Convenient synthesis and diversification of dehydroalaninyl phosphinic peptide analogues.

Article abstract of DOI:10.1021/ol0069103

[structure: see text]. Dehydroalaninyl phosphinic dipeptide analogues were synthesized, via an efficient tandem Arbuzov addition/allylic rearrangement, in high yields. The susceptibility of the conjugate system to 1,4 nucleophilic additions was investigat

Full text of DOI:10.1021/ol0069103

ORGANIC
LETTERS
2001
Vol. 3, No. 5
659-662
Convenient Synthesis and
Diversification of Dehydroalaninyl
Phosphinic Peptide Analogues
Magdalini Matziari,† Dimitris Georgiadis,† Vincent Dive,‡ and
,†
Athanasios Yiotakis*
Department of Chemistry, Laboratory of Organic Chemistry, UniVersity of Athens,
Panepistimiopolis Zografou 15771, Athens, Greece, and CEA,
De´partement d’Inge´nierie et d'Etudes des Prote´ines, 91191 Gif/YVette Cedex, France
agiotak@cc.uoa.gr
Received November 22, 2000
ABSTRACT
Dehydroalaninyl phosphinic dipeptide analogues were synthesized, via an efficient tandem Arbuzov addition/allylic rearrangement, in high
yields. The susceptibility of the conjugate system to 1,4 nucleophilic additions was investigated. C-Elongation of the dipeptides was performed,
and the efficiency of 1,4 addition to the resulting acrylamidic moiety was evaluated. Derivatization of such phosphinic templates is a powerful
approach for rapid access to large number of phosphinic pseudopeptides bearing various side chains in the P ′ position.
1
Several studies have demonstrated that the synthesis of
phosphinic peptides is a very effective approach for the
development of highly potent and selective inhibitors of
various Zn metalloproteases.1,2 In many zinc metallopro-
teases, one of the key side chain for the control of the
inhibitor selectivity is the so-called P1′ position,3 (Figure 1),
which in the case of phosphinic peptide inhibitors corre-
sponds to the side chain situated at the right of the phosphinic
moiety (standard representation of peptides).
The classical approach to prepare phosphinic peptides
relies on the synthesis of phosphinic pseudodipeptidic units,
which are obtained by an Arbuzov addition4 of N-protected
silyl aminoalkylphosphonites to suitably substituted acry-
lates.5
† University of Athens.
‡ De´partement d′Inge´nierie et d'Etudes des Prote´ines.
(1) (a) Dive, V.; Cotton, J.; Yiotakis, A.; Michaud, A.; Vassiliou, S.;
Jiracek, J.; Vazeaux, G.; Chauvet, M.-T.; Cuniasse, P.; Corvol, P. Proc.
Natl. Acad. Sci. U.S.A. 1999, 96, 4330. (b) Chen, H.; Noble, F.; Coric, P.;
Fournie-Zaluski, M. C.; Roques, B. P. Proc. Natl. Acad. Sci. U.S.A. 1998,
96, 12028. (c) Chackalamannil, S.; Chung, S.; Stamford, A. W.; McKittrick,
A. B.; Wang, Y.; Tsai, H.; Cleven, R.; Fawzi, A.; Czarniecki, M. Bioorg.
Med. Chem. Lett. 1996, 6, 1257.
(2) (a) Georgiadis, D.; Vazeux, G.; Llorens-Cortes, C.; Yiotakis, A.; Dive,
V. Biochemistry 2000, 39, 1152. (b) Jiracek, J.; Yiotakis, A.; Vincent, B.;
Checler, F.; Dive, V. J. Biol. Chem. 1996, 271, 19606. (c) Jiracek, J.;
Yiotakis, A.; Vincent, B.; Lecoq, A.; Nicolaou, A.; Checler, F.; Dive, V. J.
Biol. Chem. 1995, 270, 21701.
(3) Schechter, I.; Berger, A. Biochem. Biophys. Res. Commun. 1967, 27,
157.
Figure 1.
10.1021/ol0069103 CCC: $20.00 © 2001 American Chemical Society
Published on Web 02/10/2001

Such an approach, which implies several steps and depends
on the availability of acrylates, is not convenient to prepare
rapidly large series of P1′ substituted phosphinic peptides.
Herein, we report a strategy allowing diversification of the
P1′ position of phosphinic peptides via the functionalization,
at the final step of the synthesis, of phosphinic precursors.
Scheme 1
Esters of 2-(acetoxymethyl) and 2-(bromomethyl) acrylic
acid have been widely used as substrates for nucleophilic
additions, mainly of organometallic species and in some cases
of other nucleophiles such as phenoxides, thiolates, and
hydrides.6,15 In all cases, the reaction leads efficiently to
â-substituted acrylates. We speculated that a similar rear-
rangement would occur during an Arbuzov reaction of silyl
aminoalkylphosphonites with this kind of acrylates. As it is
a TMSCl (4.5 equiv), DIPEA (4.5 equiv) in CH2Cl2, 0 °C to rt,
3 h. bHMDS (3 equiv), 110 °C, 1 h. c(for TMSCl activation)
H2CdC(CH2L)COX3 L ) Br or OAc (1.3 equiv), 0 °C to rt, 24 h,
then EtOH. d(for HMDS activation) H2CdC(CH2Br)COX3 (1.3
equiv), 110 °C, 3 h, then EtOH. All steps are performed under an
inert atmosphere.
(4) (a) Boyd, E. A.; Boyd, M. E.; Loh, V. M. Tetrahedron Lett. 1996,
37, 1651. (b) Boyd, E. A.; Corless, M.; James, K.; Regan, A. C. Tetrahedron
Lett. 1990, 31, 2933. (c) Thottathil, J. K.; Przybyla, C. A.; Moniot, J. L.;
Neubeck, R. Tetrahedron Lett. 1984, 25, 4737. (d) Thottathil, J. K.; Ryono,
D. E.; Przybyla, C. A.; Moniot, J. L.; Neubeck, R. Tetrahedron Lett. 1984,
25, 4741.
(5) Yiotakis, A.; Vassiliou, S.; Jiracek, J.; Dive, V. J. Org. Chem. 1996,
61, 6601.
(6) (a) Amri, H.; Rambaud, M.; Villieras, J. J. Organomet. Chem. 1990,
384, 1. (b) Rabe, J.; Hoffmann, M. R. Angew. Chem., Int. Ed. Engl. 1983,
22, 796.
(7) (a) Deane, P. O.; Guthrie-Strachan, J. J.; Kaye, P. T.; Whittaker, R.
E. Synth. Commun. 1998, 28, 2601, (b) Bauchat, P.; Le Rouille, E.; Foucaud,
A. Bull. Soc. Chim. Fr. 1991, 128, 267. (c) Drewes, S. E.; Slater-Kinghorn,
B. J. Synth. Commun. 1986, 16, 603.
shown in Scheme 1, aminoalkylphosphonous acids were
activated in the form of their silyl esters, and their subsequent
reaction with 1.3 equiv of any of these acrylates led smoothly
to the formation of compound 1. Actually, dehydroalanine
derivative 1 can be formed either by nucleophilic substitution
(pathway A) or by allylic rearrangement (pathway B) since
the allylic cation is symmetrical. According to literature
references, the reaction should follow pathway B when L )
OAc and mainly pathway A when L ) Br. Indeed, the
structure of the main products obtained by similar additions
of carbanions and thiolates to unsymmetrical allylic cations
strongly supports these mechanistic pathways.7
(8) Experimental Procedure for the Synthesis of Compound 1a. To
an ice-cold suspension of (R,S)-((1-N-(benzyloxycarbonyl)amino)-2-phe-
nylethyl)phosphinic acid (1 mmol) in CH2Cl2 (7 mL) were added N,N-
diisopropylethylamine (4.5 mmol, 0.58 g, 0.78 mL) and chlorotrimethyl-
silane (4.5 mmol, 0.49 g, 0.57 mL) under an argon atmosphere. This solution
was stirred for 3 h at room temperature. Then, the mixture was cooled to
0 °C, and ethyl 2-(bromomethyl) acrylate (1.3 mmol) was added dropwise.
The solution was stirred for 24 h at room temperature. Then, absolute ethanol
(0.8 mL) was added dropwise, and the mixture was stirred for 20 min. The
solvents were evaporated. The residue was dissolved in 5% NaHCO3 (10
mL), and the resulting suspension was extracted with diethyl ether (2 × 3
mL). The crude product was precipitated by acidification with 1 N HCl to
pH 1. Purification by column chromatography using chloroform/methanol/
acetic acid, (7:0.4:0.4) as eluent afforded the product as a white solid, mp
90-93 °C. NMR and typical analysis data for compound 1a: 1H NMR
(200 MHz, CDCl3/d1-TFA 99.5/0.5) δ 1.27 (t, 3JHH ) 7.3 Hz, 3H, CH2CH3),
2.78-3.20 (m, 3H, PCH2, PhCHH), 3.20-3.35 (m, 1H, PhCHH), 4.15-
4.46 (m, 3H, CH2CH3, PCH), 4.82-5.07 (br s, 2H, OCH2Ph), 5.70-5.92
(m, 2H, NH, CdCHH), 6.35 (s, 1H, CdCHH), 7.05-7.34 (m, 10H, aryl);
13C NMR (50 MHz, CDCl3/d1-TFA 99.5/0.5) δ 13.9 (CH2CH3), 29.7 (d,
As illustrated in Table 1, compounds type 1, harboring
Table 1. List of Compounds of Type 1
entry
X1
R1
X2
L
yields (%)
1a 8
1a
1b
1c
Cbz
Cbz
Cbz
Fmoc
PhCH2
PhCH2
PhCH2
PhCH2
OEt
OEt
OBut
OBut
Br
OAc
Br
92
89
94
85
1
1JPC ) 86.9 Hz, PCH2), 33.7 (CH2Ph), 50.5 (d, JPC ) 104.8 Hz, PCH),
61.4 (CH2CH3), 66.7 (OCH2Ph), 126.5, 126.9, 127.6, 127.8, 128.2, 128.3,
129.1, 129.5, 130.6, 130.7, 136.3, 136.6, 136.8 (aryl, vinyl), 156.1 (s,
OCONH), 166.5 (s, COOEt); 31P NMR (81 MHz, CDCl3/d1-TFA 99.5/0.5)
δ 48.66; ESMS m/z calcd for C22H25NO6P (M - H)- 430.4, found 430.2.
Anal. Calcd for C22H26NO6P (431.4): C, 61.25; H, 6.07; N, 3.25. Found:
C, 61.59; H, 5.89; N, 3.30.
Br
different protecting groups, can be easily obtained using the
experimental procedure described in Scheme 1. The reaction
is mild and versatile, proceeds with excellent yields, and
involves no byproducts. Moreover, there is no need for the
prior protection of the hydroxyphosphinyl function. In
addition, the reactants are easily accessible since â-ami-
noalkyl phosphonous acids are prepared by the method
described by Baylis et al.9 and 2-(bromomethyl) acrylic acid
is commercially available. As compared to the method of
Schoen et al., which consists of three synthetic steps and
prior protection of the hydroxyphosphinyl function, the
present procedure is more convenient.10
(9) Baylis, E. K.; Campbell, C. D.; Dingwall, J. D. J. Chem. Soc., Perkin
Trans. 1 1984, 2845.
(10) Schoen, W. R.; Parsons, W. H. Tetrahedron Lett. 1988, 41, 5201.
(11) (a) Miller, D. J.; Hammond, S. M.; Anderluzzi, D.; Bugg, T. D. H.
J. Chem. Soc., Perkin Trans. 1 1998, 131. (b) Allen, M. C.; Fuhrer, W.;
Tuck, B.; Wade, R.; Wood, J. M. J. Med. Chem. 1989, 32, 1652.
(12) Makaritis, A. M.Sc. Dissertation, University of Athens, Greece,
2000.
(13) (a) Rouvier, E.; Giacomoni, J. C.; Cambon, A. Bull. Soc. Chim. Fr.
1971, 5, 1717. (b) Crossley, M. J.; Fung, Y. M.; Potter, J. J.; Stamford, A.
W. J. Chem. Soc., Perkin Trans. 1 1998, 1113.
(14) To reduce the number of diastereoisomers, the pure diastereoisomeric
form (R,S) of compound 3c was used for the reactions described in Scheme
4. (R,S)-3c was prepared by the procedures described in this letter starting
from optically pure (R)-ZPhePO2H2. The choice of the (R) configuration
was based exclusively on data concerning enzymatic preferences.
(15) Vassiliou, S.; Mucha, A.; Cuniasse, P.; Georgiadis, D.; Lucet-
Levannier, K.; Beau, F.; Kannan, R.; Murphy, G.; Knauper, V.; Rio, M.
C.; Basset, P.; Yiotakis, A.; Dive, V. J. Med. Chem. 1999, 42, 2610.
Phosphinic peptides type 1 undergo a variety of transfor-
mations that increase their value as synthetic intermediates.
660
Org. Lett., Vol. 3, No. 5, 2001

Sulfur and nitrogen nucleophiles, as well as carbanions, can
be added to the acrylic unit of compounds type 1, as shown
in Scheme 2.
byproduct formation.11 These drawbacks are overcome by
short reaction times and the use of a large excess of the
carbodiimide coupling reagent in slightly acidic solutions.12
Under these conditions, phosphinic tripeptides of type 3 were
produced in satisfactory yields, as illustrated in Table 2.
Scheme 2
Table 2. List of Compounds of Type 3
entry
R3
X3
yields (%)
3a
3b
3c
PhCH2
PhCH2
3-indolylmethyl
OBut
OMe
NH2
72
65
69
Pseudotripeptides 3 can also serve as Michael-type sub-
strates undergoing nucleophilic additions. Alkyl, benzyl, and
aryl thiols react readily with the phoshinopeptidic precursor
3c, leading to cysteine analogues in high yields. However,
secondary amines such as piperidine do not add to 3c. This
can be attributed to the reduced reactivity of the acrylamidic
system as a result of inductive and mesomeric effects, which
cause an increase on the â carbon electron density.13 Thereby,
nucleophilic additions occur only when the nucleophile is
strong enough to attack the relatively inactivated conjugate
amide system. Reaction conditions are outlined in Scheme
4.14
a BnSH, Et3N in CH2Cl2, 8 h, rt. bPiperidine in CH2Cl2, 48 h, rt.
cn-BuLi, CuJ, TMSCl in Et2O/THF, 4 h, -20 °C. dSodium
diethylmalonate, in EtOH, 12 h, rt.
Scheme 4
To explore the utility of our strategy, we checked the
possibility to functionalize directly phosphinic peptides type
3. Scheme 3 outlines the general method used for the
Scheme 3
a TFA/CH2Cl2 50%, 1 h, rt. bEDC‚HCl (4 equiv), HOBt (1 equiv),
DIPEA (1.9 equiv) in CH2Cl2/THF, 1 h, rt.
a Cyclohexyl mercaptan (4 equiv), EtONa/EtOH (2 equiv) in
b
THF, 1 h, rt. 4-Methoxy-R-toluenethiol (4 equiv), EtONa/EtOH
c
(2 equiv) in THF, 8 h, rt. 2-Naphthalenethiol (4 equiv), EtONa/
d
EtOH (2 equiv) in THF, 40 h, rt. Piperidine in THF, CH2Cl2,
synthesis of compounds type 3.
MeOH, heat, various bases.
Phosphinic dipeptide 1b was chosen as starting material.
This compound was deprotected under acidic conditions to
afford quantitatively pseudodipeptide 1d. Coupling of such
units to aminopeptidyl moieties, without protection of the
hydroxyphosphinyl group, may imply low yields and/or
Two of the compounds described in this communication
(4b and 4c, Scheme 4) were tested toward different MMPs,
and biological results are shown in Table 3.
Org. Lett., Vol. 3, No. 5, 2001
661

specificity for small sets of MMPs. More generally, given
the key function of the P1′ position in inhibitors of many
zinc metalloproteases, this novel approach to prepare diversi-
fied phosphinic peptides will find a broad application.
Table 3. Ki Values of Compounds 4b and 4c toward MMP-8
(HNC), MMP-2 (Gel-A), and MMP-9 (Gel-B)
entry
MMP-8
MMP-2
MMP-9
4b
4c
0.7 nM
3 nM
6 nM
100 nM
3 nM
500 nM
Acknowledgment. This work was supported in part by
funds from the Department of Organic Chemistry of
Athens University, CEA/Saclay, and BIOTECH 2 (contract
ERBBIO4CT96-0464).
As already reported, compound 4b is a potent but mixed
inhibitor of MMP-8 (human neutrophil collagenase, HNC),
MMP-2 (gelatinase A, Gel-A), and MMP-9 (gelatinase B,
Gel-B).15 Compound 4c represents an example of the key
role played by the P1′ side chain in governing the selectivity
of the inhibitors toward MMPs. Given the wide and easy
diversification of the P1′ position of the phosphinopeptidic
precursors reported in this letter, this new chemical strategy
may lead to the development of phosphinic inhibitors with
Supporting Information Available: Experimental pro-
cedures and spectroscopic data for compounds 1a, 1b, 1d,
2a, 3a, 3c, and 4a. This material is available free of charge
via the Internet at http://pubs.acs.org.
OL0069103
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Org. Lett., Vol. 3, No. 5, 2001