Lipo α-amino-β-hydroxy acids and O-linked glycosides: Building blocks for ceramyl and glycosphingoyl peptides

Full text of DOI:10.1021/jo015844v

7178
J . Org. Chem. 2001, 66, 7178-7183
Notes
Sch em e 1
Lip o r-Am in o-â-h yd r oxy Acid s a n d
O-Lin k ed Glycosid es: Bu ild in g Block s for
Cer a m yl a n d Glycosp h in goyl P ep tid es
Michael M. Palian and Robin Polt*
Department of Chemistry, The University of Arizona,
Tucson, Arizona 85721
polt@u.arizona.edu
Received J une 17, 2001
In tr od u ction
cosphingopeptides. The synthesis represents the first of
its type, possessing an O-linked glycoside (as in endog-
enous glycoproteins) and a C-linked lipid chain to the
amino acid, to provide a higher level of enzymatic
stability in vivo.
â-hydroxy R-amino acids, including threonine, serine,
and other unusual amino acids, are an important class
of chiral, bioactive molecules.1 In addition to being
constituents of bioactive peptides such as cyclosporin,2
they are also components of various natural products
such as vancomycin and bouvardin. â-Hydroxy R-amino
acids are also synthetic intermediates for complex prod-
ucts,3 such as â-lactams,4 â-fluoro amino acids,5 and
aziridines.6
The presence of â-hydroxy amino acids within a peptide
allows for additional functionality, e.g., glycosylation.7
Glycosides are critical for a number of biological pro-
cesses, including molecular recognition,8 stability to
enzymatic degradation,9 and enhanced transport and
biodistribution.10 In addition, compounds of this type
constitute ceramide and glycosylceramide analogues and
could provide biologically interesting peptide-glycosphin-
golipid chimeras.
Resu lts a n d Discu ssion
In all experiments, D-serine Schiff base 1 was used as
the starting material. Reductive alkylation of the methyl
i
ester14 with Bu5Al2H15 and alkyl Grignard reagents led
to protected amino diols 2a -d in enantiomerically pure
form and in good yield16 (Scheme 1). Regardless of chain
length, all reductive alkylations proceeded in good yield
(60-72%) with excellent diastereoselectivity for the threo
product. The products of these reactions were then
converted to their respective â-hydroxy amino acids.
In three cases, the reductive alkylation products 2a -c
were hydrogenated and reprotected as the Fmoc carbam-
ates without purification (Scheme 2). This proceeded in
75-82% yield over two steps. The Fmoc-protected silyl
amino diols 3a -c were desilylated with BF3‚Et2O (78-
92%) and subjected to selective oxidation of the primary
alcohol in the presence of the unprotected secondary
alcohol. This was accomplished using the TEMPO oxida-
tion procedure17 as refined by a group at Merck18 for
substrates containing a single hydroxyl group. We ob-
A number of lipo-amino acid syntheses exist,11 but few
possess a side chain capable of glycosylation. The glyco-
sides12 of differentially protected amino diols13 were
assembled via three different routes and can be used to
create several amphiphilic motifs, including novel gly-
(1) For recent syntheses of â-hydroxy amino acids, see: (a) Felice,
P. D.; Porzi, G.; Sandri, S. Tetrahedron: Asymmetry 1999, 10, 2191-
2201. (b) Horikawa, M.; Shigeri, Y.; Yumoto, N.; Yoshikawa, S.;
Nakajimi, T.; Ohfune, Y. Bioorg. Med. Chem. Lett. 1998, 8, 2027-2032.
(c) Hutton, C. A. Org. Lett. 1999, 1, 295-297. (d) Koskinen, A. M. P.;
Hasilla, H.; Myllymaki, V. T.; Rissanen, K. Tetrahedron Lett. 1995,
36, 5619-5622. (e) Shoa, H.; Goodman, M. J . Org. Chem. 1996, 61,
2582-2583. For reviews, see: (f) Genet, J . P. Pure Appl. Chem. 1996,
68, 593-596. (g) Goleciowski, A.; J urczak, J . Synlett 1993, 4, 241-5.
(2) Williams, D. H. Acc. Chem. Res. 1984, 17, 364.
(11) (a) Continantinou-Kototou, V.; Kototos, G. Amino Acids 1999,
16, 273-275. (b) Kototos, G.; Padron, J . M.; Martin, T.; Gibbons, W.
A.; Martin, V. S. J . Org. Chem. 1998, 63, 3741-3744. (c) Kototos, G.;
Padron, J . M.; Noula, C.; Gibbons, W. A.; Martin, V. S. Tetrahedron:
Asymmetry 1996, 7, 857-866. (d) Pignatello, R.; J ansen, G.; Kathmann,
I.; Puglisi, G.; Toth, I. J . Pharm. Sci. 1998, 87, 25-30.
(12) Peterson, M. A.; Polt, R. J . Org. Chem. 1993, 58, 4309-4314.
(13) Mitchell, S. A.; Oates, B. D.; Razavi, H. R.; Polt, R. J . Org.
Chem. 1998, 63, 8837-8842.
(3) Coppola, G. M., Schuster H. F. Asymmetric Syntheses. Construc-
tion of Chiral Molecules Using Amino Acids; J ohn Wiley and Sons:
Toronto, 1987.
(4) (a) Miller, M. J . Acc. Chem. Res. 1986, 19, 45-56. (b) Lotz, B.
T.; Miller M. J . J . Org. Chem. 1983, 58, 618-624.
(14) In the hexyl and decyl case, the ethyl ester was also used, and
produced no increase in yield, compared to the methyl ester.
(15) Alkylaluminum species aggregate into fluxional trimers in
hydrocarbon solution or dimers in more coordinating solvents. NMR
studies suggest that the Schiff base esters used in this study react
with the [iBu3Al]3 and [iBu2AlH]3 trimers to promote the formation of
a dimeric [iBu3Al‚iBu2AlH or iBu5Al2H] complex prior to reductive
alkylation. (a) Eisch, J . J .; Rhee, S. G. J . Organomet. Chem. 1974, 42,
C73. (b) Polt, R.; Peterson, M. A.; DeYoung, L. J . Org. Chem. 1992,
57, 5469-5480.
(5) Pansare, S. V.; Vederas, J . C. J . Org. Chem. 1987, 52, 4804-
4810.
(6) Tanner, D. Angew. Chem., Int. Ed. Engl. 1994, 33, 599.
(7) For reviews on glycosylation, see: (a) Whitfield, D. M.; Douglas
S. P. Glycoconjugate J . 1994, 13, 5-17. (b) Toshima, K.; Tatsuta, K.
Chem. Rev. 1993, 93, 1503-1531.
(8) Hruby, V. J . Alobeidi, F.; Kazmierski, W.; Biochemistry J . 1990,
268, 249-262.
(9) Rush, B. D.; Ruwart, M. J . J . Med. Chem. 1991, 34, 3140-3143.
(10) Polt, R.; Porreca, R.; Szabo`, L. Z.; Bilsky, E. J .; Davis, P.; Davis,
T. P.; Horvath, R.; McCormick, J . M.; Yamamura, H. I.; Hruby, V.
J .Proc. Natl. Acad. Sci U.S.A. 1994, 91, 7114-7118.
(16) Polt, R.; Peterson, M. A. Tetrahedron Lett. 1990, 31, 4985-6.
(b) Peterson, M. A.; Polt, R. Synth. Commun. 1992, 22, 477. (c) Sames,
D.; Polt, R. Synlett 1995, 552.
10.1021/jo015844v CCC: $20.00 © 2001 American Chemical Society
Published on Web 09/21/2001

Notes
J . Org. Chem., Vol. 66, No. 21, 2001 7179
Sch em e 2
Sch em e 4
provided the Fmoc methyl â-glycosyl amino acid in a 77%
yield.
Glycosylation of 3b and 3c failed using these same
conditions. Similar electrophilic reactions also failed,
including the Koenigs-Knorr, Glc(OAc)5 with BF3‚OEt2
or TMSOTf, Schmidt’s trichloroacetimidate method, as
well as tert-butylation, acylation, and benzylation. A
priori, these transformations appear to be facile, but from
our experience with these compounds the secondary
hydroxyl is much more hindered than expected, and its
nucleophilicity is reduced due to unfavorable hydrogen
bonding with the carbamate NH.20
Therefore, a different route to the other two glycosides
was required. The unprotected hexyl â-hydroxy lipo
amino acid (5b) was directly glycosylated with â-glucose
penta-acetate21 (Scheme 4). While yields in this reaction
were very modest, they were comparable to those seen
in similar cases and provided a direct route to the desired
glycoside without any further protection or deprotection.
Sch em e 3
A slightly longer route was devised for synthesis of the
C13 â-hydroxy amino acid glycoside (decyl adduct), which
involved a protecting group switch to alleviate some steric
hindrance at the secondary hydroxyl (Scheme 5). The
reductive alkylation product 2c was subjected to 2 M HCl
in THF, resulting in simultaneous cleavage of the Schiff
base and the silyl ether to provide the amino diol. This
was protected with Fmoc-Cl without purification to yield
4c. This diol was then regioselectively protected at the
primary alcohol with benzyl chloroformate to provide 6c.
We hoped this compound would be less hindered than
silyl-protected 3c and the benzyl carbonate would com-
pete for the carbamoyl N-H hydrogen bond. When the
Fmoc alcohol 6c was treated with the trichloroacetimi-
date and TMSOTf, this glycosylation proceeded in good
yield and selectivity for the desired â glycoside 7c. The
benzyl ether was then cleaved by hydrogenolysis and
oxidized in two steps via the aldehyde to give the final
product (9c) in good yield.
served no over-oxidized (diketo) products in the reaction
mixtures. With increasing alkyl chain length, it was
observed that the oxidation rate slowed, probably due to
steric interactions and/or micelle formation. The final
step of this sequence proceeded in 65-96% yield. In the
decyl case, phase-transfer conditions were required as a
result of the high lipophilicity. This provided the pro-
tected C4, C9, and C13 â-hydroxy lipo amino acids in
respectable overall yields, in five steps from the crystal-
line serine derivative 1.
This note describes the stereoselective synthesis of
novel lipo-amino acids and three different routes to their
glycosides. This approach appears to be the method of
choice for the synthesis of these lipid-like glycosyl amino
alcohols and acids, and allows for the preparation of
lipophilic glycopeptides and peptides, prepared by solid-
phase methods.22 The resulting amphipathic glycopep-
tides may possess interesting drug transport activities.23
Glycosylation was achieved directly for protected amino
diol 3a (Scheme 3), using Helferich19 conditions (HgBr2),
to give the glycoside in 72% yield with greater than 20:1
selectivity for the â-product. Using BF3‚Et2O, the silyl
ether was removed in 71% yield and the primary alcohol
oxidized to the acid. However, the TEMPO oxidation was
much slower than the simpler cases, proceeding to an
unoptimized yield of 43%. Since there is no secondary
alcohol in this case, another less selective method of
oxidation was employed. Oxidation with RuCl3/NaIO4
(20) Mitchell, S. A.; Pratt, M. R.; Hruby, V. J .; Polt, R. J . Org. Chem.
2001, 66, 2327-2342.
(21) Salvador, L. A.; Elofsson, M.; Kilhberg, J . Tetrahedron 1995,
51, 5643-5656.
(22) The glycopeptide enkephalin analogue H2N-Tyr-D-Thr-Gly-Phe-
Leu-[9c]-CONH2 has been synthesized, and its pharmacology is under
investigation.
(17) (a) Siedlecha, R.; Skazewski, L.; Mlochowski, J . Tetrahedron
Lett. 1990, 31, 2177. (b) Rychnovsky, S.; Vaidyananthan, R. J . Org.
Chem. 1999, 64, 310-312.
(18) Zhoa, M.; Li, J .; Mano, E.; Song, Z.; Tschaen, D. M.; Grabowski,
E. J . J .; Reider, P. J . J . Org. Chem. 1999, 64, 2564-2566.
(19) Helferich, B.; Weis, K. Chem Ber. 1956, 89, 314-321.
(23) (a) See ref 10. (b) Polt, R.; Mitchell, S. A. In Glycoscience:
Chemistry and Chemical Biology; Fraser-Reid, B., Ed.; Springer-
Verlag: New York, 2000; pp 2355-92. (c) Kriss C. T.; Lou B. S.; Szabo`
L. Z.; Mitchell, S. A.; Hruby, V. J . Polt, R. Tetrahedron: Asymmetry
2000, 11, 9-25.

7180 J . Org. Chem., Vol. 66, No. 21, 2001
Notes
HPO4 buffer) and 3 mL of MeCN and heated to 60 °C in an oil
bath. To the rapidly stirring solution was added TEMPO (0.20
equiv) in one portion. Sodium hypochlorite, NaOCl (0.20 equiv,
5.25% commercial bleach dissolved in 0.5 mL of H2O), and
sodium chlorite, NaClO2 (80%, 2.0 equiv dissolved in 0.5 mL of
H2O), were then added simultaneously over 1 h to the mixture,
which was heated at 45 °C for the amount of time specified. The
reaction was then acidified to pH 3 with dilute HCl and extracted
3× with EtOAc. The combined extracts were dried over MgSO4,
filtered, and concentrated in vacuo.
Sch em e 5
(2R,3R)-2-(Ben zh yd r ylid en ea m in o)-1-(ter t-bu tyld im eth -
ylsila n yloxy)bu ta n -3-ol, 2a . P r oced u r e A. The crude reduc-
tive alkylation product was chromatographed (4.5% EtOAc/
hexanes/0.1% Et3N, Rf ) 0.40). Yield: 60% as a yellow oil. IR
(cm-1): 3302.2, 3061.4, 2925.5, 2332.7, 1659.6, 1449.7, 1252.1,
1091.6. 1H NMR (CDCl3) δ: 7.62 (d, 2H, J ) 7.5 Hz), 7.46 (d,
2H, J ) 7.5 Hz), 7.23 (m, 6H), 4.01 (m, 1H), 3.70 (ddd, 2H, J )
4.5, 4.5, 10.5, 32.0 Hz), 2.97 (bs, 1H), 2.86 (m, 1H), 1.22 (d, 3H,
J ) 6.0 Hz), 0.81 (s, 9H), 0.00, 0.00 (s, 6H). 13C NMR (CDCl3) δ:
145.7, 145.4, 128.0, 127.8, 127.3, 127.1, 126.5, 125.9, 75.8, 66.5,
61.2, 25.7, 19.4, 18.1, -5.9. HRMS: calcd for C23H34NO2Si
384.2359, found 384.2358 (diff ) 0.3 ppm).
(2R,3R)-2-(Ben zh yd r ylid en ea m in o)-1-(ter t-bu tyld im eth -
ylsila n yloxy)n on a n -3-ol, 2b. P r oced u r e A. Crude 2b was
chromatographed (2.5% EtOAc/hexanes/0.1% Et3N, Rf ) 0.40).
Yield: 60% as a yellow oil. IR (cm-1): 3506.0, 3061.4, 2956.4,
2925.5, 2851.46, 2357.46, 1449.7, 1252.14, 1091.6. 1H NMR δ:
7.70 (d, 2H, J ) 7.5 Hz), 7.54 (d, 2H, J ) 7.5 Hz), 7.30 (m, 2H),
7.24 (m, 2H), 3.95 (m, 1H), 3.77 (dd, 1H, J ) 5.0, 10.5 Hz), 3.72
(dd, 1H, J ) 3.0, 10.5 Hz), 3.00 (m, 1H), 1.58 (m, 1 H), 1.47 (m,
3H), 1.33 (m, 4 H), 1.01 (t, 2H, J ) 6.5 Hz), 0.92 (t, 3H, J ) 7.5
Hz), 0.89 (s, 9H), 0.07, 0.05 (s, 6H). 13C NMR δ: 145.5, 145.2,
127.9, 127.7, 127.0, 126.4, 125.9, 79.7, 65.2, 61.7, 43.7, 34.6, 31.6,
29.2, 26.4, 25.8, 22.5, 18.4, 14.0, 0.9, -5.6. HRMS: calcd for
C28H44NO2Si 454.3141, found 454.3154 (diff ) 2.7 ppm).
(2R,3R)-2-(Ben zh yd r ylid en ea m in o)-1-(ter t-bu tyld im eth -
ylsila n yloxy)tr id eca n -3-ol. P r oced u r e A. Crude 2c was
chromatographed (2.5% EtOAc/hexanes, with 0.1% Et3N, Rf )
0.40). Yield: 72% as a yellow oil. IR (cm-1): 3320.7, 3055.2,
2925.5, 2851.4, 2357.4, 1449.7, 1252.1, 1091.6. 1H NMR (CDCl3)
δ: 7.69 (d, 2H, J ) 7.0 Hz), 7.53 (d, 2H, J ) 7.5 Hz), 7.31 (m,
6H), 3.95 (m, 1H), 3.77 (dd, 1H, J ) 4.5, 10.3 Hz), 3.71 (dd,1H,
J ) 3.0, 10.5 Hz) 2.99 (m, 1H), 1.57, 1.47, 1.31 (m, 18H), 0.93 (t,
3H, J ) 6.5 Hz), 0.88 (s, 9H), 0.07, 0.05 (s, 6H). 13C NMR (CDCl3)
δ: 145.6, 145.4, 127.9, 127.2, 127.0, 126.4, 125.9, 98.7, 79.7, 65.2,
61.7, 34.6, 31.4, 29.6, 29.5, 29.5, 29.5, 29.3, 26.5, 25.7, 22.6, 14.0,
-6.2. HRMS: calcd for C32H52NO2Si 510.3767, found 510.3678
(diff ) 0.2 ppm).
(2R,3R)-2-(Ben zh yd r ylid en ea m in o)-1-(ter t-bu tyld im eth -
ylsila n yloxy)octa d eca n -3-ol, 2d . P r oced u r e A. Crude 1d was
chromatographed (35% DCM/hex with 0.1% Et3N, Rf ) 0.24).
Yield: 65.6% as a yellow oil. IR (cm-1): 3320.3, 3055.6, 2924.9,
2852.1, 2357.0, 1449.2, 1252.0, 1089.1. 1H NMR (CDCl3): 7.69
(d, J ) 7.5 Hz, 2H), 7.54 (d, J ) 7.0 Hz, 2H), 7.24 (m, 4H), 3.95
(dt, 1H), 3.73 (ddd, J ) 15.0, 5.0, 3.5 Hz, 2H), 2.99 (m, 1H), 1.28
(m, 28H), 0.93 (t, J ) 8.0 Hz, 3H), 0.90 (s, 9H), 0.06 (s, 3H),
0.04(s, 3H). 13C(CDCl3):145.8,145.6, 128.0, 127.9, 126.5, 126.0,
79.8, 65.3, 61.8, 34.7, 32.0, 29.7, 29.6, 29.4, 26.6, 25.8, 22.7, 14.1,
-5.4. HRMS: (m/z) obsd ) 580.4559, calcd ) 580.4557 (diff )
1.9 ppm).
Exp er im en ta l Section
P r oced u r e A. R ed u ct ive Alk yla t ion w it h Gr ign a r d s
(2a -d ). Compound 1 was dried overnight in vacuo over P2O5.
A solution of 1 (1 equiv in 30-60 mL of CH2Cl2) was chilled to
-78 °C under argon for 30 min. A solution of iBu5Al2H (1.0 equiv,
0.5 M of each in hexanes) was added dropwise via syringe to a
stirring solution of 1 over 45 min at -78 °C. Immediately after
i
the Bu5Al2H addition was complete, the alkylmagnesium bro-
mide (3 equiv in Et2O) was added dropwise via syringe to the
stirring solution over 45 min at -78 °C. The solution was allowed
to warm to rt and stir overnight. The resulting yellow solution
was chilled to 0 °C, carefully quenched with 5 mL of saturated
NaHCO3, and then diluted with 100 mL of CH2Cl2 and washed
3× with saturated NaHCO3 and 1× with brine. The organic layer
was dried over MgSO4, filtered, and concentrated in vacuo.
P r oced u r e B. Sch iff Ba se Clea va ge a n d F m oc Rep r o-
tection (3a -c). Compound 2a -c was dissolved in 100 mL of
MeOH before 10% Pd-C (500 mg, regardless of amount of 2)
was added in one portion under Ar. The reaction was vigorously
stirred under 1 atm of hydrogen (balloon) at rt. After 2 h, all of
the starting material had been consumed, as judged by TLC.
The reaction was quenched with 50 mL of CH2Cl2, filtered
through Celite, and concentrated in vacuo. The crude mixture
i
was then dissolved in dry CH2Cl2, and 3 equiv of Pr2NEt was
added in one portion, before Fmoc-Cl (1.0 equiv in 5 mL of CH2-
Cl2) was added dropwise over 30 min. The reaction was stirred
at rt overnight, diluted with 100 mL of CH2Cl2, and washed 1×
with aqueous HOAc (pH ∼3), 3× with saturated NaHCO3, and
1× with brine. The organic layer was dried over MgSO4, filtered,
and concentrated in vacuo.
P r oced u r e C. Silyl Eth er Clea va ge (4a -c). Compound
3a -c was dissolved in 50 mL of dry CH2Cl2. Freshly distilled
BF3‚OEt2 (6 equiv) was added to the solution in one portion and
stirred at rt. After 2 h, all of the starting material had been
consumed, as judged by TLC. The reaction was then chilled to
0 °C and quenched with 5 mL of saturated NaHCO3. The
solution was diluted with 100 mL of CH2Cl2 and washed 3× with
saturated NaHCO3 and 1× with brine. The organic layer was
dried over MgSO4, filtered, and concentrated in vacuo.
P r oced u r e D. TEMP O Oxid a tion (5a -c). Compound 4a -c
was dissolved in 3 mL of aqueous buffer (0.67 M KH2PO4/Na2-
(2R,3R)-2-(9H-F lu or en -9-ylm eth oxyca r bon yla m in o)-1-O-
(ter t-bu tyld im eth ylsilyl)bu ta n e-1,3-d iol, 3a . P r oced u r e B.
Crude 3a was chromatographed (20% EtOAc/hexanes Rf ) 0.35).
Yield: 82% as a yellow oil. IR (cm-1): 3438.0, 3061.4, 2925.5,
1702.9, 1511.4, 1252.1, 1103.9. 1H NMR (CDCl3) δ: 7.69 (d, 2H,
J ) 7.5 Hz), 7.53 (t, 2H, J ) 7.0 Hz), 7.32 (t, 2H, J ) 7.5 Hz)
7.23 (t, 2H, J ) 7.5 Hz), 5.38 (d, J ) 8.5 Hz), 4.33 (m, 2H), 4.15
(t, 1H, J ) 7.0 Hz), 4.12 (m, 1H), 3.78 (ddd, 2H, J ) 2.0, 3.5,
10.5, 30.0), 3.48 (m, 1H), 3.20 (bs, 1H), 1.12 (d, 3H, J ) 7.0 Hz),
0.83 (s, 9H), 0.00, 0.00 (s, 6H). 13C NMR δ: 156.5, 143.9, 141.2,
127.6, 126.9, 125.0, 119.9, 69.0, 66.7, 66.1, 55.2, 47.2, 25.7, 19.8,
17.0, -5.9. HRMS: calcd for C25H36NO4Si 442.2414, found
442.2435 (diff ) 4.9 ppm).
(2R,3R)-2-(9H-F lu or en -9-ylm eth oxyca r bon yla m in o)-1-O-
(ter t-bu tyld im eth ylsilyl)n on a n e-1,3-d iol, 3b. P r oced u r e B.
Crude 3b was chromatographed (20% EtOAc/hexanes, Rf
)
0.40). Yield: 82% as a yellow oil. IR (cm-1): 3431.9, 2950.26,

Notes
J . Org. Chem., Vol. 66, No. 21, 2001 7181
2925.5, 2857.63, 1696.7, 1503.32, 1449.7, 1252.1, 1103.95. 1H
NMR δ: 7.77 (d, 2H, J ) 7.5 Hz), 7.63 (t, 2H, J ) 6.5 Hz), 7.40
(t, 2H, J ) 7.5 Hz) 7.31 (t, 2H, J ) 7.5 Hz), 5.46 (d, J ) 8.5 Hz),
4.41 (m, 2H), 4.24 (t, 1H, J ) 7.5 Hz), 4.00 (m, 1H), 3.92, 3.85
(dd, 2H, J ) 2.0, 10.5 Hz), 3.63 (d, 1H J ) 8.0 Hz), 3.28 (bs,
1H), 1.56, 1.45 1.30 (m, 10H), 0.92 (s, 9H), 0.90 (d, 3H, J ) 6.5
Hz), 0.00, 0.00 (s, 6H). 13C NMR (CDCl3) δ: 156.3, 143.9, 141.2,
127.5, 126.9, 125.0, 119.8, 73.1, 66.7, 66.4, 53.8, 47.2, 33.8, 31.6,
29.1, 25.6, 25.4, 18.0, 14.0, -5.2. HRMS: calcd for C30H46NO4Si
512.3196, found 512.3181 (diff ) -2.9 ppm).
(2R,3R)-2-(9H-F lu or en -9-ylm eth oxyca r bon yla m in o)-1-O-
(ter t-bu tyld im eth ylsilyl)tr id eca n e-1,3-d iol, 3c. P r oced u r e
B. Crude 3c was chromatographed (17% EtOAc/hexanes, Rf )
0.40). Yield: 81% as a yellow oil. IR (cm-1): 3438.0, 3073.7,
2925.5, 2851.4, 1696.7, 1505.3, 1449.7, 1252.1, 1103.9. 1H NMR
(CDCl3) δ: 7.77 (d, 2H, J ) 7.5 Hz), 7.61 (t, 2H, J ) 7.5 Hz),
7.40 (t, 2H, J ) 7.5 Hz), 7.31 (t, 2H, J ) 7.5 Hz), 5.46 (d, J ) 9.0
Hz), 4.39 (m, 2H), 4.24 (t, 1H, J ) 7.5 Hz), 3.99 (t, 1H, J ) 5.0
Hz), 3.92 (dd, 1H, J ) 3.0, 10.5 Hz), 3.84 (dd, 1H, J ) 2.0, 10.5
Hz), 1.55 (m, 2H), 1.28-1.20 (m, 16H), 0.91 (s, 9H), 0.87 (t, 3H,
J ) 7.5 Hz), 0.08 (s, 3H), 0.07 (s, 3H). 13C NMR (CDCl3) δ: 156.3,
143.9, 141.2, 127.5, 126.9, 125.0, 119.9, 73.2, 66.7, 66.5, 53.8,
47.3, 33.8, 31.8, 29.5, 29.5, 29.2, 25.7, 25.5, 22.6, 18.0, 14.0, -5.6.
HRMS: calcd for C34H54NO4Si 568.3822, found 568.3839 (diff
) 2.9 ppm).
(2S,3R)-(9H-F lu or en -9-ylm eth oxyca r bon yla m in o)-3-h y-
d r oxybu ta n oic Acid , 5a . P r oced u r e D. Total reaction time
was 12 h. Crude 5a was chromatographed (gradient: 100%
EtOAc, followed by EtOAc with 0.5% HOAc, Rf ) 0.60). Yield:
96% as a white solid. IR (cm-1): 3376.3, 2944.0, 1752.3, 1517.6,
1369.4, 1221.2, 1042.2. 1H NMR δ: 7.77 (d, 2H, J ) 7.0 Hz),
7.61 (dd, 2H, J ) 7.5, 11.5 Hz), 7.33 (t, 2H, J ) 7.5), 7.26 (t, 2H,
J ) 7.5 Hz), 4.32 (1H, d, J ) 7.5 Hz), 4.30 (2H, m), 4.17 (1H, m),
4.15 (1H, t, J ) 7.5 Hz), 1.19 (3H, d, J ) 6.5 Hz). 13C NMR
(MeOH) δ: 174.5, 158.8, 145.0, 142.4, 128.7, 128.0, 126.1, 120.8,
68.5, 68.0, 61.0, 48.2, 20.3. HRMS: calcd for C19H20NO5 342.1341,
found 342.1352 (diff ) 3.1 ppm).
(2S,3R)-2-(9H -F lu or en -9-ylm et h oxyca r b on yla m in o)-3-
h yd r oxyn on a n oic a cid , 5b. P r oced u r e D. Total reaction time
24 h. Crude 5b was chromatographed (gradient: 100% EtOAc,
followed by EtOAc with 0.5% HOAc, Rf ) 0.65). Yield: 94% as
a yellow oil. IR (cm-1): 3444.2, 2931.7, 2061.0, 1690.5, 1641.1,
1517.6, 1227.4, 1054.5. 1H NMR (CDCl3) δ: 7.73 (d, 2H, J ) 7.5
Hz), 7.58 (t, 2H, J ) 8.5 Hz), 7.37 (m, 2H), 7.27 (t, 2H, J ) 7.5
Hz), 5.95 (1H, d, J ) 8.5 Hz), 4.42 (1H, d, J ) 8.5 Hz), 4.36 (2H,
d, J ) 7.5 Hz), 4.23 (1H, t, J ) 6.5 Hz), 4.19 (1H, t, J ) 7.5 Hz),
1.52 (2H, m), 1.26 (10H, m), 0.85 (3H, t, J ) 7.5 Hz). 13C NMR
(CDCl3) δ: 175.0, 157.8, 143.6, 141.2, 128.2, 127.5, 125.0, 120.2,
71.7, 67.4, 57.8, 46.9, 33.2, 31.5, 29.0, 25.4, 22.3, 13.9. HRMS:
calcd for C24H30NO5 412.2124, found 412.2127 (diff ) 0.8 ppm).
(2S,3R)-2-(9H -F lu or en -9-ylm et h oxyca r b on yla m in o)-3-
h yd r oxytr id eca n oic Acid , 5c. P r oced u r e D. Total reaction
time was 24 h. Crude 5c was chromatographed (gradient: 100%
EtOAc, followed by EtOAc with 0.5% HOAc, Rf ) 0.70). Yield:
66% as a yellow oil. IR (cm-1): 3357.8, 3607.5, 2925.5, 2851.4,
1721.4, 1530.0, 1449.7, 1252.1, 1085.4. 1H NMR (CDCl3/MeOH)
δ: 7.75 (d, 2H, J ) 8.0 Hz), 7.63 (t, 2H, J ) 8.5 Hz), 7.36 (t, 2H,
J ) 7.5 Hz), 7.28 (t, 2H, J ) 7.5 Hz), 6.53 (d, 1H, J ) 9.5 Hz),
4.39 (dd, 1H, J ) 7.5, 11.0 Hz), 4.34 (dd, 1H, J ) 7.0, 11.0 Hz),
4.27 (bs, 1H), 4.22 (t, 1H, J ) 7.0 Hz), 4.11 (t, 1H, J ) 6.5), 1.49
(2R,3R)-2-(9H-F lu or en -9-ylm eth oxyca r bon yla m in o)bu -
ta n e-1,3-d iol, 4a . P r oced u r e C. Crude 4a was chromato-
graphed (50% EtOAc/hexanes, Rf ) 0.35). Yield: 80% as a white
1
solid. H NMR (CDCl3/MeOH) δ: 7.75 (d, 2H, J ) 8.0 Hz), 7.62
(d, 2H, J ) 7.5 Hz), 7.39 (t, 2H, J ) 7.5 Hz), 7.31 (t, 2H, J ) 8.0
Hz), 5.96 (d, 1H, J ) 9.0 Hz), 4.44 (dd, 1H, J ) 7.0, 10.5 Hz),
4.37 (dd, 1H, J ) 7.0, 10.5 Hz), 4.21 (t, 1H, J ) 7.0 Hz), 4.06 (m,
1H), 3.75 (bs, 1H), 3.65 (d, 2H, J ) 5.5 Hz), 3.52 (m, 1H), 1.17
(d, 3H, J ) 6.5 Hz). 13C NMR (CDCl3/CD3OD) δ: 157.2, 143.5,
141.0, 127.4, 126.7, 124.7, 119.6, 66.4, 66.3, 62.5, 56.6, 48.4, 46.9,
19.3. HRMS: calcd for C19H22NO4 328.1549, found 328.1552 (diff
) 1.0 ppm).
(t 2H, J ) 8.0), 1.28-1.20 (m 16H), 0.85 (t, 3H, J ) 7.5 Hz). 13
C
NMR (CDCl3/MeOH) δ: 173.5, 157.3, 143.2, 140.5, 127.0, 126.2,
124.2, 119.2, 70.6, 66.6, 57.7, 47.2, 33.2, 31.1, 28.7, 28.7, 28.7,
28.7, 24.8, 21.8, 12.8. HRMS: calcd for C28H38NO5 468.2750,
found 468.2745 (error ) -1.0 ppm).
(2R ,3R )-2-(9H -F lu or e n -9-ylm e t h oxyca r b on yla m in o)-
n on a n e-1,3-d iol, 4b. P r oced u r e C. Crude 4b was chromato-
graphed (50% EtOAc/hexanes, Rf ) 0.35). Yield: 92% as a light
yellow oil. IR (cm-1): 3438.0, 2931.7, 1641.17, 1233.1, 1036.0.
1H NMR (CDCl3) δ: 7.77 (d, 2H, J ) 7.5 Hz), 7.60 (d, 2H, J )
7.5 Hz), 7.40 (t, 2H, J ) 7.5 Hz), 7.31 (t, 2H, J ) 7.5 Hz), 5.48
(d, 1H, J ) 8.0 Hz), 4.43 (m, 2H), 4.22 (t, 1H, J ) 7.0 Hz), 3.93
(t, 1H, J ) 6.5 Hz), 3.81 (m, 2H), 3.64 (t, 1H, J ) 6.5 Hz), 1.48
(m, 2H), 1.28-1.20 (m, 8H), 0.92 (dd, 1H, J ) 7.0, 9.5 Hz), 0.87
(t, 3H, J ) 7.0 Hz). 13C NMR (CDCl3) δ: 156.2, 143.8, 141.3,
127.6, 127.0, 124.9, 119.9, 72.5, 66.7, 64.9, 54.8, 47.2, 34.1, 31.7,
29.1, 25.5, 22.5, 22.1, 13.9. HRMS: calcd for C24H32NO4 398.2331,
found 398.2325 (diff ) 1.6 ppm).
(2R,3R)-2-(9H-Flu or en -9-ylm eth oxycar bon ylam in o)tr ide-
ca n e-1,3-d iol, 4c. P r oced u r e C. Crude 4c was chromato-
graphed (50% EtOAc/hexanes, Rf ) 0.40). Yield: 78% as a white
solid. IR (cm-1): 3345.4, 3061.4, 2919.3, 2845.2, 1690.5, 1536.1,
1449.7, 1252.1, 1079.2. 1H NMR (CDCl3) δ: 7.76 (d, 2H, J ) 8.0
Hz), 7.60 (d, 2H, J ) 7.0 Hz), 7.40 (t, 2H, J ) 7.5 Hz), 7.31 (t,
2H, J ) 7.5 Hz), 5.50 (d, 1H, J ) 8.0 Hz), 4.43 (dd, 2H, J ) 7.0,
15.0 Hz), 4.22 (t, 1H, J ) 7.0 Hz), 3.92 (t, 1H, J ) 6.5 Hz), 3.81
(bs, 2H), 3.64 (bs, 1H), 1.48 (m, 2H), 1.28-1.20 (m, 16H), 0.88
(t, 3H, J ) 7.0 Hz). 13C NMR (CDCl3) δ: 156.8, 143.8, 141.3,
127.6, 127.0, 125.0, 119.9, 72.8, 66.7, 65.2, 54.6, 47.2, 34.1, 31.8,
29.5, 29.5, 29.5, 29.5, 29.3, 25.5, 22.6, 14.0. HRMS: calcd for
C28H40NO4 454.2957, found 454.2957 (diff ) 0.1 ppm).
Alt er n a t e P r oced u r e for (2R,3R)-2-(9H -F lu or en -9-yl-
m eth oxyca r bon yla m in o)tr id eca n e-1,3-d iol, 4c. Compound
2c (161 mg, 0.3163 mmol) was dissolved in 2 M HCl (3 mL) and
THF (3 mL) and stirred at rt for 2 h. Upon completion, as judged
by TLC, the crude reaction mixture was made basic (pH ≈ 8.5)
with solid NaHCO3. Fmoc-Cl (108 mg, 0.4174 mmol, 1.3 equiv
in 1 mL dioxane) was then added via syringe to the stirring
mixture over 30 min at rt and allowed to react overnight. The
mixture was diluted with 50 mL of EtOAc and washed 3× with
saturated NaHCO3 and 1× with brine. The organic layer was
dried over MgSO4, filtered, and concentrated in vacuo. Crude
4c was chromatographed (50% EtOAc/hexanes, Rf ) 0.40).
Yield: 110.1 mg (77% over three transformations, as a light
yellow oil).
(2R,3R)-Ca r bon ic Acid Ben zyl Ester 2-(9H-F lu or en -9-
ylm et h oxyca r b on yla m in o)-3-h yd r oxyt r id ecyl E st er , 6c.
Diol 4c (930.0 mg, 2.052 mmol) and DMAP (36.1 mg, 14.4 mol
%) were placed in a flame-dried flask. CH2Cl2 (25 mL) was added,
and the resulting suspension was chilled to -78 °C. iPr2NEt (700
µL, 1.96 equiv) and benzylchloroformate (300 µL, 1.02 equiv)
were then added sequentially to the stirring suspension. The
mixture was slowly allowed to warm to rt and reacted for a total
of 48 h. The product was diluted with 50 mL of CH2Cl2 and
washed 1× with dilute HCl (pH ∼3), 3× with saturated
NaHCO3, and 1× with brine. The organic layer was dried over
MgSO4, filtered, and concentrated in vacuo. Crude 4c was
chromatographed (30% EtOAc/hexanes, Rf ) 0.45). Yield: 1.09
g, 96% as a white solid. IR (cm-1): 3376.3, 2944.0, 1752.3, 1517.6,
1369.4, 1221.2, 1042.2. 1H NMR (CDCl3) δ: 7.75 (d, 2H, J ) 7.5
Hz), 7.57 (d, 2H, J ) 7.5, 11.5 Hz), 7.35 (m, 6H), 7.29 (t, 2H, J
) 7.5 Hz), 5.19 (d, 1H, J ) 9.0 Hz), 5.15 (s, 2H), 4.40 (2H, d, J
) 6.0 Hz), 4.29 (1H, dd, J ) 11.5, 7.0 Hz), 4.21 (1H, dd, J )
11.5, 7.0 Hz), 4.20 (1H, t, J ) 7.5 Hz), 3.87 (1H, d, J ) 6.5 Hz),
3.74 (1H, bs), 1.42 (4H, m), 1.24 (14H, m), 0.87 (3H, t, J ) 6.5
Hz). 13C NMR (CDCl3) δ: 156.4, 155.3, 143.8, 141.3, 134.9, 128.6,
128.3, 127.6, 127.0, 125.0, 119.9, 70.0, 69.8, 67.1, 66.8, 53.1, 47.2,
33.7, 31.8, 29.5, 29.5, 29.4, 29.3, 25.6, 22.6, 14.0.
(2R,3R)-2-(9H-F lu or en -9-ylm eth oxyca r bon yla m in o)-1-O-
(ter t-bu tyld im eth ylsilyl)-3-O-(2,3,4,6-tetr a -O-a cetylglu co-
syl)bu ta n e-1,3-d iol, 7a . In
a flame-dried flask, the Fmoc
acceptor 3a (80.1 mg, 0.1813 mmol), acetobromoglucose (120.0
mg, 0.2919 mmol, 1.61 equiv), and powdered 3 Å molecular
sieves (200 mg) were dissolved in CH2Cl2 and the mixture chilled
to 0 °C. A mixture of Hg(CN)2 (60.0 mg, 0.2375 mmol, 1.30 equiv)
and HgBr2 (81.1 mg, 0.2250 mmol, 1.24 equiv) was added
portionwise over 45 min by solid-addition funnel to the stirring
suspension. The suspension was then allowed to warm to rt and
stirred for a total of 40 h. After being quenched with Et3N (0.2
mL), the solution was diluted with 50 mL of CH2Cl2 and filtered
through Celite. The mixture was then washed 1× with saturated
aqueous Na2SO4, 1× with saturated aqueous NaHCO3, and 1×

7182 J . Org. Chem., Vol. 66, No. 21, 2001
Notes
1
with brine, dried with MgSO4, filtered, and concentrated in
vacuo. Crude 7a was chromatographed (35% EtOAc/hexanes, Rf
) 0.40). Yield: 101 mg, 72%, as a yellow oil. IR (cm-1): 3067.5,
2950.2, 1752.3, 1511.4, 1369.4, 1221.2, 1042.2. 1H NMR (CDCl3)
δ: 7.73 (d, 2H, J ) 8.0 Hz), 7.60 (dd, 2H, J ) 7.5, 4.5 Hz), 7.37
(t, 2H, J ) 7.5 Hz), 7.29 (m, 2H), 5.21 (t, 1H, J ) 9.5 Hz), 5.06
(t, 1H, J ) 9.5 Hz), 5.03 (d, 2H, J ) 8.0 Hz), 4.94 (t, 1H, J ) 8.5
Hz), 4.52 (d, 1H, J ) 8.0 Hz), 4.35 (t, 1H, J ) 6.5 Hz), 4.20 (m,
1H), 4.13 (dd, 1H, J ) 2.0, 6.0 Hz), 4.07 (dd, 1H, J ) 2.0, 12.5
Hz), 3.64 (m, 2H), 3.63 (t, 1H, J ) 8.0 Hz), 3.57 (dd, 1H, J )
4.0, 9.0 Hz), 2.02, 2.00, 2.00, 1.99 (s, 12H), 1.14 (d, 3H, J ) 6.5
Hz), 0.85 (s, 9H), 0.03, 0.02 (s, 6H). 13C NMR (CDCl3) δ: 170.1,
170.0, 169.4, 169.3, 156.4, 143.9, 141.2, 127.6, 127.0, 125.1, 119.9,
98.3, 72.4, 72.0, 71.8, 71.4, 68.3, 66.6, 61.8, 56.2, 47.2, 25.7, 20.6,
mg (80.6%, as a colorless oil). H NMR (CDCl3) δ: 7.76 (d, 2H,
J ) 7.5 Hz), 7.60 (m, 2H,), 7.38 (t, 2H, J ) 8.0 Hz), 7.32 (q, 2H,
J ) 7.5 Hz), 5.23 (t, 1H, J ) 9.5 Hz), 5.02 (t, 1H, J ) 9.0 Hz),
4.99 (t, 1H, J ) 9.0 Hz), 4.56 (d, 1H, J ) 8.0 Hz), 4.38 (t, 2H, J
) 7.0 Hz), 4.29 (dd, 1H, J ) 7.0, 10.0 Hz), 4.23 (t, 1H, J ) 7.0
Hz), 4.16 (dd, 1H, J ) 7.0, 12.0 Hz), 4.05 (m, 1H,), 3.78 (d, 1H,
J ) 8.0 Hz), 3.73 (m, 1H, J ) 9.5 Hz), 2.09, 2.05, 2.05, 2.02 (s,
12H), 1.57 (m, 2H), 1.25 (m, 16H, J ) 6.5 Hz), 0.87 (t, 3H, J )
7.0 Hz). HRMS: calcd for C42H58NO13 784.3908, found 784.3912
(error ) 0.5 ppm).
(2S,3R)-2-(9H-F lu or en -9-ylm eth oxyca r bon yla m in o)-3-O-
(2,3,4,6-tetr a -O-a cetylglu cosyl)bu ta n oic Acid , 9a . Protected
glycoside 7a (61.6 mg, 0.0936 mmol) was dissolved in aqueous
MeCN (6 mL, 50%) before NaIO4 (200 mg, 0.9350 mmol, 9.98
equiv) and RuCl3‚H2O (3.0 mg, 0.0144 mmol, 15 mol %) were
added in one portion. The resulting mixture was stirred at rt
for 4 h. Once all of the starting material had been consumed,
20.6, 20.5, 20.5, 18.1, 16.3, -5.9. HRMS: calcd for C39H54NO13
Si 772.3364, found 772.3370 (error ) 0.7 ppm).
-
(2R,3R)-Ca r bon ic Acid Ben zyl Ester 2-(9H-F lu or en -9-
ylm eth oxyca r bon yla m in o)-3-O-(2,3,4,6-tetr a -O-a cetylglu -
cosyl)tr id ecyl Ester , 7c. To a flame-dried flask were added
acceptor 6c (31.3 mg, 0.0576 mmol) and tetra-O-acetyl-glucose
R-trichloroacetimidate (69.1 mg, 2.44 equiv), and the mixture
was azeotroped 2× with PhCH3. Molecular sieves (4 Å, ∼100
mg) were added to the mixture before it was dissolved in CH2-
Cl2 (6 mL) and chilled to 0 °C. TMSOTf (23 µL, 2.20 equiv) was
then added to the stirring solution dropwise over 10 min. The
mixture was stirred and allowed to warm to rt overnight. The
reaction was filtered through Celite, washed three times with
saturated aqueous NaHCO3, dried with MgSO4, filtered again,
and concentrated in vacuo. The crude was chromatographed
(25% EtOAc/hexanes, Rf ) 0.35). Yield: 27.7 mg (55%, as brittle
white foam). 1H NMR (CDCl3/CD3OD) δ: 7.77 (d, 2H, J ) 7.5
Hz), 7.62 (t, 2H, J ) 6.0 Hz), 7.40 (t, 2H, J ) 7.5 Hz), 7.33 (m,
8H), 5.97 (d, 1H, J ) 9.0 Hz), 5.23 (t, 1H, J ) 9.5 Hz), 5.13 (d,
2H, J ) 8.0 Hz), 5.06 (t, 1H, J ) 10.0 Hz), 4.97 (t, 1H, J ) 9.5
Hz), 4.56 (d, 1H, J ) 8.0 Hz), 4.37 (t, 2H, J ) 6.0 Hz), 4.29 (dd,
1H, J ) 7.0, 10.0 Hz), 4.22 (t, 1H, J ) 7.0 Hz), 4.16 (dd, 1H, J
) 7.0, 12.0 Hz), 4.16 (m, 1H), 4.10 (dd, 1H, J ) 2.5, 12.0 Hz),
4.05 (m, 1H,), 3.78 (m, 1H,), 3.72 (m, 1H), 2.08, 2.05, 2.04, 2.03
(s, 12H), 1.57 (m, 2H), 1.25 (m, 16H, J ) 6.4 Hz), 0.87 (t, 3H, J
) 7.5 Hz), 13C NMR (CDCl3/CD3OD) δ: 171.5, 170.8, 170.2,
170.1, 157.2, 144.1, 141.5, 128.8, 127.9, 125.3, 120.1, 100.5, 78.8,
73.2, 73.0, 72.0, 71.8, 70.2, 70.0, 68.7, 62.1, 47.4, 32.1, 32.0, 29.5,
29.3, 29.1, 25.8, 23.5, 20.4, 20.4, 14.9.
(2R,3R)-2-(9H-F lu or en -9-ylm eth oxyca r bon yla m in o)-3-O-
(2,3,4,6-tetr a -O-a cetylglu cosyl)bu ta n e-1,3-d iol, 8a . To a stir-
ring solution of (1.56 g, 2.021 mmol, in 20 mL of CH2Cl2) was
added by syringe freshly distilled BF3‚OEt2 (1.53 mL, 12.129
mmol, 6.0 equiv) in one portion and the mixture stirred at rt for
2 h. The reaction was then chilled to 0 °C before 3 mL of
saturated aqueous NaHCO3 was added to quench the reaction.
The mixture was then washed three times with saturated
aqueous NaHCO3, dried with MgSO4, filtered, and concentrated
in vacuo. The crude was chromatographed (66% EtOAc/hexanes,
Rf ) 0.35). Yield: 870 mg (66%, as brittle white foam). IR (cm-1):
3342.2, 2950.2, 1752.3, 1511.4, 1375.6, 1221.2, 1036.0. 1H NMR
(CDCl3) δ: 7.71 (d, 2H, J ) 7.5 Hz), 7.56 (d, 2H, J ) 7.0 Hz),
7.35 (t, 2H, J ) 7.5 Hz), 7.27 (m, 2H), 5.19 (t, 1H, J ) 9.5 Hz),
5.08 (d, 2, J ) 9.0 Hz), 4.99 (t, 1H, J ) 9.5 Hz), 4.91 (t, 1H, J )
9.0 Hz), 4.48 (d, 1H, J ) 8.0 Hz), 4.38 (t, 1H, J ) 8.5 Hz), 4.32
(t 1H, J ) 7.0 Hz), 4.22 (d, 1H, J ) 11.5 Hz), 4.18 (t, 1H, J ) 7.0
Hz), 4.07 (m, 1H), 3.67 (m, 2H), 3.59 (t, 1H, J ) 5.7 Hz), 2.03,
1.99, 1.99, 1.97 (s, 12H), 1.12 (d, J ) 6.0 Hz). 13C NMR (CDCl3)
δ: 170.6, 170.1, 169.3, 169.3, 156.6, 143.8, 141.2, 127.6, 127.0,
125.1, 119.9, 99.3, 77.3, 74.2, 72.4, 71.9, 71.1, 68.5, 66.7, 62.1,
61.8, 55.7, 47.2, 20.5, 20.5, 20.5, 20.5, 16.7. HRMS: calcd for
i
the reaction was quenched with PrOH (20 mL) and stirred for
an additional 2 h. The mixture was then filtered through Celite,
washed twice with saturated aqueous sodium sulfate, washed
one time with brine, dried with MgSO4, filtered, and concen-
trated in vacuo. The crude was chromatographed (gradient:
100% EtOAc, followed by 100% EtOAc with 0.5% HOAc, Rf )
0.65). Yield: 48.9 mg (77%, as a white solid). IR (cm-1): 3376.3,
2944.0, 1752.3, 1517.6, 1369.4, 1221.27, 1042.2. 1H NMR δ: 7.76
(d, 2H, J ) 8.0 Hz), 7.63 (t, 2H, J ) 8.0 Hz), 7.39 (t, 2H, J ) 7.5
Hz), 7.32 (m, 2H), 5.66 (d, 1H, J ) 9.0 Hz), 5.19 (t, 1H, J ) 9.5
Hz), 5.09 (t, 1H, J ) 9.5 Hz), 4.95 (t, 1H, J ) 8.0 Hz), 4.54 (d,
1H, J ) 8.0 Hz), 4.43 (d, 1H, J ) 8.0 Hz), 4.39 (m, 2H), 4.39 (m,
1H), 4.38 (dd, 1H, J ) 2.0, 6.0 Hz), 4.25 (t, 1H, J ) 7.5 Hz), 4.09
(dd, 1H, J ) 3.5, 12.5 Hz), 3.65 (d, 1H, J ) 9.5 Hz), 2.10, 2.04,
2.03, 2.01 (s, 12H), 1.23 (d, 3H, J ) 6.5 Hz). 13C NMR δ: 172.4,
171.7, 170.2, 169.3, 169.2, 156.7, 143.7, 141.1, 127.6, 127.0, 125.1,
119.8, 99.4, 75.8, 72.5, 71.5, 71.0, 68.3, 67.2, 61.5, 58.0, 47.0,
29.5, 20.7, 20.5, 20.5, 20.3, 17.5. HRMS: calcd for C33H38NO14
672.2292, found 672.2288 (error ) -0.7 ppm).
(2S,3R)-2-(9H-F lu or en -9-ylm eth oxyca r bon yla m in o)-3-O-
(2,3,4,6-tetr a -O-a cetylglu cosyl)n on a n oic a cid, 9b. Threonine
analogue 5b (63.3 mg, 0.1540 mmol) and â-glucose penta-acetate
(71.0 mg, 0.1820 mmol, 1.18 equiv) were placed in a 50 mL
round-bottom flask and azeotroped 2× with toluene. The mixture
was dissolved in CH2Cl2 and treated with BF3‚OEt2 (60 µL,
0.4739 mmol, 3.07 equiv). The solution was then stirred at rt
for 36 h. After being judged complete by TLC, the reaction
mixture was diluted with 15 mL of CH2Cl2 and quenched with
1 mL of sat. NaHCO3. The mixture was then washed 1× with
brine, dried with MgSO4, filtered, and concentrated in vacuo.
The crude was chromatographed (5% MeOH/95% CH2Cl2 with
0.4% HOAc, Rf ) 0.35). Yield: 40.2 mg (36%, as a yellow oil).
1H NMR (CDCl3/CD3OD/toluene-d8) δ: 7.75 (d, 2H, J ) 7.5 Hz),
7.62 (t, 2H, J ) 8.0 Hz), 7.39 (t, 2H, J ) 7.5 Hz), 7.31 (t, 2H, J
) 7.5 Hz), 5.60 (d, 1H, J ) 9.0 Hz), 5.18 (t, 1H, J ) 9.5 Hz) 5.10
(t, 1H, J ) 10.0 Hz), 4.99 (t, 1H, J ) 9.0 Hz), 4.56 (d, 1H, J )
8.0 Hz), 4.47 (m, 1H,), 4.38 (m, 2H), 4.25 (m, 1H), 4.20 (m, 1H),
4.09 (m, 2H), 3.62 (d, 1H, J ) 10.5 Hz), 2.10, 2.03, 2.02, 2.00 (s,
12H), 1.58, 1.50 (m, 2H), 1.25 (m, 8H), 0.87 (t, 3H, J ) 6.5 Hz).
13C NMR (CDCl3/MeOH/PhCH3) δ: 172.0, 171.8, 170.2, 169.3,
169.1, 156.7, 143.3, 141.2, 128.8, 128.1, 125.2, 119.9, 100.9, 80.7,
72.7, 71.7, 71.2, 68.3, 67.6, 67.4, 61.4, 56.8, 47.2, 29.6, 25.3, 22.5,
21.4, 20.9, 13.9. HRMS: calcd for C38H47NO14Na 764.2889, found
764.2909 (error ) 2.6 ppm).
(2S,3R)-2-(9H-F lu or en -9-ylm eth oxyca r bon yla m in o)-3-O-
(2,3,4,6-tetr a -O-a cetylglu cosyl)tr id eca n oic Acid , 9c. Gly-
coside 8a (17.2 mg, 0.02193 mmol) was azeotroped with toluene
×2. One milliliter of CH2Cl2 was added to a round-bottom flask
and chilled to -40 °C. Oxayl chloride (15 µL, 0.1713 mmol, 7.8
equiv) and DMSO (15 µL, 0.2111 mmol, 9.6 equiv) were
sequentially added in an inert atmosphere, and the mixture was
stirred for 2 min. Compound 8a was then dissolved in 1 mL of
CH2Cl2 and added via syringe. The mixture was stirred at -40
°C for 30 min prior to the addition of Et3N (51 µL, 0.3635 mmol,
16.5 equiv). The reaction was allowed to warm to rt and stirred
for 1 h until judged complete by TLC. The completed reaction
was then diluted with 10 mL of CH2Cl2, washed with saturated
aqueous NH4Cl ×4, and concentrated in vacuo. The residue was
C
33H40NO13 658.2500, found 658.2502 (error ) 0.4 ppm).
(2R,3R)-2-(9H-F lu or en -9-ylm eth oxyca r bon yla m in o)-3-O-
(2,3,4,6-tetr a -O-a cetylglu cosyl)tr id eca n e-1,3-d iol, 8c. Ben-
zyl carbonate 7c (22.4 mg, 0.0256 mmol) was placed in a round-
bottom flask. To this were added MeOH (5 mL), EtOAc (5 mL),
aqueous HOAc (0.5 mL, pH ∼3.5), and Pt-C (24.0 mg). The
reaction was purged with H2 four times and stirred under 1 atm
of H2 until judged complete by TLC (2 h). The reaction was
quenched with 20 mL of CH2Cl2, filtered through Celite, and
washed three times with saturated aqueous NaHCO3, dried with
MgSO4, filtered again, and concentrated in vacuo. The crude was
chromatographed (54% EtOAc/hexanes, Rf ) 0.45). Yield: 16.2
t
redissolved in BuOH (5 mL) and EtOAc (5 mL), charged with
NaClO2 (46 mg, 0.3376 mmol, 15.0 equiv) and KH2PO4 (55.2 mg,

Notes
J . Org. Chem., Vol. 66, No. 21, 2001 7183
0.4029 mmol, 18.3 equiv), and stirred for 30 min at rt. The crude
was chromatographed (5% MeOH/ 95% CH2Cl2 with 0.2% HOAc,
Rf ) 0.35). Yield: 11.3 mg (65%, as a yellow oil). 1H NMR (CDCl3/
MeOH) δ: 7.74 (d, 2H, J ) 8.0 Hz), 7.62 (t, 2H, J ) 6.5 Hz),
7.37 (t, 2H, J ) 7.5 Hz), 7.29 (t, 2H, J ) 7.5 Hz), 5.88 (d, 1H, J
) 9.5 Hz), 5.16 (t, 1H, J ) 9.5 Hz), 5.09 (t, 1H, J ) 10.0 Hz),
4.97 (t, 1H, J ) 8.5 Hz), 4.56 (d, 1H, J ) 8.0 Hz), 4.37 (t, 1H, J
) 7.5 Hz,), 4.32 (d, 1H, J ) 4.5 Hz), 4.26 (m, 1H), 4.24 (m, 1H),
4.20 (m, 2H), 3.64 (d, 1H, J ) 9.5 Hz), 2.05, 2.03, 2.00, 1.99 (s,
12H), 1.58, (m, 2H), 1.25 (m, 16H, J ) 6.5 Hz), 0.85 (t, 3H, J )
8.0 Hz), HRMS: calcd for C42H55NO14Na 820.3515, found
820.3478 (error ) 4.5 ppm).
Ack n ow led gm en t. We thank the A.R.C.S. Founda-
tion (Phoenix Chapter - Spetzler Fellowship), the U.S.
Army (DAMD17-99-1-9539), the National Science Foun-
dation (CHE-9526909 and CHE-920112), and NIDA
(DA-06284) for partial funding.
Su p p or tin g In for m a tion Ava ila ble: NMR spectra for
obtained compunds. This material is available free of charge
via the Internet at http://pubs.acs.org.
J O015844V