Catalytic antibodies in synthesis: Design and synthesis of a hapten for application to the preparation of a scalemic pyrrolidine ring synthon for ptilomycalin A

Article abstract of DOI:10.1021/jo951469t

A catalytic antibody-based approach toward the synthesis of an optically active pyrrolidine ring synthon potentially useful for ptilomycalin A is described. Enantiomerically pure hapten 37 was designed and constructed with the eventual goal of generating antibodies for the enantioselective partial hydrolysis of a mesoo diester such as 44 into a monoacid 45. This transition state analog possesses a phosphonate group containing the requisite oxyanionic character of the tetrahedral intermediate for ester hydrolysis. A newly developed carbamate-based linker, which was found to be much more hydrolytically stable than the commonly used glutarate ester, was developed for coupling of the hapten to a carrier protein.

Full text of DOI:10.1021/jo951469t

J . Org. Chem. 1996, 61, 125-132
125
Ca ta lytic An tibod ies in Syn th esis: Design a n d Syn th esis of a
Ha p ten for Ap p lica tion to th e P r ep a r a tion of a Sca lem ic
P yr r olid in e Rin g Syn th on for P tilom yca lin A
Glen T. Anderson, Michael D. Alexander, Scott D. Taylor,† David B. Smithrud,
Stephen J . Benkovic, and Steven M. Weinreb*
Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
Received August 8, 1995X
A catalytic antibody-based approach toward the synthesis of an optically active pyrrolidine ring
synthon potentially useful for ptilomycalin A is described. Enantiomerically pure hapten 37 was
designed and constructed with the eventual goal of generating antibodies for the enantioselective
partial hydrolysis of a meso diester such as 44 into a monoacid 45. This transition state analog
possesses a phosphonate group containing the requisite oxyanionic character of the tetrahedral
intermediate for ester hydrolysis. A newly developed carbamate-based linker, which was found to
be much more hydrolytically stable than the commonly used glutarate ester, was developed for
coupling of the hapten to a carrier protein.
In tr od u ction
Recently the groups of Kashman and Kakisawa re-
ported the isolation of the novel polycyclic guanidine
alkaloid ptilomycalin A (1) from the Caribbean sponge
Ptilocaulis spiculifer and from a red Hemimycale sp.
found in the Red Sea.1 Shortly afterward, a related series
of alkaloids, exemplified by the crambescidins 800 (2),
816 (3), and 844 (4), was obtained from the Mediter-
ranean sponge Crambe crambe.2 This alkaloid group is
characterized by a structurally unique pentacyclic guani-
dinium core that has a spermidine or hydroxyspermidine
residue tethered by a long-chain ω-hydroxy carboxylic
acid spacer.
Ptilomycalin A shows cytotoxicity against P388, L1210,
and KB cells with an IC50 ) 0.1, 0.4, and 1.3 µg/mL,
respectively, and antifungal and antimicrobial activity
against Candida albicans (MIC ) 0.8 µg/mL) as well as
antiviral activity (HSV) at 0.2 µg/mL.1 Overman and co-
workers have recently reported an elegant enantioselec-
tive total synthesis of (-)-ptilomycalin A,3 and notable
progress toward assembling the guanidinium core of this
alkaloid group by a biomimetic strategy has been re-
ported by Snider and co-workers.4
obtained in optically pure form by first effecting an
enzymatic enantiospecific conversion of meso diester 6
We envisioned a synthetic approach to ptilomycalin A
(1) starting from an N-protected pyrrolidine derivative
5, which corresponds to the C(8)-C(15) portion of the
guanidinium core. It was initially hoped that 5 could be
into the monoacid 7 (eq 1). A closely related transforma-
tion has been reported by Norin and co-workers,5 who
used pig liver esterase (PLE) to convert meso diester 8
into monoacid 9 in 100% ee (eq 2). However, we were
disappointed to find that treatment of diester 6 with PLE
under a variety of conditions gave only poor yields and
low ee’s of the desired monoacid 7.6
This failure to prepare acid 7 by partial enzymatic
hydrolysis prompted us to investigate the use of catalytic
antibodies for the preparation of the desired intermedi-
ate.7 A wide range of chemical transformations have
been shown to be catalyzed by antibodies, including
† Current address: Department of Chemistry, University of Toronto,
Erindale College, 3359 Mississauga, Ontario, Canada L5L 1C6.
X Abstract published in Advance ACS Abstracts, December 15, 1995.
(1) (a) Kashman, Y.; Hirsh, S.; McConnell, O. J .; Ohtani, I.; Kusumi,
T.; Kakisawa, H. J . Am. Chem. Soc. 1989, 111, 8925. (b) Ohtani, I.;
Kusumi, T.; Kakisawa, H.; Hirsh, S. J . Am. Chem. Soc. 1992, 114, 8472.
(c) Ohtani, I.; Kusumi, T.; Kakisawa, H. Tetrahedron Lett. 1992, 33,
2525.
(2) (a) J ares-Erijman, E. A.; Sakai, R.; Rinehart, K. L. J . Org. Chem.
1991, 56, 5712. (b) J ares-Erijman, E. A.; Ingrum, A. L.; Carney, J . R.;
Rinehart, K. L.; Sakai, R. J . Org. Chem. 1993, 58, 4805. (c) Taveras,
R.; Daloze, D.; Braekman, J . C.; Hajdue, E. Biochem. Syst. Ecol. 1994,
22, 645.
(5) Boutelje, J .; Hjalmarsson, M.; Hult, K.; Lindback, M.; Norin, T.
Bioorg. Chem. 1988, 16, 364.
(3) Overman, L. E.; Rabinowitz, M. H.; Renhowe, P. A. J . Am. Chem.
Soc. 1995, 117, 2657.
(4) Snider, B. B.; Shi, Z. J . Am. Chem. Soc. 1994, 116, 549. See
also: Grillot, A.-L.; Hart, D. J . Heterocycles 1994, 39, 435. Rama Rao,
A. V.; Gurjar, M. K.; Vasudevan, J . J . Chem. Soc., Chem. Commun.
1995, 1369.
(6) Alexander, M. D. Ph.D. Thesis, The Pennsylvania State Univer-
sity, University Park, PA, 1991.
(7) For reviews of catalytic antibodies, see: (a) Lerner, R. A.;
Benkovic, S. J .; Schultz, P. G. Science 1991, 252, 659. (b) Schultz, P.
G.; Lerner, R. A.; Benkovic, S. J . Chem. Eng. News 1990, 68, 26. (c)
Schultz, P. G. Angew. Chem., Int. Ed. Engl. 1989, 28, 1283.
0022-3263/96/1961-0125$12.00/0 © 1996 American Chemical Society

126 J . Org. Chem., Vol. 61, No. 1, 1996
Anderson et al.
Sch em e 1
hydrolysis of esters and carbonates.8 In addition, Lerner,
Danishefsky, et al. have produced antibodies which
hydrolyze meso-1,4-diacetoxycyclopent-2-ene to give a
monoester alcohol with >98% ee.9 Therefore, it seemed
reasonable that the conversion of meso diester 6 into
scalemic acid ester 7 might be effected in high ee (eq 1).
In order to generate the required catalytic antibodies for
such a transformation, it is necessary to first prepare an
appropriate transition state analog which would mimic
the tetrahedral intermediate of the ester hydrolysis. We
envisioned that a scalemic phosphonate derivative such
as 10 might function in this role. This substrate pos-
sesses the required oxyanionic character of the tetrahe-
dral intermediate, as well as a hydroxyl group which
could be attached to a linker to couple the hapten to a
carrier protein.10 We hope that the antibodies produced
Sch em e 2
will ultimately lead to an efficient enantioselective
synthesis of the desired scalemic pyrrolidine 5. In
addition, these studies should provide a good opportunity
to evaluate the potential of catalytic antibodies in com-
plex natural product synthesis.11
With suitable reaction conditions available for prepar-
ing this model phosphonate, we set out to construct the
desired hapten 10. Scalemic monoester 9, prepared as
described by Norin,5 was reduced to alcohol 15 via a
mixed anhydride (73%) (Scheme 2). Alcohol 15 was then
protected as the tetrahydropyranyl ether, and the ester
group was reduced with LiAlH4 to give primary alcohol
16 (96%). Hydrogenation of 16 with Pearlman’s cata-
lyst,15 followed by protection of the amine as its benzyl
carbamate, provided 17 (69%), which upon reaction with
mesyl chloride, followed by treatment with LiI16 in DMF,
afforded the requisite iodide 18 (51%).
Many attempts were then made to prepare the di-
methyl phosphonate derivative 19 by displacement of
iodide 18 with the anion of dimethyl phosphite, analogous
to the preparation of phosphonate 14 (cf. Scheme 1).
However, a variety of bases, solvents, and reaction
temperatures were tried in this process with no success.
In all cases, either starting iodide 18 or decomposition
products were obtained with no trace of the desired
phosphonate 19.
Resu lts a n d Discu ssion
Before the synthesis of the desired transition state
analog was attempted, it was decided that it would be
beneficial to work out the requisite chemistry on a simple
model system such as the (S)-proline-derived phospho-
nate 11. The approach used for the synthesis of 11 is
outlined in Scheme 1. Treatment of (S)-prolinol12 with
benzyl chloroformate, followed by O-mesylation and
reaction with NaI, afforded iodide 13 (80%). A Michae-
lis-Becker13 reaction of 13 with the sodium salt of
dimethyl phosphite gave phosphonate 14 (56%), and this
intermediate was then hydrolyzed with 0.4 M NaOH14
at 90 °C to afford, after acidification, the desired phos-
phonic acid monomethyl ester 11 (60%).
It is not immediately evident why this reaction works
for the model iodide 13 but not for iodide 18. One
conceivable explanation is that the bulky (tetrahydropy-
ranyloxy)methyl group at C(5) sterically hinders the
approach of the dimethyl phosphite anion in the SN2
displacement reaction. With this possibility in mind, we
decided to prepare the cyclic carbamate derivative (cf.
22, Scheme 3) in hope that displacement of the iodide
(8) For example, see: J anda, K. D.; Benkovic, S. J .; Lerner, R. A.
Science 1989, 244, 437.
(9) Ikeda, S.; Weinhouse, M. I.; J anda, K. D.; Lerner, R. A.;
Danishefsky, S. J . J . Am. Chem. Soc. 1991, 113, 7763.
(10) (a) Erlanger, B. Methods Enzymol. 1980, 70, 104. (b) Nishima,
T.; Tsuji, A.; Fukushima, D. Steroids 1974, 24, 861.
(11) The first use of catalytic antibodies in a natural product total
synthesis has recently been reported: Sinha, S. C.; Keinan, E. J . Am.
Chem. Soc. 1995, 117, 3653.
(12) Enders, D.; Fey, P.; Kipphardt, H. Org. Synth. 1989, 65, 173.
(13) Myers, T. C.; Preis, S.; J ensen, E. V. J . Am. Chem. Soc. 1954,
76, 4172.
(14) Yamauchi, K.; Kinoshita, M.; Imoto, M. Bull. Chem. Soc. J pn.
1972, 45, 2528.
(15) Bernotas, R. C.; Cube, R. V. Synth. Commun. 1990, 20, 1209.
(16) Dean, P. D. J . Am. Chem. Soc. 1965, 87, 6655.

Catalytic Antibodies in Synthesis
J . Org. Chem., Vol. 61, No. 1, 1996 127
Sch em e 3
Sch em e 4
would be less sterically hindered. Deprotection of me-
sylate 20 with PPTS, followed by cyclization with NaH
in THF, afforded bicyclic mesylate 21 (69%) (Scheme 3).
This compound was then converted to the desired iodide
22 with LiI in DMF (47%).
Unfortunately, all attempts at displacing the iodide
with the Na, K, or Li anion of dimethyl phosphite led
only to decomposition products or recovered starting
material, with none of the desired phosphonate 23
detected. It therefore seems likely that the failures in
these displacements may be due to a long-range elec-
tronic effect rather than a steric one.17
It was then decided to investigate an alternative route
for the synthesis of phosphonates using the Pudovik
reaction,18a which involves preparation of R-(hydroxy-
methyl) phosphonates through addition of phosphite to
carbonyl compounds under base catalysis.18b We ex-
pected that the resultant secondary alcohol functionality
could then be removed by a two-step radical deoxygen-
ation process19 to afford the dialkyl phosphonate deriva-
tive.
Protection of scalemic alcohol 15 as its (tert-butyldi-
methyl)silyl ether (95%), followed by reduction of the
ester with DIBALH, provided alcohol 24 (78%) (Scheme
4). Swern oxidation20 of 24 gave aldehyde 25 (96%),
which was treated with dimethyl phosphite in the pres-
ence of basic alumina to afford R-hydroxy phosphonate
26 as an inseparable mixture of alcohol diastereomers
in 69% yield. Reaction of 26 with NaH in the presence
of carbon disulfide and methyl iodide gave a mixture of
diastereomeric xanthates 27 (81%), which was reduced
with tributyltin hydride to afford the desired dimethyl
phosphonate 28 (85%). Removal of the silyl ether was
then effected under acidic conditions21 to provide the
desired alcohol phosphonate 29 (87%).
cern that protonation of the pyrrolidine nitrogen was
occurring upon acidification, forming the amino acid salt,
thus making purification even more difficult.
Since a benzyl carbamate protecting group had been
used on the pyrrolidine nitrogen in the model study in
Scheme 1, the same was done in this system, hoping to
simplify the purification process by eliminating the basic
nitrogen. Thus, hydrogenation of silyl ether 24 with
Pearlman’s catalyst, followed by protection of the second-
ary amine as its benzyl carbamate, provided compound
31 (93%) (Scheme 5). Swern oxidation of alcohol 31 gave
aldehyde 32 (96%). However, on reaction with dimethyl
phosphite in the presence of basic alumina, this aldehyde
epimerized to give after addition a complex mixture of
the cis and trans R-hydroxy phosphonates. It was
discovered that this epimerization could be prevented by
using a preformed solution of sodium dimethyl phosphite
in DMF at 0 °C, which afforded R-hydroxy phosphonate
33 as an inseparable mixture of alcohol diastereomers
(91%). Conversion of alcohols 33 to xanthates 34 (92%),
followed by reduction with tributyltin hydride (94%),
successfully provided the key phosphonate 35. Depro-
tection of the silyl ether was again done under acidic
conditions to afford phosphonate alcohol 36 (95%).
The next step was to prepare the desired phosphonic
acid monoester 37. However, hydrolysis of intermediate
36 with 0.4 M NaOH at 90 °C led only to decomposition
products, and running the reaction at lower temperatures
resulted in only recovered starting material. It is not
evident why this hydrolysis, which worked well in
previous examples, affords none of the desired monoester
37. Some of the other known methods for monode-
methylation of dimethyl phosphonates were then tried,
and we were pleased to discover that refluxing 36 in tert-
butylamine22 for 7 days, followed by acidification by
passage through a Dowex H+ ion exchange column,
afforded monoester 37 (46%).
We next attempted to hydrolyze phosphonate 29 with
0.4 M NaOH, as was done in the simpler proline model
system (cf. Scheme 1). Reaction of 29 under these
conditions met with only partial success. Although it
appeared that product 30 had formed, the compound
proved too polar to be easily separated from the inorganic
byproducts. Numerous attempts to purify phosphonic
acid 30 via ion exchange, reverse phase, or alumina
chromatography all failed. In addition, there was con-
(17) For lead references to retardation of SN2 reactions by remote
electronegative substituents, see: Behrens, C. H.; Sharpless, K. B.
Aldrichchimica Acta 1983, 16, 67.
(18) (a) Burke, T. R.; Li, Z. H.; Bolen, J . B.; Marquez, V. E. J . Med.
Chem. 1991, 34, 1577. (b) Engel, R. Synthesis of Carbon-Phosphorous
Bonds; CRC Press: Boca Raton, FL, 1987; p 101.
(19) (a) Chen, S. Y.; J ouille, M. M. J . Org. Chem. 1984, 49, 2168.
(b) Hartwig, W. Tetrahedron 1983, 39, 2609.
(20) Mancuso, A. J .; Huang, S. L.; Swern, D. J . Org. Chem. 1978,
43, 2480.
(21) Corey, E. J .; Venkateswarlu, A. J . Am. Chem. Soc. 1972, 94,
6190.

128 J . Org. Chem., Vol. 61, No. 1, 1996
Anderson et al.
Sch em e 5
Sch em e 7
ological conditions. What was needed, therefore, was an
alternative linker system which would be more stable,
and we focused our efforts on developing a new type of
carbamate-based linker.
Thus, succinic anhydride was combined with 2-(tri-
methylsilyl)ethanol to afford acid 40 (72%), which was
converted to an intermediate acyl azide with diphenyl
phosphorazidate (DPPA) (Scheme 7).23 After Curtius
rearrangement of the azide to the isocyanate 41, formed
in situ, addition of alcohol 36 produced the stable
carbamate ester 42 (38%).24
Sch em e 6
With carbamate 42 in hand, all that was needed to
complete the synthesis of the hapten was to demethylate
the phosphonate to the monoacid and remove the silyl-
ethyl ester protecting group. Refluxing 42 in tert-
butylamine for 7 days, followed by acidification with a
Dowex H+ ion exchange column, achieved the required
transformation and afforded a crude phosphonate mo-
noester. Cleavage of the â-(trimethylsilyl)ethyl ester
group was then effected with TBAF,25 which after acidi-
fication with Dowex H+ and purification by reverse phase
HPLC afforded the desired phosphonate monoester 43
in 57% yield. This carbamate-linked hapten was indeed
much more stable than glutarate ester 39, with no
decomposition being detected after storage at 0 °C for
several months. We anticipate that isocyanate 41 should
be generally useful as a linker in the field of catalytic
antibodies.
Although phosphonate ester cleavage worked success-
fully, for simplicity of operation and purification it
seemed preferable to attach the requisite linker to the
alcohol functionality prior to the demethylation step.
Typically, a five-carbon spacer such as a glutarate ester
has been used as the linker in hapten syntheses.7
Reaction of alcohol 36 with glutaric anhydride in the
presence of triethylamine in fact afforded glutarate 38
(82%) (Scheme 6). This compound was then refluxed in
tert-butylamine for 7 days and acidified on a Dowex H+
ion exchange column, and the crude product was purified
by reverse phase HPLC to give the desired acid 39 in
47% yield.
It was discovered, however, that monoester 39 was
surprisingly unstable, and after storage in the freezer at
0 °C for 1 week, a major decomposition product was
detected in the sample of 39 which was determined to
be monoester alcohol 37. Since this decomposition hap-
pened simply on storage in the freezer, presumably via
hydrolysis by adventitious water, there were concerns
that this same hydrolysis might also occur under physi-
Work is beginning on using hapten 43 to generate
catalytic antibodies, which will then be screened for
activity in the partial hydrolysis of meso diester 44 to
produce scalemic monoester 45 (eq 3). These studies will
be reported in due course.
Exp er im en ta l Section
Chemical ionization mass spectra (CIMS) were obtained
using isobutane as a carrier gas. Analytical and preparative
(23) (a) Shioiri, T.; Ninomiya, K.; Yamada, S. J . Am. Chem. Soc.
1972, 94, 6203. (b) Ninomiya, K.; Shioiri, T.; Yamada, S. Tetrahedron
1974, 30, 2151.
(22) Patel, D.; Gauvin, K.; Ryono, D. E. Tetrahedron Lett. 1990, 31,
5591.
(24) Satchell, D. P. N.; Satchell, R. S. Chem. Soc. Rev. 1975, 4, 231.
(25) Capson, T. L.; Poulter, C. D. Tetrahedron Lett. 1984, 25, 3515.

Catalytic Antibodies in Synthesis
J . Org. Chem., Vol. 61, No. 1, 1996 129
extracted three times with ethyl acetate. The aqueous layer
was then acidified with 5% HCl and extracted five times with
ethyl acetate. The organic layers from this latter extraction
were washed with brine and dried over anhydrous MgSO4. The
solvents were removed in vacuo to afford 0.012 g (60%) of
monoacid 11 as a colorless oil: IR (film) 3350, 3020, 1690 cm-1
;
1H NMR (CDCl3, 200 MHz) δ 7.24 (m, 5 H), 5.11 (s, 2 H), 4.73
(bs, 1 H), 4.15 (m, 1 H), 3.62 (m, 3 H), 3.40 (m, 2 H), 2.41 (m,
2 H), 1.90 (m, 4 H); MS (FAB+, glycerol) m/ z 314 (M + H+,
100).
TLC were performed on E. M. Science silica gel 60 PF254. Flash
column chromatography was performed using Baker silica gel
(25-40 mm). THF was dried over and distilled from sodium/
benzophenone ketyl. Methylene chloride, triethylamine, pyr-
idine, DMF, and DMSO were distilled from CaH2 and metha-
nol was distilled from magnesium turnings.
P r ep a r a tion of Iod id e 13. To a solution of amine 12 (2.93
g, 0.029 mol) in CH2Cl2 (60 mL) at 0 °C under argon was added
triethylamine (5.24 mL, 0.038 mol), followed by dropwise
addition of benzyl chloroformate (4.95 mL, 0.035 mol). The
reaction mixture was slowly warmed to rt and stirred for 18
h. Water was added to the mixture, and the aqueous layer
was extracted three times with CH2Cl2. The combined organic
layers were washed with brine and dried over anhydrous
MgSO4. The solvents were removed in vacuo, and the residue
was purified by column chromatography, eluting with ethyl
acetate/hexanes (1/2), to afford 6.07 g of the intermediate
benzyl carbamate as a colorless oil.
P r ep a r a tion of Ester Alcoh ol 15. To a solution of
monoacid 9 (2.9 g, 0.011 mol) in THF (120 mL) at 0 °C under
argon was added triethylamine (1.7 mL, 0.012 mol), followed
by dropwise addition of ethyl chloroformate (1.19 mL, 0.012
mol). The reaction mixture was stirred for 3 h, the triethyl-
amine hydrochloride was filtered off, and the filter cake was
washed three times with THF. The filtrate was then added
dropwise to a suspension of NaBH4 (1.67 g, 0.044 mol) in water
(5.0 mL) at 0 °C. The reaction mixture was stirred at 0 °C for
1 h, water was added, and the mixture was extracted three
times with ether. The organic layer was dried over anhydrous
MgSO4 and concentrated in vacuo. The residue was purified
by column chromatography, eluting with hexanes/ethyl acetate
(1/1), to afford 2.01 g (73%) of ester alcohol 15: [R]21 +16.4°
D
(c 0.01, CH2Cl2); IR (film) 3430, 3020, 2940, 1730 cm-1
;
1H
To the above benzyl carbamate (5.5 g, 0.023 mol) in CH2Cl2
(80 mL) at 0 °C under argon was added triethylamine (4.24
mL, 0.030 mol), followed by dropwise addition of methane-
sulfonyl chloride (2.17 mL, 0.028 mol). The mixture was slowly
warmed to rt and was stirred for 18 h. Water was added to
the mixture, and the aqueous layer was extracted three times
with CH2Cl2. The combined organic layers were washed with
brine and dried over anhydrous MgSO4. The solvents were
removed in vacuo to afford 7.3 g of the intermediate mesylate
as a colorless oil.
NMR (CDCl3, 200 MHz) δ 7.25 (m, 5 H), 3.79 (AB q, J ) 13.5
Hz, 2 H), 3.50 (s, 3 H), 3.50 (m, 2 H), 3.34 (m, 2 H), 3.07 (bs,
1 H), 1.90 (m, 4 H); 13C NMR (CDCl3, 50 MHz) δ 175.6, 138.3,
128.9, 128.2, 127.2, 66.0, 65.4, 61.9, 57.9, 51.7, 29.8, 27.3; CIMS
(M+ + 1/z) 250, 232, 218, 91, 65; HRMS exact mass calcd for
C14H19NO3 249.1365, found 249.1372. Anal. Calcd for
C14H19NO3: C, 67.45; H, 7.68; N, 5.62. Found: C, 67.05; H,
7.71; N, 5.54.
P r ep a r a tion of Tetr a h yd r op yr a n yl Eth er 16. To ester
alcohol 15 (0.42 g, 1.70 mmol) in toluene (5 mL)/CH2Cl2 (5 mL)
under argon was added a catalytic amount of PPTS followed
by dihydropyran (0.76 mL, 8.30 mmol). The reaction mixture
was heated at 90 °C for 3 h and cooled to rt, and toluene (20
mL) was added. The organic solution was washed sequentially
with saturated NaHCO3, water, and brine and was dried over
anhydrous MgSO4. The solvents were removed in vacuo, and
the residue was purified by column chromatography, eluting
with hexanes/ethyl acetate (7/3), to afford a colorless oil, which
was dissolved in THF (50 mL) and added dropwise to LiAlH4
(0.52 g, 13.0 mmol) in dry THF (50 mL) at 0 °C under argon.
The reaction mixture was warmed to rt and stirred for 24 h.
Excess hydride was destroyed by the sequential addition of
ethyl acetate (0.8 mL), 15% NaOH (0.6 mL), water (0.6 mL),
and saturated NH4Cl (1.7 mL). The aluminum salts were
filtered off, and the filter cake was washed with THF. The
filtrate was dried over anhydrous MgSO4 and concentrated in
vacuo to afford 1.28 g (96%) of THP ether 16, which was used
directly in the next step without further purification: IR (film)
3400, 3040, 2900 cm-1; 1H NMR (CDCl3, 200 MHz) δ 7.25 (m,
5 H), 4.45 (m, 1 H), 3.80 (m, 3 H), 3.56-2.94 (m, 8 H), 1.89-
1.47 (m, 10 H); CIMS (M+ + 1/z) 306, 204, 190, 85.
P r ep a r a tion of Ben zyl Ca r ba m a te 17. To THP ether
alcohol 16 (0.18 g, 0.57 mmol) and 20% Pd(OH)2/C (0.035 g)
at rt under argon was added ethanol (5 mL). The reaction
flask was evacuated and filled with hydrogen gas (1 atm), and
the mixture was stirred for 18 h. The catalyst was removed
by filtration through Celite, and the pad was washed with
ethyl acetate (5 × 10 mL). The solvents were removed in vacuo
to afford the intermediate amine as a pale yellow oil.
The above amine was dissolved in CH2Cl2 (5 mL), and
triethylamine (0.098 mL, 0.70 mmol) was added at 0 °C under
argon, followed by dropwise addition of benzyl chloroformate
(0.085 mL, 0.59 mmol). The reaction mixture was stirred at
0 °C for 18 h, water was added, and the aqueous layer was
extracted with CH2Cl2. The combined organic layers were
washed with brine and dried over anhydrous MgSO4. The
solvent was removed in vacuo, and the residue was purified
by column chromatography, eluting with hexanes/ethyl acetate
(1/1), to afford 0.096 g (73%) of benzyl carbamate 17 as a
colorless oil: IR (film) 3400, 2920, 1685 cm-1; 1H NMR (CDCl3,
200 MHz) δ 7.33 (m, 5 H), 5.14 (m, 2 H), 4.55 (m, 1 H), 4.31
To a solution of the above mesylate (5.35 g, 0.017 mol) in
acetone (200 mL) at rt under argon was added NaI (25.6 g,
0.17 mol). The reaction mixture was heated at 55 °C and
stirred for 24 h. The sodium salts were removed by filtration,
and the solvent was concentrated in vacuo. The residue was
extracted three times with ether, and the organic layer was
washed with brine and dried over anhydrous MgSO4. The
solvents were removed in vacuo to afford 5.25 g (80% overall)
of iodide 13 as a dark yellow oil: IR (film) 3020, 2950, 1690
1
cm-1; H NMR (CDCl3, 200 MHz) δ 7.34 (m, 5 Η), 5.12 (bs, 2
H), 3.95 (m, 1 H), 3.38 (m, 4 H), 1.98 (m, 4 H); CIMS (M+
1/z) 346, 204, 149, 128, 91; HRMS exact mass calcd for C13H16
NO2I 345.0228, found 345.0225. Anal. Calcd for C13H16
+
-
-
NO2I: C, 45.24; H, 4.67; N, 4.06. Found: C, 45.25; H, 4.71;
N, 4.09.
P r ep a r a tion of P h osp h on a te 14. To NaH (80% disper-
sion in mineral oil, 0.308 g, 0.010 mol) in DMF (8.0 mL) at rt
under argon was added dropwise dimethyl phosphite (0.94 mL,
0.010 mol). The reaction mixture was stirred at rt for 1 h,
and then iodide 13 (0.354 g, 0.001 mol) in DMF (4 mL) was
added dropwise over 5 min. The reaction mixture was heated
at 55 °C for 18 h, and saturated NH4Cl (10 mL) was added.
The solvents were removed in vacuo, and the residue was
extracted three times with ether. The organic layer was
washed twice with water and then brine and was dried over
anhydrous MgSO4. The solvent was removed in vacuo, and
the residue was purified by column chromatography, eluting
with ethyl acetate/methanol (9/1), to afford 0.190 g (56%) of
phosphonate 14 as a colorless oil: 1H NMR (CDCl3, 200 MHz)
δ 7.26 (m, 5 H), 5.05 (s, 2 H), 4.01 (m, 1 H), 3.57 (m, 6 H), 3.28
(m, 2 H), 2.30 (m, 1 H), 1.88 (m, 2 H), 1.68 (m, 3 H); 13C NMR
(CDCl3, 90 MHz) δ 154.3, 154.2, 136.6, 136.3, 128.2, 127.9,
127.7, 127.5, 66.8, 66.3, 53.0, 52.9, 52.4, 52.3, 52.0, 46.4, 46.0,
31.2, 30.6, 30.3, 29.0, 28.9, 27.5, 23.5, 22.6; 31P NMR (CDCl3,
146 MHz) δ 30.3, 29.9; amide rotamer ratio 1.2/1.0; HRMS
exact mass calcd for C15H22NO5P 327.1236, found 327.1216.
P r ep a r a tion of P h osp h on a te Mon oa cid 11. To phos-
phonate 14 (0.21 g, 0.064 mmol) at rt was added 0.4 M NaOH
(1.6 mL, 0.64 mmol). The reaction mixture was heated at 90
°C for 18 h, and the solvents were removed in vacuo. The
residue was dissolved in water, and the aqueous layer was

130 J . Org. Chem., Vol. 61, No. 1, 1996
Anderson et al.
(bs, 1 H), 4.05 (m, 2 H), 3.80 (m, 3 H), 3.43 (m, 3 H), 1.73 (m,
10 H); CIMS (M+ + 1/z) 350, 318, 266, 222, 190, 91, 85.
P r ep a r a tion of Iod id e 18. To a solution of benzyl car-
bamate 17 (1.53 g, 4.40 mmol) in CH2Cl2 (50 mL) at 0 °C under
argon was added triethylamine (0.79 mL, 5.70 mmol), followed
by dropwise addition of methanesulfonyl chloride (0.41 mL,
5.30 mmol). The reaction mixture was slowly warmed to 25
°C and was stirred for 18 h. Water was added to the reaction
mixture, and the aqueous layer was extracted with CH2Cl2.
The combined organic layers were washed with brine and dried
over anhydrous MgSO4. The solvents were removed in vacuo,
and the residue was purified by column chromatography,
eluting with hexanes/ethyl acetate (1/1), to afford the inter-
mediate mesylate as a colorless oil.
P r ep a r a tion of Alcoh ol 24. To ester alcohol 15 (1.73 g,
6.94 mmol) in DMF (35 mL) at rt under argon was added
imidazole (1.04 g, 15.3 mmol) followed by (tert-butyldimethyl)-
silyl chloride (1.19 g, 7.89 mmol). The reaction mixture was
stirred at 25 °C for 24 h, poured into water, and extracted with
CH2Cl2. The organic layer was washed sequentially with
saturated NaHCO3, water, and brine and was dried over
anhydrous MgSO4. The solvents were removed in vacuo, and
the residue was purified by column chromatography, eluting
with hexanes/ethyl acetate (3/1), to afford 2.40 g of the
intermediate silyl ether as a pale yellow oil.
To the above silyl ether (3.43 g, 9.43 mmol) in toluene (85
mL) at 0 °C under argon was added DIBALH (18.0 mL, 1.0 M
solution in hexanes). The reaction mixture was stirred at 25
°C for 50 min, poured into a saturated solution of Rochelle’s
salts, and stirred with ethyl acetate for 1 h. The solution was
extracted with ethyl acetate, washed with Rochelle’s salts and
brine, and dried over anhydrous MgSO4. The solvents were
removed in vacuo, and the residue was purified by column
chromatography, eluting with hexanes/ethyl acetate (1/1), to
To a solution of the above mesylate (0.053 g, 0.12 mmol) in
DMF (2.0 mL) at rt under argon was added LiI (0.33 g, 2.48
mmol). The reaction mixture was stirred at 80 °C for 18 h,
water was added, and the mixture was extracted three times
with ether. The organic layer was washed with water and
brine and was dried over anhydrous MgSO4. The solvents
were removed in vacuo, and the residue was purified by
column chromatography, eluting with ethyl acetate/hexanes
(1/1), to afford 0.026 g (51% overall) of iodide 18 as a light
afford 3.17 g (78%) of alcohol 24 as a pale yellow oil: [R]23
D
-10.6° (c 0.01, CH2Cl2); IR (neat) 3429 cm-1; 1H NMR (CDCl3,
200 MHz) δ 7.28 (m, 5 H), 3.79 (s, 2 H), 3.30 (m, 4 H), 2.96 (m,
3 H), 1.74 (m, 4 H), 0.81 (s, 9 H), -0.04 (d, J ) 4.5 Hz, 6 H);
CIMS (M+ + 1/z) 336, 320, 318, 304, 278, 258, 204, 190, 156,
91.
1
yellow oil: IR (film) 3010, 2920, 1690 cm-1; H NMR (CDCl3,
200 MHz) δ 7.33 (m, 5 H), 5.13 (s, 2 H), 4.56 (m, 1 H), 4.12 (m,
2 H), 3.57 (m, 5 H), 3.20 (m, 1 H), 2.00 (m, 4 H), 1.57 (m, 6 H);
CIMS (M+ + 1/z) 460, 419, 414, 376, 332, 149, 91.
P r ep a r a tion of r-Hyd r oxy P h osp h on a tes 26. To oxalyl
chloride (1.8 mL, 20.6 mmol) in CH2Cl2 (18 mL) at -78 °C
under argon was added DMSO (2.5 mL, 35.2 mmol) in CH2-
Cl2 (4 mL). The mixture was stirred for 2 min, and then
alcohol 24 (2.48 g, 7.39 mmol) in CH2Cl2 (11 mL) was added
over 5 min. The reaction mixture was stirred at -78 °C for
15 min, and triethylamine (8.2 mL, 58.8 mmol) was added.
The mixture was stirred for 5 min, warmed to rt, poured into
water, and extracted with CH2Cl2. The organic layer was
washed sequentially with 1% HCl, water, 5% Na2CO3, water,
and brine and was dried over anhydrous Na2SO4. The solvents
were removed in vacuo to afford 2.35 g (96%) of aldehyde 25
as a pale yellow oil, which was used directly in the next step
without purification.
P r ep a r a tion of Mesyla te 20. To a solution of benzyl
carbamate 17 (1.53 g, 4.40 mmol) in CH2Cl2 (50 mL) at 0 °C
under argon was added triethylamine (0.79 mL, 5.70 mmol),
followed by dropwise addition of methanesulfonyl chloride
(0.41 mL, 5.30 mmol). The reaction mixture was slowly
warmed to 25 °C and was stirred for 18 h. Water was added
to the reaction mixture, and the aqueous layer was extracted
with CH2Cl2. The combined organic layers were washed with
brine and dried over anhydrous MgSO4. The solvents were
removed in vacuo, and the residue was purified by column
chromatography, eluting with hexanes/ethyl acetate (1/1), to
afford 1.80 g (96%) of mesylate 20 as a colorless oil: IR (film)
2920, 1680, 1350, 1170 cm-1 1H NMR (CDCl3, 200 MHz) δ
;
7.25 (m, 5 H), 5.04 (bs, 2 H), 4.47 (m, 1 H), 4.23 (m, 1 H), 4.03
(m, 3 H), 3.63 (m, 2 H), 3.35 (m, 2 H), 2.84 (m, 3 H), 1.93 (m,
4 H), 1.42 (m, 6 H); CIMS (M+ + 1/z) 428, 390, 386, 384, 344,
300, 268, 158, 91.
P r ep a r a tion of Cyclic Ca r ba m a te Mesyla te 21. To a
solution of mesylate 20 (0.389 g, 0.91 mmol) in methanol (20
mL) at 25 °C under argon was added a catalytic amount of
PPTS. The reaction mixture was heated to 40 °C and stirred
for 18 h. The solvent was removed in vacuo, and the residue
was purified by column chromatography, eluting with ethyl
acetate/hexanes (4/1), to afford 0.287 g of the intermediate
alcohol as a colorless oil.
To a solution of NaH (60% dispersion in mineral oil, 0.030
g, 0.75 mmol) in dry THF (20 mL) at rt under argon was added
the above alcohol (0.180 g, 0.52 mmol) in THF (5 mL). The
reaction mixture was stirred for 48 h, poured into water, and
extracted with ethyl acetate. The organic extracts were
washed with brine, dried with anhydrous MgSO4, and con-
centrated in vacuo. The residue was purified by column
chromatography, eluting with ethyl acetate, to afford 0.090 g
(69% overall) of cyclic carbamate mesylate 21 as a pale yellow
oil: 1H NMR (CDCl3, 200 MHz) δ 5.02 (dd, J ) 3.7, 10.6 Hz,
1 H), 4.52 (t, J ) 7.8 Hz, 1 H), 4.37 (dd, J ) 3.3, 10.6 Hz, 1 H),
4.18 (m, 1 H), 3.86 (m, 1 H), 3.02 (s, 3 H), 2.29 (m, 2 H), 1.97
(m, 1 H), 1.72 (m, 2 H).
P r ep a r a tion of Iod id e 22. To a solution of mesylate 21
(0.084 g, 0.36 mmol) in dry DMF (10 mL) under argon was
added LiI (0.86 g, 6.43 mmol). The reaction mixture was
heated at 80 °C for 24 h, poured into water, and extracted with
ether. The organic extracts were washed with brine, dried
with anhydrous MgSO4, and concentrated in vacuo. The
residue was purified by column chromatography, eluting with
ethyl acetate, to afford 0.045 g (47%) of iodide 22 as a pale
yellow oil: 1H NMR (CDCl3, 200 MHz) δ 4.49 (t, J ) 8.2 Hz,
1 H), 4.20 (m, 2 H), 3.70 (m, 3 H), 2.30 (m, 2 H), 1.89 (m, 2 H);
CIMS (M+ + 1/z) 268, 176, 140, 126.
To the above aldehyde (1.15 g, 3.45 mmol) in dimethyl
phosphite (0.4 mL, 4.36 mL) at rt under argon was added basic
aluminum oxide (Brockmann Activity I, 1.0 g, 9.8 mmol). The
reaction mixture was stirred at 25 °C for 48 h, the alumina
was filtered off and washed with CH2Cl2 (100 mL). The
solvents were removed in vacuo, and the residue was purified
by column chromatography, eluting with ethyl acetate, to
afford 1.05 g (69%) of a diastereomeric mixture of R-hydroxy
phosphonates 26 as a pale yellow oil: 1H NMR (CDCl3, 200
MHz) δ 7.27 (m, 5 H), 3.90 (AB q, J ) 15.8 Hz, 2 H), 3.78 (m,
1 H), 3.72 (d, J ) 10.9 Hz, 3 H), 3.67 (d, J ) 10.9 Hz, 3 H),
3.48 (m, 2 H), 3.20 (m, 2 H), 3.02 (m, 1 H), 1.76 (m, 4 H), 0.78
(s, 9 H), -0.07 (d, J ) 4.5 Hz, 6 H); CIMS (M+ + 1/z) 444, 376,
334, 304, 188, 111, 91.
P r ep a r a tion of Xa n th a tes 27. To phosphonates 26 (0.88
g, 1.87 mmol) in DMF (10 mL) at rt under argon were added
carbon disulfide (1.2 mL, 19.95 mmol) and NaH (60% disper-
sion in mineral oil, 0.083 g, 2.08 mmol). The reaction mixture
was stirred for 30 min, and iodomethane (1.2 mL, 19.28 mmol)
was added. This mixture was stirred for 30 min, concentrated
in vacuo, poured into water, and extracted with ethyl acetate.
The organic extract was washed with brine and dried over
anhydrous MgSO4. The solvents were removed in vacuo, and
the residue was purified by column chromatography, eluting
with ethyl acetate, to afford 0.81 g (81%) of a diastereomeric
mixture of xanthates 27 as a brown oil: CIMS (M+ + 1/z) 534,
518, 474, 426, 388, 304, 218, 111, 91.
P r ep a r a tion of P h osp h on a te 28. To xanthates 27 (1.14
g, 2.14 mmol) in toluene (28 mL) at rt under argon were added
tributyltin hydride (0.85 mL, 3.16 mmol) and AIBN (0.007 g,
0.04 mmol). The reaction mixture was stirred at 115 °C for 3
h. The solvents were removed in vacuo, and the residue was
purified by column chromatography, eluting with ethyl acetate,
to afford 0.77 g (85%) of phosphonate 28 as a pale yellow oil:
1H NMR (CDCl3, 300 MHz) δ 7.24 (m, 5 H), 3.78 (AB q, J )
13.9 Hz, 2 H), 3.57 (d, J ) 10.9 Hz, 3 H), 3.56 (d, J ) 10.9 Hz,

Catalytic Antibodies in Synthesis
J . Org. Chem., Vol. 61, No. 1, 1996 131
3 H), 3.22 (m, 2 H), 3.03 (m, 1 H), 2.83 (m, 1 H), 2.1-1.6 (m,
6 H), 0.79 (s, 9 H), -0.11 (d, J ) 2.6 Hz, 6 H); 13C NMR (CDCl3,
75 MHz) δ 139.7, 128.9, 128.0, 126.8, 67.0, 65.7, 60.5, 58.3,
51.9, 31.3 (d, J ) 133.1 Hz), 30.9, 26.9, 25.8, -5.5; CIMS (M+
+ 1/z) 428, 412, 380, 304, 282, 192, 125, 91.
MHz) δ 7.32 (m, 5 H), 5.11 (s, 2 H), 4.25 (m, 3 H), 3.73 (d, J )
10.7 Hz, 6 H), 3.59 (m, 4 H), 1.90 (m, 3 H), 0.82 (s, 9 H), -0.07
(d, J ) 4.5 Hz, 6 H); CIMS (M+ + 1/z) 488, 430, 378, 348, 304,
156, 111, 91.
P r ep a r a tion of P h osp h on a te 35. To a mixture of dia-
stereomeric phosphonates 33 (1.47 g, 3.01 mmol) in dry DMF
(40 mL) at rt under argon were added carbon disulfide (2.0
mL, 33.3 mmol) and NaH (60% dispersion in mineral oil, 0.145
g, 3.63 mmol). The reaction mixture was stirred for 30 min,
and iodomethane (2.0 mL, 32.1 mmol) was added. The mixture
was stirred for 30 min, poured into water, and extracted with
ethyl acetate. The organic extract was washed with brine and
dried over anhydrous MgSO4. The solvents were removed in
vacuo, and the residue was purified by column chromatogra-
phy, eluting with ethyl acetate, to afford 1.60 g (92%) of a
diastereomeric mixture of xanthates 34 as a brown oil which
was used without further purification: CIMS (M+ + 1/z) 578,
506, 464, 356, 111, 91.
P r ep a r a tion of Hyd r oxy P h osp h on a te 29. To TBDMS
phosphonate 28 (0.11 g, 0.26 mmol) in THF (1 mL) were added
acetic acid (3 mL) and water (1 mL). The reaction mixture
was stirred at 60 °C for 24 h. The solvents were removed in
vacuo, and the residue was purified by column chromatogra-
phy, eluting with ethyl acetate/methanol (20/1), to afford 0.071
g (87%) of phosphonate 29 as a pale yellow oil: 1H NMR
(CDCl3, 300 MHz) δ 7.28 (m, 5 H), 5.05 (bs, 1 H), 3.78 (AB q,
J ) 14.0 Hz, 2 H), 3.58 (d, J ) 10.9 Hz, 3 H), 3.57 (d, J ) 10.9
Hz, 3 H), 3.20 (m, 3 H), 2.97 (m, 1 H), 2.10-1.60 (m, 6 H); 13
C
NMR (CDCl3, 75 MHz) δ 138.4, 129.1, 128.4, 127.4, 65.3, 62.6,
60.0, 57.6, 52.2, 31.2, 30.7 (d, J ) 135.7 Hz), 26.7; CIMS (M+
+ 1/z) 314, 282, 264, 224, 190, 125, 91; HRMS exact mass calcd
for C15H24NO4P 313.1443, found 313.1433.
To the above xanthates 34 (1.60 g, 2.77 mmol) in dry toluene
(40 mL) at rt under argon were added tributyltin hydride (0.95
mL, 3.53 mmol) and AIBN (0.020 g, 0.12 mmol). The reaction
mixture was stirred at 115 °C for 3 h. The solvents were
removed in vacuo, and the residue was purified by column
chromatography, eluting with ethyl acetate, to afford 1.22 g
P r ep a r a tion of Ben zyl Ca r ba m a te 31. To alcohol 24
(2.13 g, 6.35 mmol) and 20% Pd(OH)2/C (0.35 g) at 25 °C under
argon was added ethanol (25 mL). The reaction flask was
evacuated and filled with hydrogen gas (1 atm), and the
mixture was stirred for 18 h. The catalyst was removed by
filtration through a Celite pad, and the pad was washed with
ethyl acetate (5 × 25 mL). The solvents were removed in vacuo
to afford 1.56 g (100%) of the intermediate amino alcohol as a
pale yellow oil, which was used directly in the next step
without further purification.
(94%) of phosphonate 35 as a pale yellow oil: [R]23 -10.4° (c
D
0.01, CH2Cl2); IR (neat) 3470, 2940, 1755, 1682 cm-1; 1H NMR
(DMSO, 300 MHz, 345 K) δ 7.32 (m, 5 H), 5.09 (s, 2 H), 4.03
(bs, 1 H), 3.83 (bs, 1 H), 3.62 (m, 2 H), 3.58 (d, J ) 11.0 Hz, 3
H), 3.57 (d, J ) 11.0 Hz, 3 H), 1.93 (m, 6 H), 0.87 (s, 9 H),
-0.07 (d, J ) 2.6 Hz, 6 H); 13C NMR (DMSO, 75 MHz, 383 K)
δ 153.5, 136.3, 127.5, 127.0, 126.8, 65.5, 62.9, 59.0, 53.4, 50.9,
29.5 (d, J ) 132.5 Hz), 28.9, 25.3, 25.0, 17.2, -6.2; CIMS (M+
+ 1/z) 472, 414, 364, 282, 91.
To a solution of the above amino alcohol (2.45 g, 9.98 mmol)
in dry CH2Cl2 (40 mL) at 0 °C under argon was added
triethylamine (1.45 mL, 10.4 mmol), followed by dropwise
addition of benzyl chloroformate (1.80 mL, 12.6 mmol). The
reaction mixture was stirred at 0 °C for 18 h, water was added,
and the aqueous layer was extracted with CH2Cl2. The
combined organic layers were washed with brine and dried
over anhydrous MgSO4. The solvents were removed in vacuo,
and the residue was purified by column chromatography,
eluting with hexanes/ethyl acetate (1/3), to afford 3.50 g (93%)
P r ep a r a tion of P h osp h on a te 36. To TBDMS phospho-
nate 35 (0.59 g, 1.25 mmol) in THF (2 mL) were added acetic
acid (6 mL) and water (2 mL). The reaction mixture was
stirred at 60 °C for 24 h. The solvents were removed in vacuo,
and the residue was purified by column chromatography,
eluting with ethyl acetate/methanol (20/1), to afford 0.43 g
of benzyl carbamate 31 as a pale yellow oil: [R]23 -16.9 (c
(95%) of phosphonate 36 as a pale yellow oil: [R]23 -1.1° (c
D
D
0.01, MeOH); IR (neat) 3445, 3025, 2940, 1675 cm-1; 1H NMR
(DMSO, 300 MHz, 345 K) δ 7.34 (m, 5 H), 5.08 (s, 2 H), 4.37
(t, J ) 5.5 Hz, 1 H), 3.84 (m, 2 H), 3.69 (dd, J ) 3.5, 9.8 Hz, 1
H), 3.57 (m, 2 H), 3.38 (m, 1 H), 1.89 (m, 4 H), 0.86 (s, 9 H),
0.00 (s, 6 H); 13C NMR (DMSO, 75 MHz, 383 K) δ 154.1, 136.5,
127.5, 127.1, 126.7, 65.4, 63.2, 59.7, 59.1, 25.5, 25.1, 25.0, 17.2,
-6.1; CIMS (M+ + 1/z) 380, 362, 322, 304, 233, 214, 190, 156,
108, 91; HRMS exact mass calcd for C20H33NO4Si 379.2179,
found 379.2163. Anal. Calcd for C20H33NO4Si: C, 63.29; H,
8.76; N, 3.69. Found: C, 63.06; H, 8.66; N, 3.78.
0.01, CH3OH); IR (neat) 3240, 2850, 1660 cm-1
;
1H NMR
(DMSO, 300 MHz, 345 K) δ 7.33 (m, 5 H), 5.09 (s, 2 H), 4.57
(bs, 1 H), 4.04 (m, 1 H), 3.81 (m, 1 H), 3.60 (d, J ) 10.9 Hz, 6
H), 3.44 (m, 2 H), 1.89 (m, 6 H); 13C NMR (DMSO, 75 MHz,
383 K) δ 153.6, 136.9, 127.6, 127.0, 126.8, 65.2, 61.9, 59.9, 53.0,
50.9, 29.5 (d, J ) 138.0 Hz), 29.0, 25.2; CIMS (M+ + 1/z) 358,
326, 250, 115, 91; HRMS exact mass calcd for C16H24NO6P
357.1341, found 357.1341. Anal. Calcd for C16H24NO6P: C,
53.78; H, 6.77; N, 3.92. Found: C, 53.43; H, 6.84; N, 3.86.
P r ep a r a tion of Glu ta r a te 38. To a solution of phospho-
nate 36 (0.120 g, 0.34 mmol) in dry CH2Cl2 (4 mL) at rt under
argon were added triethylamine (0.10 mL, 10.4 mmol) and
glutaric anhydride (0.165 g, 1.35 mmol). The reaction mixture
was stirred for 3 d, the solvents were removed in vacuo, and
the residue was acidified with 1% HCl. The product was
purified by column chromatography, eluting with CH2Cl2/
methanol (20/1), to afford 0.130 g (82%) of glutarate 38 as a
yellow oil: [R]23D -2.5° (c 0.01, MeOH); 31P NMR (acetone, 360
MHz) δ 32.1; 1H NMR (DMSO, 300 MHz, 345 K) δ 7.35 (m, 5
H), 5.10 (s, 2 H), 4.10 (m, 4 H), 3.60 (d, J ) 10.9 Hz, 6 H), 2.33
(t, J ) 7.4 Hz, 2 H), 2.24 (t, J ) 7.4 Hz, 2 H), 1.80 (m, 8 H);
13C NMR (DMSO, 75 MHz, 383 K) δ 172.7, 171.5, 153.7, 136.2,
127.5, 126.9, 126.7, 65.7, 64.0, 56.5, 56.4, 53.7, 53.3, 51.0, 32.3,
28.4 (d, J ) 149.0 Hz), 25.8, 19.4; MS (FAB-, glycerol) m/ z
471, 456, 379, 358, 342, 336, 293, 265, 190, 145, 131.
P r ep a r a tion of P h osp h on a te 33. To oxalyl chloride (0.80
mL, 9.17 mmol) in dry CH2Cl2 (10 mL) at -78 °C under argon
was added DMSO (0.70 mL, 9.86 mmol) in CH2Cl2 (1 mL). The
mixture was stirred for 2 min, and then alcohol 31 (1.25 g,
3.29 mmol) in CH2Cl2 (5 mL) was added over 5 min. The
reaction mixture was stirred at -78 °C for 15 min, and
triethylamine (3.40 mL, 24.3 mmol) was added. The mixture
was stirred for 5 min, warmed to rt, poured into water, and
extracted with CH2Cl2. The organic layer was washed se-
quentially with 1% HCl, water, 5% Na2CO3, water, and brine
and was dried over anhydrous Na2SO4. The solvents were
removed in vacuo to afford 1.24 g (100%) of aldehyde 32 as a
pale yellow oil, which was used directly in the next step
without purification.
To dimethyl phosphite (0.35 mL, 3.82 mmol) in dry DMF
(100 mL) under argon was added NaH (60% dispersion in
mineral oil, 0.131 g, 3.28 mmol). The reaction mixture was
stirred for 1 h and cooled to 0 °C, and the above aldehyde (1.24
g, 3.28 mmol) in DMF (5 mL) was added. The mixture was
stirred at 0 °C for 48 h, poured into saturated NH4Cl, and
extracted with ethyl acetate. The organic layer was washed
twice with water and then brine and dried over anhydrous
MgSO4. The solvents were removed in vacuo, and the residue
was purified by column chromatography, eluting with ethyl
acetate, to afford 1.46 g (91%) of a diastereomeric mixture of
phosphonates 33 as a pale yellow oil: 1H NMR (CDCl3, 200
P r ep a r a tion of P h osp h on ic Acid 39. To glutarate 38
(0.098 g, 0.208 mmol) under argon was added dry tert-
butylamine (5 mL). The reaction mixture was stirred at 50
°C for 7 d. The solvents were removed in vacuo, and the
residue was acidified by ion exchange chromatography (Dowex
50X-8), eluting with H2O, to give 0.075 g of crude product. This
material was purified by reverse phase HPLC (Partisil 10
ODS, 10 µm × 50 cm) with a linear gradient of 0.1% TFA in
H2O/CH3CN (80-50% over 30 min) to give 0.045 g (47%) of
phosphonic acid 39 as a pale yellow oil: [R]23 -2.3° (c 0.01,
D
MeOH); 31P NMR (DMSO, 360 MHz) δ 23.2, 26.9; 1H NMR

132 J . Org. Chem., Vol. 61, No. 1, 1996
Anderson et al.
(DMSO, 300 MHz, 345 K) δ 7.35 (m, 5 H), 5.10 (s, 2 H), 4.08
(m, 4 H), 3.53 (d, J ) 10.9 Hz, 3 H), 2.32 (t, J ) 7.2 Hz, 2 H),
2.24 (t, J ) 7.3 Hz, 2 H), 1.80 (m, 8 H); 13C NMR (DMSO, 75
MHz, 385 K) δ 171.9, 171.4, 153.7, 136.3, 127.5, 126.9, 126.8,
65.6, 64.0, 61.9, 56.4, 54.1, 50.4, 48.0, 31.3 (d, J ) 136.2 Hz),
29.0, 25.8, 19.3; MS (FAB-, glycerol) m/ z 456, 442, 362, 342,
324, 310, 234, 208, 190, 176, 145, 131.
P r ep a r a tion of Acid Ester 40. To succinic anhydride
(0.50 g, 5.0 mmol) in dry CH2Cl2 (10 mL) at rt under argon
were added triethylamine (0.70 mL, 5.0 mmol) and (trimeth-
ylsilyl)ethanol (0.75 mL, 5.2 mmol). The reaction mixture was
stirred at rt for 24 h, the solvents were removed in vacuo, and
the residue was purified by flash chromatography, eluting with
ethyl acetate, to afford 0.78 g (72%) of acid ester 40 as a pale
yellow oil: 1H NMR (CDCl3, 200 MHz) δ 9.92 (bs, 1 H), 4.12
(t, J ) 8.5 Hz, 2 H), 2.54 (m, 4 H), 0.90 (t, J ) 8.5 Hz, 2 H),
-0.05 (s, 9 H).
P r ep a r a tion of P h osp h on ic Acid 43. To phosphonate
42 (0.051 g, 0.089 mmol) under argon was added dry tert-
butylamine (5 mL). The reaction mixture was stirred at 50
°C for 7 d. The solvents were removed in vacuo, and the
residue was purified by ion exchange chromatography (Dowex
50X-8), eluting with H2O, to give 0.043 g of a brown oil. This
material was dissolved in dry THF (5 mL) under argon, and
TBAF (0.1 mL, 0.10 mmol) was added. The reaction mixture
was stirred at rt for 2 h. The solvents were removed in vacuo,
and the residue was acidified by ion exchange chromatography
(Dowex 50X-8), eluting with H2O, to give 0.035 g of crude
product. This compound was purified by reverse phase HPLC
(Partisil 10 ODS, 10 µm × 50 cm) with a linear gradient of
0.1% TFA in H2O/CH3CN (80-50% over 30 min) to give 0.020
g (57%) of phosphonic acid 43 as a pale yellow oil: [R]23D -13.4°
(c 0.005, MeOH); 31P NMR (DMSO, 360 MHz) δ 27.3, 27.0; 1H
NMR (DMSO, 300 MHz, 345 K) δ 7.35 (m, 5 H), 6.80 (bs, 1
H), 5.10 (s, 2 H), 4.02 (m, 4 H), 3.52 (d, J ) 10.9 Hz, 3 H), 3.19
(m, 2 H), 2.38 (t, J ) 7.0 Hz, 2 H), 1.87 (m, 6 H); 13C NMR
(DMSO, 75 MHz, 385 K) δ 171.6, 155.3, 153.7, 136.5, 127.6,
126.4, 65.5, 64.0, 56.7, 56.5, 53.9, 48.0, 36.2, 33.8, 29.0, 26.8
(d, J ) 136.4 Hz); MS (FAB-, glycerol) m/ z 457, 443, 342, 323,
310, 234, 220, 208, 190, 176, 162, 135.
P r ep a r a tion of P h osp h on a te 42. To acid ester 40 (0.15
g, 0.69 mmol) in dry toluene (5 mL) under argon were added
triethylamine (0.10 mL, 0.72 mmol), DPPA (0.15 mL, 0.70
mmol), and alcohol 36 (0.083 g, 0.23 mmol) in toluene (2 mL).
The reaction mixture was stirred at 80 °C for 24 h. The solvent
was removed in vacuo, and the residue was dissolved in ethyl
acetate. This solution was washed with dilute NaOH, dried
over MgSO4, concentrated in vacuo, and purified by column
chromatography, eluting with ethyl acetate, to give 0.103 g of
crude product as a yellow oil. This material was further
purified by HPLC using ethyl acetate as an eluant to give 0.051
Ack n ow led gm en t. The Weinreb group thanks the
National Science Foundation for financial support on
Grant CHE-94-23670. D.B.S. was supported on NIH
Postdoctoral Fellowship 5F32-GM-15536.
g (38%) of phosphonate 42 as a yellow oil: [R]23 -3.4 (c 0.01,
D
MeOH); IR (neat) 3270, 2945, 1726, 1696 cm-1
;
1H NMR
(DMSO, 300 MHz, 345 K) δ 7.35 (m, 5 H), 6.84 (bs, 1 H), 5.10
(s, 2 H), 4.13 (t, J ) 8.2 Hz, 2 H), 4.05 (m, 4 H), 3.59 (d, J )
10.8 Hz, 6 H), 3.24 (t, J ) 7.0 Hz, 2 H), 2.42 (t, J ) 7.0 Hz, 2
H), 1.91 (m, 6 H), 0.95 (t, J ) 8.2 Hz, 2 H), 0.03 (s, 9 H); 13C
NMR (DMSO, 75 MHz, 385 K) δ 170.3, 155.2, 153.7, 136.3,
127.7, 126.9, 126.7, 65.6, 63.9, 61.1, 56.9, 53.7, 53.1, 50.9, 36.1,
33.9, 29.2, 26.6 (d, J ) 130.8 Hz), 16.4, -2.2; MS (FAB-,
glycerol) m/ z 571, 557, 463, 437, 423, 364, 342, 291, 248, 232,
208, 176, 131.
Su p p or tin g In for m a tion Ava ila ble: NMR spectra of new
compounds (23 pages). This material is contained in libraries
on microfiche, immediately follows this article in the microfilm
version of the journal, and can be ordered from the ACS; see
any current masthead page for ordering information.
J O951469T