Improvements to the synthesis of isofagomine, noeuromycin, azafagomine, and isofagomine lactam, and a synthesis of azanoeuromycin and guanidine isofagomine

Article abstract of DOI:10.1071/CH06241

Improvements in the preparation of a key imidazylate and the reduction of the derived nitrile have led to more efficient syntheses of isofagomine, noeuromycin, azafagomine, and isofagomine lactam. As well, a precursor of azafagomine has been converted int

Full text of DOI:10.1071/CH06241

Full Paper
CSIRO PUBLISHING
www.publish.csiro.au/journals/ajc
Aust. J. Chem. 2006, 59, 827–833
Improvements to the Synthesis of Isofagomine, Noeuromycin,
Azafagomine, and Isofagomine Lactam, and a Synthesis
of Azanoeuromycin and ‘Guanidine’ Isofagomine
Peter J. MeloncelliA and Robert V. StickA,B
A Chemistry M313, School of Biomedical, Biomolecular and Chemical Sciences,
University of Western Australia, Crawley WA 6009, Australia.
B Corresponding author. Email: rvs@chem.uwa.edu.au
Improvements in the preparation of a key imidazylate and the reduction of the derived nitrile have led to more
efficient syntheses of isofagomine, noeuromycin, azafagomine, and isofagomine lactam. As well, a precursor of
azafagomine has been converted into azanoeuromycin, and the nitrogen atom of isofagomine has been incorporated
into a guanidine residue.
Manuscript received: 11 July 2006.
Final version: 25 September 2006.
Introduction
Results and Discussion
The inspirational work of Bols has seen the design and syn-
thesis of isofagomine 1 (with Lundt), noeuromycin 2, and
azafagomine 3 (Scheme 1), powerful inhibitors of various
glycoside hydrolases.[1–3] In parallel with Bols, we reported
a synthesis of the related isofagomine lactam 4.[4,5] Some of
these molecules have proven of great use to structural biolo-
gists trying to decipher the various conformational itineraries
that glycoside hydrolases employ in the cleavage of the
glycosidic linkage.[6,7]
This paper reports on significant improvements to our syn-
thesis of isofagomine and isofagomine lactam, application of
the same improvements to a synthesis of noeuromycin and
azafagomine, and a synthesis of azanoeuromycin 5 and the
novel ‘guanidine’ isofagomine 6, a molecule with the poten-
tial for displaying interesting biological activity (based on the
successes of Relenza[8]).
Our synthesis of isofagomine[9] starts from l-xylose and pro-
ceeds easily to the alcohol 7 (Scheme 2). The conversion of
7 into the imidazylate 8 was never satisfactory with sodium
hydride as the (insoluble) base but was significantly improved
by the use of lithium bis(trimethylsilyl)amide. The nitrile 9
was then obtained from 8 and trimethylsilyl azide as in our
original report and, in a second improvement, acid-catalyzed
hydrolysis gave the diol 10 that was efficiently reduced to the
amine, isolated as the carbamate 11. Our early attempts at the
reduction of the nitrile 9 with lithium aluminium hydride had
been plagued by the formation of a by-product, now identi-
fied as the isopropyl ether 12. The transformation of 11 into
isofagomine 1 followed our original report.
With these two major improvements, we believe that our
synthesis of isofagomine ranks with the best; we routinely
make 0.4 g of isofagomine from 2.3 g of l-xylose, in the
OH
OH
OH
NH
HO
HO
HO
HO
HO
NH
HO
NH
NH
OH
1
2
3
OH
OH
OH
HO
HO
HO
NH
OH
HO
HO
NH
HO
N
NH2
NH
O
NH
4
5
6
Scheme 1.
© CSIRO 2006
10.1071/CH06241
0004-9425/06/110827

828
P. J. Meloncelli and R. V. Stick
(a)
(c)
OBn
OBn
OBn
O
O
O
HO
O
O
ImSO2O
L-xylose
O
O
O
7
8
HO
O
NC
O
(b)
OH
OBn
CN
9
10
58% (d)
85% (d)
O
HO
O
O
BocNH
BocNH
OH
OH
OBn
OBn
12
11
Scheme 2. (a) (Me3Si)2NLi, (Im)2SO2,THF, 90%. (b) Me3SiCN, Bu4NF, MeCN, 80%. (c) Camphor-10-sulfonic
acid, MeOH, 90%. (d) (i) AlH3, THF; (ii) (Boc)2O, THF, H2O.
OH
O
OH
OH
HO
HO
(a)
ClH3N
11
NH2Cl
OH
OH
13
Scheme 3. (a) (i) Pd/C, H2, THF, H2O; (ii) 1 M HCl, 86%.
OH
NBoc
NH
OBn
O
O
(a)
(b)
(c)
O
O
3
8
H2NNHBoc
O
Boc(NH2)N
15
16
14
Scheme 4. (a) (Me3Si)2NLi, 14, THF, 69%. (b) Pd/C, H2, THF, 88%. (c) (i) CF3COOH; (ii) Amberlite IRA 400 (OH−), 99%.
CO2Me
O
O
BMSO
BocNH
OBMS
OH
CN
CH2OH
17
OH
18
O
OBn
O
OH
(a)
(b)
11
BocNH
BocNH
OBMS
OBMS
OBMS
OBMS
19
20
(c)
O
O
4
BocNH
OBMS
OBMS
21
Scheme 5. (a) BMSCl, ImH, DMF, 85%. (b) H2, Pd/C, THF, H2O. (c) Pr4NRuO4, N-methylmorpholine
N-oxide, CH2Cl2, 86% (b and c). BMS = ButMe2Si.

Isofagomine, Noeuromycin, Azafagomine, Isofagomine Lactam, Azanoeuromycin, and ‘Guanidine’ Isofagomine
829
OH
O
Me3SiO
O
BocNH
(a)
(b)
BocNH
11
OSiMe3
OSiMe3
OBn
OSiMe3
22
23
(c)
O
O
(d)
4
BocNH
OSiMe3
OSiMe3
24
Scheme 6. (a) Me3SiCN, DMF, 100%. (b) H2, Pd/C, THF. (c) Pr4NRuO4, N-methylmorpholine N-oxide,
CH2Cl2, 65% (b and c). (d) (i) CF3COOH, H2O; (ii) MeOH, Amberlite IRA 400 (OH−), 80%.
OBn
OH
OBn
OH
O
O
OBn
O
(a)
(b)
(c)
O
8
O
Boc[N(Boc)2]N
Boc(NHBoc)N
Boc[N(Boc)2]N
OH
OH
26
27
28
OH
NH
N
OH
OH
O
HO
HO
ϩ
(Boc)2NNHBoc 25
BocNHNHBoc 29
(d)
(e)
5
Boc(NHBoc)N
31
OH
30
Scheme 7. (a) (Me3Si)2NLi, 25, THF, 89%. (b) Pyridinium tosylate, MeOH, 89%. (c) Mg(ClO4)2, MeCN, 85%. (d) Pd/C, H2, THF/H2O, 75%.
(e) 1 M HCl.
OAc
OAc
(a)
(b)
AcO
AcO
AcO
AcO
1
NBoc
NH
32
33
OAc
OH
NTf
AcO
AcO
HO
HO
(c)
(d)
N
NHBoc
NBoc
BocHN
NHBoc
N
NH2
NH2Cl
35
34
Scheme 8. (a) (i) NaHCO3, (Boc)2O, Me2CO, H2O; (ii) Ac2O, pyridine, CHCl3, 83%. (b) CF3COOH. (c) 34, EtPri2N,
CH2Cl2, 95% (b and c). (d) (i) HCl, MeOH; (ii) CF3COOH; (iii) 1 M HCl, 95%.
space of ten days. A recent report by Fan and co-workers uses
a similar route, from benzyl α-l-xylopyranoside, to produce
just isofagomine in good yield.[10]
NMR spectra—there was always the hint, as alluded to by
Andersch and Bols,[11] of the presence of the tautomeric
pyranose 13 forms.
We required some noeuromycin 2 for mechanistic stud-
ies related to a β-mannosidase. Thus, the carbamate 11 was
subjected to the conditions of hydrogenolysis, followed by a
brief treatment with acid (akin to the procedure described by
Andersch and Bols[11]), to provide noeuromycin hydrochlo-
ride (Scheme 3). We were able to obtain a very pure sample
Withtheimidazylate8asthecentralpivotforasynthesisof
isofagomine and noeuromycin, it was too tempting to ignore
a related synthesis of azafagomine 3. Thus, treatment of the
imidazylate 8 with tert-butyl carbazate 14 gave the hydrazide
15 (Scheme 4). A subsequent hydrogenolysis/reductive ami-
nation gave the pyridazine 16 that was a direct precursor of
azafagomine.
of this hydrochloride and so collected excellent 1H and 13
C

830
P. J. Meloncelli and R. V. Stick
Our synthesis of isofagomine lactam 4[5] was never
Benzyl 4-O-(Imidazolyl-1-sulfonyl)-2,3-O-isopropylidene-
β-L-xyloside 8
entirely satisfactory, proceeding via the acyclic ester 17
(Scheme 5). Our original intention, never realized, was to
proceed via the lactone 18. Here we report a much better
synthesis of the lactam 4.
Lithium bis(trimethylsilyl)amide in THF (1 M, 30 mL, 30 mmol) was
added dropwise to the alcohol 7[9] (7.22 g, 26.1 mmol) in dry THF
(150 mL, 0◦C) and the solution stirred (30 min, 0◦C). The solution was
cooled (−30◦C) and freshly prepared N,Nꢀ-sulfuryldiimidazole[13,14]
(5.94 g, 30.0 mmol) was added portionwise (30 min); the solution was
then stirred (30 min, room temp.). Methanol (3 mL) was added and,
after 30 min, the solution was poured into EtOAc, washed with saturated
NaHCO3 and dried. Flash chromatography (EtOAc/petrol 1/4, contain-
ing 0.5% Et3N) gave the imidazylate 8 (9.53 g, 90%) as a colourless
solid, mp 89–90◦C (lit.[9] 90–92◦C), [α]D +85.5◦ (lit.[9] +86.6◦). The
1H (300 MHz) and 13C (75.5 MHz) NMR spectroscopic data were in
good agreement with those reported.[9]
The carbamate 11 was converted into the bis(tert-
butyldimethylsilyl) ether 19 (we were never able to determine
unequivocally the conformation of the molecules prepared in
this section[5] and so have resorted to planar depictions of
such structures), and a subsequent hydrogenolysis gave the
hemiacetal 20 (Scheme 5). Oxidation of 20 with tetrapropy-
lammonium perruthenate gave the lactone 21; however, we
never found the correct conditions for deprotection of 21
and the subsequent conversion into the lactam 4. As there
were indications that the hindered silyl ethers of 21 were
resistant to removal, we repeated the sequence from 11 with
just trimethylsilyl ethers, via compounds 22, 23, and 24
(Scheme 6). Now, the lactone 24 was easily converted into
isofagomine lactam 4 under acidic, then basic, conditions.
We next decided to attempt a preparation of the unknown
azanoeuromycin 5, along lines similar to those for the prepa-
ration of noeuromycin itself. Thus, the imidazylate 8 was
treated with the carbazate 25 to give the hydrazide 26
(Scheme 7). We were unable to access 26 from the hydrazide
15, through treatment with di(tert-butyl) dicarbonate; in fact,
it was advantageous to remove the isopropylidene protecting
group from 26 (to give 27), and then one of the tert-
butoxycarbonyl groups, to provide the more stable hydrazide
28. Again, 28 could not be formed satisfactorily from the
direct acylation of 15; as well, treatment of the imidazylate
8 with the carbazate 29 failed to give 28 directly. The nuclear
magnetic resonance spectra of 28 were so broadened as to be
of little use for structural authentification.
The subsequent hydrogenolysis of 28 proved irksome,
requiring just a trace of water for success, but presumably
gave the hemiacetal 30 that, upon treatment with aqueous
acid, gave azanoeuromycin 5, along with various amounts
of the cyclic hydrazone 31, the presence of the latter indi-
cated by nuclear magnetic resonance signals at δH 6.85 and
δC 146.00. In fact, the use of neat trifluoroacetic acid maxi-
mized the formation of 31, almost to the detriment of 5, but
dilute mineral acid saw good conversion of 31 into the desired
azanoeuromycin. At equilibrium in dilute aqueous acid, the
α- and β-‘anomers’ of azanoeuromycin 5, and the hydrazone
31 were present in a ratio of 1.0:0.4:0.7.
Benzyl 4-C-[(tert-Butoxycarbonyl)amino]methyl-4-deoxy-
α-D-arabinoside 11
Freshly prepared AlH3 in THF[15] (0.66 M, 5.6 mL, 3.6 mmol) was
added to the nitrile 10 (297 mg, 1.19 mmol) in dry THF (15 mL,
0◦C) and the solution stirred (2 h). Further portions of AlH3 (0.66 M,
5.6 mL, 3.6 mmol) were added (2 h and 4 h) and the solution was
stirred overnight. The mixture was quenched by the addition of H2O
(5.0 mL) and NaOH (1.0 M, 5.0 mL), followed by treatment with
(Boc)2O(520 mg, 2.4 mmol)(5 h, roomtemp.).Themixturewasthenfil-
tered, diluted with EtOAc (200 mL), dried, and the filtrate concentrated
to give a colourless oil, which was subjected to flash chromatogra-
phy (EtOAc/petrol 1/1) to give the carbamate 11 (350 mg, 85%) as a
colourless solid, mp 157–159◦C (lit.[9] 158–160◦C), [α]D +75.9◦ (lit.[9]
+77.8◦). The 1H (300 MHz) and 13C (75.5 MHz) NMR spectroscopic
data were in good agreement with those reported.[9]
Benzyl 4-C-[(tert-Butoxycarbonyl)amino]methyl-4-deoxy-
2-O-isopropyl-α-D-arabinoside 12
Freshly prepared AlH3 in THF (1.1 M, 3.6 mL, 4.0 mmol) was added
to the nitrile 9 (610 mg, 2.2 mmol) in dry THF (30 mL, 0◦C) and the
solution stirred (2 h). The mixture was quenched by the addition of
H2O (2.0 mL) and NaOH (1.0 M, 2.5 mL), followed by treatment with
(Boc)2O(640 mg, 2.8 mmol)(5 h, roomtemp.).Themixturewasfiltered,
the filtrate concentrated, and the residue subjected to flash chromatog-
raphy (EtOAc/petrol 3/7) to give the alcohol 12 (500 mg, 58%) as a
colourless oil, [α]D +68.7◦. δH (300 MHz) 1.13, 1.15 (2d, 6H, J 6.0,
6.0, CH3CH), 1.44 (s, 9H, CH3C), 2.21–2.31 (br m, H4), 3.18–3.25
(br s, CH2NH), 3.32 (br d, J 8.3, H2), 3.44 (br s, OH), 3.57 (dd,
J 11.5, 3.9, H5), 3.70–3.80 (m, 3H, H3, H5, CH3CH), 4.80, 4.52
(AB, J 11.8, PhCH2), 4.71 (br s, H1), 4.90 (br m, NH), 7.30–7.40
(m, Ph). δC (75.5 MHz) 22.46, 22.57 (2C, CH3CH), 28.33 (CH3C),
36.20 (C4), 39.54 (CH2NH), 58.39 (CH2Ph), 69.55 (C5), 68.61, 71.83,
73.32 (C2, C3, CH3CH), 79.20 (CH3C), 98.98 (C1), 127.89, 127.98,
128.50, 136.79 (Ph), 156.12 (C=O). m/z (FAB) 396.2379 (C21H34NO6
[M + H]+ requires 396.2386).
Benzyl 3-O-Acetyl-4-C-[(tert-butoxycarbonyl)amino]methyl-4-deoxy-
2-O-isopropyl-α-D-arabinoside
Our last task was to prepare the interesting ‘guanidine’
isofagomine 6. Isofagomine itself was easily converted into
the fully protected carbamate 32; selective deprotection of
32 gave the amine 33 (Scheme 8). Treatment of 33 with
the reagent 34 then gave the triacetate 35, deprotection
of which yielded the desired ‘guanidine’ isofagomine 6,
again isolated as its hydrochloride. Early indications are that
this ‘guanidine’ isofagomine is not an effective inhibitor of
glycoside hydrolases.
A small sample of the alcohol 12 (10 mg) in pyridine (1 mL) and Ac2O
(0.5 mL) was stirred (2 h). The reaction was quenched with MeOH
(2 mL), the solution concentrated and subjected to flash chromatog-
raphy (EtOAc/petrol 3/7) to give the title acetate (10 mg, 90%) as a
colourless oil. δH (300 MHz) 1.13, 1.15 (2d, 6H, J 5.9, 5.9, CH3CH),
1.44 (s, 9H, CH3C), 2.02 (s, CH3CO), 2.35 (m, H4), 3.25 (m, CH2NH),
3.45–3.55 (m, 2H, H2, H5), 3.70–3.90 (m, 2H, H5, CH3CH), 4.62 (m,
H1), 4.48, 4.81 (AB, J 12.1, PhCH2), 4.85 (dd, J 4.2, 3.4, H3), 7.25–7.35
(m, Ph).
(2R/S,3S,4R,5R)-5-(Hydroxymethyl)piperidine-2,3,4-triol
(Noeuromycin) 2 Hydrochloride
A stirred solution of the carbamate 11 (22 mg) inTHF/H2O (1/1, 15 mL)
was treated with Pd/C (10%, 10 mg) and H2 (1 atm, 12 h). The mix-
ture was filtered, concentrated, and subjected to flash chromatography
Experimental
General experimental procedures have been given previously.[12]

Isofagomine, Noeuromycin, Azafagomine, Isofagomine Lactam, Azanoeuromycin, and ‘Guanidine’ Isofagomine
831
(THF/petrol 7/3) to give a colourless oil. The oil was treated with
hydrochloric acid (1 M, 1 mL) and kept (10 min). The solvent was
removed to give noeuromycin 2 hydrochloride (10.5 mg, 86%) as a
colourless oil. δH (600 MHz, D2O) 1.90–2.02 (br m, H5), 2.98 (dd,
J6,6 13.0, J5,6 13.1, H6α), 3.25–3.33 (m, H6β), 3.46 (dd, J5,6 4.6, H6α),
3.53–3.57 (m, H3α, H4α), 3.63–3.66 (m, H3β), 3.70–3.85 (m, H4β,
CH2O), 4.61 (d, J2,3 7.5, H2α), 5.26 (d, J2,3 2.7, H2β). δC (150.9 MHz,
D2O) 41.26 (C6β), 43.47 (C5α), 43.74 (C5β), 44.15 (C6α), 61.66,
61.79 (CH2O), 69.54 (C4β), 72.53 (C4α), 74.60 (C3β), 76.99 (C3α),
80.79 (C2β), 83.85 (C2α). m/z (FAB) 164.0908 (C6H14NO4 [M + H]+
requires 164.0922).
(CH2Cl2). δH (600 MHz) −0.01, 0.03, 0.05, 0.06 (4s, 12H, CH3Si),
0.84, 0.85 (2s, 18H, CH3CSi), 1.44 (s, 9H, CH3C), 2.22 (m, 1H), 3.02
(m, 2H), 3.40 (m, 1H), 3.59 (m, 1H), 3.71 (br s, 1H), 3.95 (m, 1H),
4.43, 4.71 (AB, J 11.9, PhCH2), 4.54 (br s, 1H), 4.58–4.64 (m, 1H),
7.28–7.35 (m, Ph). δC (150.9 MHz) −4.83, −4.66, −4.48, −3.82 (4C,
CH3Si), 18.12, 18.20 (2C, CH3CSi), 25.81, 25.92 (CH3CSi), 28.55
(CH3CO), 36.73 (C4), 40.24 (CH2NH), 58.11, 71.28, 70.43 (C2, C3,
C5), 69.35 (PhCH2), 79.24 (CH3CO), 99.95 (C1), 127.57, 128.29,
128.34 (Ph), 156.07 (C=O). m/z (FAB) 582.3620 (C30H56NO6Si2
[M + H]+ requires 582.3646).
4-C-[(tert-Butoxycarbonyl)amino]methyl-2,3-di-O-(tert-
butyldimethylsilyl)-4-deoxy-D-arabinono-1,5-lactone 21
Benzyl 4-[N-Amino-N-(tert-butoxycarbonyl)]amino-4-deoxy-
2,3-O-isopropylidene-α-D-arabinoside 15
The disilyl ether 19 (80 mg, 0.138 mmol) in THF/H2O (1/1, 15 mL) was
treated with Pd/C (10%, 15 mg) and H2 (1 atm, 1 day). The suspension
was filtered through Celite and the filtrate freeze-dried to give a colour-
less oil. This oil in dry CH2Cl2 was treated with 4 Å sieves (100 mg)
and N-methylmorpholine N-oxide (22 mg, 0.19 mmol) and stirred (1 h).
The mixture was then treated with Pr4NRuO4 (4.7 mg, 0.013 mmol),
stirred (4 h, 25◦C), filtered through Celite and concentrated. Flash
chromatography (EtOAc/petrol 3/7) gave the lactone 21 as a colour-
less solid (55 mg, 86%), mp 96–97◦C, [α]D −22.9◦. νmax/cm−1 (film)
1747, 1716. δH (600 MHz) 0.11, 0.11, 0.13, 0.15 (4s, 12H, CH3Si),
0.89 (s, 18H, CH3CSi), 1.44 (s, 9H, CH3C), 2.57–2.66 (m, 1H), 3.09–
3.15 (m, 2H), 3.33 (m, 1H), 3.85–3.88 (br s, 1H), 4.25–4.33 (m, 2H),
4.37–4.66 (m, 1H). δC (150.9 MHz) −5.16, −4.78, −4.75, −4.28 (4C,
CH3Si), 18.06, 18.17 (2C, CH3CSi), 25.77, 25.79 (CH3CSi), 28.49
(CH3CO), 34.08 (CH2NH), 39.27 (C4), 68.13 (C5), 71.09, 71.63 (C2,
C3), 79.86 (CH3CO), 156.07 (C=O), 169.55 (C1). m/z (FAB) 490.2989
Lithium bis(trimethylsilyl)amide in THF (1 M, 6.10 mL, 6.10 mmol)
was added dropwise to tert-butyl carbazate 14 (805 mg, 6.10 mmol)
in dry THF (10 mL, −78◦C) and the solution stirred (30 min, −30◦C).
The imidazylate 8 (490 mg, 1.20 mmol) was added and the solution
heated to reflux (5 h).The solution was concentrated and the residue dis-
solved in EtOAc, washed with water and dried. Flash chromatography
(EtOAc/petrol 3/7) gave the hydrazide 15 (290 mg, 69%) as a colourless
oil, [α]D +59.1◦. δH (600 MHz) 1.44 (s, (CH3)3C), 1.47 (s, (CH3)2C),
3.71 (m, H3), 3.76 (dd, 1H, J5,5 11.9, J4,5 6.7, H5), 3.83 (s, NH2), 4.18
(dd, 1H, J4,5 6.9, H5), 4.65, 4.86 (AB, J 12.0, PhCH2), 4.67 (dd, J2,3 10.5,
J1,2 6.8, H2), 4.72–4.77 (br m, H4), 4.80 (d, H1), 7.25–7.40 (m, Ph).
δC (150.9 MHz) 27.08, 27.23 ((CH3)2C), 28.44 ((CH3)3C), 51.83 (C4),
62.01 (C5), 69.84 (PhCH2), 74.70 (C3), 76.16 (C2), 81.33 ((CH3)3C),
101.42 (C1), 111.92 ((CH3)2C), 127.86, 128.20, 128.52, 137.53 (Ph),
157.31 (C=O). δN (60.82 MHz) −316.64 (t, J 65.3, NH2), −274.73 (s,
N). m/z (FAB) 394.2131 (C20H30N2O6 [M]+• requires 394.2131).
(C23
H
48NO6Si2 [M + H]+ requires 490.3020).
(3aR,4R,7aR)-5-N-(tert-Butoxycarbonyl)-2,2-dimethyl-
1,3-dioxolo[4,5-d]hexahydropyridazine-4-methanol 16
Benzyl 4-C-[(tert-Butoxycarbonyl)amino]methyl-4-deoxy-
2,3-bis-O-trimethylsilyl-α-D-arabinoside 22
The hydrazide 15 (13.3 mg) inTHF (15 mL) was treated with Pd/C (10%,
5 mg) and H2 (1 atm, 12 h). The mixture was filtered, concentrated and
subjected to flash chromatography (EtOAc/petrol 7/3) to give the pyri-
dazine 16 (8.4 mg, 88%) as a colourless oil, [α]D −82.4◦. δH (600 MHz)
1.46, 1.49 (s, 15H, CH3), 2.92 (dd, 1H, J7,7 9.8, J7,7a 9.1, H7), 3.64 (dd,
1H, J7,7a 7.4, H7), 3.71 (ddd, J3a,7a 8.2, H7a), 3.83–3.87 (m, 2H, H4,
CH2O), 3.91–3.96 (m, 2H, H3a, CH2O). δC (150.9 MHz) 27.06, 27.16,
28.51 (CH3C), 48.97 (C7), 62.61 (CH2O), 62.67 (C4), 75.52, 75.62
(C3a, C7a), 81.97 ((CH3)3C), 112.77 ((CH3)2C), 155.81 (C=O). m/z
(FAB) 288.1685 (C13H24N2O5 [M]+• requires 288.1685).
The carbamate 11 (197 mg, 0.558 mmol) in dry DMF (2 mL) was treated
with (CH3)3SiCN (138 mg, 1.40 mmol) and stirred (40 min). The solu-
tion was concentrated to give the disilyl ether 22 as a colourless oil
(277 mg, 100%), [α]D −3.85◦. δH (300 MHz) 0.08, 0.14 (2s, 18H,
CH3Si), 1.43 (s, 9H, CH3C), 2.05 (m, H4), 3.20–3.4 (m, CH2NH),
3.43 (dd, J5,5 11.9, J4,5 2.6, H5), 3.51 (dd, J2,3 7.0, J1,2 5.7, H2), 3.70
(dd, J3,4 4.7, H3), 3.89 (dd, J4,5 4.7, H5), 4.30 (d, H1), 4.51, 4.83 (AB,
J 11.9, PhCH2), 4.94 (br s, NH), 7.25–7.37 (m, Ph). δC (75.5 MHz)
0.40, 0.63 (CH3Si), 28.56 (CH3C), 39.62 (CH2NH), 40.22 (C4), 62.41
(PhCH2), 70.31 (C5), 73.81, 72.28 (C2, C3), 79.11 (CH3C), 102.58
(C1), 137.89, 128.31, 127.93, 127.59 (Ph), 156.00 (C=O). m/z (FAB)
498.2744 (C24H44NO6Si2 [M + H]+ requires 498.2707).
(3R,4R,5R)-4,5-Dihydroxy-3-(hydroxymethyl)hexahydropyridazine
(Azafagomine) 3
The pyridazine 16 (8 mg) was treated with CF3COOH (20 min, room
temp.). The solution was concentrated, the residue dissolved in MeOH,
and neutralized with resin (Amberlite IRA 400, OH−), filtered, and con-
centrated. The residual gum was dissolved in hydrochloric acid (1 M,
1 mL) and applied to a cation-exchange column (Dowex 50W-X2, H+).
The column was washed with water and eluted with aqueous NH3
(1.5 M). The eluate was concentrated to give azafagomine 3 (5.1 mg,
99%) as a colourless oil, [α]D +38◦ (H2O, pH 2.5). δH (600 MHz, D2O,
pH 2.5) 2.89 (dd, 1H, J6,6 12.5, J5,6 12.1, H6), 3.02 (ddd, J 9.6, 6.2, 2.7,
H3), 3.45–3.49 (m, 2H, H6, H4), 3.70–3.75 (m, 2H, H5, CH2O), 3.84
(dd, 1H, J 12.4, 2.7, CH2O). δC (150.9 MHz, D2O, pH 2.5) 48.52 (C6),
57.97 (CH2O), 60.78 (C3), 67.91 (C5), 69.17 (C4).
4-C-[(tert-Butoxycarbonyl)amino]methyl-4-deoxy-2,3-bis-O-
trimethylsilyl-D-arabinono-1,5-lactone 24
The disilyl ether 22 (50 mg) in THF (20 mL) was treated with Pd/C
(10%, 10 mg) and H2 (1 atm, 4 days, 40◦C). The solution was then
filtered and concentrated to give a colourless oil (40 mg). The oil was
dissolved in dry CH2Cl2 (10 mL) and stirred with 4 Å sieves (100 mg).
N-Methylmorpholine N-oxide (22 mg, 0.186 mmol) in CH2Cl2 (3 mL)
was also stirred with 4 Å sieves (100 mg). The two solutions were com-
bined and then treated with Pr4NRuO4 (4 mg, 0.012 mmol), stirred (1 h),
and then filtered, concentrated and subjected to flash chromatography
(EtOAc/petrol 1/4, containing 2% Et3N) to give 24, essentially pure, as a
colourless oil (26 mg, 65%). A small sample was further purified using
flash chromatography to give 24, [α]D −14.5◦ (CH2Cl2), νmax/cm−1
(film) 1740, 1717. δH (500 MHz) 0.17, 0.19 (2s, 18H, CH3Si), 1.46
(s, 9H, CH3C), 2.51–2.57 (m, H4), 3.12–3.27 (m, CH2NH), 3.91–3.94,
4.03–4.05, 4.25–4.34 (3 × m, 4H, H2, H3, H5), 4.71 (br s, NH). δC
(125.8 MHz) 0.01 (CH3Si), 28.67 (CH3C), 35.62 (C4), 39.04 (CH2NH),
67.69 (C5), 72.14, 72.26 (C2, C3), 79.83 (CH3C), 156.01 (C=O),
170.36 (C1). m/z (FAB) 406.2100 (C30H56NO6Si2 [M + H]+ requires
406.2081).
Benzyl 4-C-[(tert-Butoxycarbonyl)amino]methyl-2,3-di-O-(tert-
butyldimethylsilyl)-4-deoxy-α-D-arabinoside 19
The carbamate 11 (145 mg, 0.411 mmol) in dry DMF (10 mL) was
treated with imidazole (280 mg, 4.11 mmol) and BMSCl (308 mg,
2.05 mmol) and stirred (4 days, 75◦C). The solution was concentrated
and subjected to flash chromatography (EtOAc/petrol 3/7) to give
the disilyl ether 19 as a colourless oil (204 mg, 85%), [α]D +69.2◦

832
P. J. Meloncelli and R. V. Stick
(3S,4R,5R)-3,4-Dihydroxy-5-(hydroxymethyl)piperidin-2-one
(Isofagomine Lactam) 4
(Azanoeuromycin) 5 hydrochloride and the hydrazone 31 hydrochloride
as a colourless oil. δH (600 MHz, D2O) 3.05–3.08 (m, H6α), 3.17–3.23
(m, H6β, H6), 3.48 (dd, J4,5 9.0, J3,4 8.5, H4α), 3.53 (dd, J5,6 9.2,
H5α), 3.62–3.73, 3.76–3.81 (2 m, CH2α, CH2β, CH2, H4β, H5β, H5),
3.95 (dd, J 12.8, 3.15, CH2β), 4.19 (dd, J4,5 8.0, J3,4 1.2, H4), 4.50
(d, H3α), 4.88 (d, J3,4 3.3, H3β), 6.85 (d, H3). δC (150.9 MHz, D2O)
57.21 (CH2β), 57.74 (CH2α), 58.37, 61.99 (C6β, C6), 58.79 (CH2),
60.59 (C6α), 64.94, 67.14, 71.06 (C4β, C5β, C5), 68.15, 73.85 (C4α,
C5α), 69.46 (C4), 78.29 (C3β), 81.75 (C3α), 146.00 (C3). m/z (FAB)
165.0865 (5, C5H13N2O4 [M + H]+ requires 165.0875); 146.0690 (31,
C5H10N2O3 [M]+• requires 146.0691).
The disilyl ether 24 (18 mg) was treated with CF3COOH/H2O (1/1,
3 mL) and stirred (1 h). The solution was then concentrated and the
residue in MeOH treated with resin (Amberlite IRA 400, OH−) until
neutral.Thesolutionwasfilteredandconcentrated, andflashchromatog-
raphy (EtOAc/MeOH/H2O 17/2/1) gave isofagomine lactam 4 as a solid
(5.5 mg, 80%), [α]D +9.5◦ (MeOH; lit.[5] +11.0◦). The 1H (300 MHz)
and 13C (75.5 MHz) NMR spectroscopic data were in good agreement
with those reported.[5]
(b) The hemiacetal 30 (5.5 mg) was treated with CF3COOH (1 mL)
for 15 min. The solvent was removed, the residue dissolved in a lit-
tle hydrochloric acid (1 M) and the solvent again removed. The 1H
(600 MHz) and 13C (150.9 MHz) NMR spectra were consistent with
those reported for 5 and 31 in (a).
Benzyl 4-[N-tert-Butoxycarbonyl-N-di(tert-butoxycarbonyl)-
amino]amino-4-deoxy-2,3-O-isopropylidene-α-D-arabinoside 26
Lithium bis(trimethylsilyl)amide in THF (1 M, 3.5 mL, 3.5 mmol) was
added dropwise to tri(tert-butoxycarbonyl)hydrazine 25[16] (1.36 g,
3.95 mmol) in dry THF (10 mL, −30◦C) and the solution stirred
(30 min). The imidazylate 8 (200 mg, 0.488 mmol) was added and the
solution heated to reflux (14 h). The solution was concentrated and the
residue dissolved in EtOAc, washed with H2O and dried. Flash chro-
matography (EtOAc/petrol 3/7) gave the hydrazide 26 (240 mg, 89%)
as a colourless oil, [α]D −4.3◦. δH (300 MHz) 1.39, 1.44, 1.50 (3s, 33H,
CH3), 3.49 (dd, J5,5 13.2, J4,5 2.1, H5), 3.65 (dd, J3,4 4.1, J2,3 10.1,
H3), 3.85 (dd, J1,2 7.5, H2), 4.36–4.43 (m, H4, H5), 4.52 (d, H1), 4.64,
4.88 (AB, J 11.7, PhCH2), 7.25–7.37 (m, Ph). δC (75.5 MHz) 26.51,
26.65((CH3)2C), 27.74, 27.85((CH3)3C), 56.24(C4), 65.36(C5), 69.79
(PhCH2), 73.53, 77.12 (C2, C3), 81.47 ((CH3)3C), 102.09 (C1), 110.21
((CH3)2C), 127.54, 128.05, 128.15, 137.06 (Ph), 154.03 (C=O).
(4R,5R,6R)-4,5-Dihydroxy-6-hydroxymethyl-1,4,5,6-
tetrahydropyridazine 31 (Salt with CF3COOH)
The hemiacetal 30 (5.0 mg) was treated with CF3COOH (2 mL) for
20 min. The solvent was removed to give predominantly the hydrazone
31 (salt with CF3COOH) (2.1 mg) as a colourless oil. δH (600 MHz,
[D]6DMSO) 2.85 (ddd, J5,6 10.2, J 7.7, 3.0, H6), 3.27 (dd, J4,5 7.6,
H5), 3.36 (dd, 1H, J 11.1, 7.7, CH2), 3.74 (dd, 1H, J 11.1, 3.0, CH2),
3.82 (dd, J3,4 1.4, H4), 6.31 (d, H3). δC (150.9 MHz, [D]6DMSO) 59.91
(C6), 60.52 (CH2), 69.11 (C5), 70.55 (C4), 117.01 (CF3), 140.41 (C3),
158.40 (C=O).
(3R,4R,5R)-3,4-Diacetoxy-5-acetoxymethyl-N-(tert-
butoxycarbonyl)piperidine 32
Benzyl 4-[N-tert-Butoxycarbonyl-N-di(tert-butoxycarbonyl)amino]-
amino-4-deoxy-α-D-arabinoside 27
Isofagomine 1 (110 mg, 0.600 mmol) in Me2CO/H2O (7/3, 10 mL)
was treated with NaHCO3 (500 mg, 6.0 mmol) and (Boc)2O (310 mg,
1.20 mmol) and stirred (2 h, room temp.). The mixture was then
somewhat concentrated, extracted with EtOAc, the extract dried and
concentrated, and the residue dissolved in CHCl3 (10 mL).This solution
was treated with pyridine (4 mL),Ac2O (3 mL), and DMAP (10 mg) and
stirred (2 h). Treatment with MeOH (5 mL, 1 h), followed by concentra-
tion of the mixture and flash chromatography (EtOAc/petrol 1/4), gave
the carbamate 32 (220 mg, 83%) as a colourless oil, [α]D +31.2◦. δH
(600 MHz) 1.45 (s, 9H, CH3C), 2.02, 2.04, 2.05 (3s, CH3C=O), 2.03–
2.05 (m, 1H), 2.72–3.14 (m, 2H), 3.97–4.15 (m, 4H), 4.78 (br m, 1H),
4.97 (t, 1H). δC (150.9 MHz) 20.61, 20.64, 20.70 (3C, CH3C=O), 28.14
(CH3C), 39.32 (C5), 43.90, 45.50 (C2, C6), 61.64 (CH2O), 70.04, 71.27
(C3, C4), 80.55 (CH3C), 154.23 (NC=O), 169.98, 170.55 (CH3C=O).
m/z (FAB) 374.1804 (C17H28NO8 [M + H]+ requires 374.1815).
The hydrazide 26 (240 mg) in MeOH (20 mL) was treated with pyri-
dinium tosylate (30 mg) and the mixture refluxed (2 h).The solution was
concentrated and the residue dissolved in EtOAc, washed with H2O, and
dried. Flash chromatography (EtOAc/petrol 1/1) gave the hydrazide 27
(201 mg, 89%) as a colourless oil, [α]D +64.3◦. δH (600 MHz) 1.48,
1.50, 1.53 (3s, 27H, CH3), 3.57 (dd, J5,5 12.3, J4,5 3.5, H5), 3.72
(dd, J2,3 7.9, J1,2 5.4, H2), 3.84 (dd, J3,4 4.7, H3), 4.21 (dd, J4,5 4.8,
H5), 4.39 (d, H1), 4.57, 4.82 (AB, J 11.9, PhCH2), 4.71 (ddd, H4),
7.28–7.37 (Ph). δC (150.9 MHz) 27.97, 28.14, 28.17 (CH3), 54.94 (C4),
61.63 (C5), 70.05 (PhCH2), 71.56, 71.84 (C2, C3), 82.27, 84.03, 85.03
(CH3C), 101.43 (C1), 128.00, 128.14, 128.58, 137.22 (Ph), 151.37,
153.44, 154.61 (C=O). m/z (FAB) 555.2906 (C27H43N2O6 [M + H]+
requires 555.2918).
Benzyl 4-[N-tert-Butoxycarbonyl-N-(tert-butoxycarbonyl)amino]-
amino-4-deoxy-α-D-arabinoside 28
(3R,4R,5R)-3,4-Diacetoxy-5-acetoxymethyl-N,Nꢀ-di-(tert-
butoxycarbonyl)piperidine-1-carboxamidine 35
The hydrazide 27 (185 mg) in CH3CN was treated with Mg(ClO4)2
(74 mg) and the solution heated (50◦C, 3 h). The solution was con-
centrated and the residue dissolved in EtOAc, washed with H2O, and
dried. Flash chromatography (EtOAc/petrol 1/1) gave the hydrazide 28
(129 mg, 85%) as a colourless solid, a small portion of which was recrys-
tallized, mp 166–167◦C (CH2Cl2/petrol) (Found C 58.3, H 7.6, N 6.1.
C22H34N2O8 requires C 58.1, H 7.5, N 6.2%), [α]D +54.8◦.
The carbamate 32 (33 mg, 0.088 mmol) was treated with CF3COOH
(1 mL) for 5 min. The solution was then concentrated and azeotrop-
ically dried with CH2Cl2/PhMe and redissolved in CH2Cl2 (1 mL).
This solution was then treated with ethyldiisopropylamine (45 mg,
0.35 mmol) and N,Nꢀ-di-(tert-butoxycarbonyl)-Nꢀꢀ-trifluoromethane-
sulfonylguanidine 34 (34 mg, 0.087 mmol) and stirred (5 days, room
temp.). Concentration of the mixture followed by flash chromatography
(EtOAc/petrol 1/4) gave the triacetate 35 (38 mg, 95%) as a colour-
less oil, [α]D +1.1◦ (CH2Cl2). δH (600 MHz) 1.49 (s, 18H, CH3C),
2.03, 2.05, 2.06 (3s, 9H, CH3C=O), 2.37 (br s, 1H), 3.00 (m, 2H),
4.01 (dd, 1H, J 11.7, 3.3), 4.05–4.12 (br s, 1H), 4.11 (dd, 1H, J 11.7,
5.7), 4.23–4.35 (br s, 1H), 4.99–5.03 (m, 1H), 5.08 (t, 1H, J 8.8 Hz). δC
(150.9 MHz) 20.86, 20.89, 20.94 (3C, CH3C=O), 28.22 (CH3C), 38.93
(C5), 48.10 (C2, C6), 61.71 (CH2O), 70.23, 71.54 (C3, C4), 155.64
(NC=O), 169.97, 170.40, 170.86 (3C, CH3C=O). m/z (FAB) 516.2545
(C23H38N3O10 [M + H]+ requires 516.2557).
4-[N-tert-Butoxycarbonyl-N-(tert-butoxycarbonyl)amino]-
amino-4-deoxy-D-arabinose 30
The hydrazide 28 (16 mg) in THF/H2O (100/0.1, 15 mL) was treated
with Pd/C (10%, 4 mg) and H2 (12 h, 1 atm). The mixture was filtered,
concentrated, and subjected to flash chromatography (THF/petrol 4/1)
to give, presumably, the hemiacetal 30 (10 mg, 75%) as a colourless oil.
(3R/S,4S,5R,6R)-3,4,5-Trihydroxy-6-(hydroxymethyl)
hexahydropyridazine(azanoeuromycin) Hydrochloride
(Azanoeuromycin) 5 and
(4R,5R,6R)-4,5-Dihydroxy-6-hydroxymethyl-1,4,5,6-
tetrahydropyridazine 31 Hydrochloride
(3R,4R,5R)-3,4-Dihydroxy-5-(hydroxymethyl)piperidine-
1-carboxamidine 6 Hydrochloride
(a)Thehemiacetal 30 (10.0 mg) was treatedwith hydrochloric acid(1 M,
The triacetate 35 (62 mg, 0.120 mmol) was treated with hydrochlo-
2 mL) for 15 min.The solvent was removed to give a mixture (4.3 mg) of
ric acid in MeOH (1 M, 4 mL) and stirred (12 h). The solution was

Isofagomine, Noeuromycin, Azafagomine, Isofagomine Lactam, Azanoeuromycin, and ‘Guanidine’ Isofagomine
833
concentrated and treated with CF3COOH (1 mL, 20 min), then again
concentrated. The residue was dissolved in hydrochloric acid (1 M,
2 mL) and the mixture evaporated (this procedure was repeated another
two times) to give the hydrochloride of 6 as a colourless oil (26 mg),
[α]D +101◦ (H2O). δH (600 MHz, D2O) 1.74 (m, H5), 2.89 (dd, 1H, J
13.4, 11.4, H2), 2.95 (dd, 1H, J 14.0, 11.8, H6), 3.38 (dd, J 10.1, 8.8,
H4), 3.51–3.55 (m, H3), 3.76 (dd, 1H, J 11.6, 3.4, CH2O), 3.59 (dd, 1H,
J 6.9, CH2O), 3.79–3.84 (m, 2H, H2, H6). δC (150.9 MHz, D2O) 42.79
(C5), 46.55 (C6), 49.02 (C2), 59.53 (CH2O), 69.93 (C3), 72.65 (C4),
156.15 (C=N). m/z (FAB) 190.1201 (C7H16N3O3 [M + H]+ requires
190.1201).
[4] V. H. Lillelund, H. Liu, X. Liang, H. Søhoel, M. Bols, Org. Biomol.
Chem. 2003, 1, 282. doi:10.1039/B208784G
[5] J. M. Macdonald, R. V. Stick, Aust. J. Chem. 2004, 57, 449.
doi:10.1071/CH03228
[6] D. L. Zechel, A. B. Boraston, T. Gloster, C. M. Boraston,
J. M. Macdonald, D. M. G. Tilbrook, R. V. Stick, G. J. Davies,
J. Am. Chem. Soc. 2003, 125, 14313. doi:10.1021/JA036833H
[7] T. Gloster, S. J. Williams, S. Roberts, C. A. Tarling, J. Wicki,
S. G. Withers, G. J. Davies, Chem. Commun. 2004, 1794.
doi:10.1039/B405152A
[8] M. J. Kiefel, M. von Itzstein, Prog. Med. Chem. 1999, 36, 1.
[9] W. M. Best, J. M. Macdonald, B. W. Skelton, R. V. Stick,
D. M. G. Tilbrook, A. H. White, Can. J. Chem. 2002, 80, 857.
doi:10.1139/V02-060
Acknowledgments
We thank Ian D. Jenkins for suggesting the guanidine 6
as an interesting synthetic target, and Gideon Davies and
Tracey Gloster for investigating its potential as an inhibitor
of glycosidases.
[10] X. Zhu, K. A. Sheth, S. Li, H.-H. Chang, J.-Q. Fan, Angew. Chem.
Int. Ed. 2005, 44, 7450. doi:10.1002/ANIE.200502662
[11] J. Andersch, M. Bols, Chem. Eur. J. 2001, 7, 3744. doi:
10.1002/1521-3765(20010903)7:17<3744::AID-CHEM3744>
3.0.CO;2-3
[12] J. C. McAuliffe, R. V. Stick, Aust. J. Chem. 1997, 50, 193.
doi:10.1071/C96151
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