Simplified chemical and radiochemical synthesis of 2-arachidonoyl-glycerol, an endogenous ligand of cannabinoid receptors

Article abstract of DOI:10.1016/j.tetlet.2004.02.045

Endocannabinoids have emerged as a new class of lipid mediators, with manifold roles in the central nervous system and in the periphery. Several studies have identified 2-arachidonoyl-glycerol (2-AG) as a major endogenous agonist of cannabinoid receptors. Here, the chemical synthesis of 2-AG is reported, along with the synthesis of its tritium-labeled derivative. These unlabeled and radiolabeled compounds are suitable tools for unravelling some metabolic routes and biological activities of 2-AG in various cells and tissues.

Full text of DOI:10.1016/j.tetlet.2004.02.045

Tetrahedron
Letters
Tetrahedron Letters 45 (2004) 2723–2726
Simplified chemical and radiochemical synthesis of 2-arachidonoyl-
glycerol, an endogenous ligand of cannabinoid receptors
b
b
ꢀc
Antonella Cartoni,a, Andrea Margonelli, Giancarlo Angelini, Alessandro Finazzi-Agro
*
and Mauro Maccarroned,*
aDepartment of Chemical Sciences and Technologies, University of Roma ‘Tor Vergata’, 00168Rome, Italy
bInstitute of Nuclear Chemistry, National Council of Research, Monterotondo, Rome, Italy
cDepartment of Experimental Medicine and Biochemical Sciences, University of Roma ‘Tor Vergata’, Rome, Italy
dDepartment of Biomedical Sciences, University of Teramo, Teramo, Italy
Received 6 November 2003;revised 4 February 2004;accepted 11 February 2004
Abstract—Endocannabinoids have emerged as a new class of lipid mediators, with manifold roles in the central nervous system and
in the periphery. Several studies have identified 2-arachidonoyl-glycerol (2-AG) as a major endogenous agonist of cannabinoid
receptors. Here, the chemical synthesis of 2-AG is reported, along with the synthesis of its tritium-labeled derivative. These unla-
beled and radiolabeled compounds are suitable tools for unravelling some metabolic routes and biological activities of 2-AG in
various cells and tissues.
ꢀ 2004 Elsevier Ltd. All rights reserved.
The importance of phospholipid-derived molecules as
intra and extracellular signals in animal cells is well-
known and documented.1 Among these molecules,
endocannabinoids have emerged as a new class of
mediators, present in the central nervous system and in
peripheral tissues.2 They are amides, esters and ethers
of long chain polyunsaturated fatty acids, and to date
N-arachidonoylethanolamine (anandamide, AEA) and
2-arachidonoyl-glycerol (2-AG) are the most studied
members.3 They bind to both type-1 (CB1) and type-2
(CB2) cannabinoid receptors, thus mimicking some of
the psychotropic and analgesic effects of D9-tetrahy-
drocannabinol, the psychoactive principle of hashish
and marijuana.2b;4 The first studies on endocannabi-
noids focused on metabolism and biological activity of
AEA.5 Later on it also became clear that 2-AG has a
critical role in the endocannabinoid system, to such an
extent that it has been proposed as the real endogenous
ligand of CB1 and CB2 receptors in vivo. 6 In addition, a
number of recent studies have identified 2-AG as a key
regulator of microglial cells in the central nervous sys-
tem,7 and of blood cell migration in the periphery.8 It is
worth noting that the pathways for the biosynthesis and
degradation of 2-AG are different from those of AEA,9
and include a recently identified monoglyceride lipase
as the primary mechanism for 2-AG inactivation.10
Therefore, in order to shed light on the metabolic routes
and biological activity of 2-AG, it was necessary to
synthesize the labeled compound, which was not yet
commercially available at the beginning of this work.
We could not find a simple synthesis in the literature
suitable for labeling 2-AG. In fact, in one study, 2-[1-
14C]arachidonoyl-sn-glycerol was prepared by digestion
of 1-stearoyl-2-[1-14C]-arachidonoyl-sn-glycerol with
Rhizopus arrhizus lipase,11 and in another study [3H]2-
AG was synthesized from [3H]AA and 1,3-benzylid-
eneglycerol.12 However, neither investigation reported
enough experimental details to reproduce the synthetic
steps.11;12 Therefore, we sought to develop an easy and
reproducible preparation of [3H]2-AG, based on a new
radiochemical synthesis, which was a slight modification
of the synthesis of unlabeled 2-AG reported in this
paper (Scheme 1). A preliminary account of the syn-
thetic route to [3H]2-AG has been presented.13
Abbreviations: 2-AG, 2-arachidonoyl-glycerol;[ 3H]2-AG, labeled
2-arachidonoyl-glycerol;1-AG, 1-arachidonoyl-glycerol;AEA, N-ara-
chidonoylethanolamine;AA, arachidonic acid;[ 3H]AA, labeled ara-
chidonic acid.
Keywords: 2-Arachidonoyl-glycerol (2-AG);Endocannabinoids;
Radiosynthesis;Synthesis.
* Corresponding authors. Tel.: +39-06-3012270;fax: +39-06-72596468
(A.C.), tel.: +39-0861-266875;fax: +39-0861-412583 (M.M.);e-mail
addresses: cartoni@virgilio.it; Maccarrone@vet.unite.it
0040-4039/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2004.02.045

2724
A. Cartoni et al. / Tetrahedron Letters 45 (2004) 2723–2726
O
CH2OCH2Ph
CH
O
1. ClCOCOCl, CH2Cl2
O
OH
CH2OCH2Ph
2. 1,3-dibenzyloxy-2-propanol,
CH2Cl2
(70-80%)
1
O
Cl
,
B
O
CH2OH
CH
CH2Cl2
3.
4.
O
O
1
CH2OH
H2O, CH3OH
(2-AG)
(30-70%)
2
Scheme 1.
reaction with activated
arachidonic acid
CH2OH
CH2OP
CH2OH
CH2OP
CHOH
CH2OP
protecting group P
deprotection
CHOH
CHOCOR
CH2OP
CHOCOR
CH2OH
CH2OH
3
Scheme 2.
In the literature, different synthetic routes towards
unlabeled 2-AG have been reported. They were devel-
oped to avoid two main problems associated with
the preparation of this compound: (i) rearrangement of
2-AG to the more stable 1-AG isomer, favored by heat,
acids and bases;and (ii) air oxidation of the arachidonic
acid chain.14 Common sequences for 2-AG synthesis are
reported in Scheme 2.
steps only, which avoided by-products and allowed a
good yield of product in each step. The experimental
conditions were also advantageous for the use of the
expensive [3H]AA as starting material. Our previous
experience on the synthesis of N-acylethanolamines such
as N-arachidonoylethanolamine, N-oleoylethanolamine,
N-palmitoylethanolamine and N-steroylethanolamine,
prompted us to add the commercial (unlabeled or triti-
ated) arachidonoyl moiety to the 1,3-protected glycerol
by activating the carboxylic group of the acid with
oxalyl chloride.16;17 We chose to use 1,3-dibenzyloxy-2-
propanol as a commercially available 1,3-protected
glycerol, because it is possible to remove the protecting
groups in a clean and quantitative manner using
B-chlorocatecholborane as a selective reagent.18 The
main problem in performing the last step was to find the
optimal reaction time and experimental conditions for
the work-up of the final reaction mixture in order to
prevent the isomerisation of the 2-AG product into its
regioisomer 1-AG.19 To overcome this problem, we
performed the last step over different reaction times
and tried to cleave the complex formed between 1 and
B-chlorocatecholborane with different solvent mixtures:
(i) H2O and 0.1 M NaOH;(ii) ice-cold water and 0.1 M
In general, the primary hydroxyl groups of the starting
material (glycerol) are protected using different reagents
(benzaldehyde, boric acid derivatives, triisopropylsilyl
chloride). Then the protected glycerol is reacted with the
activated arachidonic acid. The intermediate 3 is puri-
fied and stored under argon at low temperature. When
2-AG is required, the protecting groups are eliminated
from 3, using different experimental conditions, which
should prevent rearrangement of 2-AG to 1-AG. If
isomerization takes place or if the deprotection step is
not performed to completion, the isomeric products
are separated by HPLC. Another synthesis of 2-AG
circumvents these shortcomings, by using glycidyl ara-
chidonate as starting material, obtained from commer-
cially available ( )-glycidol and arachidonic acid.15 The
different synthetic routes reported for unlabeled
2-AG14;15 may not represent per se useful procedures for
the synthesis of the corresponding radiolabeled com-
pound, because radiochemical reactions need to be
planned in such a way that formation of by-products
and side reactions are avoided, and the number of
purification steps of the labeled compounds is mini-
mized. To meet these requirements, we carried out a
synthesis of unlabeled 2-AG, taking advantage of the
experimental conditions found by others to prevent
isomerization and oxidation of 2-AG.14 In this frame-
work, we developed a synthetic strategy based on two
NaOH;and (iii) H O and CH3OH (1:1). After several
2
attempts, we found that the yield of 2-AG was higher
when the reaction was stopped after 2 h, and the reac-
tion mixture was treated with a solution of ice-cold
water and methanol to remove the two benzyl groups
from compound 1. Only 5% or less of 1-AG was present
under these conditions, whereas longer reaction times or
dilute solutions of NaOH in the work-up led to large
amounts of 1-AG. The presence of both isomers in the
final reaction mixture was evident after NMR analysis
of the material. Indeed the chemical shifts of the protons
in the glycerol moiety are different and well separated in

A. Cartoni et al. / Tetrahedron Letters 45 (2004) 2723–2726
2725
1-AG and 2-AG.20 The experimental conditions found
2001, 22, 346–349;(c) Maccarrone, M.;Bari, M.;Battista,
ꢀ
N.;Finazzi-Agr o, A. Blood 2002, 100, 4040–4048.
to be suitable to obtain the highest yield of 2-AG were
used to synthesize labeled 2-AG successfully.21 [3H]2-
AG has been used to assay binding, transport and
hydrolysis of 2-AG in different cells and tissues.22 In
particular, the synthesis of [3H]2-AG reported here has
allowed us to demonstrate for the first time that human
platelets have the biochemical tools to bind and
metabolize 2-AG,23;24 a finding, which opens new per-
spectives in the control of platelet aggregation, and
more generally in our understanding of vascular biol-
ogy.
6. (a) Mechoulam, R.;Ben-Shabat, S.;Hanus, L.;Ligumsky,
M.;Kaminski, N. E.;Schatz, A. R.;Gopher, A.;Almog,
S.;Martin, B. R.;Compton, D. R. Biochem. Pharmacol.
1995, 50, 83–90;(b) Sugiura, T.;Kondo, S.;Sukagawa, A.;
Nakane, S.;Shinoda, A.;Itoh, K.;Yamashita, A.;Waku,
K. Biochem. Biophys. Res. Comm. 1995, 215, 89–97;(c)
Stella, N.;Schweitzer, P.;Piomelli, D. Nature 1997, 338,
773–778;(d) Sugiura, T.;Waku, K. Chem. Phys. Lipids
2000, 108, 89–106.
7. Walter, L.;Franklin, A.;Witting, A.;Wade, C.;Xie, Y.;
Kunos, G.;Mackie, K.;Stella, N. J. Neurosci. 2003, 23,
1398–1405.
ꢀ
8. Alberich Jorda, M.;Verbakel, S. E.;Valk, P. J.;Vankan-
Although we cannot prevent some formation of 1-AG
(less than 5%) during the preparation of the 2-AG iso-
mer, we have developed a simple and convenient syn-
thesis of unlabeled and tritiated 2-AG. The labeled
compound has been shown to be useful for the study of
the metabolism and biological activity of 2-AG, and it
is anticipated that it will be a suitable tool for unravel-
ling, at least in part, the complex involvement of this
lipid messenger in several aspects of human patho-
physiology.
ꢀ
Berkhoudt, Y. V.;Maccarrone, M.;Finazzi-Agr o, A.;
Lowenberg, B.;Delwel, R. Blood 2002, 99, 2786–2793.
9. Sugiura, T.;Kobayashi, Y.;Oka, S.;Waku, K.
Prosta-
glandins Leukot. Essent. Fatty Acids 2002, 66, 173–
192.
10. Dinh, T. P.;Carpenter, D.;Leslie, F. M.;Freund, T. F.;
Katona, I.;Sensi, S. L.;Kathuria, S.;Piomelli, D.
Natl. Acad. Sci. U.S.A. 2002, 99, 10819–10824.
11. Goparaju, S. K.;Ueda, N.;Yamaguchi, H.;Yamamoto,
S. FEBS Lett. 1998, 422, 69–73.
Proc.
12. Di Marzo, V.;Bisogno, T.;Sugiura, T.;Melck, D.;De
Petrocellis, L. Biochem. J. 1998, 331, 15–19.
13. Work presented at the 13th Symposium on Radiophar-
maceutical Chemistry (St. Louis, USA 27 Giugno–1
ꢀ
Luglio 1999) Margonelli, A.;Angelini, G.;Attin a, M.;
Cartoni, A.;Finazzi Agr o, A.;Maccarrone, M. J. Labelled
Acknowledgements
ꢀ
Compd. Radiopharm. 1999, 275, 31938–31945.
14. (a) Han, L.;Razdan, R. K. Tetrahedron Lett. 1999, 40,
1631–1634;(b) Sltzman, H. H.;Fleming, D. N.;Hawkins,
G. D.;Carroll, F. I. Tetrahedron Lett. 2000, 41, 3589–
3592.
Financial support through National Research Council
(to G.A.), II AIDS Project (to A.F.-A.), and Cofin 2002
(to M.M.) is gratefully acknowledged. Our thanks go to
Drs. Monica Bari, Natalia Battista, Filomena Fezza and
Valeria Gasperi for excellent assistance in the cellular
and biochemical assays using unlabeled and tritium-
labeled 2-AG.
15. Stamatov, S. D.;Stawinski, J. Tetrahedron Lett. 2002, 43,
1759–1761.
ꢀ
16. (a) Maccarrone, M.;Attin a, M.;Cartoni, A.;Bari, M.;
Finazzi-Agro, A. J. Neurochem. 2001, 76, 594–601;(b)
ꢀ
Maccarrone, M.;Cartoni, A.;Parolaio, D.;Margonelli,
A.;Massi, P.;Bari, M.;Battista, N.;Finazzi-Agr
Mol. Cell. Neurosci. 2002, 21, 126–140.
ꢀ
o, A.
17. Preparation of unlabeled 2-arachidonoyl-1,3-dibenzylglyc-
erol 1: To solution of arachidonic acid (14 mg,
References and notes
a
0.045 mmol, 1 equiv) in 500 lL of anhydrous dichlorom-
ethane, oxalyl chloride (15 lL, 0.18 mmol, 4 equiv) was
added under an argon atmosphere. The mixture was
stirred in the dark, to avoid the oxidation of arachidonic
acid, at room temperature. After 4 h, excess oxalyl
chloride was eliminated by flushing the reaction mixture
with argon, adding 300 lL of anhydrous CH2Cl2 three
times. Afterwards the activated archidonic acid was
dissolved in 500 lL of CH2Cl2 and an excess of
1,3-dibenzyloxy-2-propanol (120 lL, 0.48 mmol, 10 equiv)
was added to the solution under argon. The mixture was
left to react with stirring in the dark at room temperature
for 24 h. The reaction was monitored by thin-layer
chromatography (TLC, silica gel 60 F254 plates) using
hexane/ethyl acetate (5:1) as eluent and spraying the plate
with ammonium molybdate–cerium(IV) sulfate. The
organic phase was washed with NaOH (0.1 M) and then
with distilled water until neutral and then dried over
anhydrous Na2SO4. After filtration and evaporation, the
residue was purified via preparative TLC (Merck, art.
13894, 20 · 20 · 0.05 cm) using hexane/ethyl acetate (20%)
as eluent. The product was recovered from silica gel
using CH2Cl2. A colourless dense oil was obtained (yield:
70–80%). The crude material (when more than 100 mg)
1. Vance, D. E.;Vance, J. Biochemistry of Lipids, Lipopro-
teins and Membranes;Elsevier: Amsterdam, 1991.
2. (a) Devane, W. A.;Hanus, L.;Breuer, A.;Pertwee, R. G.;
Stevenson, L. A.;Griffin, G.;Gibson, D.;Mandelbaum,
A.;Etinger, A.;Mechoulam, R. Science 1992, 258, 1946–
1949;(b) Salzet, M.;Breton, C.;Bisogno, T.;Di Marzo, V.
Eur. J. Biochem. 2000, 267, 4917–4927;(c) Mechoulam,
R.;Panikashvili, D.;Shohami, E. Trends Mol. Med. 2002,
8, 58–61.
3. (a) Mechoulam, R.;Fride, E.;Di Marzo, V.
Eur. J.
Pharmacol. 1998, 359, 1–18;(b) Di Marzo, V.;Bisogno,
T.;De Petrocellis, L.;Melck, D.;Martin, B. R. Curr. Med.
Chem. 1999, 6, 721–744;(c) Hanus, L.;Breuer, A.;
Tchilibon, S.;Shiloah, S.;Goldenberg, D.;Horowitz,
M.;Pertwee, R. G.;Ross, R. A.;Mechoulam, R.;Fride, E.
Proc. Natl. Acad. Sci. U.S.A. 1999, 96, 14228–14233.
4. (a) Di Marzo, V.;Deutsch, D. G. Neurobiol. Dis. 1998, 5,
386–404;(b) Howlett, A. C.;Mukhopadhyay, S. Chem.
Phys. Lipids 2000, 108, 123–134.
5. (a) De Petrocellis, L.;Melck, D.;Palmisano, A.;Bisogno,
T.;Laezza, C.;Bifulco, M.;Di Marzo, V.
Proc. Natl.
Acad. Sci. U.S.A. 1998, 95, 8375–8380;(b) Di Marzo, V.;
Bisogno, T.;De Petrocellis, L. Trends Pharmacol. Sci.

2726
A. Cartoni et al. / Tetrahedron Letters 45 (2004) 2723–2726
was purified by flash chromatography (Merck silica gel
60, 70–230 mesh) using hexane/ethyl acetate (5%) as
eluent.
1H NMR (600 MHz, CD2Cl2, 298 K, see Scheme 1); d 0.90
(3H, t, 3J ¼ 7:1 Hz, –CH3);1.29–1.37 (6H, m,
–(CH2)3CH3);1.69 (2H, p, 3J ¼ 7:4 Hz, –CH2CH2CH2CO);
2.06–2.13 (4H, m, –CH2CH2CH@CH–);2.34 (2H, t,
1H NMR (1-AG, 600 MHz, CD3OD, 298 K): d 0.97 (3H, t,
3J ¼ 7:1 Hz, –CH3);1.35–1.45 (6H, m, –(C H2)3CH3);1.76
(2H, p, 3J ¼ 7:4 Hz, –CH2CH2CH2CO);2.12–2.21 (4H, m,
–CH2CH2CH@CH–);2.43 (2H, t, 3J ¼ 7:4 Hz, –CH2CO);
2.87–2.92 (6H, m, –CH@CHCH2CH@CH–);3.60–3.62
(2H, m, –CH2OH);3.88 (1H, br p, –CH CH(OH)CH2–);
2
4.11
–CH2CH(OH)CHHOCO);4.20 (1H, dd,
2J ¼ 11:4 Hz, –CH2CH(OH)CHHOCO);5.39–5.47 (8H,
(1H,
dd,
3J ¼ 6:3 Hz,
2J ¼ 11:4 Hz,
3J ¼ 7:4 Hz,
–CH2CO);2.82–2.85
(6H,
m,
3J ¼ 4:4 Hz,
–CH@CHCH2CH@CH–);3.63 (4H, br d, 3J ¼ 6:0 Hz,
OCH2CH(OCO)CH2O);4.49 (4H, AB system, 2J ¼ 12 Hz,
m –CH@CH–).
–OCH2Ph);5.22
(1H,
br
p,
3J ¼ 6:0 Hz,
GC–MS analysis of 1-AG: 105 (56%);91 (86%), 79
(100%).
–CH2CH(OCO)CH2–);5.33–5.40 (8H, m, –C H@CH–);
7.29–7.34 (10H, m, ArH). Anal. Calcd (%) for C37H50O4
(558.79): C, 79.53;H, 9.02. Found: C, 79.40;H, 9.13.
The geminal coupling of the –OCH2Ar protons was
confirmed using 1H–1H COSY NMR (not shown). The
same protons gave a singlet in the 1H NMR of 1,3-
dibenzyloxy-2-propanol.
21. Radiosynthesis
of
2-AG:
The
solution
of
[5,6,8,9,11,12,14,15-3H(N)] arachidonic acid (250 lCi;
200 Ci/mmol) in ethanol was evaporated by adding anhy-
drous CH2Cl2 (100 lL) and applying three cycles of
evaporation in the dark and under an argon flow.
Afterwards the reaction system, dissolved in 50 lL of
CH2Cl2, was tightly sealed (hole cap with a silicon Teflon
liner) under argon and a large excess of oxalyl chloride
(5 lL, 2 M solution in CH2Cl2) was added. We proceeded
as described for the preparation of unlabeled 1 using 50 lL
of CH2Cl2 to dissolve the activated [3H]AA then adding
3 lL of 1,3-dibenzyloxy-2-propanol. The work-up was
carried out with NaOH 0.1 M (300 lL) and brine (300 lL)
until the solution became neutral. The organic phase was
dried over Na2SO4 and the salt was successively filtered
with a SPE minicolumn filter. The solvent was evaporated
and, after dissolving the reaction products in a hexane/
ethyl acetate mixture (20%), the excess of 1,3-dibenzyloxy-
2-propanol was eliminated by chromatography using
SepPaKe silica gel cartridges. The protected [3H]2-AG
so recovered was checked by TLC (see preparation of 1)
and showed a very high level of purity and a radiochemical
yield greater than 90% (static b-counter recovered
225 lCi). The solvent was evaporated and a freshly
prepared solution of B-chlorocatecholborane (6 mg) in
CH2Cl2 (50 lL) was added. We proceeded as described for
the preparation of 2: 500 lL of CH2Cl2 was added and the
reaction mixture treated with 200 lL of brine. The organic
phase was checked by TLC (see above), counted for
radioactivity (about 215 lCi) and dried over Na2SO4.
After evaporating the organic phase, [3H]2-AG was
dissolved in a hexane/ethyl acetate mixture (1:1) and
purified on a SepPaKe silica gel cartridge by elution with
a CHCl3/CH3OH mixture (5%). After two cycles of
evaporation–dissolution with absolute EtOH, 200 lCi of
(2)-[5,6,8,9,11,12,14,15-3H(N)]-arachidonoyl-glycerol (over-
all radiochemical yield 80%) were recovered and stored in
ethanol.
18. Boeckman, R. K.;Potenza, J. C. Tetrahedron Lett. 1985,
26, 1411–1414.
19. (a) Martin, J. B. J. Am. Chem. Soc. 1953, 75, 5483–5486;
(b) Jensen, R. G.;Pitas, R. E. Adv. Lipid Res. 1976, 14,
213;(c) Gunston, F. D. Lipids in Comprehensive Organic
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pp 633–664, 1979, Pergamon Press, Oxford.
20. Preparation of unlabeled 2-arachidonoylglycerol 2: To a
solution of 1 (20 mg, 0.036 mmol, 1 equiv) in 400 lL of
anhydrous CH2Cl2, B-chlorocatecholborane (18 mg,
0.12 mmol, 3 equiv) was added. After stirring for 2 h in
the dark at room temperature the reaction was checked by
TLC using hexane/ethyl acetate (1:1) with tetrabutyl-
ammonuium hydroxide (1%) as eluent. A single spot was
observed (Rf ¼ 0:2), which was different from that of 1
(Rf ¼ 0:7), and from that of B-chlorocatecholborane
(Rf ¼ 0:5). The organic phase was washed once with cold
distilled water (200 lL) and methanol (200 lL) until
neutrality and then dried over anhydrous Na2SO4. After
filtration and elimination of the solvent by flushing the
solution with argon the product was purified by pre-
parative TLC (Merck, art. 1.11798) using hexane/ethyl
acetate (1:1) as eluent. The final product was recovered
from silica gel with CH2Cl2. A colourless oil was obtained
(yield: 30–70%).
1H NMR (2-AG, 600 MHz, CD3OD, 298 K see Scheme 1);
0.97 (3H, t, 3J ¼ 7:1 Hz, –CH3);1.37–1.44 (6H, m,
–(CH2)3CH3);1.76 (2H, p, 3J ¼ 7:4 Hz, –CH2CH2CH2CO);
2.13–2.21 (4H, m, –CH2CH2CH@CH–);2.45 (2H, t,
3J ¼ 7:4 Hz,
–CH2CO);2.89–2.92
–CH@CHCH2CH@CH–);3.69 (2H, dd,
(6H,
m,
3J ¼ 5:8 Hz,
2J ¼ 11:8 Hz, OCHHCH(OCO)CHHO);3.73 (2H, dd,
3J ¼ 4:7 Hz, 2J ¼ 11:8 Hz, OCHHCH(OCO)CHHO);
4.96 (1H, br p, –CH2CH(OCO)CH2–);5.41–5.45 (8H, m,
–CH@CH–).
GC–MS analysis of 2-AG: 105 (49%);91 (74%), 79
(100%).16a
ꢀ
22. Maccarrone, M.;Finazzi-Agr o, A. Vitam. Horm. 2002, 65,
225–255.
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Del Principe, D.;Finazzi-Agr o, A. Eur. J. Biochem. 2001,
268, 819–825.
24. Maccarrone, M.;Bari, M.;Del Principe, D.;Finazzi-
Anal. Calcd (%) for C23H38O4 (378.56): C, 72.98;H, 10.12.
Found: C, 72.87;H, 10.06.
ꢀ
Agro, A. Thromb. Haemost. 2003, 89, 340–347.