LETTER 45
A No el App oach o he Syn hesis o N-Subs i u ed 1-C-Aminome hyl
Glyco u anosides
Syn hesis o N-Subs i u ed 1-
C
-Aminome hyl Glyco u anosides
Yolanda Ve a-Ayoso,a Pas o a Bo ache o,a F ancisca Cab e a-Esc ibano,*a Manuel Gómez-Guillén,a Pie e Vogelb
aDepa amen o de Química O gánica ‘P o eso Ga cía González’, Facul ad de Química, Uni e sidad de Se illa,
Apa ado de Co eos No. 553, 41071 Se illa, Spain
Fax +34(95)4624960; E-mail: cab e [email protected]
bLabo a oi e de Glycochimie e Syn hèse Asymé ique, Swiss Fede al Ins i u e o Technology (EPFL),
BCH-EPFL, 1015 Lausanne, Swi ze land
Recei ed 18 Oc obe 2005
SYNLETT 2006, No. 1, pp 0045–0048
05.01.2006
Ad anced online publica ion: 16.12.2005
DOI: 10.1055/s-2005-922762; A ID: D32105ST
© Geo g Thieme Ve lag S u ga · New Yo k
Abs ac : Reduc i e amina ion o o myl C-glyco u anosides, eas-
ily a ailable om hexose-de i ed equa o ial-2-OH-glycopy ano-
sides by DAST-p omo ed ing con ac ion, a o ded N-subs i u ed
1-C-aminome hyl glyco u anosides in mos cases in high yields.
Key wo ds: 1-C-aminome hyl glyco u anosides, o myl C-glyco-
u anosides, educ i e amina ion, DAST-p omo ed ing con ac-
ion, suga diamines
The s e eoselec i e syn hesis o unc ionalized C-glyco-
sides has become an impo an a ea o ca bohyd a e e-
sea ch, as many na u ally occu ing C-glycosides show
use ul an ibac e ial, an i i al, and an i umo al p ope ies.1
One signi ican ype o C-glycoside de i a i es a e 1-C-
aminome hyl glycosides. These compounds a e key in e -
media es o glycoconjuga e syn heses, and a numbe o
hem ha e p o ed o be glycosidase inhibi o s.2 Suga
amino acids 23 and 3,4 which con aining he subs uc u e
1 (Figu e 1), a e dipep ide isos e s and ha e been used as
seconda y s uc u e inducing elemen s o he gene a ion
o pep ide-based d ugs. This kind o subs uc u e is also
ound in he na u ally occu ing alkaloid musca ine (4), a
igid musca inic agonis o ace ylcholine,5 o which a
enewed in e es is due, in pa , o he sugges ion ha
a ious sub ypes o musca inic ecep o s seem o be
implica ed6 in Alzheime ’s disease.
Syn heses o 1-C-aminome hyl glycosides so a de-
sc ibed ely on he in oduc ion o a CH2NH2 equi alen
a he anome ic posi ion: (a) as CH3NO2 ia nucleophilic
aldol eac ion,7 (b) by educing he co esponding glyco-
syl cyanide8 o , (c) by deg ada ion o a C- inyl glycoside
and subsequen o ma ion o he azidome hyl in e medi-
a e.3b Al e na i ely, ea angemen in ol ing 5-exo SN2-
opening o a e minal azi idine ing, and ans o ma ion o
a p ima y hyd oxyl unc ion in o he co esponding azide
ga e access o he 2,5-anhyd o de i a i es 34 and 4,9 e-
spec i ely. These ou es a e a he complica ed, and o
hose in ol ing an anome ic ca bon–ca bon bond- o m-
ing eac ion, chemical e iciency and s e eocon ol emain
a di icul ask. Mo eo e , o eaching an N-subs i u ed
1-C-aminome hyl glycoside, addi ional N-alkyla ion p o-
cess would be s ill equi ed.
He e we in oduce a s aigh o wa d app oach o N-sub-
s i u ed 1-C-aminome hyl glyco u anosides om hexose-
de i ed equa o ial-2-OH-glycopy anosides (Scheme 1).
The s a egy akes ad an age o a die hylaminosul u
i luo ide (DAST)-p omo ed ing con ac ion ha , unde
ema kably mild condi ions, leads o o myl C-glyco-
u anosides.10 The use o hese compounds in s anda d
coupling eac ions wi h nucleophiles should p o ide a
eady access o hyd oly ically s able C-glyco u anoside-
based molecules (C-oligosaccha ides and C-glycocon-
juga es). Wi h his aim, ou i s goal has been o explo e
hei coupling wi h biologically ele an amines as ni o-
gen-con aining nucleophiles.
Scheme 1
We desc ibe he ein he syn hesis o enan iopu e o hogo-
nally p o ec ed C-glyco u anosyl diamines by educ i e
amina ion o o myl C-glyco u anosides, easily ob ained
as hei syn he ic equi alen s 6 and 12 om he me hyl
equa o ial-2-OH-glycohexopy anosides 5 and 11, espec-
i ely, by DAST me hodology.10,11
T ea men o he c ude aldehyde ob ained in si u by hy-
d olysis (9:1 TFA–H2O, . ., 1 h) o he dime hyl ace al 6,
wi h di e se p ima y o seconda y amines (1.4 mol equi )
+
HNR1R2
O
HOOMe
R
O
HO
R
OMe
OH
R
O
ONR1R
2
R
F
igu e 1
O
Me CH2NM
e2
HO
4
O
O
OH
HO
HO
HOOC
NH2
2
3
CH2NH2
H
OOC
O
n
NH2
R
1 n = 0, 1
HO OH
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46 Y. Ve a-Ayoso e al. LETTER
Synle 2006, No. 1, 45–48 © Thieme S u ga · New Yo k
in d y 1,2-dichlo oe hane, and subsequen educ ion o he
espec i e, no isola ed, imine using sodium iace oxy-
bo ohyd ide (1.4 mol equi ), a o ded he espec i e com-
pounds 7a–h in mode a e o high yields (Scheme 2,
Table 1).12 Thei dep o ec ion wi h 1 M NaMeO–MeOH
ga e he co esponding p oduc s 8a–h.13
As shown in Table 1, p ima y and seconda y alipha ic
amines (benzylamine, pipe idine, benzyloxyca bonyl pip-
e azine, and mo pholine, en ies 1–4), as well as he a o-
ma ic amine 4-hyd oxyme hyl aniline (en y 6), ga e he
co esponding educ i e amina ion compounds 7a–e as
he sole p oduc . In he case o he o he aniline de i a-
i es (2-biphenylamino, e hyl 4-aminobenzoa e and 4-
aminobenzoni ile, en ies 8–10), howe e , educ i e
amina ion p oduc s 7 –h we e ob ained oge he wi h he
p ima y alcohol 10.
S a ing om N-aminomo pholine as he amine (en y 5),
he only isola ed p oduc was he hyd azone 9, which
could no be educed by he eagen employed. When us-
ing imidazole as he s a ing amine (en y 7), he expec ed
S
cheme 2
O
OO
P
h
N3HOOMe O
AcO
N3
AcO
OMe
6OMe
1. 9:1 TFA/H2O,
. ., 1 h
2. RNH2 o R1R2NH,
NaBH(OAc)3
DCE, 25 °C
2. i. MeOH, PTSA,
. ., 1 h
ii. Ac2O,
py idine, 0 °C
O
AcO
N3
AcO
NR1R2
7
(35–88%)
MeONa,
MeOH
1M
. ., 2 h
O
HO
N3
HO
NR1R
2
8
(75–95%)
1. DAST, MeCN,
e lux, 12 min
(69%)
5
T
able 1 Reduc i e Amina ion P oduc s 7 o he Fo myl Azido-C-glyco u anoside Syn he ic Equi alen 6 wi h Va ious Amines, and Thei
D
eace yla ed P oduc s 8a
E
n y Amines R1R2NH Reac ion ime (h) P oduc s 712 (yield a e pu i ica ion, %) P oduc s 813 (yield, %)
137a (55) 8a (75)
257b (65) 8b (92)
32.57c (80) 8c (95)
467d (67) 8d (87)
51.5
9 (88)
–b
627e (77) 8e (90)
720
1011 (56)
–
8187 (63) + 10 (19) 8 (85)
9187g11 (47) + 10 (34) 8g (86)
1
0187h (35) + 10 (48) 8h (89)
a All p oduc s we e ully cha ac e ized by hei IR, 1H NMR, 13C NMR, and HRMS spec al da a.14
b Complex mix u e o p oduc s.
H
2N
H
N
H
N
NCb
z
H
N
O
O
N
H2
N
O
A
cO
N3
AcO
NN
O
H2
N
O
H
N
N
H
O
A
cO
N
3
AcO
O
H
Ph
H2
N
H2
N
COOE
H2
N
CN
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LETTER Syn hesis o N-Subs i u ed 1-C-Aminome hyl Glyco u anosides 47
Synle 2006, No. 1, 45–48 © Thieme S u ga · New Yo k
2,5-anhyd o-1-(imidazol-1-yl)-D-al i ol de i a i e was
no ob ained, only 10 was ob ained. The eason o his be-
ha io o imidazole may be i s weak nucleophilic cha ac-
e , much lowe han hose o he emainde amines used.
In he same way, o ma ion o he p ima y alcohol 10 as
accompanying p oduc o 7 –h, a ise om he lack o
nucleophilici y p o oked by he elec on-wi hd awing
subs i uen a he pa a posi ion o he anilines.
A sho e expe imen al p o ocol, in which a 2,5-anhyd o-
1- luo o-1-O-me hylhexi ol (a o myl C-glyco u anoside
syn he ic equi alen di ec ly o med in he ing-con ac-
ion eac ion p omo ed by DAST) is subjec ed o hyd o-
lysis and subsequen in si u educ i e amina ion p ocess,
can be applied. Adop ing his one-po p ocedu e, luo o
aldehyde 13 ob ained in si u by hyd olysis (9:1 TFA–
H2O, . ., 1 h) o (1R,1S)-2,5-anhyd o-3,6-di-O-benzyl-4-
deoxy-1,4-di luo o-1-O-me hyl-D- ali ol (12),10a was
made eac wi h diamine 14,15 u nishing luo o-C-glyco-
u anosyl aminome hylpy olidine de i a i e 15 in good
yield (Scheme 3).16
In conclusion, his wo k p o ides a simple app oach o he
syn hesis o unc ionalized N-subs i u ed aminome hyl C-
glyco u anosides by educ i e amina ion o o myl C-gly-
co u anosides, eadily a ailable by DAST me hodology
om hexose-de i ed equa o ial-2-OH-glycopy anosides.
The me hod wo ks well wi h good nucleophilic amines
and allows comple e s e eocon ol a he anome ic cen e .
S e eo- and unc ional di e si y on he u anoid ing could
be achie ed on s a ing om di e en equa o ial-2-OH-
glycohexopy anosides. Ex ension o his wo k o o he
subs a es as well as s udies wi h o he nucleophiles is
cu en ly unde in es iga ion.
Acknowledgmen
We hank he Eu opean Commission, Di ec o a e Gene al o
Science and De elopmen (FP6-508430), he Spanish ‘Minis e io
de Ciencia y Tecnología’ (p edoc o al ellowship o Y.V.-A.), and
he ‘Jun a de Andalucía’ (FQM142) o inancial suppo .
Re e ences and No es
(1) (a) Fische , C.; Lipa a, F.; Roh , J. J. Am. Chem. Soc. 2003,
125, 7818. (b) Faizi, S.; Ali, H. Plan a Med. 1999, 65, 383.
(2) (a) G emyachinskiy, D. E.; Samoshin, V. V.; G oss, P. H.
Te ahed on Le . 2003, 44, 6587. (b) Bha , A. S.; Ge ay-
Hague, J. O g. Le . 2001, 3, 2081. (c) BeMille , J. N.;
Gilson, R. J.; Mye s, R. W.; San o o, M. M.; Yada , M. P.
Ca bohyd . Res. 1993, 250, 93. (d) Lai, W.; Ma in, O. R.
Ca bohyd . Res. 1993, 250, 185. (e) Mai y, S. K.; Du a, S.
K.; Bane jee, A. K.; Acha i, B.; Singh, M. Te ahed on
1994, 50, 6965. Fo 2-(aminome hyl)py olidine-3,4-diol
de i a i es, see: ( ) Sao ome, C.; Wong, C.-H.; Kanie, O.
Chem. Biol. 2001, 8, 1061. (g) Popowycz, F.; Ge be -
Lemai e, S.; Schü z, C.; Vogel, P. Hel . Chim. Ac a 2004,
87, 800. (h) Fiaux, H.; Popowycz, F.; Fa e, S.; Schü z, C.;
Vogel, P.; Ge be -Lemai e, S.; Juille a -Jeanne e , L. J.
Med. Chem. 2005, 48, 4237. (i) Popowycz, F.; Ge be -
Lemai e, S.; Rod iguez-Ga cía, E.; Schü z, C.; Vogel, P.
Hel . Chim. Ac a 2003, 86, 1914.
(3) (a) G une , S. A. W.; Loca di, E.; Loho , E.; Kessle , H.
Chem. Re . 2002, 102, 491. (b) Du a , F.; Xie, J.; Valé y,
J.-M. Te ahed on Le . 2004, 45, 1477.
(4) Fo ecen e iews see: (a) Chak abo y, T. K.; S ini asu,
P.; Tapada , S.; Mohan, B. K. Glycoconjuga e J. 2005, 22,
83. (b) Chak abo y, T. K.; S ini asu, P.; Tapada , S.;
Mohan, B. J. Chem. Sci. 2004, 116, 187. See also:
(c) P asad, S.; Ma hu , A.; Jaggi, M.; Sha ma, R.; Gup a, N.;
Reddy, V. R.; Sudhaka , G.; Kuma , S. U.; Kuma , S. K.;
Kunwa , A. C.; Chak abo y, T. K. J. Pep . Res. 2005, 66,
75. (d) Chak abo y, T. K.; Jayap akash, S.; Diwan, P. V.;
Naga aj, R.; Jampani, S. R. B.; Kunwa , A. C. J. Am. Chem.
Soc. 1998, 120, 12962. (e) Chak abo y, T. K.; Ghosh, S.;
Jayap akash, S.; Sa ma, J. A. R. P.; Ra ikan h, V.; Diwan, P.
V.; Naga aj, R.; Kunwa , A. C. J. O g. Chem. 2000, 65,
6441.
(5) Pa ick, G. L. An In oduc ion o Medicinal Chemis y, 2nd
ed.; Ox o d Uni e si y P ess: Ox o d, 2002, 446.
(6) (a) B oadley, K. J.; Kelly, D. R. Molecules 2001, 6, 142.
(b) Liu, J.-K. Chem. Re . 2005, 105, 2723.
(7) (a) Loca di, E.; S öke, M.; G une , S.; Kessle , H. J. Am.
Chem. Soc. 2001, 123, 8189. (b) G a on Roede n, E.;
Kessle , H. Angew. Chem., In . Ed. Engl. 1994, 33, 687.
(c) G a on Roede n, E.; Kessle , H. Angew. Chem., In . Ed.
Engl. 1994, 33, 684.
(8) Benksim, A.; Beaupè e, D.; Wadouahi, A. O g. Le . 2004,
6, 3913.
(9) Man ell, S. J.; Flee , G. W. J.; B own, D. J. Chem. Soc.,
Pe kin T ans. 1 1992, 3023.
S
cheme 3
O
H
O
BnO
HO
DAST, CH
2
Cl
2
,
e lux, 1.5 h
BnO OMe O
BnO OMe
12
9:1 TFA/H2O,
. ., 1 h
NaBH(OAc)3
DCE, . ., 1.5 h
(65–79%)
FOBn
F
H
O
B
nO
13
FOBn
O
HO
BnO
15
FOBn
N
11
NH2
OO
Boc 14 NH N
Boc
OO
(92%)
(70% om 12)
1
26' 1'
2'
3' 4'
5
'
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48 Y. Ve a-Ayoso e al. LETTER
Synle 2006, No. 1, 45–48 © Thieme S u ga · New Yo k
(10) (a) Ve a-Ayoso, Y.; Bo ache o, P.; Cab e a-Esc ibano, F.;
Ca mona, A. T.; Gómez-Guillén, M. Te ahed on:
Asymme y 2004, 15, 429. (b) Bo ache o, P.; Cab e a-
Esc ibano, F.; Ca mona, A. T.; Gómez-Guillén, M.
Te ahed on: Asymme y 2000, 11, 2927. (c) Bo ache o-
Moya, P.; Cab e a-Esc ibano, F.; Gómez-Guillén, M.;
Mad id-Díaz, F. Te ahed on Le . 1997, 38, 1231.
(11) Ve a-Ayoso, Y.; Bo ache o, P.; Cab e a-Esc ibano, F.;
Gómez-Guillén, M. Te ahed on: Asymme y 2005, 16, 889.
(12) Gene al P ocedu e o he One-Po P epa a ion o
Compounds 7.
Compound 6 (100 mg, 0.315 mmol) was dissol ed in a 9:1
TFA–H2O mix u e (2.7 mL) and he solu ion was kep a . .
o 1 h. The eac ion mix u e was pou ed in o ice-wa e (100
mL) and ex ac ed wi h CH2Cl2 (4 ×20 mL). The combined
o ganic laye s we e successi ely washed wi h sa . aq
NaHCO3 and b ine, hen d ied (Na2SO4), and concen a ed.
The esidue (c ude aldehyde) was dissol ed in 1,2-
diclo oe hane (3.1 mL) and ea ed wi h he amine (0.437
mmol) and sodium iace oxybo ohyd ide (93.0 mg, 0.441
mmol). The eac ion was s i ed a . . o he app op ia e
ime (Table 1). The mix u e was hen dilu ed wi h sa . aq
NaHCO3 (25 mL) and he aqueous laye was ex ac ed wi h
E OAc (3 ×20 mL). The combined o ganic laye s we e
d ied (Na2SO4), and concen a ed unde educed p essu e o
gi e he c ude p oduc , which was pu i ied by column
ch oma og aphy using E OAc–hexane, E 2O–hexane o
E 2O–ace one as eluen .
Compound 7a: R = 0.37 (5:1 E 2O–ace one); [a]D26 +19.3 (c
0.56, CH2Cl2). IR: nmax = 3324 (NH), 2106 (N3), 1746 (CO),
1231 and 1119 (CO) cm–1. 1H NMR (300 MHz, ace one-d6):
d = 7.25–7.08 (m, 5 H, Ph), 5.31 (dd, 1 H, J4,5 = 7.8 Hz,
J3,4 = 5.1 Hz, H-4), 4.48 (dd, 1 H, J2,3 = 3.9 Hz, H-3), 4.32
(ddd, 1 H, J1,2 =J1¢,2 = 6.6 Hz, H-2), 4.23 (dd, 1 H,
J6,6¢= 10.8 Hz, J5,6 = 2.4 Hz, H-6), 4.07–3.95 (m, 2 H, H-5
and H-6′), 3.83 (d, 1 H, JH,H¢= 13.5 Hz, CHaPh), 3.78 (d, 1
H, JH,H¢= 13.8 Hz, CHbPh), 2.82 (d, 2 H, H-1 and H-1′), 2.11
and 2.02 (each 2 s, 3 H, 2 COMe) ppm. 13C NMR (75.4 MHz,
ace one-d6): d = 170.8, 170.7 (2 CO), 141.8–127.5 (Ph), 80.0
(C-2), 78.1 (C-5), 75.8 (C-4), 64.6 (C-6), 64.4 (C-3), 54.4
(CH2Ph), 49.4 (C-1), 20.7 and 20.4 (2 COMe) ppm. HRMS
(CI): m/z calcd o C17H22N4O5 + H: 363.1668; ound
363.1671.
(13) Gene al P ocedu e o Deace yla ion o 7 and
P epa a ion o Compounds 8.
The co esponding educ i e amina ion p oduc 7 (0.070
mmol) was dissol ed in: (i) (2 mL o 1:1 MeOH–CHCl3), (ii)
(2 mL o MeOH), o (iii) (2 mL o E OH abs.), and 5 d ops
o 1 M MeONa–MeOH we e added o he solu ion [ o he
dep o ec ion o 7g was used E ONa–E OH abs. (1 M)]. The
eac ion mix u e was kep a . . o 2 h. Wo k-up was done
by one o he ollowing p ocedu es.
P ocedu e 1 (8b–d, ): he eac ion mix u e was cooled and
600 mL TFA was added. The esidue was pu i ied by a
Dowex 50 ×8 W column, using MeOH (50 mL), H2O (50
mL) and NH4OH (10% aq soln; 100 mL) as eluen s.
P ocedu e 2 (8a,e,g,h): he eac ion mix u e was neu alized
wi h Ambe lys 15, he esin was emo ed by il a ion and
he sol en unde educed p essu e.
(14) In compa ison wi h he NMR spec a o each di ec
p ecu so , each ace yla ed compound 7a–h lacked any signal
o aldehyde p o on and ca bon, bu showed ins ead he
signals co esponding o he wo new dias e eo opic p o ons
a C(1). Fo he compounds ob ained om some p ima y
amines (7e, –h), he amine p o on ga e ise o he ypical
b oad signal in he 1H NMR spec um a d = 4.41 (7e), 4.44–
4.38 (7 ), 5.81 (7g), and 6.00 ppm (7h), alues ha can be
co ela ed wi h he elec on-wi hd awing o elec on-
dona ing cha ac e o he subs i uen a he pa a posi ion o
he a oma ic g oup. Howe e , he amine p o on signal o 7a
was no obse ed, p obably because i is o e lapped. The
molecula weigh ound o 9 in i s HRMS ag eed wi h he
aldimine s uc u e assigned, while i s NMR spec a showed
he sp2 (C)H signal a d = 6.86 ppm and he imine ca bon a
d = 134.1 ppm, hus co obo a ing he assigna ion. Fo he
deace yla ed compounds 8a–h, hei espec i e calcula ed
molecula weigh s we e in ag eemen wi h hose ound by
HRMS. Fu he mo e, he 1H NMR and 13C NMR spec a o
hese compounds showed no signal co esponding o he O-
ace yl g oups p esen in he p ecu so s 7a–h, as expec ed.
(15) Popowycz, F.; Ge be -Lema ie, S.; Demange, R.;
Rod iguez-Ga cía, E.; Asenjo, A. T. C.; Robina, I.; Vogel, P.
Bioo g. Med. Chem. Le . 2001, 11, 2489.
(16) Compound 15 was ob ained om 12 (100 mg, 0.265 mmol)
and diamine 14 (78 mg, 0.287 mmol) in he p esence o
NaBH(OAc)3 (60.2 mg, 0.287 mmol) by a simila one-po
p ocedu e o ha desc ibed abo e o he p epa a ion o
compounds 7 om 6.
Mo e ele an da a o 15: R = 0.45 (E 2O); [a]D24 +14.6 (c
0.63, ace one). IR: nmax = 3295 (NH), 1692 (CO), 1370
(NCO), 1157, 1059 (COC), and 991 (CF) cm–1. 1H NMR
(500 MHz, DMSO-d6, 363 K): d = 7.41–7.25 (m, 5 H, Ph),
5.27 (d , 1 H, 2J4,F = 54.9 Hz, J3,4 =J4,5 = 3.0 Hz, H-4), 4.79,
4.63 (2 d, 1 H each, JH,H¢= 11.5 Hz, CH2Ph), 4.69 (dd, 1 H,
J4¢,3¢=J4¢,5¢b=5.7 Hz, H-4′), 4.62 (d, 1 H, H-3′), 4.55 (s, 2 H,
CH2Ph), 4.38 (dddd, 1 H, 3J5,F = 30.5 Hz, J5,6a =J5,6b =6.0
Hz, H-5), 4.33–4.21 (m, 2 H, H-2 and H-2′), 4.17 (d , 1 H,
3J3,F = 23.5 Hz, J2,3 = 8.5 Hz, H-3), 3.75 (dd, 1 H,
J6a,6b = 10.2 Hz, H-6a), 3.75 (d, 1 H, J5¢a,5¢b= 14.0 Hz, H-5′a),
3.60 (ddd, 1 H, 4J6b,F = 1.8 Hz, H-6b), 3.32 (dd, 1 H, H-5′b),
3.20–2.91 (m, 4 H, H-1a, H-1b, H-6′a, H-6′b), 1.41 (s, 9 H,
CMe3), 1.34 and 1.25 (each 2 s, 3 H, CMe2) ppm. 13C NMR
(125.7 MHz, DMSO-d6, 363 K): d = 152 (CO), 137.7–126.8
(Ph), 110.6 (CMe2), 89.1 (d, 1J4,F = 188.2 Hz, C-4), 81.6 (C-
3′), 80.1 (d, 2J3,F = 16.2 Hz, C-3), 79.5 (C-4′), 78.4 (d,
2J5,F = 17.1 Hz, C-5), 78.3 (CMe3), 74.7 (C-2), 72.2 and 71.2
(CH2Ph), 67.0 (d, 3J6,F = 11.6 Hz, C-6), 59.8 (C-2′), 50.4 (C-
5′), 49.0, 46.6 (C-1, C-6′), 27.6 (CMe3), 26.3 and 26.2
(CMe2). HRMS (CI): m/z calcd o C33H45N2O7F + H:
601.3289; ound: 601.3281.
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