, s), 6.47 (1H, s), 11.98
(1H, br s); EI-MS m/z: 245 (1.15, Mꢁ), 227 (9), 184 (25), 112 (26), 97 (100),
85 (66).
Acknowledgements This work was partially supported by a Grant-in-
Aid (96107) for Scientific Research from the Ministry of Chemical Industry
of China.
References and Notes
1
CHCl3)}. IR (KBr) nmax 1776, 1705, 1210, 1185, 1028, 970 cmꢃ1; H-NMR
1) Chen F. E., Chen X. X., Dai H. F., Kuang Y. Y., Xie B. Zhao J. F., Adv.
Synth. & Catal., 347, 549—554 (2005).
2) Mistry P. S., Dakshinamurti K., Vitam. Horm., 22, 1—55 (1964).
3) Maebashi M., Makino Y., Furukawa Y., Ohinata K., Kimura S., Sato
T., J. Clin. Biochem, Nurt., 14, 211—218 (1993).
(CDCl3) d: 3.25 (1H, dd, Jꢂ2.3, 12.8 Hz), 3.35 (1H, dd, Jꢂ5.6, 12.8 Hz),
3.96 (1H, d, Jꢂ8.8 Hz), 4.20 (1H, ddd, Jꢂ2.3, 5.4, 8.0 Hz), 4.24, 4.32, 4.46,
4.95 (4H, 4d, Jꢂ14 Hz), 7.27—7.38 (10H, m); EI-MS m/z: 322 (25, Mꢁ),
265 (58), 245 (78), 187 (62), 91 (100).
(3aS,6aR)-1,3-Dibenzyl-tetrahydro-4H-thieno[3.4-d]imidazole-
2.4(1H)-dione (7) Potassium butylthioxanthogerate (30.7 g, 0.15 mol) was
added to a stirred solution of 6 (48.3 g, 0.15 mol) in DMA (125 ml) and the
mixture was heated at 125 °C for 6 h under N2. After cooling to r.t., H2O
(250 ml) was added. The mixture was extracted with toluene (4ꢄ60 ml); the
combined organic layers were washed with sat. aq. NaCl (3ꢄ45 ml) and
H2O (3ꢄ40 ml), and then dried over Na2SO4. The solvent was evaporated
under reduced pressure to give the crude product, which was recrystallized
from EtOAc to afford 7 as colorless crystals (41.6 g, 82%), mp 125—126 °C,
[a]D20 ꢁ90.8° (cꢂ1, CHCl3) {lit.37): mp 125—128 °C, [a]D20 ꢁ90.5° (cꢂ1.0,
CHCl3)}. IR (KBr) nmax 1705, 1695, 1424, 1225 cmꢃ1; 1H-NMR (CDCl3) d:
3.24 (1H, dd, Jꢂ2.2, 12.8 Hz), 3.35 (1H, dd, Jꢂ5.5, 12.8 Hz), 3.82 (1H, d,
Jꢂ8.0 Hz), 4.14 (1H, ddd, Jꢂ2.2, 5.5, 8.0 Hz), 4.35, 4.38, 4.67, 5.00 (4H,
4d, Jꢂ15.2 Hz), 7.27—7.35 (10H, m); EI-MS m/z: 338 (5, Mꢁ), 310 (25),
277 (8), 264 (66), 91 (100).
(3aS,4S,6aR)-1,3-Dibenzyl-tetrahydro-1H-thieno[3,4-d]imidazole-
2(3H)-one-4-yl-pentanoic Acid (8) t-BuOK (10.8 g, 90 mmol) was added
to a suspension of 4-carboxybutyltriphenylphosphonium bromide (19.95 g,
45 mmol) in anhydrous toluene (100 ml) at 10 °C and the reaction mixture
was stirred at 25 °C for 45 min. A solution of 7 (13.5 g, 40 mmol) in anhy-
drous toluene (100 ml) was added, and the resulting mixture was placed in a
standard stainless steel vessel under a nitrogen atmosphere and stirred at
135 °C for 7 h. After cooling to r.t., H2O (150 ml) was added. The organic
layer was separated and the aqueous layer was extracted with toluene
(3ꢄ35 ml). The combined organic layers were washed with sat. aq. NaCl
(3ꢄ40 ml) and H2O (3ꢄ40 ml), dried over Na2SO4, and concentrated under
reduced pressure to give the crude product, which was purified by column
chromatography (silica gel, benzene/EtOAc 4 : 1) to afford 8 as a white solid
(13.7 g, 81%), mp 84—85 °C, [a]D20 ꢁ236° (cꢂ1.0, 0.1 N NaOH) {lit.38) mp
84—85 °C, [a]D20 ꢁ236.2° (cꢂ1, 0.1 N NaOH)}. IR (KBr) nmax 3432, 1725,
4) Coggeshall C. J., Heggers J. P., Robson C. M., Baker H., Ann. N.Y.
Acad. Sci., 447, 389—392 (1985).
5) Parry R. J., Naidu M. V., Tetrahedron Lett., 21, 4783—4786 (1980).
6) Trainor D. A., Parry R. J., Gitterman A., J. Am. Chem. Soc., 102,
1467—1468 (1980).
7) Ahler M., Muller W., Reichert A., Ringsdorf H., Venzmer J., Angew.
Chem., Int. Ed. Engl., 29, 1269—1285 (1990).
8) Marquet A., Frappier F., Guillerm G., Azoulav M., Florentin D., J. Am.
Chem. Soc., 115, 2139—2145 (1993).
9) De Clercq P. J., Chem. Rev., 97, 1755—1792 (1997).
10) Shimizu T., Seki M., Tetrahedron Lett., 41, 5099—5101 (2000).
11) Shimizu T., Seki M., Tetrahedron Lett., 42, 429—432 (2001).
12) Shimizu T., Seki M., Tetrahedron Lett., 43, 1039—1042 (2002).
13) Mori Y., Seki M., Heterocycles, 58, 125—127 (2002).
14) Mori Y., Seki M., J. Org. Chem., 68, 1571—1574 (2003).
15) Seki M., Hatsuda M., Mori Y., Yamada S., Tetrahedron Lett., 43,
3269—3272 (2002).
16) Seki M., Mori Y., Hatsuda M., Yamada S., J. Org. Chem., 67, 5527—
5536 (2002).
17) Seki M., Shimizu T., Inubushi K., Synthesis, 2003, 361—364 (2003).
18) Mori Y., Kimura M., Seki M., Synthesis, 2003, 2311—2316 (2003).
19) Seki M., Kimura M., Hatsuda M., Yoshida S., Shimizu T., Tetrahedron
Lett., 44, 8905—8907 (2003).
20) Kimura M., Seki M., Tetrahedron Lett., 45, 1635—1637 (2004).
21) Kimura M., Seki M., Tetrahedron Lett., 45, 3219—3223 (2004).
22) Uskokovic M. R., “Encyclopedia of Chemical Technology,” 3rd ed.,
Vol. 24, ed. by Kirk D. E., Othmer D. E., Wiley, New York, 1984, pp.
41—49.
23) Chen F. E., Yuan J. L., Dai H. F., Kuang Y. Y., Chu Y., Synthesis, 2003,
2155—2160 (2003).

746
Vol. 53, No. 7
24) We noticed that the polymer-supported chiral sulfonamide was par- 32) Itsuno S., Nakano M., Ito K., J. Chem. Soc. Perkin Trans. I, 1985,
tially decomposed in the sixth cycle in the enantioselective reduction
of 4 into 5. This made the work-up procedure very difficult to carry
out and recycling of the polymer inefficient.
2615—2619 (1985).
33) Aoki Y., Suzuki H., Akiyama H., Akano S., U.S. Patent, 3 876 659
(1975) [Chem. Abstr. 80, 95951z (1974)].
25) Price M. O., Sui J. K., Kurth M. J., Schore N. E., J. Org. Chem., 67, 34) Ohashi N., Ikeda T., Shimage K., Takakashi T., Ishizumi K., Eur.
8086—8089 (2002). Patent Appl., EP 84 377 (1983) [Chem. Abstr. 100, 34338q (1983)].
26) Zhao G., Hu J. B., Qian Z. S., Yin W. X., Tetrahedron: Asymmetry, 13, 35) Chen F. E., Huang Y. D., Fu H., Cheng Y., Zhang D. M., Li Y. Y., Peng
2095—2098 (2002). Z. Z., Synthesis, 2000, 2004—2008 (2000).
27) Itsuno S., Ito K., J. Chem, Soc, Perkin Trans I, 1984, 2887—2893 36) Chen F. E., Dai H. F., Kuang Y. Y., Jia H. Q., Tetrahedron: Asymmetry,
(1984). 14, 3667—3672 (2003).
28) Brown H. C., Jadhav P. K., Mandal A. K., Tetrahedron, 37, 3547— 37) Yamano T., Tokuyama S., Aoki I., Nishiguchi Y., Nakahama K.,
3587 (1981).
Takanohashi T., Bull. Chem. Soc. Jpn., 66, 1456—1460 (1993).
38) Hirata N., Miyamoto Y., Mizuno M., Takahashi T., Mizuno T., Jpn.
Kokai Tokkyo Koho JP 188247 (1996) [Chem. Abstr. 124, 8815u
(1996)].
29) Apsimo J. W., Sequin R. P., Tetrahedron, 35, 2797—2842 (1979).
30) Itsuno S., Matsumoto T., Sato D., Inoue T., J. Org. Chem., 65, 5879—
5881 (2000).
31) Felder M., Giffels G., Wandrey C., Tetrahedron: Asymmetry, 8,
1975—1977 (1997).
39) Takahash T., Minai M., Yamamoto T., Mizuno T., Miyamoto Y., Eur.
Pat. Appl., EP 0633 263 (1995) [Chem. Abstr. 122, 187270r (1995)].