A straightforward protocol for the solution-phase parallel synthesis of ceramide analogues

Article abstract of DOI:10.1002/ejoc.200700814

A simple solution-phase protocol for the synthesis of ceramide analogues from easily accessible enantiopure scaffolds is disclosed. The method relies on the use of nucleophilic thiolates or phenoxides and appropriate supported reagents or scavengers to gi

Full text of DOI:10.1002/ejoc.200700814

FULL PAPER
DOI: 10.1002/ejoc.200700814
A Straightforward Protocol for the Solution-Phase Parallel Synthesis of
Ceramide Analogues
Santiago Grijalvo,[a,b] Xavier Matabosch,[a] Amadeu Llebaria,[a] and Antonio Delgado*[a,b]
Keywords: Ceramide analogues / Amino alcohols / Scavengers / Supported reagents / Combinatorial chemistry
A simple solution-phase protocol for the synthesis of ceram-
ide analogues from easily accessible enantiopure scaffolds is
disclosed. The method relies on the use of nucleophilic thio-
lates or phenoxides and appropriate supported reagents or
scavengers to give the target compounds in good overall
yields. The method is easily adaptable to combinatorial pro-
tocols and also amenable to automated processes for the gen-
eration of small-to-medium-sized libraries for further screen-
ing.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
synthesis and metabolism. In order to better understand the
biological and biophysical roles of sphingolipids, many ef-
Introduction
Sphingolipids are an important group of biomolecules that forts have been made to design analogues to enable a de-
play important functions in the regulation of many cell tailed study of the structure–activity relationships.[3] Very
functions and also as cell membrane components.[1] From recently, we reported on a new class of sphingosine-1-phos-
a structural standpoint, they all share a sphingoid base con- phate and ceramide analogues that incorporate a bioiso-
sisting of a 2-amino-1,3-diol core and an unsaturated hy- steric sulfur atom as part of the sphingoid backbone.[4,5] On
drocarbon chain.[2] N-Acylation of the sphingoid base leads the basis of these precedents, we became interested in “sec-
to ceramide, which plays a pivotal role in sphingolipid bio- ond generation” analogues containing both a sulfur atom
–
Scheme 1. Reagents and conditions: (a) R1SH (A–C) or R1OH (D), NaH, DMF, 60–90 °C; (b) 20% TFA/DCM, r.t.; (c) IRA900 (NaCO3
form), EtOAc, r.t.; (d) Amberlyst A15, DCM, r.t.; (e) MeOH/NH3, r.t.; (f) PS-EDC, R2COOH (a–c), solvent, r.t.; (g) Amberlyst A21,
DCM, r.t.
[a] Research Unit on BioActive Molecules (RUBAM), De-
and the 3-hydroxy motif present in natural sphingolipids. In
partament de Química Orgànica Biològica, Institut d’Investiga-
addition, the possibility to gain access to oxygen analogues
cions Químiques i Ambientals de Barcelona (IIQAB-C.S.I.C),
Jordi Girona 18–26, 08034 Barcelona, Spain
Fax: +34-932-045-904
E-mail: adelgado@cid.csic.es
seemed also promising for structure–activity studies.
Combinatorial chemistry has become a useful tool for
the discovery and development of new bioactive com-
pounds. An efficient combinatorial approach for library
generation and high-throughput screening requires minimal
methodological complexity with maximal synthetic effi-
[b] Universitat de Barcelona, Facultat de Farmàcia, Unitat de
Química Farmacèutica (Unitat Associada al CSIC),
Avgda. Juan XXIII, s/n, 08028 Barcelona, Spain
Supporting information for this article is available on the
WWW under http://www.eurjoc.org or from the author.
150
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2008, 150–155

Protocol for the Solution-Phase Parallel Synthesis of Ceramide Analogues
ciency. In this context, the use of classical solution-phase
It is worth mentioning that the overall three-step process
methods has gained new impetus with the use of solid-sup- can be carried out without isolation of any of the synthetic
ported reagents and scavengers.[6] In this context, we have intermediates leading ultimately to the target compounds in
developed a fast and reliable methodology, amenable to high purities and acceptable yields. Workup protocols are
combinatorial protocols, to gain access to the new families reduced to a minimum with the help of supported scaven-
of ceramide analogues 1 and 2 (Scheme 1). Interestingly, de- gers and reagents (Scheme 1).
spite the fact that we[7] and others[8,9] have recently reported
The reaction took place both with aliphatic and aromatic
on combinatorial approaches to the synthesis of these kinds thiols A–C and carboxylic acids a–c with different steric
of analogues, examples in the literature on this topic are and/or electronic demands. Nucleophilic displacement of
still scarce.
the tosyloxy group in 3 or epoxide opening in 5 was carried
out by the corresponding thiolates, which were generated in
situ under basic conditions.[5] Acetonide hydrolysis and N-
Boc removal was carried out simultaneously in acidic me-
Results and Discussion
The methodology here reported starts from enantiopure dium (TFA/DCM) to afford corresponding amines 4 and 6
scaffolds 3[5] and 5,[10] which are easily available from Gar- (trifluoroacetate salts), together with the excess thiol of the
ner aldehyde following described methods. To exemplify the previous step. Purification at this stage was carried out by
versatility of our synthetic protocol, the above scaffolds amine deprotonation with Amberlyst A21 resin (sodium
were treated with thiols A–C and carboxylic acids a–c to carbonate form) and subsequent capture of the free amine
afford a small test library in excellent purities and good with the sulfonic acid resin A15.[11,17] Amines 4 and 6 were
overall yields (Table 1, Scheme 1).
finally released by treatment with 2  NH3 in MeOH, fil-
Table 1. Solution-phase synthesis of Cer analogues by using solid-supported reagents and scavengers.
Entry
Scaffold
R1SH
R2COOH
Compound
Yield [%]
1
2
3
CH3(CH2)5COOH (a)
(CH3)3CCOOH (b)
p-tBuPhCOOH (c)
1Aa
1Ab
1Ac
80
75
83
CH3(CH2)13SH (A)
4
5
6
CH3(CH2)5COOH (a)
(CH3)3CCOOH (b)
p-tBuPhCOOH (c)
1Ca
1Cb
1Cc
75
90
68
3
2-naphthyl-SH (C)
7
8
9
CH3(CH2)5COOH (a)
(CH3)3CCOOH (b)
p-tBuPhCOOH (c)
1Da
1Db
1Dc
65
72
63
p-(CH3O(CH2)2Ph-OH (D)
CH3(CH2)12SH (B)
10
11
12
CH3(CH2)5COOH (a)
(CH3)3CCOOH (b)
p-tBuPhCOOH (c)
2Ba
2Bb
2Bc
69
79
69
13
14
15
CH3(CH2)5COOH (a)
(CH3)3CCOOH (b)
p-tBuPhCOOH (c)
2Ca
2Cb
2Cc
62
88
52
5
2-naphthyl-SH (C)
16
17
18
CH3(CH2)5COOH (a)
(CH3)3CCOOH (b)
p-tBuPhCOOH (c)
2Da
2Db
2Dc
65[a]
72[a]
63[a]
p-[CH3O(CH2)2]Ph-OH (D)
[a] Overall yield including hydrolysis of 7 to give 6 (see Scheme 2).
Scheme 2. Reagents and conditions: (a) NaH, p-[CH3O(CH2)2]Ph-OH (D), DMF, followed by steps b–e (Scheme 1); (b) 2  NaOH/EtOH,
80 °C; (c) PS-EDC, R2COOH (a–c), CHCl3/tBuOH, r.t.; (d) Amberlyst A21, DCM, r.t.
Eur. J. Org. Chem. 2008, 150–155
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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151

S. Grijalvo, X. Matabosch, A. Llebaria, A. Delgado
FULL PAPER
tration, and concentration.[12] Acylations were carried out
by coupling the product with the corresponding carboxylic
acid in the presence of polymer-supported EDC (PS-EDC)
in DCM at room temperature.[13] Only N-acylation com-
General Method for the Synthesis of Libraries 1 and 2: A solution
of the corresponding thiol or phenol (0.25 mmol) in DMF (0.5 mL)
was added dropwise to a suspension of NaH (ca. 60% dispersion
in mineral oil, 12 mg, equivalent to 7 mg, 0.25 mmol) in DMF
(0.5 mL) at room temperature. After 10 min, the resulting mixture
was transferred by cannula to a solution of tosylate 3 (65 mg,
0.17 mmol) or epoxide 5 (45 mg, 0.18 mmol) in DMF (0.5 mL).
The reaction mixture was stirred at 60–80 °C for 2 h, cooled to
room temperature, and the solvents evaporated to dryness. The re-
sulting residue was taken up in DCM (0.5 mL), treated with TFA
1
pounds were observed by H NMR spectroscopic analysis
of the crude mixtures, and no trace amounts of O-acylated
compounds were observed. Excess carboxylic acid was re-
moved with the help of amino resin A21.[14]
Attempts to widen the reaction scope to phenoxides by
taking phenol D as a model were also successful from tosyl- in DCM (20% solution, 1.0 mL), and stirred at room temperature
for 10 min. The solvent was next removed under vacuum to afford
crude amino alcohols as the corresponding trifluoroacetate salts.
The residue was taken up in EtOAc (1 mL) and treated with IRA
900 resin (sodium carbonate form, 600 mg, equivalent to 2.0 mmol,
based on resin loading). After 1 h stirring, the resin was filtered off
and washed thoroughly with EtOAc (3ϫ5.0 mL). The combined
filtrates were concentrated under vacuum, and the residue was
taken up in DCM (3 mL). Amberlyst A15 resin (400 mg, equivalent
to 2.0 mmol based on resin loading) was next added to the solution,
and the mixture was stirred until disappearance of the amino
alcohol (checked by TLC). The reaction mixture was filtered; the
resin was suspended in a solution of NH3 (2  in MeOH, 5 mL)
and agitated overnight. The resin was filtered off and washed thor-
oughly with additional NH3 (2  in MeOH, 3ϫ2.0 mL). The fil-
ate 3, which led to corresponding analogues 1D(a–d) in
good yields (Table 1). However, application of the above
protocol to epoxide 5 led to oxazolidinone 7,[15] which re-
quired a subsequent hydrolytic cleavage to 6D for further
amidation under the above conditions (Scheme 2). Never-
theless, although this additional step did not substantially
affect the overall reaction yields (Table 1, Entries 16–18),
the required isolation of 7 precludes the applicability of the
above one-pot protocol.
Conclusions
A simple solution-phase protocol for the synthesis of cer- trates were collected, and the solvents were evaporated to dryness
to give amino alcohols 4(A,C,D), 6(B,D) (see Scheme 1) or 7 (see
Scheme 2).
amide analogues 1 and 2 from scaffolds 3 and 5 is disclosed.
The method relies on the use of nucleophilic thiolates or
phenoxides and the appropriate supported reagents or scav-
engers to obtain the target compounds in good overall
yields. The method here reported is easily adaptable to com-
Acylation step: A suspension of PS-EDC (250 mg, 0.35 mmol
based on resin loading, previously swollen in 1 mL of CHCl3 for
20 min) and the corresponding carboxylic acid (0.3 mmol) in
binatorial protocols and also amenable to automated pro- CHCl3 (0.5 mL) was stirred for 20 min. A solution of the above
amino alcohols in DCM (1 mL, for amino alcohols 4) or tBuOH
(for amino alcohols 6) was next added over the above suspension.
After stirring for 16 h at room temperature, PS-EDC was filtered
off and washed thoroughly with DCM (3ϫ2.0 mL). The combined
filtrates and washings were next treated with Amberlyst A21
(400 mg, equivalent to 2.0 mmol based on resin loading) and stirred
until disappearance of the carboxylic acid (checked by TLC). The
resin was filtered off and washed with additional DCM
(3ϫ2.0 mL). The combined filtrates were evaporated to dryness to
afford the corresponding ceramide analogues 1(A,C,D)(a–c) and
2(B,C,D)(a–c).
cesses for the generation of small-to-medium-sized libraries
for further screening.
Experimental Section
General Methods: Unless otherwise specified, all moisture-sensitive
reactions were handled under an argon atmosphere. All the materi-
als were obtained commercially and used without further purifica-
tion. Solvents were distilled prior to use and dried by standard
methods.[16] Analytical samples were homogeneous as confirmed
by TLC and afforded spectroscopic results consistent with the as-
signed structures. Melting points were determined with a SMP10
melting point apparatus and are uncorrected. Chemical shifts are
reported in parts per million (ppm) relative to the singlet at δ =
(S)-N-[1-Hydroxy-3-(tetradecylthio)propan-2-yl]heptanamide (1Aa):
1
Yield: 56 mg, 80%. H NMR (400 MHz, CDCl3): δ = 6.07 (br. d,
1 H), 4.03 (m, 1 H), 3.78 (dd, J = 4.9 Hz, JЈ = 11.1 Hz, 1 H), 3.69
(dd, J = 3.7 Hz, JЈ = 11.1 Hz, 1 H), 2.71 (m, 2 H), 2.52 (m, 2 H),
2.21 (t, J = JЈ = 7.4 Hz, 2 H), 1.62 (m, 2 H), 1.56 (m, 2 H), 1.27
(m, 26 H), 0.87 (m, 6 H) ppm. 13C NMR (125 MHz, CDCl3): δ =
174.3, 64.6, 50.9, 37.0, 33.3, 32.7, 32.1, 31.7, 29.9, 29.9, 29.8, 29.8,
29.7, 29.5, 29.4, 29.1, 29.0, 25.8, 22.9, 22.7, 14.3, 14.2 ppm. IR
1
7.24 ppm of CHCl3 and 3.31 ppm of MeOH for H NMR and to
the centre line of the triplet at δ = 77.0 ppm of CDCl3 and
49.0 ppm of MeOD for 13C NMR. IR spectra were measured in
film and were recorded with a BOMEM MB-120. [α]D values are
given in 10–1 degcm2 g–1 and were measured with a Perkin–Elmer
341 polarimeter. Thin-layer chromatography (TLC) was performed
on silica gel (Alugram Sil G/UV). The following resins were used
(film): ν = 3230, 2954, 2923, 2856, 1705, 1592, 1459, 1182, 808,
˜
745, 719 cm–1. HRMS: calcd. for C24H50NO2S 416.3562; found
416.3565. [α]D = +15.4 (c = 1.0, CHCl3).
–
in this study: IRA900 (Fluka, ref 21850, 3.5 mmolg–1 NaCO3
loading), Amberlyst A15 (Fluka, ref 06423, 4.7 meqg–1), and PS-
EDC (Fluka, ref 09657, 1.4 mmolg–1). Amberlyst A21 (Aldrich, ref
216410, alkylamine, 4.7 meqmL–1). Amberlite IR120 (Aldrich, ref
216534, 4.4 meqg–1) was cleaned by washing several times with
aqueous 1  HCl and rinsed with water until neutral pH, followed
by drying in vacuo for 15 h. Amberlyst A15 resin was conditioned
as described in the literature.[17] Amberlyst A21, IRA900, and PS-
EDC resins were used as received.
(S)-N-[1-Hydroxy-3-(tetradecylthio)propan-2-yl]pivaloylamide (1Ab):
Yield: 49 mg, 75%. H NMR (400 MHz, CDCl3): δ = 6.32 (br. d,
1
1 H), 3.98 (m, 1 H), 3.77 (dd, J = 11.1 Hz, JЈ = 5.0 Hz, 1 H), 3.68
(dd, J = 11.1 Hz, JЈ = 3.3 Hz, 1 H), 2.72 (m, 2 H), 2.52 (m, 2 H),
1.56 (m, 2 H), 1.24 (m, 20 H), 1.21 (s, 9 H), 0.86 (t, J = 6.9 Hz, 3
H) ppm. 13C NMR (125 MHz, CDCl3): δ = 179.8, 65.0, 50.9, 39.1,
33.2, 32.5, 32.1, 29.9, 29.9, 29.8, 29.8, 29.7, 29.5, 29.4, 29.0, 27.7,
22.9, 14.3 ppm. IR (film): ν = 3376, 2926, 2854, 1641, 1509,
˜
152
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Eur. J. Org. Chem. 2008, 150–155

Protocol for the Solution-Phase Parallel Synthesis of Ceramide Analogues
1461 cm–1. HRMS: calcd. for C22H46NO2S 388.3249; found
388.3240. [α]D = +8.38 (c = 1.0, CHCl3).
for C19H32NO4 338.2331; found 338.2336. [α]D = –16.8 (c = 1.0,
CHCl3).
(S)-4-tert-Butyl-N-[1-hydroxy-3-(tetradecylthio)propan-2-yl]benz- (S)-N-{1-Hydroxy-3-[4-(2-methoxyethyl)phenoxy]propan-2-yl}pival-
1
1
amide (1Ac): Yield: 65.5 mg, 83%. H NMR (400 MHz, CDCl3): δ
oylamide (1Db): Yield: 38 mg, 72%. H NMR (300 MHz, CDCl3):
= 7.74 (d, J = 8.39 Hz, 2 H), 7.45 (d, J = 8.35 Hz, 2 H), 6.81 (br.
δ = 7.14 (d, J = 8.6 Hz, 2 H), 6.84 (d, J = 8.6 Hz, 2 H), 6.36 (br.,
d, 1 H), 4.23 (m, 1 H), 3.91 (dd, J = 11.2 Hz, JЈ = 4.9 Hz, 1 H), 1 H), 4.23 (m, 1 H), 4.13 (dd, J = 9.6 Hz, JЈ = 4.1 Hz, 1 H), 4.06
3.80 (dd, J = 11.2 Hz, JЈ = 3.7 Hz, 1 H), 2.83 (m, 2 H), 2.56 (t, J
= JЈ = 7.4 Hz, 2 H), 1.58 (m, 2 H), 1.32 (s, 9 H), 1.24 (m, 22 H),
(dd, J = 9.6 Hz, JЈ = 4.9 Hz, 1 H), 3.91 (dd, J = 11.2 Hz, JЈ =
4.5 Hz, 1 H), 3.76 (dd, J = 11.2 Hz, JЈ = 4.7 Hz, 1 H), 3.55 (t, J =
0.87 (t, J = JЈ = 7.4 Hz, 3 H) ppm. 13C NMR (125 MHz, CDCl3): JЈ = 7.0 Hz, 2 H), 3.34 (s, 3 H), 2.81 (t, J = JЈ = 7.0 Hz, 2 H), 1.20
δ = 168.2, 155.5, 131.3, 127.1, 125.7, 64.8, 51.3, 35.1, 33.4, 32.7,
(s, 9 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 179.2, 156.6, 131.8,
32.1, 31.3, 30.0, 29.9, 29.8, 29.8, 29.8, 29.7, 29.5, 29.4, 29.0, 22.9,
129.8, 114.4, 73.6, 67.2, 62.8, 58.5, 50.3, 38.7, 35.1, 27.4 ppm. IR
14.3 ppm. IR (film): ν = 3423, 2961, 2870, 1718, 1640, 1532, 1499,
(film): ν = 3376, 2964, 2934, 2869, 2358, 1647, 1509, 1465, 1240,
˜
˜
1463, 1211, 1071, 851, 813, 756 cm–1. HRMS: calcd. for
1110, 1045, 824 cm–1. HRMS: calcd. for C17H28NO4 310.2018;
C28H50NO2S 464.3562; found 464.3552. [α]D = +47.3 (c = 1.0, found 310.2011. [α]D = –14.5 (c = 1.0, CHCl3).
CHCl3).
(S)-4-tert-Butyl-N-{1-hydroxy-3-[4-(2-methoxyethyl)phenoxy]propan-
(S)-N-[1-Hydroxy-3-(2-naphthylthio)propan-2-yl]heptanamide (1Ca):
Yield: 44 mg, 75%. H NMR (400 MHz, CDCl3): δ = 7.87 (d, J =
1.5 Hz, 1 H), 7.77 (m, 3 H), 7.45 (m, 3 H), 6.08 (br. d, 1 H), 4.12
2-yl}benzamide (1Dc): Yield: 41 mg, 63 %. 1H NMR (400 MHz,
CDCl3): δ = 7.73 (d, J = 8.5 Hz, 2 H), 7.45 (d, J = 8.5 Hz, 2 H),
7.15 (d, J = 8.6 Hz, 2 H), 6.88 (d, J = 8.6 Hz, 2 H), 6.82 (br., 1 H),
1
(m, 1 H), 3.88 (dd, J = 11.2 Hz, JЈ = 4.5 Hz, 1 H), 3.70 (dd, J = 4.49 (m, 1 H), 4.22 (dd, J = 9.5 Hz, JЈ = 4.0 Hz, 2 H), 4.04 (dd, J
11.2 Hz, JЈ = 3.8 Hz, 1 H), 3.28 (dd, J = 13.9 Hz, JЈ = 6.2 Hz, 1
H), 3.23 (dd, J = 13.9 Hz, JЈ = 6.8 Hz, 1 H), 2.10 (t, J = JЈ =
= 11.2 Hz, JЈ = 4.4 Hz, 1 H), 3.88 (dd, J = 11.5 Hz, JЈ = 4.9 Hz, 1
H), 3.55 (t, J = JЈ = 7.0 Hz, 2 H), 3.34 (s, 3 H), 2.82 (t, J = JЈ =
8.1 Hz, 2 H), 1.53 (m, 2 H), 1.24 (m, 6 H), 0.86 (t, J = JЈ = 6.8 Hz, 7.0 Hz, 2 H), 1.65 (br., 1 H), 1.32 (s, 9 H) ppm. 13C NMR
3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 174.2, 133.9, 132.8,
(125 MHz, CDCl3): δ = 167.7, 156.6, 155.2, 131.9, 131.0, 129.8,
132.1, 128.9, 127.9, 127.5, 127.4, 127.3, 126.9, 126.1, 63.7, 51.1,
126.8, 125.4, 114.3, 73.6, 67.4, 62.9, 58.5, 50.7, 35.1, 34.8, 31.0,
36.9, 34.4, 31.6, 29.0, 25.8, 22.7, 14.2 ppm. IR (film): ν = 3269,
29.6 ppm. IR (film): ν = 3389, 2967, 2934, 2872, 1641, 1611, 1536,
˜
˜
2957, 2928, 2858, 2360, 1646, 1538, 1459, 1069, 1036, 812, 1510, 1461, 1235, 1107, 1039, 750 cm–1. MS (ESI): m/z = 404 [M
741 cm–1. HRMS: calcd. for C20H28NO2S 346.1841; found
+ 23]+. HRMS: calcd. for C23H32NO4 386.2331; found 386.2332.
346.1835. [α]D = +15.9 (c = 1.0, CHCl3).
[α]D = –19.3 (c = 1.0, CHCl3).
(S)-N-[1-Hydroxy-3-(2-naphthylthio)propan-2-yl]pivaloylamide (1Cb):
Yield: 48.5 mg, 90%. H NMR (500 MHz, CDCl3): δ = 7.88 (m, 1
H), 7.78 (m, 3 H), 7.47 (m, 3 H), 6.29 (br. d, 1 H), 4.11 (m, 1 H),
3.88 (dd, J = 11.1 Hz, JЈ = 4.6 Hz, 1 H), 3.72 (dd, J = 4.0 Hz, JЈ
= 11.1 Hz, 1 H), 3.28 (m, 2 H), 1.15 (s, 9 H) ppm. 13C NMR
(2ЈS,3ЈS)-N-[1,3-Dihydroxy-4-(tridecylthio)-2-butyl]heptanamide
(2Ba): Yield: 53.5 mg, 69%. 1H NMR (400 MHz, CDCl3): δ = 6.37
(br., 1 H), 4.00 (dd, J = 11.5 Hz, JЈ = 3.0 Hz, 1 H), 3.94 (m, 1 H),
3.82 (m, 1 H), 3.68 (dd, J = 11.5 Hz, JЈ = 3.5 Hz, 1 H), 2.79 (m, 1
H), 2.59 (m, 1 H), 2.51 (m, 2 H), 2.22 (t, J = JЈ = 7.4 Hz, 2 H),
1
(125 MHz, CDCl3): δ = 179.6, 133.9, 132.8, 132.1, 129.0, 127.9, 1.63 (m, 2 H), 1.56 (m, 2 H), 1.24 (m, 26 H), 0.87 (t, J = JЈ =
127.7, 127.4, 126.9, 126.2, 64.0, 51.1, 39.0, 34.6, 27.6 ppm. IR 6.8 Hz, 3 H), 0.86 (t, J = JЈ = 7.0 Hz, 3 H) ppm. 13C NMR
(film): ν = 3327, 2965, 2933, 2364, 1636, 1510, 1202, 1071, 812, (125 MHz, CDCl3): δ = 173.8, 71.5, 62.2, 53.3, 37.1, 37.0, 32.2,
˜
738 cm–1. HRMS: calcd. for C18H24NO2S 318.1528; found
32.1, 31.7, 29.9, 29.8, 29.8, 29.7, 29.5, 29.4, 29.1, 29.0, 25.9, 22.9,
318.1537. [α]D = +26.1 (c = 1.0, CHCl3).
22.7, 14.3, 14.2 ppm. IR (film): ν = 3674, 3295, 2920, 2851, 2360,
˜
1747, 1635, 1536, 1433, 1359 cm–1. HRMS: calcd. for C24H50NO3S
(S)-4-tert-Butyl-N-[1-hydroxy-3-(2-naphthylthio)propan-2-yl]benz-
amide (1Cc): Yield: 45.5 mg, 68 %. M.p. 120 °C. 1H NMR
(400 MHz, CDCl3): δ = 7.90 (m, 1 H), 7.75 (m, 4 H), 7.49 (d, J =
8.60 Hz, 2 H), 7.45 (m, 2 H), 7.25 (d, J = 8.60 Hz, 2 H), 6.75 (br.,
432.3511; found 432.3498. [α]D = +2.2 (c = 1.0, CHCl3).
(2ЈS,3ЈS)-N-[1,3-Dihydroxy-4-(tridecylthio)-2-butyl]pivaloylamide
1
(2Bb): Yield: 57 mg, 79%. H NMR (400 MHz, CDCl3): δ = 6.55
1 H), 4.34 (m, 1 H), 3.93–3.80 (m, 2 H), 3.34 (m, 2 H), 1.27 (s, 9 (br., 1 H), 4.00 (dd, J = 11.5 Hz, JЈ = 3.1 Hz, 1 H), 3.91 (m, 1 H),
H) ppm. 13C NMR (125 MHz, CDCl3): δ = 167.8, 155.2, 133.6,
132.6, 131.9, 130.7, 128.7, 127.5, 127.1, 126.7, 125.9, 125.2, 63.3,
3.82 (m, 1 H), 3.68 (dd, J = 11.5 Hz, JЈ = 3.6 Hz, 1 H), 2.76 (m, 1
H), 2.60 (m, 1 H), 2.52 (m, 2 H), 1.56 (m, 2 H), 1.24 (m, 20 H),
1.22 (s, 9 H), 0.87 (t, J = JЈ = 6.6 Hz, 3 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 179.2, 71.5, 62.3, 53.6, 39.0, 37.1, 37.0,
32.2, 32.1, 30.0, 29.9, 29.8, 29.8, 29.7, 29.7, 29.5, 29.4, 29.0, 27.7,
51.5, 34.7, 31.6, 30.9 ppm. IR (film): ν = 3423, 2961, 2870, 1718,
˜
1640, 1532, 1499, 1463, 1211, 1071, 851, 813, 756 cm–1. MS (ESI):
m/z = 416.5 [M + 23]+. HRMS: calcd. for C24H28NO2S 394.1841;
found 394.1838. [α]D = +47.38 (c = 1.0, CHCl3).
22.9, 14.3 ppm. IR (film): ν = 3233, 3134, 2923, 2853, 2360, 1637,
˜
1586, 1537, 1456, 1371, 1082 cm–1. HRMS: calcd. for C22H46NO3S
(S)-N-{1-Hydroxy-3-[4-(2-methoxyethyl)phenoxy]propan-2-yl}hep-
404.3198; found 404.3183. [α]D = +2.6 (c = 1.0, CHCl3).
1
tanamide (1Da): Yield: 37 mg, 65%. H NMR (400 MHz, CDCl3):
δ = 7.14 (d, J = 8.7 Hz, 2 H), 6.84 (d, J = 8.7 Hz, 2 H), 6.18 (br.,
1 H), 4.27 (m, 1 H), 4.12 (dd, J = 9.5 Hz, JЈ = 4.1 Hz, 1 H), 4.05
(dd, J = 9.5 Hz, JЈ = 4.7 Hz, 1 H), 3.92 (dd, J = 11.2 Hz, JЈ =
4.5 Hz, 1 H), 3.77 (dd, J = 11.2 Hz, JЈ = 4.7 Hz, 1 H), 3.55 (t, J =
(2ЈS,3ЈS)-4-tert-Butyl-N-[1,3-dihydroxy-4-(tridecylthio)-2-butyl]benz-
amide (2Bc): Yield: 59.5 mg, 69%. H NMR (400 MHz, CDCl3): δ
= 7.76 (d, J = 8.5 Hz, 2 H), 7.45 (d, J = 8.5 Hz, 2 H), 7.07 (br., 1
H), 4.15 (m, 1 H), 4.11 (m, 1 H), 3.96 (m, 1 H), 3.81 (dd, J =
1
JЈ = 7.0 Hz, 2 H), 3.34 (s, 3 H), 2.81 (t, J = JЈ = 7.0 Hz, 2 H), 2.21 11.5 Hz, JЈ = 3.5 Hz, 1 H), 2.79 (m, 2 H), 2.54 (m, 2 H), 1.56 (m,
(t, J = JЈ = 7.4 Hz, 2 H), 1.62 (m, 2 H), 1.27 (m, 6 H), 0.86 (t, J 2 H), 1.33 (s, 9 H), 1.24 (m, 20 H), 0.87 (t, J = JЈ = 6.7 Hz, 3
= JЈ = 6.7 Hz, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 174.1,
H) ppm. 13C NMR (CDCl3, 400 MHz): δ = 167.7, 155.6, 131.2,
156.8, 132.1, 130.1, 114.6, 73.9, 67.6, 63.2, 58.8, 50.6, 36.9, 35.4,
127.1, 125.7, 71.6, 62.3, 53.9, 35.1, 32.1, 31.4, 31.3, 29.9, 29.8, 29.8,
31.7, 29.1, 25.8, 22.7, 14.2 ppm. IR (film): ν = 3293, 2924, 2857,
29.7, 29.7, 29.5, 29.4, 29.0, 22.9, 14.3 ppm. IR (film): ν = 3668,
˜
˜
2365, 2332, 1637, 1536, 1511, 1462, 1238, 1047 cm–1. HRMS: calcd.
2922, 2851, 2359, 1716, 1608, 1538, 1425, 1360 cm–1. HRMS: calcd.
Eur. J. Org. Chem. 2008, 150–155
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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153

S. Grijalvo, X. Matabosch, A. Llebaria, A. Delgado
FULL PAPER
for C28H50NO3S 480.3511; found 480.3507. [α]D = +4.2 (c = 1.0,
CHCl3).
(400 MHz, CDCl3): δ = 7.75 (d, J = 7.6 Hz, 2 H), 7.46 (d, J =
8.2 Hz, 2 H), 7.14 (d, J = 8.2 Hz, 2 H), 7.09 (br., 1 H), 6.85 (d, J
= 8.1 Hz, 2 H), 4.31 (m, 1 H), 4.27 (m, 1 H), 4.13 (m, 1 H), 4.09
(m, 2 H), 3.85 (m, 1 H), 3.55 (t, J = JЈ = 6.9 Hz, 2 H), 3.34 (s, 3
H), 2.81 (t, J = JЈ = 6.9 Hz, 2 H), 1.32 (s, 9 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 168.4, 156.6, 155.8, 132.3, 130.2, 130.1,
127.1, 125.8, 114.7, 73.9, 71.9, 69.4, 62.5, 58.8, 53.4, 35.4, 31.4,
(2ЈS,3ЈS)-N-[1,3-Dihydroxy-4-(2-naphthylthio)-2-butyl]heptanamide
1
(2Ca): Yield: 42 mg, 62%. H NMR (400 MHz, CDCl3): δ = 6.37
(br., 1 H), 4.00 (dd, J = 11.5 Hz, JЈ = 3.0 Hz, 1 H), 3.94 (m, 1 H),
3.82 (m, 1 H), 3.68 (dd, J = 11.5 Hz, JЈ = 3.5 Hz, 1 H), 2.79 (m, 1
H), 2.59 (m, 1 H), 2.51 (m, 2 H), 2.22 (t, J = JЈ = 7.4 Hz, 2 H),
1.63 (m, 2 H), 1.56 (m, 2 H), 1.24 (m, 26 H), 0.87 (t, J = JЈ =
6.8 Hz, 3 H), 0.86 (t, J = JЈ = 7.0 Hz, 3 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 173.8, 71.5, 62.2, 53.3, 37.1, 37.0, 32.2,
32.1, 31.7, 29.9, 29.8, 29.8, 29.7, 29.5, 29.4, 29.1, 29.0, 25.9, 22.9,
31.3 ppm. IR (film): ν = 3384, 2966, 1643, 1509, 1242, 1116 cm–1.
˜
HRMS: calcd. for C24H34NO5 416.2437; found 416.2446. [α]D
–2.1 (c = 1.0, CHCl3).
=
(4S,5S)-4-(Hydroxymethyl)-5-{[4-(2-methoxyethyl)phenoxy]methyl}-
oxazolidin-2-one (7): Yield: 48 mg, 95%. 1H NMR (400 MHz,
MeOD): δ = 7.14 (d, J = 8.69 Hz, 2 H), 6.87 (d, J = 8.69 Hz, 2 H),
4.99 (m, 1 H), 4.31 (dd, J = 10.7 Hz, JЈ = 4.3 Hz, 1 H), 4.29 (dd,
J = 10.7 Hz, JЈ = 6.2 Hz, 1 H), 4.03 (m, 1 H), 3.70 (m, 2 H), 3.55
(t, J = JЈ = 7.0 Hz, 2 H), 3.31 (s, 3 H), 2.78 (t, J = JЈ = 7.0 Hz, 2 H),
2.78 (t, J = JЈ = 7.0 Hz, 2 H) ppm. 13C NMR (125 MHz, MeOD): δ
= 160.4, 157.0, 131.8, 129.7, 114.3, 77.2, 73.7, 66.0, 60.2, 57.5, 55.9,
22.7, 14.3, 14.2 ppm. IR (film): ν = 3674, 3295, 2920, 2851, 2360,
˜
1747, 1635, 1536, 1433, 1359 cm–1. HRMS: calcd. for C21H30NO3S
376.1946; found 376.1942. [α]D = +2.2 (c = 1.0, CHCl3).
(2ЈS,3ЈS)-N-[1,3-Dihydroxy-4-(2-naphthylthio)-2-butyl]pivaloylamide
1
(2Cb): Yield: 55 mg, 88%. H NMR (400 MHz, CDCl3): δ = 6.55
(br. d, 1 H), 4.00 (dd, J = 11.5 Hz, JЈ = 3.1 Hz, 1 H), 3.91 (m, 1
H), 3.82 (m, 1 H), 3.68 (dd, J = 11.5 Hz, JЈ = 3.6 Hz, 1 H), 2.76
(m, 1 H), 2.60 (m, 1 H), 2.52 (m, 2 H), 1.56 (m, 2 H), 1.24 (m, 20
H), 1.22 (s, 9 H), 0.87 (t, J = JЈ = 6.6 Hz, 3 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 179.2, 71.5, 62.3, 53.6, 39.0, 37.1, 37.0,
32.2, 32.1, 30.0, 29.9, 29.8, 29.8, 29.7, 29.7, 29.5, 29.4, 29.0, 27.7,
34.9 ppm. IR (KBr): ν = 3321, 2632, 2543, 1735, 1515, 1321,
˜
855 cm–1. [α]D = +3.3 (c = 1.0, MeOH).
Basic Hydrolysis of 7: A mixture of oxazolidinone 7 (114 mg,
0.405 mmol), aqueous NaOH (2 , 12 mL) and EtOH (12 mL) was
heated at 80 °C for 3 h. The mixture was cooled to room tempera-
ture, the solvent was removed under vacuum, and the residue was
taken up in Et2O. The organic layer was washed with brine and
dried, and the solvent was evaporated to give 98.3 mg (0.385 mmol,
95%) of amino alcohol 6D, which was used in the acylation step
without further purification.
22.9, 14.3 ppm. IR (film): ν = 3233, 3134, 2923, 2853, 2360, 1637,
˜
1586, 1537, 1456, 1371, 1082 cm–1. HRMS: calcd. for C19H46NO3S
348.1633; found 348.1616. [α]D = +2.6 (c = 1.0, CHCl3).
(2ЈS,3ЈS)-N-[1,3-Dihydroxy-4-(2-naphthylthio)-2-butyl]benzamide
(2Cc): Yield: 39.5 mg, 52%. 1H NMR (400 MHz, CDCl3): δ = 7.76
(d, J = 8.5 Hz, 2 H), 7.45 (d, J = 8.5 Hz, 2 H), 7.07 (br., 1 H), 4.15
(m, 1 H), 4.11 (m, 1 H), 3.96 (m, 1 H), 3.81 (dd, J = 11.5 Hz, JЈ =
3.5 Hz, 1 H), 2.79 (m, 2 H), 2.54 (m, 2 H), 1.56 (m, 2 H), 1.33 (s,
9 H), 1.24 (m, 20 H), 0.87 (t, J = JЈ = 6.7 Hz, 3 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 167.7, 155.6, 131.2, 127.1, 125.7, 71.6, 62.3,
53.9, 35.1, 32.1, 31.4, 31.3, 29.9, 29.8, 29.8, 29.7, 29.7, 29.5, 29.4,
Supporting Information (see footnote on the first page of this arti-
cle): 1H and 13C NMR copies of all library members and com-
pound 7.
Acknowledgments
29.0, 22.9, 14.3 ppm. IR (film): ν = 3668, 2922, 2851, 2359, 1716,
˜
1608, 1538, 1425, 1360 cm–1. HRMS: calcd. for C25H30NO3S
Partial financial support from the Ministerio de Ciencia y Tecnol-
ogía (Spain) (Project MCYT CTQ2005–00175/BQU), Fondos
Feder (EU), Fundació “La Marató de TV3” (Projects 040730 and
040731), Fundación Ramón Areces, and Generalitat de Catalunya
(Project 2005SGR0163) is acknowledged. S. G. is grateful to CSIC
for a predoctoral fellowship. The authors also thank Dr. Fabrizio
Badalassi for his contribution at the preliminary stages of this
work.
424.1947; found 424.1953. [α]D = +4.2 (c = 1.0, CHCl3).
(2ЈS,3ЈS)-N-{1,3-Dihydroxy-4-[4-(2-methoxyethyl)phenoxy]-2-
butyl}heptanamide (2Da): Yield: 43.6 mg, 66 %. 1H NMR
(400 MHz, CDCl3): δ = 7.14 (d, J = 8.5 Hz, 2 H), 6.84 (d, J =
8.5 Hz, 2 H), 6.36 (br., 1 H), 4.13 (m, 2 H), 4.02 (m, 3 H), 3.75 (m,
1 H), 3.56 (t, J = JЈ = 7.0 Hz, 2 H), 3.34 (s, 3 H), 2.82 (t, J = JЈ =
6.9 Hz, 2 H), 2.24 (t, J = JЈ = 7.0 Hz, 2 H), 1.63 (m, 2 H), 1.28
(m, 6 H), 0.87 (t, J = JЈ = 7.0 Hz, 3 H) ppm. 13C NMR (125 MHz,
CDCl3): δ = 174.6, 156.6, 132.3, 130.1, 114.7, 73.9, 72.1, 69.3, 62.6,
[1] A. Morales, J. C. Fernandez-Checa, Mini-Rev. Med. Chem.
2007, 7, 371–382.
58.8, 53.1, 36.9, 35.4, 31.7, 29.1, 25.9, 22.7, 14.2 ppm. IR (film): ν
˜
.
= 3301, 2933, 2857, 1642, 1550, 1514, 1242, 1114, 802 cm–1
[2] J. Y. Liao, J. H. Tao, G. Q. Lin, D. G. Liu, Tetrahedron 2005,
61, 4715–4733.
HRMS: calcd. for C20H34NO5 368.2437; found 368.2432. [α]D
+3.3 (c = 1.0, CHCl3).
=
[3] A. Delgado, J. Casas, A. Llebaria, J. L. Abad, G. Fabrias,
ChemMedChem 2007, 2, 580–606.
[4] S. Grijalvo, A. Llebaria, A. Delgado, Synth. Commun. 2007,
(2ЈS,3ЈS)-N-{1,3-Dihydroxy-4-[4-(2-methoxyethyl)phenoxy]-2-
butyl}pivaloylamide (2Db): Yield: 31.2 mg, 56 %. 1H NMR
(400 MHz, CDCl3): δ = 7.15 (d, J = 7.9 Hz, 2 H), 6.84 (d, J =
7.4 Hz, 2 H), 6.56 (br., 1 H), 4.15 (m, 1 H), 4.10 (m, 1 H), 4.01 (m,
3 H), 3.75 (m, 1 H), 3.56 (t, J = JЈ = 7.0 Hz, 2 H), 3.34 (s, 3 H),
2.82 (t, J = JЈ = 7.0 Hz, 2 H), 1.22 (s, 9 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 180.1, 156.6, 132.3, 130.1, 114.6, 73.9, 72.0,
37, 2737–2751.
[5] S. Grijalvo, C. Bedia, G. Triola, J. Casas, A. Llebaria, J. Teix-
ido, O. Rabal, T. Levade, A. Delgado, G. Fabrias, Chem. Phys.
Lipids 2006, 144, 69–84.
[6] S. V. Ley, I. R. Baxendale, Nat. Rev. Drug Discovery 2002, 1,
573–586.
[7] G. Villorbina, D. Canals, L. Carde, S. Grijalvo, R. Pascual, O.
Rabal, J. Teixido, G. Fabrias, A. Llebaria, J. Casas, A. Delgado,
Bioorg. Med. Chem. 2007, 15, 50–62.
[8] Y. T. Chang, J. Choi, S. Ding, E. E. Prieschl, T. Baumruker,
J. M. Lee, S. K. Chung, P. G. Schultz, J. Am. Chem. Soc. 2002,
124, 1856–1857.
69.4, 62.6, 58.9, 53.3, 39.0, 35.4, 27.7 ppm. IR (film): ν = 3386,
˜
2932, 2360, 1640, 1512, 1242, 1109 cm–1. HRMS: calcd. for
C17H28NO4 310.2018; found 310.2011. [α]D = +2.2 (c = 1.0,
CHCl3).
(2ЈS,3ЈS)-4-tert-Butyl-N-{1,3-dihydroxy-4-[4-(2-methoxyethyl)phen-
oxy]-2-butyl}benzamide (2Dc): Yield: 39 mg, 52 %. 1H NMR
[9] J. Park, Q. Li, Y. T. Chang, T. S. Kim, Bioorg. Med. Chem.
2005, 13, 2589–2595.
154
www.eurjoc.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2008, 150–155

Protocol for the Solution-Phase Parallel Synthesis of Ceramide Analogues
[10] W. J. Moore, F. A. Luzzio, Tetrahedron Lett. 1995, 36, 6599–
6602.
[15] Formation of 7 can be interpreted as a result of an intramolec-
ular displacement of the tert-butoxide group by a transient alk-
oxide. This process seems sensitive to the electronic effects of
the aromatic ring, as the reaction from p-chloro-3-methylphe-
nol led to an approximately 1:1 mixture of the intermediate
oxazolidinone and the corresponding ceramide analogue. For
a related example of this intramolecular cyclization, see: G. Tri-
ola, G. Fabrias, J. Casas, A. Llebaria, J. Org. Chem. 2003, 68,
9924–9932.
[11] I. R. Baxendale, G. Brusotti, M. Matsuoka, S. V. Ley, J. Chem.
Soc. Perkin Trans. 1 2002, 143–154.
[12] Some of the intermediate amines were checked by 1H NMR
spectroscopy and were consistently pure enough for the next
step.
[13] M. C. Desai, L. M. S. Stramiello, Tetrahedron Lett. 1993, 34,
7685–7688.
[14] When required, traces of unreacted starting amine were re-
moved with the acidic resin Amberlyte IR120 hydrogen form
(Aldrich, ref 216534) as follows: A solution of the correspond-
ing ceramide analogue in MeOH (2.0 mL) was treated with
Amberlyte IR120 (100 mg, equivalent to 0.4 mmol based on
resin loading) and stirred overnight at room temperature. The
resin was filtered out, and the solution was evaporated to dry-
ness to afford the required ceramide analogues.
[16] D. D. Perrin, W. L. F. Armarego, Purification of Laboratory
Chemicals, 3rd ed., Pergamon Press, Oxford, 1988.
[17] Y. S. Liu, C. X. Zhao, D. E. Bergbreiter, D. Romo, J. Org.
Chem. 1998, 63, 3471–3473.
Received: September 3, 2007
Published Online: November 12, 2007
Eur. J. Org. Chem. 2008, 150–155
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
155