Catalytic enantioselective synthesis of a novel inhibitor of ceramide trafficking, (1R,3R)-N-(3-hydroxy-1-hydroxymethyl-3-phenylpropyl)-dodecanamide (HPA-12)

Article abstract of DOI:10.1016/S0040-4039(01)01658-6

A novel inhibitor of ceramide trafficking, (1R,3R)-N-(3-hydroxy-1-hydroxymethyl-3-phenylpropyl)dodecanamide (HPA-12), has been synthesized using a chiral zirconium-catalyzed asymmetric Mannich-type reaction as a key-step.

Full text of DOI:10.1016/S0040-4039(01)01658-6

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 42 (2001) 7863–7865
Catalytic enantioselective synthesis of a novel inhibitor of
ceramide trafficking,
(1R,3R)-N-(3-hydroxy-1-hydroxymethyl-3-phenylpropyl)-
dodecanamide (HPA-12)
Masaharu Ueno,a,b Hidetoshi Kitagawa,a,b Haruro Ishitani,a,b Satoshi Yasuda,b,c
Kentaro Hanadab,c and Shu¯ Kobayashia,b,
*
aGraduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
bCREST, Japan Science and Technology Corporation, 4-1-8, Honchou, Kawaguchi-City, Saitama 332-0012, Japan
cDepartment of Biochemistry and Cell Biology, National Institute of Infectious Diseases ( former National Institute of Health),
Toyama, Shinjuku-ku, Tokyo 162-8640, Japan
Received 15 August 2001; revised 4 September 2001; accepted 5 September 2001
Abstract—A novel inhibitor of ceramide trafficking, (1R,3R)-N-(3-hydroxy-1-hydroxymethyl-3-phenylpropyl)dodecanamide
(HPA-12), has been synthesized using a chiral zirconium-catalyzed asymmetric Mannich-type reaction as a key-step. © 2001
Elsevier Science Ltd. All rights reserved.
Sphingolipid biosynthesis is now of great interest
because of its important roles in cell growth, differenti-
ation, and apotosis, etc.1 Enzymes that catalyze sphingo-
lipid biosynthesis are targets for chemists as well as
biologists to create new drugs. Our group has accom-
plished total synthesis of sphingofungin B,2 an inhibitor
of serinepalmitoyl transferase (SPT), and more recently,
khafrefungin,3 an inhibitor of inositol phosphoryl-
ceramide (IPC), and the structural relationship of bio-
logical activity has been clarified. In the course of our
investigations to search for a new molecule that shows
a characteristic property in sphingolipid biosynthesis,
we have found that (1R,3R)-N-(3-hydroxy-1-hydroxy-
methyl-3-phenylpropyl)dodecanamide (HPA-12, 1) is a
novel inhibitor of ceramide trafficking from endoplas-
mic reticulum to the site of sphingomyelin (SM) synthe-
sis. HPA-12 is the first compound of the specific
inhibitor for SM synthesis in mammalian cells, and a
potential drug that inhibits intracellular trafficking of
sphingolipids.4 In this report, we describe the first syn-
thesis of HPA-12 using a chiral zirconium-catalyzed
enantioselective Mannich reaction as a key-step.
OH
Zr(OtBu)4 (10 mol%)
HO
O
(R)-6,6'-Br2BINOL (22 mol%)
OSiMe3
SEt
RO
+
+
N-methylimidazole (12 mol%)
NH
O
H
H2N
MS4A (250 mg/mmol)
2
RO
SEt
CH2Cl2, -45 ˚C
3
R = Bn(3a) 39% yield, 54% ee.
R = TBDPS(3b) 71% yield, 16% ee.
R = TBS(3c) 47% yield, 80% ee.
Scheme 1.
Keywords: HPA-12; a novel inhibitor of ceramide trafficking; Mannich-type reaction; asymmetric reaction.
* Corresponding author.
0040-4039/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4039(01)01658-6

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M. Ueno et al. / Tetrahedron Letters 42 (2001) 7863–7865
In the initial and key-step, we examined the three-com-
ponent reaction of an a-alkoxy aldehyde, 2-amino-m-
cresol, and 1-ethylthio-1-trimethylsiloxyethene in the
presence of a catalytic amount of a chiral zirconium
complex prepared from zirconium tert-butoxide, (R)-
6,6%-Br2BINOL, and N-methylimidazole(Scheme 1).5 It
was found that the alkoxy part of the aldehyde signifi-
cantly influenced the enantioselectivity of the product,
and that a high level of selectivity was obtained when
the tert-butyldimethylsiloxy group was used. The ben-
zyloxy group and more bulky tert-butyldiphenylsiloxy
group gave much lower selectivity.
deprotection of the t-butyldimethylsiloxy group gave
the desired lactone 6 in high yield. Comparison of the
optical rotation of 6 with that in literature7 revealed
that the absolute configuration of Mannich adduct 3c
was R.
The preparation of HPA-12 from 3c was performed
according to the transformations shown in Scheme 3.
The adduct 4 was acylated under standard conditions
to give amide 7 in 81% yield. Conversion of 7 to ketone
8 was performed using diphenylcopper lithium in THF
at −15°C for 1 h. While the yield of 8 was moderate
(37%), 55% of the starting material (7) was recovered
(82% conversion yield). Anti-selective reduction of 8
proceeded using L-Selectride® in THF at −78°C (92%,
syn/anti=23/77).8 The use of lithium borohydride
instead of L-Selectride® gave lower selectivity (82%,
syn/anti=54/46). These selectivity would be explained
by the preferential conformation of 8.9 Finally, depro-
tection of the tert-butyldimethylsiloxy group of 9 using
tetrabutylammonium fluoride gave HPA-12 in 99%
yield. After recrystallization from ether/hexane, HPA-
12 was obtained in 96% ee.10
O
NH OH
HO
(1R,3R)-HPA-12 (1)
The absolute configuration of the product 3c6 was
determined after converting to literature-known lactone
6 as shown in Scheme 2. Treatment of 3c with cerium
ammoniumnitrate (CAN) in acetonitrile–water (3:1)
gave amine-free adduct 4 in 61% yield. t-Butoxycar-
bonyl (Boc) protection of the amino group followed by
Thus, HPA-12, a novel inhibitor of ceramide traffick-
ing, has been synthesized using a chiral zirconium-cata-
lyzed Mannich-type reaction as a key-step. Based on
OH
CAN (2.2 eq.)
NH2
O
Boc2O (2.0 eq.)
CH3CN:H2O = 3:1
TBSO
NH
O
CH2Cl2, rt
84%
SEt
0 °C, 0.5 h
TBSO
4
SEt
61%
3c
BocHN
Boc
O
TBAF (2.0 eq.)
HN
TBSO
O
THF, 0 °C
O
SEt
80%
6
5
[α]D26+47.2 (c 0.43, EtOH, 80% ee)
(lit.7)(S): [α]D25-61 (c 1.0, EtOH))
Scheme 2.
O
C11H23COCl
NEt3
Ph2CuLi (2.0 eq.)
THF, -15 °C, 1 h
NH
O
4
CH2Cl2, rt
81%
37%
55% recovery
TBSO
SEt
7
O
O
L-Selectride® (3.0 eq.)
NH OH
Ph
NH
O
THF, -78 °C, 1 h
92% (Syn/Anti = 23/77)
7% recovery
TBSO
TBSO
Ph
9
8
O
TBAF (2.0 eq.)
NH OH
Ph
THF, 0 °C, 10 min
HO
(1R,3R)-HPA-12 (1)
99%
Scheme 3.

M. Ueno et al. / Tetrahedron Letters 42 (2001) 7863–7865
7865
O
O
MeI
Ag2O
conc. HCl aq.
MeOH, reflux
NH OH
Ph
NH OH
Ph
HO
MeO
MeO
HN
O
H
NH2 OH
Ph
HN
O
CDI
H
O
Ph
MeO
MeO
DMF
Ph
H
O
H
J = 4.8, 11.7 Hz
J = 2.2, 11.7 Hz
Scheme 4.
this synthetic scheme, we have synthesized all four
stereoisomers of HPA-12, and confirmed that only the
(1R,3R)-isomer showed high activity.4 Further investi-
gations to search for more active compounds as well as
to clarify biological aspects of the inhibition are now in
progress.
6. Compound 3c: [h]2D1 +8.26 (c 1.23, CHCl3, 80% ee); IR
(neat): 3358, 2928, 2856, 1680, 1589, 1476, 1254, 836
cm−1 1H NMR (CDCl3): l 0.00 (s, 6H), 0.85 (s, 9H),
;
1.18 (t, 3H, J=7.4 Hz), 2.18 (s, 3H), 2.66 (dd, 1H,
J=4.7, 13.9 Hz), 2.82 (q, 2H, J=7.5 Hz), 2.85 (m,
1H), 3.40 (dd, 1H, J=3.6, 8.2 Hz), 3.45–3.56 (m, 2H),
6.56 (dd, 1H, J=0.7, 7.2 Hz), 6.68 (dd, 1H, J=1.3, 7.2
Hz), 6.79 (t, 1H, J=7.7 Hz); 13C NMR (CDCl3): l
−5.6, −5.5, 14.6, 17.6, 18.3, 23.6, 25.9, 46.1, 55.7, 64.0,
113.5, 121.6, 124.8, 131.5, 132.4, 152.1, 199.7; HPLC:
Daicel Chiralpak AD, hexane/iPrOH=200/1, flow rate=
1.0 ml/min: tR=16.5 min (3R), tR=20.3 min (3S);
HRMS: calcd for C19H33NO3SSi (M+) 383.1950, found
383.1932.
Acknowledgements
This work was partially supported by a Grant-in-Aid
for Scientific Research from the Ministry of Education,
Science, Sports, and Culture, Japan. M.U. thanks the
JSPS fellowship for Japanese Junior Scientists.
7. Nitta, H.; Ueda, I.; Hatanaka, M. J. Chem. Soc.,
Perkin Trans. 1 1997, 1973.
8. The stereochemical assignment of the syn-adduct was
performed by 1H NMR analysis after converting to the
3,4,5,6-tetrahydro-1,3-oxazin-2-one (Scheme 4).
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96% ee); IR (neat): 3293, 2919, 2849, 1643, 1551, 1493,
1
1054, 746 cm−1; H NMR (CDCl3): l 0.88 (t, 3H, J=6.8
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1H, J=6.6, 8.5, 15.1 Hz), 2.03 (ddd, 1H, J=3.6, 5.7, 14.6
Hz), 2.15 (t, 2H, J=7.7 Hz), 3.65 (ddd, 1H, J=4.1, 11.3,
15.5 Hz), 4.01–4.08 (m, 1H), 4.79 (dd, 1H, J=3.4, 8.8
Hz), 6.48 (d, 1H, J=6.8 Hz), 7.23–7.36 (m, 5H); 13C
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29.6, 29.6, 31.9, 36.8, 40.7, 50.4, 65.5, 71.8, 125.5, 127.7,
128.5, 144.2, 174.3; HPLC: Daicel Chiralpak AD, hex-
t
ane/iPrOH=19/1, flow rate=1.0 ml/min: R=11.4 min
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(1S,3S), tR=15.0 min (1R,3R); HRMS: calcd for
C22H37NO3 (M+) 363.2273, found 363.2279.