Stereoselective synthesis and biological evaluation of anisomycin and 2- substituted analogues

Article abstract of DOI:10.1055/s-1999-3661

The naturally occurring pyrrolidine anisomycin 1, its deacetyl derivative 9k, and some previously unknown analogues were prepared from 2-O- benzyl-3,4-O-isopropylidene-L-threose 2, via the N-benzylimine 3, using highly threo-selective additions of organol

Full text of DOI:10.1055/s-1999-3661

PAPER
1473
Stereoselective Synthesis and Biological Evaluation of Anisomycin and
2-Substituted Analogues1
Oliver Schwardt,a Ulrich Veith,a Christiane Gaspard,b Volker Jägera*
aInstitut für Organische Chemie der Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
Fax +49(711)6854321; E-mail jager.ioc@po.uni-stuttgart.de
bInstitut de Chimie des Substances Naturelles, CNRS, F-91198 Gif-sur-Yvette cedex, France
Received 19 April 1999
Dedicated to the memory of Professor Robert Burns Woodward, born 14.10.1917, deceased 8.7.1979
Since these derivatives were all obtained semi-syntheti-
cally starting from anisomycin produced by fermentation,
short alternative approaches to 1 and the family of deriv-
atives and analogues deemed worthwhile to be sought. In
Abstract: The naturally occurring pyrrolidine anisomycin 1, its
deacetyl derivative 9k, and some previously unknown analogues
were prepared from 2-O-benzyl-3,4-O-isopropylidene-L-threose 2,
via the N-benzylimine 3, using highly threo-selective additions of
organolithium and Grignard compounds and subsequent cyclization the literature, about 15 syntheses of 1 or the precursor,
deacetylanisomycin (9k), are found.6-11 Most impressive
as key steps. Anisomycin 1 was obtained in 8 steps/44% total yield
from L-threose 2 (12 steps/23% from diethyl L-tartrate). The overall
is the route shown by Yoda and Takabe, starting from tri-
yields for deacetylanisomycin 9k were 54% (5 steps from L-threose
O-benzyl-L-arabinose.7d The anisylmethyl side-chain was
2) and 28% (9 steps from diethyl L-tartrate), respectively. The com-
introduced into the N,O-acetal by imine addition7d (vide
pounds 1, 8i, 8k, 9k, 18, 20, and 23 showed good to high cytotoxic
infra); after 7 steps a 34% overall yield of N-Z-deacetyl-
anisomycin was reported. Similarly, in our preliminary
paper 9k was obtained in 7 steps/34% total yield from 2-
activity towards three tumour and non-tumour cell lines.
Key words: threose imine, diastereoselective 1,2-addition, 1,4-
amino alcohol cyclization, dihydroxypyrrolidine, anisomycin, cyto-
toxicity
O-benzylthreitol,
with
N,2-O-dibenzyl-3,4-O-iso-
propylidene-L-threose imine 3 as the key intermediate.1a
In many syntheses, deacetylanisomycin (9k) was the final
product, since its transformation into 1 in a sequence of 5
steps/45% yield8c is known. Actually, a shorter, more ef-
ficient, and regioselective introduction of the 3-O-acetyl
group presented another challenge to be dealt with.
There is considerable interest in the synthesis of optically
active cyclic amino alcohols, e.g. iminopolyols, imino
sugars, and cyclic amino acids since many representatives
have been reported to exhibit diverse, strong physiologi-
cal effects.2,3 One of these classes of compounds we are
concerned with is that of 2-alkyl- and 2-aryl- hydroxypyr-
rolidines. Representative examples are the antibiotic
preussin A,4 the hypertensive alkaloid codonopsine B,5
and the antibiotic anisomycin 1,6-11 a fermentation prod-
uct of various species of Streptomyces, known for its
marked, but not outstanding activity towards some patho-
genic protozoa and fungi6a (Figure 1).
In earlier work, we investigated the synthesis of aminodi-
ols and -polyols as key intermediates, e.g. in the prepara-
tion of dipeptide isosteres (statine family), inter alia by
addition of organometallic reagents to imines13 of 2-O-
benzylglyceraldehyde.14-17 It was shown that the dia-ste-
reoselectivity in this kind of reaction is greatly influenced
by the solvent, the metal counterion, and, notably, by in-
troducing a chiral auxiliary at the imine nitrogen.15b,c This
was applied also to reactions of Grignard and organolith-
ium compounds with Schiff bases of tetroses.1,18 Subse-
quent cyclization of such addition products should give
access to dihydroxypyrrolidines. While earlier attempts at
practicable syntheses of anisomycin 1 had failed, both us-
ing a furoisoxazoline derivative2d and via nitroaldol addi-
tion,17a,c we now report on a new, highly efficient, and
diastereoselective synthesis of anisomycin 1 and of previ-
ously unknown analogues. This details and extends our
preliminary communication on a "concise synthesis of
deacetylanisomycin and analogues". The highly threo-se-
lective addition of organolithium or Grignard reagents to
the L-threose imine 3 forms the key step of these syntheses
(Scheme 1). The starting material, 2-O-benzyl-3,4-O-iso-
propylidene-L-threose 2, is easily available in four steps
from diethyl L-tartrate via 2-O-benzyl-L-threitol,14b ac-
cording to ref.14c,19,20 (50% overall yield). Condensation21
of 2, with benzylamine quantitatively yielded the N-ben-
zylimine 3,1,18 which was then treated with 3 equivalents
Figure 1
Practical syntheses of the latter have met with increased
interest when high anti-tumour activity in vitro, with IC50
values in the nanomolar range, was reported for the parent
1 and some analogues in 1993.12a Further, in 1995 some
anisomycin derivatives with 3-O-carbamoyl- or 3-O-alkyl
groups have been patented due to their improved in vivo
stability and activity.12b
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1474
O. Schwardt et al.
PAPER
of organolithium compound at –78 °C or with 2 to 5 one (MeLi, entry 1), a single isomer with D-xylo configu-
equivalents of Grignard reagent at 0 °C to room tempera- ration was found by 1H and 13C NMR analysis of the crude
ture in diethyl ether. Use of less, that is 1–1.5 equivalents acetonide-protected material 4/5. Yields were in the range
of organolithium or Grignard reagent, gave a considerable of 37–70% after chromatography on silica. The addition
amount (10–20%) of unidentified byproducts. Alkyl Grig- of Grignard reagents (entries 7–10) gave comparable re-
nard compounds could not be employed due to decompo- sults concerning diastereoselectivity and yield (65–78%).
sition of the starting material. The aminotriols 6/7 were In one case, that of allylmagnesium bromide (entry 8), the
obtained pure and in higher yield by subsequent hydroly- erythro-adduct (L-arabino isomer) was also detected. The
sis of the acetal group, without isolation of the intermedi- aminotriol adducts 6 were assigned the D-xylo (3,4-threo)
1
ates 4/5.22 The results are summarized in Table 1.
configuration based on analogies in H and 13C NMR
spectroscopic data (see Tables 2 and 3). Thus, all the ma-
jor products 6a–i showed a small coupling constant for J3,4
1.4–1.8 Hz, whereas a value of 6.0 Hz was found for 7h.
Shift differences of 13C NMR recordings for these free
aminodiols 6/7 proved too small and inconsistent for safe
assignment (see Table 3), as was the case with the 1H and
13C NMR data of the acetonide precursors 4/5.18 The con-
figurations shown were established notably by a crystal
structure analysis25 of the cyclization product 8b, and
complete agreement of all data of 1 and deacetylanisomy-
cin 9k with the published ones.
We attribute the high 3,4-threo-selectivity of these addi-
tions to prior formation of a five-membered chelate
(Cram-chelate) with the 2-benzyloxy group, due both to
the coordinative ability of OBn26 and to the Lewis basicity
of the imine nitrogen atom (cf. high threo-selectivity of
like additions to 2-O-benzyllactaldimines15a,b). The re-
spective ground and transition states of the competing
pathways are assumed to correspond closely to the ones
given for analogous additions of RM to imines of 2-O-
benzylglyceraldehyde.15a-c
Scheme 1
Several of the pure D-xylo diastereomers 6 were trans-
formed into 2-substituted trans-dihydroxypyrrolidines 8
in good to high yield (62–84%; Table 4), either by in-
tramolecular Mitsunobu reaction according to the proce-
dure of Vogel and Chen27 (Scheme 2; Method A), or by
cyclization using the Appel reaction28 (alcohol to chloride
transformation, Method B). The Mitsunobu reaction
failed for the cyclization of the vinyl compound 6g, but
the Appel procedure served well (entry 6): The dihydrox-
ypyrrolidine 8g was isolated in 63% yield after chromato-
graphic purification.
In accord with results observed with other a-alkoxy-,23 a-
aminoaldimines,24 or 2-O-benzyllactaldimines,15a,b but in
contrast to our observations with 2-O-benzylglycerald-
imines,15 the reactions of 3 with organolithium com-
pounds (Table 1, entries 1–6) showed excellent 3,4-threo-
selectivity (1,2-asymmetric induction). In all cases except
Table 1 Addition of Organometallic Reagents RM to the N-Benzyl-
threose imine 3 to give 4/5 and Hydrolysis to Aminotriols 6/7
Entry RM
4:5a
D-xylo/
L-arabino
Product
6/7
Yieldb
[%]
1
12
13
14
15
16
17
18
9
MeLi
BuLi
t-BuLi
Me3SiCH2Li
PhLi
2-C4H3SLi
VinylMgBr
AllylMgBr
PhCH2MgBr
AnCH2MgCld
89:11c
>95:5
>95:5
>95:5
>95:5
>95:5
>95:5
85:15
>95:5
>95:5
6a/7a
6b/7b
6c/7c
6d/7d
6e/7e
6f/7f
6g/7g
6h/7h
6i/7i
52c
59
70
67
66
37
65
75
78
71
10
6k/7k
a Diastereomer ratio (dr) from 1H and 13C NMR analyses of crude ad-
dition products 4/5.
Scheme 2 Cyclization of D-xylo-Aminotriols 6
b Yield based on 3 after chromatography on silica.
c Only 6a was isolated after chromatography.
d An = 4-anisyl.
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Stereoselective Synthesis and Biological Evaluation of Anisomycin and 2-Substituted Analogues
1475
Table 2 1H NMR Data of Compounds 6 and 7 Prepared
Com-
pound
Chemical Shifts, d
2-H 3-H
3.81–3.88 3.49–3.70 3.08
1-HA
1-HB
4-H
5-H
Others
6a
6b
6c
6d
6e
6f
3.49–3.70
1.27
3.63, 3.90 (NCH2Ph), 4.55, 4.64 (OCH2Ph), 7.25–7.38
(2 C6H5)
3.57
3.66
3.56
3.54
3.52
3.51
3.54
3.82–3.88
3.63
3.74
3.53
3.65
3.77
3.63
3.66
2.81
2.51
3.04
3.99
4.20
3.36
2.96
1.63, 1.74
0.89 (8-H), 1.16–1.38 (6-H, 7-H), 3.66, 3.88 (NCH2Ph), 4.51,
4.65 (OCH2Ph), 7.22–7.38 (2 C6H5)
3.71
3.80
3.87
3.82
3.86
–
1.05 [C(CH3)3], 3.90, 3.97 (NCH2Ph), 4.65 (OCH2Ph), 7.23–
7.34 (2 C6H5)
3.86
3.90
3.91
0.96, 1.01
0.03 [Si(CH3)3], 3.62, 3.83 (NCH2Ph), 4.54, 4.65 (OCH2Ph),
7.25–7.37 (2 C6H5)
–
3.48, 3.63 (NCH2Ph), 4.16, 4.30 (OCH2Ph), 7.13–7.45
(3 C6H5)
–
3.50, 3.65 (NCH2Ph), 4.46, 4.51 (OCH2Ph), 7.01–7.04, 7.19–
7.37 (2 C6H5, C4H3S)
6g
6hb
3.81–3.88
5.87
3.55, 3.81 (NCH2Ph), 4.55, 4.61 (OCH2Ph), 5.23 (6-HE), 5.31
(6-HZ), 7.23–7.37 (2 C6H5)
3.85
3.84
2.36, 2.57
3.70, 3.90 (NCH2Ph), 4.54, 4.63 (OCH2Ph), 5.04–5.17 (7-H),
5.72 (6-H), 7.24–7.35 (2 C6H5)
7hc
6i
3.62
3.53
–
4.06
3.82
3.43
3.52
3.18
3.18
–
3.71, 3.91 (NCH2Ph), 4.54, 4.63 (OCH2Ph)
3.83
2.81, 3.13
3.75, 3.88 (NCH2Ph), 4.52, 4.63 (OCH2Ph), 7.05–7.07, 7.23–
7.40 (3 C6H5)
6k
3.52
3.76–3.88
3.49
3.11
2.77, 3.07
3.75, 3.89 (NCH2Ph), 3.80 (OCH3), 4.51, 4.63 (OCH2Ph),
6.81–6.98, 7.21–7.37 (C6H4, 2 C6H5)
Coupling Constants J (Hz)
J1A,1B
J1A,2
J1B,2
J2,3
J3,4
1.4
1.4
1.8
1.5
1.5
1.8
1.8
J4,5
Others
d
d
d
d
6a
6b
6c
6d
6e
6f
–
–
–
–
6.5
JNC H Ph = 12.4, JOC H Ph = 11.3
2
2
d
12.3
11.2
12.2
11.6
11.3
10.6
5.9
4.6
5.8
4.6
4.3
4.6
–
4.7
4.5
5.0
4.1
4.1
4.4
8.4, 4.6
J7,8 = 6.8, JNC H Ph = 12.3, JOC H Ph = 11.4
2 2
5.6
3.0
2.7
2.6
–
JNC H Ph = 12.4
2
8.8, 4.6
J5A,5B = 14.7, JNC H Ph = 12.3, JOC H Ph = 11.3
2 2
–
JNC H Ph = 12.4, JOC H Ph = 11.0
2 2
–
JNC H Ph = 12.4, JOC H Ph = 10.9
2 2
d
6g
–
8.8
J5,6E = 17.3, J5,6Z = 10.2, J6E,6Z = 1.1, JNC H Ph = 12.7,
2
JOC H Ph = 11.3
2
6hb
7hc
6i
12.3
11.1
12.3
5.9
5.0
6.1
3.1
6.2
3.4
4.7
3.0
4.9
1.4
6.0
1.5
8.1, 5.2
JNC H Ph = 12.4, JOC H Ph = 11.3
2
2
d
–
JNC H Ph = 12.6, JOC H Ph = 11.2
2 2
6.7, 6.1
J5A,5B = 12.2, JNC H Ph = 12.6, JOC H Ph = 11.4
2 2
d
d
d
d
d
d
6k
–
–
–
–
–
–
JNC H Ph = 12.4, JOC H Ph = 11.4
2 2
a Recorded in CDCl3 at 250.1 MHz (6a, 6b, 6e, 6f, 6k), at 300.1 MHz (6g, 6h/7h), or at 500.1 MHz (6c, 6d).
b Major isomer of the 83:17 mixture 6h/7h.
c Minor isomer of the 83:17 mixture; signals in part not identified due to overlap with respective signals of 6h.
d J not resolved.
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1476
O. Schwardt et al.
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Table 3 13C NMR Chemical Shifts, d of Compounds 6 and 7a
Com-
pound
C-1
C-2
C-3
C-4
C-5
Others
6a
61.3
61.8
71.6
72.1
82.7
78.8
52.1
57.3
17.0
50.4 (NCH2Ph), 74.3 (OCH2Ph), 127.3, 127.8, 128.0, 128.3,
128.5, 137.9, 138.6 (2 C6H5)
6b
29.3
13.9 (C-8), 22.7 (C-7), 28.8 (C-6), 50.6 (NCH2Ph), 73.9
(OCH2Ph), 127.3, 127.8, 127.9, 128.3, 128.4, 128.5, 137.9,
138.7 (2 C6H5)
6c
6d
6e
6f
63.8
61.6
61.0
60.7
74.8
71.4
71.3
70.5
78.2
81.7
83.6
83.5
67.5
53.8
60.6
56.4
36.1
17.7
28.1 [C(CH3)3], 55.1 (NCH2Ph), 73.8 (OCH2Ph), 127.1,
127.6, 127.7, 128.3, 128.4, 138.0, 140.5 (2 C6H5)
–0.9 [Si(CH3)3], 50.7 (NCH2Ph), 73.8 (OCH2Ph), 127.4,
127.9, 128.4, 128.5, 128.6, 137.9, 138.5 (2 C6H5)
–
–
50.6 (NCH2Ph), 74.7 (OCH2Ph), 127.4, 127.5, 127.9, 128.1,
128.3, 128.6, 128.7, 137.6, 138.4, 140.6 (3 C6H5)
50.7 (NCH2Ph), 74.5 (OCH2Ph), 125.1, 126.0, 126.3, 144.6
(C4H3S), 127.5, 128.0, 128.1, 128.4, 128.6, 128.7, 137.6,
138.3 (2 C6H5)
6g
60.8
61.7
71.2
71.7
82.3
79.3
60.0
56.5
137.6
34.5
50.4 (NCH2Ph), 74.4 (OCH2Ph), 118.0 (C-6), 127.3, 127.9,
128.4, 128.5, 137.8, 138.5 (2 C6H5)
6hb
50.6 (NCH2Ph), 73.7 (OCH2Ph), 117.9 (C-7), 127.4, 127.8,
128.3, 128.4, 128.5, 128.6, 137.9, 138.5 (2 C6H5), 135.2
(d, C-6)
7hc
6i
63.8
61.9
71.7
71.5
78.6
79.2
56.9
58.4
34.7
36.1
51.9 (NCH2Ph), 72.1 (OCH2Ph), 119.0 (t, C-7), 127.4, 130.0,
137.6, 138.9 (2 C6H5), 133.8 (d, C-6)
50.9 (NCH2Ph), 73.7 (OCH2Ph), 126.5, 127.5, 127.9, 128.0,
128.5, 128.7, 128.7, 129.0, 129.2, 138.0, 138.3, 138.8
(3 C6H5)
6k
61.9
71.6
78.9
58.6
35.1
50.8 (NCH2Ph), 55.1 (OCH3), 73.6 (OCH2Ph), 127.4, 127.8,
127.8, 128.4, 128.6, 129.8, 138.0, 138.3 (2 C6H5), 114.1,
130.6, 158.1 (C6H4OMe)
a Recorded in CDCl3 at 62.9 MHz. (6a-f, 6k) or at 75.5 MHz (6g, 6h/7h, 6i).
b Major isomer 6h of the 83:17 mixture.
c Minor isomer 7h of the 83:17 mixture, signals in part not identified due to overlap with respective signal of 6h.
In order to obtain the free iminopolyols, several of the hydroxide on charcoal as catalyst. The 2-alkyl- or 2-aryl-
N,3-O-dibenzyldihydroxypyrrolidines 8 were deprotected substituted trans-dihydroxypyrrolidines 9 were obtained
by hydrogenation at 4 bar using palladium or palladium in almost quantitative yield in (95–99%), in the form of
the hydrochloride or -bromide. The hydrogenation of the
anisylmethyl derivative 8k afforded the known (+)-
deacetylanisomycin 9k as its hydrobromide, whose spec-
tral data in all respects were identical to those reported for
the corresponding hydrochloride.6a,7c,29 Thus, deacetylani-
somycin 9k was obtained in somewhat improved yield as
compared to our preliminary report,1a i.e. in 7 steps/39%
overall yield from commercially available 2-O-
benzylthreitol30 [9 steps/28% total yield from (+)-diethyl
L-tartrate]. The 1H and 13C NMR data of dihydroxypyrro-
lidines 8 and 9 are summarized in Tables 5 and 6.
Table 4 Hydroxypyrrolidines 8 and 9 from Cyclization of Amino-
triols 6 and Catalytic N,O-Debenzylation, Respectively
Entry
R
Methoda Product Yieldb Product Yield
8
[%]b 9 (X)
[%]c
1
2
3
4
5
6
7
8
Me
Bu
t-Bu
CH2SiMe3
Ph
Vinyl
CH2Ph
CH2An
A
A
A
A
A
B
A
A
8a
8b
8c
8d
8e
8g
8i
62
76
84
74
82
63
79
77
9b (Cl)
9c (Br)
9d (Cl)
95
96
96
The synthesis of anisomycin 1 was attempted next, in
view of elaborating a shorter completing sequence from
9k, for which, so far, 4 to 5 steps had been required.6c,8c In
order to solve this problem of regioselective O-acetylation
of the (more hindered) 3-OH group in 9k, enzymatic ap-
9i (Br)
9k (Br)
95
99
8k
a Method of cyclization., A. Mitsunobu, B. Appel, see text.
b After chromatography on silica.
c After crystallization.
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Stereoselective Synthesis and Biological Evaluation of Anisomycin and 2-Substituted Analogues
1477
proaches were studied. The acetylation of 9k with isopro- with palladium hydroxide on charcoal serving as catalyst
penyl acetate and Pseudomonas cepacia as a catalyst18c,31 in the presence of Boc2O (1.5 eq)18a,32 afforded the silylat-
proceeded rather slowly, and, after 6 d, led to a mixture of ed N-Boc derivatives 12 and 13 in 86 and 85% yield, re-
starting, mono-, and di-O-acetylated material (9k/1/23). spectively. Acetylation with acetic anhydride in pyridine
Likewise, selective hydrolysis of the less hindered 4-ace- with a catalytic amount of DMAP at room temperature
toxy group from 4-O-acetylanisomycin 23 by means of gave pyrrolidines 14 and 15 in 97 and 94%. After removal
Chromobacterium viscosum18c,31 failed, producing similar of TBS and Boc groups at 0 °C with anhydrous 6 M HCl
mixtures only. Advantage was then taken of the fact that in dioxane with 1.1 eq of water added at the end (after
differentiation of 3-OH vs. 4-OH was already at hand with some experimentation), anisomycin 1 and demethoxyani-
the 3-O-benzyl derivatives 8. Thus, from 8i and 8k the tar- somycin 18 were isolated almost quantitatively as hydro-
get compound anisomycin 1 as well as demethoxyaniso- chloride salts. The 3-O-benzoyl analogues 19 and 20 were
mycin 18 and the 3-O-benzoyl derivatives 19 and 20 were prepared in a similar way, by reaction of 12 and 13, re-
secured in four steps (Scheme 3).
spectively, with benzoyl chloride and subsequent depro-
tection with HCl-dioxane.
Finally, 4-O-acetylanisomycin 23, one of the substrates
for attempted enzyme-catalyzed hydrolysis (vide supra)
and also of interest for screening assays, was obtained in
three steps starting from the 2-anisylmethylpyrrolidine 8k
(Scheme 4), using the same principle: Catalytic hydroge-
nation of 8k in the presence of Boc2O (vide infra) gave
78% of the N-Boc derivative 21 with a free diol function.
After peracetylation with Ac2O in pyridine (91%) and
quantitative cleavage of the Boc group with anhydrous
HCl in dioxane (6 M), 4-O-acetylanisomycin hydrochlo-
ride (23∑HCl) was isolated in analytically pure form. Ta-
bles 7 and 8 show the 1H and 13C NMR spectroscopic data
of the dihydroxypyrrolidines 1 and 10–23.
Scheme 4
To our knowledge, the above approach offers superior6-11
access to anisomycin 1 (8 steps from 2 with 44% and 12
steps from diethyl L-tartrate with 23% overall yield) and a
wide range of 2- and 3-O-substituted analogues. Also, the
route to deacetylanisomycin 9k is improved (54% from 2)
which may be important for the preparation of non-differ-
entiated, 3-O- and 4-O-substituted derivatives12b in view
of potential anti-tumour activity (vide infra).
Scheme 3
Silylation of 8i and 8k with tert-butyldimethylsilyl chlo-
ride (TBSCl, 1.5 eq) under standard conditions gave the
silyl ethers 10 and 11 in 94 and 98% yield, respectively.
Subsequent debenzylation at 4 bar hydrogen pressure
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1478
O. Schwardt et al.
PAPER
considerable activity. It is important to note here that this
derivative synthetically is much better available than ani-
somycin itself because the two hydroxy groups need not
In Vitro Cytotoxicity of Anisomycin 1 and Some De-
rivatives
Some of the dihydroxypyrrolidines prepared, as well as be differentiated. Deacetylation of the 3-O-Ac function in
four relatives C–F with other configurations (Figure 2) 1, i.e. with deacetylanisomycin (9k), results in strong re-
which had been obtained in our group either by addition duction of activity, and the additional demethoxylation of
of Grignard reagents to imines of 2,4-O-ethylidene-D- the aromatic ring (with 9i) causes complete loss thereof.
erythrose (C and D)18c or via nitroaldol addition (E and The 3-O-benzoyl derivative 20 and, interestingly, the two
F),33 were tested with respect to in vitro-cytotoxic activity N,O-dibenzyl compounds 8i and 8k also showed approx-
against human cell lines KB, HBL 100 RAS A, and HBL imately the same effect as deacetylanisomycin 9k, with
100 (as reference, non-tumour cell line). For comparison IC50 values in the micromolar range. The 3-O-benzoyl-
the reported values of anisomycin 17 are cited: LU99 demethoxy derivative 19, all compounds with a 2-alkyl
IC50 = 0.082 µM,12a MCF7 0.074 µM,12a FM3A 0.066 side-chain, and the samples of C–F with differing con-
µM12b).
figuration turned out to be wholly inactive.
Concerning the requirements for high cytotoxic activity of
this class of compounds, the following conclusions may
be drawn: (i) activity is found only with D-xylo com-
pounds, i.e. the configuration of natural (–)-anisomycin 1;
(ii) the presence of the p-methoxy group is beneficial (fac-
tor 1.6 to 40); (iii) other substituents on the (indispens-
able) aromatic ring might be even more favourable; (iv) a
(small) 3-O-acyl group is essential (cf. ref.12); (v) addi-
tional 4-O-substituents may be tolerated (with 4-O-Ac de-
crease of activity by a factor of 4 to 10 only).
Solvents were purified and dried according to standard procedures.
MeLi (1.6 M in Et2O), BuLi (1.6 M in hexane), t-BuLi (1.6 M in
pentane), diethyl azodicarboxylate (DEAD, Merck), trimethylsilyl-
methyllithium (1.0 M in pentane), phenyllithium (2.0 M in benzene/
Et2O 7:3), vinylmagnesium bromide (1.0 M in THF), allylmagne-
sium bromide (2.0 M in Et2O), thiophene (Aldrich), benzyl bro-
mide, p-methoxybenzyl chloride, Boc2O, and PPh3 (Fluka) were
purchased and used without further purification. 2-O-Benzyl-3,4-
O-isopropylidene-L-threose 2 was prepared in four steps from
diethyl L-tartrate according to ref.14,19,20 (50% overall yield);
Figure 2
Table 9 In vitro-Cytotoxicity of Anisomycin 1 and Analogues
Com- R1
pound
R2
R3
IC50 [mM]
KBa
HBL 100 RAS Ab HBL 100c
8k
8i
9i
9k
18
1
19
20
23
C
H
OMe
H
OMe
H
14
20
51
45
79
55
[a]20D +34.6 (c = 1.51, CHCl3). TLC was performed on silica F254
-
d
d
d
H
H
Ac
H
H
H
H
H
H
Ac
–
–
–
coated aluminium sheets (E. Merck) using mixtures of EtOAc/pe-
troleum ether (bp 30–75 °C), with detection by UV at 254 nm or by
heating with a solution of cerium(IV) sulfate (1 g), ammonium mo-
lybdate (2.1 g), and concd H2SO4 (31 mL) in H2O (500 mL).34
Products were purified by chromatography on silica (Merck, 32–
63 µm). Mps were determined on a Fisher-Johns apparatus and are
uncorrected. The optical rotations were measured on a Perkin-Elm-
er 241 MC polarimeter using the Drude method to calculate [a]D
from the values found at 546 and 579 nm. IR spectra were recorded
on a Bruker IFS 28 spectrometer. NMR spectra were obtained from
Bruker AC 250, ABX 300, and ABX 500 spectrometers (1H: 250.1,
300.1, or 500.1 MHz; 13C: 62.9, 75.5, or 125.8 MHz) with TMS as
internal standard; evaluation of 1H NMR spectra according to 1st or-
der interpretation; multiplicity of 13C NMR signals from broad band
decoupled or DEPT spectra. The in vitro-cytotoxicity tests were
carried out at the Institut de Chimie des Substances Naturelles
(ICSN-CNRS) in Gif-sur-Yvette (Essonne, France).
19
50
0.094
29
0.40
0.01
0.079
0.05
OMe Ac
Bz
OMe Bz
OMe Ac
H
0.05
d
d
d
H
–
–
–
24
9
0.3
18
0.1
0.2
d
d
d
d
d
d
d
d
d
–
–
–
–
–
–
–
–
–
d
d
d
D
E
F
OMe
–
–
–
H
Bn
a Human epidermoid carcinoma.
b Human mammary cell line converted to a tumorigenic phenotype.
c Human mammary cell line.
d No inhibition at 100 mM.
As seen from Table 9, with the three new cell lines the re-
sults for anisomycin 1 itself again show IC50 values in the
nanomolar range. Omission of the methoxy group of the
aromatic ring of 1, see compound 18, causes only a slight
decrease of cytotoxicity against HBL 100 cells, but reduc-
es activity towards KB cells by a factor of 40. Acetylation
of the second hydroxy function, as seen with 4-O-acety-
lanisomycin 23, leads to somewhat lower (1/10), yet still
(2S,3S)-N,2-O-Dibenzyl-3,4-O-isopropylidene-L-threose imine
(3)
According to lit.21 L-threose 2 (2.08 g, 8.31 mmol), Al2O3 (neutral,
type 90/activity I; 63–200 µm; 1.83 g, 18.0 mmol), benzylamine
(890 mg, 8.31 mmol), and CH2Cl2 (0.5 mL) were stirred at r. t. for
1 h. To the mixture was added CH2Cl2 (10 mL) and stirring was
continued for 10 min. The suspension was filtered, the residue
washed with CH2Cl2 (2 ¥ 5 mL), and the filtrate was dried
Synthesis 1999, No. SI, 1473–1490 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Stereoselective Synthesis and Biological Evaluation of Anisomycin and 2-Substituted Analogues
1479
(MgSO4). Removal of the solvent in vacuo (1 mbar) gave the imine
3 as an analytically pure, colourless oil; yield 2.82 g (quant); [a]D
+31.1 (c = 1.50, CHCl3).
(2S,3S,4R)-4-(Benzylamino)-3-(benzyloxy)-5,5-dimethylhex-
ane-1,2-diol (6c)
20
According to the Typical Procedure A; imine 3 (1.31 g, 3.85 mmol),
Et2O (5 mL), t-BuLi (1.6 M in pentane, 7.2 mL, 11.5 mmol), Et2O
(10 mL), 15 min at –78 °C. After workup, the crude amino alcohol
4c was obtained as a yellow oil (1.38 g, dr >95:5 from 13C NMR).
The crude product was dissolved in MeOH (25 mL), then concd
HCl (0.5 mL) was added and the mixture stirred for 2 d at r. t.
Workup analogous to the Typical Procedure A afforded a brown
crude product (1.30 g) which was purified by flash chromatography
(silica gel, 30 g, column 3.5 cm ¥ 9 cm, petroleum ether/EtOAc
1:1 + 1% Et3N) to furnish 6c (6c/7c >95:5 from 13C NMR) as an
IR (film): n = 3078, 3057, 3023, 2981, 2932, 2878, 1662 (C=N),
1596, 1490, 1449, 1377, 1368, 1258, 1213, 1156, 1070, 1030, 908,
851, 740, 702 cm-1.
1H NMR (CDCl3, 250.1 MHz): d = 1.36, 1.39 [2 s, 6 H, C(CH3)2],
3
2
3.91 (dd, J3,4a = 6.5, J4a,4b = 8.7 Hz, 1 H, 4-Ha), 3.99 (dd,
3J3,4b = 6.5, J4a,4b = 8.7 Hz, 1 H, 4-Hb), 4.02 (dd, J1,2 = 5.6,
3J2,3 = 6.0 Hz, 1 H, 2-H), 4.35 (m, 1 H, 3-H), 4.61 (s, 2 H, NCH2Ph),
4.61, 4.70 (A, B of AB, 2J = 12.1 Hz, 2 H, OCHAHBPh), 7.22–7.43
(m, 10 H, 2 C6H5), 7.72 (dt, 3J1,2 = 5.6, 4J1,3 = 1.4 Hz, 1 H, 1-H).
2
3
21
analytically pure, colourless oil; yield 966 mg (70%); [a]D +26
13C NMR (CDCl3, 62.9 MHz): d = 25.2, 26.3 [2 q, C(CH3)2], 64.6
(t, C-4), 65.5 (t, NCH2Ph), 71.9 (t, OCH2Ph), 76.5 (d, C-3), 80.7 (d,
C-2), 109.6 [s, C(CH3)2], 127.0, 127.7, 127.9, 128.0, 128.3, 128.4 (6
d; o-, m-, p-C of 2 C6H5), 137.8, 138.5 (2 s, i-C of 2 C6H5), 160.9 (d,
C-1).
(c = 0.54, CHCl3).
IR (film): n = 3360 (OH; NH), 3087, 3063, 3030, 2953, 2905, 2869,
1658, 1604, 1494, 1454, 1394, 1363, 1211, 1071, 1031, 912, 869,
734, 699 cm-1.
C22H31NO3
(357.5)
calc.
C 73.92
H 8.74
H 8.86
N 3.92
N 3.91
C21H25NO3
(339.4)
calc.
C 74.31
H 7.42
H 7.65
N 4.13
N 4.07
found C 73.85
found C 74.08
(2S,3S,4S)-4-(Benzylamino)-3-(benzyloxy)-5-(trimethylsi-
lyl)pentane-1,2-diol (6d)
(2S,3S,4R)-4-(Benzylamino)-3-(benzyloxy)pentane-1,2-diol
(6a); Typical Procedure A
According to the Typical Procedure A; imine 3 (1.50 g, 4.42 mmol),
Et2O (5 mL), trimethylsilylmethyllithium (1.0 M in pentane,
13.3 mL, 13.3 mmol), Et2O (10 mL), 15 min at –78 °C. After work-
up, the crude amino alcohol 4d was obtained as a yellow oil (1.89 g,
dr >95:5 from 13C NMR). Treatment of the crude product as above
with dioxane/H2O (1:1, 30 mL)/concd HCl (0.5 mL) afforded a
brown oil (1.51 g) which was purified by flash chromatography
(silica, 31 g, column 3.5 cm ¥ 9 cm, petroleum ether/EtOAc 1:1
+ 1% Et3N) to give analytically pure 6d (6d/7d >95:5 from 13C
NMR) as a pale yellow oil; yield 1.15 g (67%); [a]D –9.40
(c = 1.57, CHCl3).
To a mixture of MeLi (1.6 M in Et2O, 4.2 mL, 6.7 mmol) and anhyd
Et2O (10 mL) at –78 °C under N2 was slowly (10 min) added a so-
lution of the imine 3 (759 mg, 2.24 mmol) in anhyd Et2O (5 mL).
The reddish mixture was stirred at –78 °C for 15 min and then
quenched at this temperature with sat. aq NH4Cl (10 mL). After
warming to r. t., the mixture was extracted with Et2O (3 ¥ 40 mL),
washed with sat. aq NaHCO3 (40 mL), dried (Na2SO4), filtered, and
evaporated in vacuo (20 mbar) to furnish the acetonide-protected
amino alcohols 4a/5a as a yellow oil (693 mg, dr 89:11 from 13C
NMR). The crude product was dissolved in dioxane/H2O (1:1,
20 mL), then concd HCl (0.5 mL) was added and the mixture stirred
for 16 h at 50 °C. After removal of the solvent under reduced pres-
sure, the residue was suspended in sat. aq NaHCO3 (20 mL), ex-
tracted with EtOAc (4 ¥ 40 mL), and the solutes were dried
(Na2SO4). Concentration in vacuo (20 mbar) afforded a brown
crude product (561 mg) which was purified by flash chromatogra-
phy (silica gel, 21 g, column 3.5 cm ¥ 6 cm, petroleum ether/EtOAc
1:1 + 1% Et3N) to give 6a (6a/7a >95:5 from 13C NMR) as an ana-
lytically pure, pale-yellow oil; 350 mg (52%); [a]D20–16 (c = 0.52,
CHCl3).
IR (film): n = 3656, 3321 (OH, NH), 3087, 3063, 3030, 2950, 2891,
1604, 1496, 1453, 1435, 1360, 1305, 1248, 1208, 1154, 1069, 1032,
985, 910, 858, 843, 735, 699 cm-1.
C22H33NO3Si calc.
(387.6) found
C 68.18
C 68.02
H 8.58
H 8.65
N 3.61
N 3.51
(2S,3S,4R)-4-(Benzylamino)-3-(benzyloxy)-4-phenylbutane-
1,2-diol (6e)
According to the Typical Procedure A; imine 3 (500 mg,
1.47 mmol), Et2O (5 mL), PhLi (2.0 M in benzene/Et2O 7:3, 2.2 ml,
4.4 mmol), Et2O (10 mL), 15 min at –78 °C. After workup, the
crude amino alcohol 4e was obtained as a yellow oil (542 mg, dr
>95:5 from 13C NMR). The crude product was dissolved in MeOH
(20 mL), then concd HCl (0.5 mL) was added and the mixture
stirred for 4 d at r. t. Workup analogous to the Typical Procedure A
afforded a brown oil (527 mg) which was purified by flash chroma-
tography (silica, 22 g, column 3.5 cm ¥ 8 cm, petroleum ether/
EtOAc 1:1 + 1% Et3N) to give analytically pure 6e (6e/7e >95:5
from 13C NMR) as a pale yellow solid; yield 362 mg (66%); mp 89–
91 °C; [a]D20 –74.1 (c = 1.00, CHCl3).
IR (film): n = 3317 (OH, NH), 3062, 3029, 2924, 1655, 1495, 1453,
1373, 1260, 1208, 1068, 1027, 788, 735, 698 cm-1.
C19H25NO3
(315.4)
calc.
C 72.35
H 7.99
H 8.13
N 4.44
N 4.54
found C 72.20
(2S,3S,4R)-4-(Benzylamino)-3-(benzyloxy)octane-1,2-diol (6b)
According to the Typical Procedure A; imine 3 (1.12 g, 3.30 mmol),
Et2O (5 mL), BuLi (1.6 M in hexane, 6.2 mL, 9.9 mmol), Et2O
(10 mL), 15 min at –78 °C. After workup, the protected amino alco-
hol 4b was obtained as a yellow oil (1.22 g, dr >95:5 from 13C
NMR). Treatment of the crude product with dioxane/H2O (1:1,
20 mL)/concd HCl (0.5 mL) as above afforded a brown oil (1.04 g)
which was purified by flash chromatography (silica gel, 40 g, col-
umn 3 cm ¥ 12 cm, petroleum ether/EtOAc 1:1+1% Et3N) to give
analytically pure 6b (6b/7b >95:5 from 13C NMR) as a pale yellow
oil; yield 699 mg (59%); [a]D20 –23.0 (c = 1.47, CHCl3).
IR (film/CH2Cl2): n = 3480, 3330 (OH; NH), 3062, 3029, 2922,
1603, 1495, 1453, 1399, 1353, 1261, 1210, 1066, 1028, 911, 874,
750, 699 cm-1.
C24H27NO3
(377.5)
calc.
C 76.36
C 76.12
H 7.21
H 7.20
N 3.71
N 3.63
found
IR (film): n = 3322 (OH, NH), 3062, 3029, 2927, 2858, 1604, 1495,
1453, 1209, 1069, 1028, 813, 800, 736, 698 cm-1.
C22H31NO3
(357.5)
calc.
C 73.92
H 8.74
H 8.91
N 3.92
N 3.81
found C 73.66
Synthesis 1999, No. SI, 1473–1490 ISSN 0039-7881 © Thieme Stuttgart · New York

1480
O. Schwardt et al.
PAPER
(2S,3S,4S)-4-(Benzylamino)-3-(benzyloxy)-4-(thien-2-yl)bu-
tane-1,2-diol (6f)
IR (film): n = 3380 (OH, NH), 3063, 3028, 2917, 2865, 1638, 1604,
1496, 1453, 1399, 1353, 1209, 1072, 1028, 1000, 915, 801, 737,
699 cm-1.
2-Thienyllithium was prepared according to lit.35 To a solution of
thiophene (283 µL, 3.54 mmol) in anhyd Et2O (5 mL) under N2 was
added (5 min) BuLi (1.6 M in hexane, 2.2 mL, 3.5 mmol). After 1 h
at –20 °C and 15 min at r. t. the yellow mixture was cooled to
–70 °C. A solution of the imine 3 (300 mg, 0.884 mmol) in anhyd
Et2O (3 mL) was slowly added (10 min). The reddish mixture was
stirred at –70 °C for 1 h and then quenched with sat. aq NH4Cl
(10 mL). Workup according to the Typical Procedure A furnished
the protected aminotriol 4f as a brown oil (343 mg, dr >95:5 from
13C NMR). The crude product was dissolved in MeOH (10 mL),
then concd HCl (0.2 mL) was added and the mixture stirred for 2 d
at r. t. Workup analogous to the Typical Procedure A afforded a
brown crude product (309 mg) which was purified by flash chroma-
tography (silica gel, 15 g, column 2.5 cm ¥ 8 cm, petroleum ether/
EtOAc 1:1 + 1% Et3N) to give analytically pure 6f (6f/7f >95:5
from 13C NMR) as a pale yellow solid; yield 123 mg (37%); mp 69–
70 °C; [a]D20 –62.5 (c = 1.42, CHCl3).
C21H27NO3
(341.5)
calc.
C 73.87 H 7.97
N 4.10
N 4.09
6h/7h
found C 73.54 H 8.16
(83:17)
(2S,3S,4R)-4-(Benzylamino)-3-(benzyloxy)-5-phenylpentane-
1,2-diol (6i)
Under N2 a solution of benzyl bromide (1.39 mL, 11.5 mmol) in an-
hyd Et2O (11 mL) was added dropwise to a vigorously stirred sus-
pension of magnesium turnings (288 mg, 11.8 mmol) in anhyd Et2O
(4 mL). The mixture was then refluxed for 15 min. A solution of the
imine 3 (1.35 g, 3.83 mmol) in anhyd Et2O (8 mL) was slowly (15
min) added at 0 °C. The yellow mixture was stirred at r. t. for 3 h
and then quenched at 0 °C with sat. aq NH4Cl (20 mL). Workup
analogous to the Typical Procedure A furnished the protected ami-
notriol 4i as a yellow oil (1.83 g, dr >95:5 from 13C NMR). Treat-
ment of the crude product with dioxane/H2O (1:1, 20 mL)/concd
HCl (0.5 mL) according to the Typical Procedure A afforded a
brown oil (1.47 g) which was purified by flash chromatography
(silica gel, 50 g, column 3 cm ¥ 14 cm, petroleum ether/EtOAc 1:1
+ 1% Et3N) to give analytically pure 6i (6i/7i >95:5 from 13C NMR)
IR (film/CH2Cl2): n = 3331 (OH; NH), 3063, 3029, 2961, 2918,
2850, 1604, 1496, 1453, 1353, 1261, 1208, 1066, 1027, 800, 733,
698 cm-1.
C22H25NO3S
(383.5)
calc.
C 68.90
C 68.96
H 6.57
H 6.67
N 3.65
N 3.61
20
found
as a pale yellow oil; yield 1.17 g (78%); [a]D –37.3 (c = 1.15,
CHCl3).
(2S,3S,4R)-4-(Benzylamino)-3-(benzyloxy)hex-5-ene-1,2-diol
(6g)
IR (film): n = 3320 (OH, NH), 3085, 3062, 3027, 2864, 1603, 1495,
1453, 1396, 1351, 1260, 1207, 1177, 1155, 1071, 1029, 912, 802,
735, 698 cm-1.
To vinylmagnesium bromide (1.0 M in THF, 8.5 mL, 8.5 mmol)
under N2 at 0 °C a solution of the imine 3 (1.45 g, 4.27 mmol) in an-
hyd Et2O (11 mL) was slowly (15 min) added. The yellow mixture
was stirred at r. t. for 5 h and then quenched at 0 °C with sat. aq
NH4Cl (20 mL). Workup analogous to the Typical Procedure A fur-
nished the amino alcohol 4g as a yellow oil (1.51 g, dr >95:5 from
13C NMR). The crude product was dissolved in MeOH (20 mL),
then concd HCl (0.5 mL) was added and the mixture stirred for 18 h
at r. t. Workup analogous to the Typical Procedure A afforded a
brown crude product (1.33 g) which was purified by flash chroma-
tography (silica gel, 45 g, column 3.5 cm ¥ 10 cm, petroleum ether/
C25H29NO3
(391.5)
calc.
C 76.70
C 76.70
H 7.47
H 7.47
N 3.58
N 3.50
found
(2S,3S,4R)-4-(Benzylamino)-3-(benzyloxy)-5-(4-methoxyphe-
nyl)pentane-1,2-diol (6k)
Under N2 magnesium turnings (17.4 g, 711 mmol) were suspended
in anhyd Et2O (20 mL), then 0.5 mL (0.58 g, 3.7 mmol) of 4-meth-
oxybenzyl chloride and a few grains of iodine were added. The mix-
ture was stirred vigorously and heated to reflux until the reaction
started. The rest of 4-methoxybenzyl chloride (3.86 g, 24.7 mmol)
in anhyd Et2O (12 mL) was added dropwise under vigorous stirring.
The mixture was refluxed for 15 min, then at 0 °C a solution of the
imine 3 (1.93 g, 5.68 mmol) in anhyd Et2O (5 mL) was slowly
(10 min) added. The yellow mixture was stirred at r. t. for 3 h and
quenched at 0 °C with sat. aq NH4Cl (20 mL). Workup analogous
to the Typical Procedure A furnished the impure amino alcohol 4k
as a yellow oil (4.78 g, dr >95:5 from 13C NMR). Treatment of the
crude product with dioxane/H2O (1:1, 30 mL)/concd HCl (0.5 mL)
according to the Typical Procedure A afforded a brown oil (3.94 g)
which was purified by flash chromatography (silica gel, 60 g, col-
umn 3 cm ¥ 15 cm, petroleum ether/EtOAc 1:1 + 1% Et3N) to fur-
nish 6k (6k/7k >95:5 from 13C NMR) as an analytically pure, pale
yellow oil; yield 1.70 g (71%); [a]D20 –39.8 (c = 1.39, CHCl3).
EtOAc 1:1 + 1% Et3N) to give analytically pure 6g (6g/7g >95:5
from 13C NMR) as a pale yellow oil; yield 901 mg (65%); [a]D
10.4 (c = 1.43, CHCl3).
–
20
IR (film): n = 3386 (OH, NH), 3063, 3028, 2867, 1639, 1605, 1586,
1496, 1453, 1352, 1210, 1066, 1028, 1000, 869, 825, 804, 734, 698
cm-1.
C20H25NO3
(327.4)
calc.
C 73.37
C 73.07
H 7.70
H 7.83
N 4.28
N 4.24
found
(2S,3S,4R)-4-(Benzylamino)-3-(benzyloxy)hept-6-ene-1,2-diol
(6h/7h)
To allylmagnesium bromide (1.0 M in Et2O, 4.6 mL, 4.6 mmol) un-
der N2 at 0 °C a solution of the imine 3 (780 mg, 2.30 mmol) in Et2O
(4 mL) was slowly (15 min) added. The yellow mixture was stirred
at r. t. for 4 h and then quenched at 0 °C with sat. aq NH4Cl
(20 mL). Workup as described in the Typical Procedure A furnished
the protected amino alcohols 4h/5h as a yellow oil (998 mg, dr
85:15 from 13C NMR). The crude product was dissolved in MeOH
(20 mL), then concd HCl (0.5 mL) was added, and the mixture was
stirred for 21 h at r. t. Workup analogous to the Typical Procedure
A afforded a light brown crude product (794 mg) which was puri-
fied by flash chromatography (silica gel, 35 g, column
3 cm ¥ 10 cm, petroleum ether/EtOAc 1:1 + 1% Et3N) to give a
mixture of 6h/7h (83:17 from 13C NMR) as an analytically pure,
IR (film): n = 3320 (OH, NH), 3062, 3029, 3004, 2926, 1611, 1512,
1496, 1453, 1397, 1352, 1301, 1246, 1209, 1178, 1070, 1030, 922,
736, 698 cm-1.
C26H31NO4
(421.5)
calc.
C 74.08
C 74.08
H 7.41
H 7.43
N 3.32
N 3.16
found
(2R,3S,4S)-1-Benzyl-3-(benzyloxy)-4-hydroxy-2-methylpyrroli-
dine (8a); Typical Procedure B (Mitsunobu Cyclization)
According to lit.27b diethyl azodicarboxylate (DEAD; 75 µL,
58 mg, 0.48 mmol) at 0 °C under N2 was added slowly to a solution
of the aminotriol 6a (126 mg, 0.400 mmol) and PPh3 (126 mg,
20
pale yellow oil; yield 590 mg (75%); [a]D –13.2 (c = 1.50,
CHCl3).
Synthesis 1999, No. SI, 1473–1490 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Stereoselective Synthesis and Biological Evaluation of Anisomycin and 2-Substituted Analogues
1481
0.480 mmol) in anhyd pyridine (2.2 mL). The mixture was stirred at
0 °C for 90 min and then quenched with ice-water (10 mL). The
aqueous layer was extracted with CH2Cl2 (4 ¥ 30 mL) and the com-
bined solutes were evaporated (20 mbar) to leave a yellow oil. The
crude product was dissolved in dioxane/H2O (1:1, 5 mL) and LiOH
monohydrate (168 mg, 4.00 mmol) was added (for destruction of
the byproduct diethyl hydrazinedicarboxylate). The mixture was
stirred at 80 °C for 20 h and then extracted with Et2O (4 ¥ 30 mL).
The combined ether layers were dried (Na2SO4), filtered, and evap-
orated in vacuo. The yellowish residue was purified by flash chro-
matography (silica gel, 12 g, column 2 cm ¥ 8 cm, petroleum ether/
Et2O 3:7) to obtain spectroscopically pure 8a as a colourless oil;
yield 74 mg (62%); [a]D20 –42.5 (c = 1.53, CHCl3).
heptane/Et2O; 8d, analytically pure, colourless needles; yield
212 mg (74%); mp 121–122 °C; [a]D20 –96.4 (c = 1.50, CHCl3).
IR (CCl4): n = 3066 (OH), 3032, 2953, 2791, 1654, 1545 (CCl4),
1511, 1497, 1459, 1249, 1216, 1115, 1070, 1006, 979, 861, 783
(CCl4), 699 cm-1.
C22H31NO2Si calc.
(369.6) found
C 71.50
C 71.70
H 8.45
H 8.55
N 3.79
N 3.75
(2S,3S,4R)-1-Benzyl-3-(benzyloxy)-4-hydroxy-2-phenylpyrroli-
dine (8e)
According to the Typical Procedure B; aminotriol 6e (225 mg,
0.596 mmol), PPh3 (188 mg, 0.715 mmol), DEAD (112 µL,
81.7 mg, 0.715 mmol), pyridine (3.3 mL), 90 min at 0 °C. After
workup treatment of the residue with dioxane/H2O (1:1, 6 mL)/
LiOH∑H2O (250 mg, 5.96 mmol) as above. Flash chromatography
(silica gel, 13 g, column 2 cm ¥ 9 cm, petroleum ether/ether 3:7)
furnished a colourless solid; after crystallization from heptane/Et2O
8e, analytically pure, colourless needles; yield 175 mg (82%); mp
82 °C; [a]D20 +37 (c = 0.90, CHCl3).
IR (film): n = 3385 (OH), 3062, 3029, 2965, 2925, 1603, 1495,
1452, 1376, 1347, 1260, 1208, 1126, 1069, 1028, 911, 798, 736,
698 cm-1.
C19H23NO2
(297.4)
calc.
C 76.74
C 76.11
H 7.79
H 7.95
N 4.71
N 4.73
found
(2R,3S,4S)-1-Benzyl-3-(benzyloxy)-2-butyl-4-hydroxypyrroli-
dine (8b)
IR (film/CH2Cl2): n = 3420 (OH), 3086, 3063, 3029, 2922, 2793,
1640, 1603, 1494, 1453, 1373, 1348, 1208, 1156, 1100, 1072, 1028,
920, 787, 759, 699 cm-1.
According to the Typical Procedure B; aminotriol 6b (190 mg,
0.532 mmol), PPh3 (167 mg, 0.638 mmol), DEAD (99 µL, 72 mg,
0.64 mmol), pyridine (3.0 mL), 90 min at 0 °C. After workup treat-
ment of the residue with dioxane/H2O (1:1, 6 mL)/LiOH∑H2O
(223 mg, 5.32 mmol) as above. Flash chromatography (silica gel,
15 g, column 2 cm ¥ 11 cm, petroleum ether/ ether 3:7) furnished a
colourless solid; after crystallization from heptane/Et2O 8b, analyt-
ically pure, colourless needles; yield 137 mg (76%) mp 68–69 °C;
[a]D20 –103 (c = 0.76, CHCl3).
C24H25NO2
(359.5)
calc.
C 80.19
C 80.24
H 7.01
H 6.93
N 3.90
N 3.88
found
(2R,3S,4S)-1-Benzyl-3-(benzyloxy)-4-hydroxy-2-vinylpyrroli-
dine (8g) by Appel Cyclization
According to lit.28b to a solution of the aminotriol 6g (500 mg,
1.53 mmol) in anhyd DMF (5.3 ml) under N2 in the dark was added
PPh3 (797 mg, 3.05 mmol), CCl4 (294 µl, 3.05 mmol), and Et3N
(413 µl, 3.00 mmol). The mixture was stirred in the dark for 5 h at
r. t., then MeOH (5 mL) was added and stirring continued for
30 min. The solvents were removed (20 mbar, 40 °C) and the brown
residue was purified by flash chromatography (silica gel, 20 g, col-
umn 2 cm ¥ 12 cm, petroleum ether/Et2O 3:7) to give 8g as an ana-
IR (CCl4): n = 3620 (OH), 3087, 3065, 3031, 2957, 2929, 2860,
2793, 1571, 1559 (CCl4), 1548, 1496, 1454, 1342, 1252, 1207,
1115, 1070, 1028, 1007, 911, 807 (CCl4), 699 cm-1.
C22H29NO2
(339.5)
calc.
C 77.84
C 77.72
H 8.61
H 8.67
N 4.13
N 4.10
found
20
lytically pure, pale yellow oil; yield 300 mg (63%); [a]D –42
(2R,3S,4S)-1-Benzyl-3-(benzyloxy)-2-tert-butyl-4-hydroxy-
pyrrolidine (8c)
(c = 0.50, CHCl3).
IR (film): n = 3405 (OH), 3063, 3029, 2978, 2919, 2796, 1743,
1640, 1604, 1586, 1495, 1453, 1423, 1370, 1349, 1314, 1209, 1111,
1071, 1029, 995, 924, 852, 774, 735, 697 cm-1.
According to the Typical Procedure B; aminotriol 6c (420 mg, 1.17
mmol), PPh3 (371 mg, 1.41 mmol), DEAD (221 µL, 161 mg, 1.41
mmol), pyridine (6.5 mL), 90 min at 0 °C. After workup treatment
of the residue with dioxane/H2O (1:1, 10 mL)/LiOH∑H2O (491 mg,
11.7 mmol) as above. Flash chromatography (silica gel, 16 g, col-
umn 2 cm ¥ 12 cm, petroleum ether/Et2O 3:7) furnished 8c; analyt-
ically pure, colourless oil; yield 336 mg (84%); [a]D20 –18 (c = 0.77,
CHCl3).
C20H23NO2
(309.4)
calc.
C 77.64
C 77.75
H 7.49
H 7.52
N 4.53
N 4.31
found
(2R,3S,4S)-1,2-Dibenzyl-3-(benzyloxy)-4-hydroxypyrrolidine
(8i)
IR (film): n = 3319 (OH), 3085, 3062, 3029, 2953, 2905, 2865,
1603, 1495, 1484, 1453, 1387, 1356, 1214, 1164, 1121, 1062, 1039,
1028, 1002, 914, 735, 697 cm-1.
According to Typical Procedure B; aminotriol 6i (1.05 g,
2.68 mmol), PPh3 (835 mg, 3.17 mmol), DEAD (499 µL, 364 mg,
3.17 mmol), pyridine (15.6 mL), 90 min at 0 °C. After workup
treatment of the residue with dioxane/H2O (1:1, 30 mL), LiOH
monohydrate (1.10 g, 31.7 mmol), 17 h at 80 °C. Yellowish crude
product, purified by flash chromatography (silica gel, 20 g, column
3 cm ¥ 7 cm, petroleum ether/Et2O 3:7) and crystallization from
heptane/Et2O; 8i, analytically pure, colourless needles; yield
792 mg (79%); mp 97–98 °C; [a]D20 –72.7 (c = 1.30, CHCl3).
C22H29NO2
(339.5)
calc.
C 77.84
C 77.72
H 8.61
H 8.63
N 4.13
N 4.07
found
(2S,3S,4S)-1-Benzyl-3-(benzyloxy)-4-hydroxy-2-(trimethylsi-
lyl)pyrrolidine (8d)
According to the Typical Procedure B; aminotriol 6d (303 mg,
0.782 mmol), PPh3 (245 mg, 0.938 mmol), DEAD (145 µL,
106 mg, 0.938 mmol), pyridine (4.4 mL), 90 min at 0 °C. After
workup treatment of the residue with dioxane/H2O (1:1, 8 mL)/
LiOH∑H2O (328 mg, 7.82 mmol) as above. Yellowish crude prod-
uct, purified by flash chromatography (silica gel, 15 g, column
2 cm ¥ 11 cm, petroleum ether/Et2O 3:7) and crystallization from
IR (KBr): n = 3190 (OH), 3043, 3015, 2825, 2801, 1487, 1443,
1430, 1398, 1342, 1331, 1208, 1187, 1169, 1094, 1059, 1048, 1014,
1002, 903, 889, 836, 748, 720, 692, 679, 613 cm-1.
C25H27NO2
(373.5)
calc.
C 80.40
C 80.33
H 7.29
H 7.35
N 3.75
N 3.76
found
Synthesis 1999, No. SI, 1473–1490 ISSN 0039-7881 © Thieme Stuttgart · New York

1482
O. Schwardt et al.
PAPER
Table 5 1H NMR Data of Compounds 8 and 9 Prepareda
Com-
pound
Chemical Shifts, d
2-H
3-H
4-H
5-HA
5-HB
1’-H
Others
8a
8b
8c
8d
8e
8g
2.75
3.65
4.06
2.01
3.03
1.15
3.07, 3.78 (NCH2Ph), 4.37, 4.51 (OCH2Ph), 7.08–7.23, 7.30–7.34
(2 C6H5)
2.63
2.74
2.78
3.69
3.76
4.04
3.96
4.01
4.16
4.17
1.96
2.21
1.89
2.03
2.08
3.19
3.13
3.16
3.30
3.15
1.53, 1.92
0.93 (4'-H), 1.20–1.46 (2'-H, 3'-H), 3.08, 3.97 (NCH2Ph), 4.34, 4.56
(OCH2Ph), 7.06–7.23, 7.32–7.37 (2 C6H5)
–
1.20 [C(CH3)3], 3.65, 4.06 (NCH2Ph), 4.34, 4.39 (OCH2Ph), 7.08–
7.34, 7.43–7.46 (2 C6H5)
3.67
0.87, 1.42
0.06 [Si(CH3)3], 2.97, 4.01 (NCH2Ph), 4.34, 4.95 (OCH2Ph), 7.08–
7.24, 7.34–7.37 (2 C6H5)
3.66–3.71
3.80
–
2.95, 3.82 (NCH2Ph), 3.93, 4.08 (OCH2Ph), 6.94–7.26, 7.56–7.59
(3 C6H5)
3.16
6.19
3.09, 3.96 (NCH2Ph), 4.45, 4.50 (OCH2Ph), 5.17 (2'-HE), 5.18 (2'-HZ),
7.11–7.25, 7.31–7.38 (2 C6H5)
8i
3.10
3.10
3.54
3.59
3.99
4.01
2.08
2.10
3.26
3.29
2.91, 3.29
2.91, 3.28
3.18, 3.95 (NCH2Ph), 4.25, 4.41 (OCH2Ph), 7.10–7.38 (3 C6H5)
8k
3.22, 4.00 (NCH2Ph), 3.38 (OCH3), 4.30, 4.46 (OCH2Ph), 6.83–6.87,
7.12–7.40 (C6H4, 2 C6H5)
9b
9c
9d
9i
3.69
3.43
3.85
3.96
3.91
4.07
4.23
3.98
4.03
4.02
4.28
4.25
4.29
4.30
4.30
3.15
3.20
3.10
3.14
3.14
3.58
3.69
3.58
3.67
3.66
1.76–1.92
–
1.02 (4'-H), 1.32–1.54 (2'-H, 3'-H)
1.22 [C(CH3)3]
1.02, 1.36
3.06, 3.27
3.00, 3.20
0.17 [Si(CH3)3]
7.32–7.42 (C6H5)
9k
3.82 (OCH3), 6.95, 7.32 (C6H4)
Coupling Constants J (Hz)
J2,3
6.8
6.3
6.9
6.3
J3,4
3.6
2.8
4.3
2.2
1.7
3.5
2.7
2.6
1.6
1.6
1.5
1.7
1.5
J4,5A
6.3
6.1
4.4
6.3
6.5
6.4
5.3
5.3
0
J4,5B
6.8
6.4
4.8
6.7
6.5
6.6
6.1
6.1
4.3
4.2
4.5
4.4
4.4
J5A,5B
9.6
J2,1’
Others
8a
8b
8c
8d
8e
8g
8i
6.5
JNC H Ph = 13.0, JOC H Ph = 12.2
2
2
9.9
9.4, 3.6
–
J
J
J
3’,4’ = 6.8, JNC H Ph = 13.1, JOC H Ph = 12.0
2 2
11.1
9.8
3,5A = 0.9, JNC H Ph = 13.9, JOC H Ph = 11.9
2 2
2.7, 11.5
–
1’A,1’B = 14.2, JNC H Ph = 13.0, JOC H Ph = 11.9
2 2
b
–
9.7
JNC H Ph = 13.1, JOC H Ph = 11.9
2 2
6.6
5.8
5.8
2.9
2.5
2.9
2.8
2.8
9.6
8.9
J
J
J
J
1’,2’E = 16.1, J1’,2’Z = 11.3, J2’E,2’Z = 2.0, JNC H Ph = 13.2, JOC H Ph = 12.2
2
2
10.2
10.2
12.4
12.3
12.4
12.5
12.4
4.6, 9.0
4.7, 9.0
7.5, 7.5
–
1’A,1’B = 13.1, JNC H Ph = 13.2, JOC H Ph = 11.9
2
2
8k
9b
9c
9d
9i
1’A,1’B = 13.2, JNC H Ph = 12.9, JOC H Ph = 11.9
2 2
3’,4’ = 7.0
0
–
0
4.4, 11.7
8.2, 7.0
8.2, 7.1
J
J
J
1’A,1’B = 13.7
1’A,1’B = 13.9
1’A,1’B = 14.0, J3’,4’ = 8.6 (o-, m-H of C6H4)
0
9k
0
a Recorded at 250.1 MHz. (8a–e, 8i in C6D6 and 9c, 9i, 9k in CD3OD) or at 300.1 MHz (8g, 8k in C6D6 and 9b, 9d in CD3OD).
b J not resolved.
Synthesis 1999, No. SI, 1473–1490 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Stereoselective Synthesis and Biological Evaluation of Anisomycin and 2-Substituted Analogues
1483
(2R,3S,4S)-1-Benzyl-3-(benzyloxy)-4-hydroxy-2-(4-methoxy-
benzyl)pyrrolidine (8k)
IR (KBr): n = 3395 (OH, NH), 2980, 2840, 1595, 1460, 1453, 1445,
1413, 1368, 1349, 1300, 1269, 1239, 1208, 1190, 1123, 1070, 1017,
According to the Typical Procedure B; aminotriol 6k (400 mg,
0.952 mmol), PPh3 (295 mg, 1.12 mmol), DEAD (175 µL, 128 mg,
1.12 mmol), pyridine (5.5 mL), 90 min at 0 °C. After workup treat-
ment of the residue with dioxane/H2O (1:1, 20 mL), LiOH∑H2O
(423 mg, 9.52 mmol), 18 h at 80 °C as above. Flash chromatogra-
phy (silica gel, 16 g, column 2 cm ¥ 10 cm, petroleum ether/Et2O
3:7) furnished a colourless solid; after crystallization from hexane/
Et2O 8k, analytically pure, colourless needles; yield 293 mg (77%);
mp 84–85 °C; [a]D20 –84.9 (c = 1.16, CHCl3)
951, 920, 808, 778, 741, 712, 677 cm-1.
C8H18ClNO2
(195.7)
calc.
C 49.10
C 49.22
H 9.27
H 9.33
N 7.16
N 7.15
found
(2R,3S,4S)-2-tert-Butyl-3,4-dihydroxypyrrolidine Hydrobro-
mide (9c∑HBr)
The hydrobromide 9c∑HBr was prepared by hydrogenation of 8c
(250 mg, 0.736 mmol) on 20% Pd(OH)2/C (120 mg) under H2
(4 bar) in MeOH (5 mL) at r. t. After 2 d, concd HBr (1 mL) was
added and the hydrogenation continued for 3 d. The mixture was
then passed through a column filled with Celite and the solvents
were removed in vacuo (40 °C/20 mbar). Crystallization of the re-
mainders from MeOH/EtOAc afforded 9c∑HBr, colourless solid;
yield 170 mg (96%); mp 232–233 °C; [a]D21 –28 (c = 0.50, MeOH).
IR (KBr): n = 3195 (OH), 3009, 2915, 2818, 1606, 1503, 1453,
1441, 1432, 1391, 1380, 1290, 1237, 1199, 1162, 1092, 1074, 1045,
1017, 902, 838, 803, 777, 740, 709, 686, 674 cm-1.
C26H29NO3
(403.5)
calc.
C 77.39
C 77.42
H 7.24
H 7.17
N 3.47
N 3.70
found
IR (KBr): n = 3410 (OH, NH), 3085, 2950, 2858, 2662, 2505, 2492,
2207, 1574, 1471, 1442, 1397, 1368, 1336, 1285, 1238, 1193, 1102,
1081, 1028, 1011, 970, 953, 919, 889, 686 cm-1.
(2R,3S,4S)-2-Butyl-3,4-dihydroxypyrrolidine Hydrochloride
(9b∑HCl)
The dihydroxypyrrolidine hydrochloride 9b∑ HCl was prepared by
hydrogenation of 8b (220 mg, 0.648 mmol) with concd HCl
(0.5 mL) on 10% Pd/C (50 mg) under H2 (4 bar) in MeOH (5 mL)
at r. t. for 3 d. The mixture was passed through a column filled with
Celite and the solvents were removed in vacuo (20 mbar). Crystal-
lization of the resulting material from MeOH/EtOAc afforded
9b∑HCl as a colourless solid; yield 119 mg (95%); mp 155–158 °C;
[a]D20 –5.5 (c = 0.53, MeOH).
C8H18BrNO2
(240.1)
calc.
C 40.01
C 39.98
H 7.56
H 7.49
N 5.83
N 5.62
found
Table 6 13C NMR Chemical Shifts, d of Compounds 8 and 9a
Com-
pound
C-2
C-3
C-4
C-5
C-1’
12.6
29.2
35.9
14.5
–
Others
8a
8b
8c
8d
8e
8g
8i
61.3
67.1
73.6
64.6
72.1
70.5
68.1
68.9
87.4
86.2
88.1
87.2
88.0
88.0
85.4
86.0
75.7
75.2
75.1
75.2
76.3
75.9
74.0
74.6
59.5
60.5
64.5
60.4
59.1
59.0
59.8
60.5
58.2 (NCH2Ph), 71.7 (OCH2Ph), 127.1, 127.6, 127.7, 128.3, 128.5, 129.1,
139.4, 139.7 (2 C6H5)
14.4 (C-4’), 23.6 (C-3’), 27.8 (C-2’), 59.3 (NCH2Ph), 71.6 (OCH2Ph), 127.1,
127.6, 127.9, 128.3, 128.5, 129.0, 139.2, 140.0 (2 C6H5)
28.6 [C(CH3)3], 58.7 (NCH2Ph), 73.0 (OCH2Ph), 126.9, 127.6, 128.0, 128.3,
128.4, 128.6, 139.1, 141.3 (2 C6H5)
-0.5 [Si(CH3)3], 58.4 (NCH2Ph), 70.8 (OCH2Ph), 127.1, 127.6, 127.7, 128.3,
128.5, 129.2, 139.2, 139.7 (2 C6H5)
58.5 (NCH2Ph), 72.2 (OCH2Ph), 127.1, 127.5, 127.6, 127.7, 128.2, 128.3,
128.4, 129.1, 130.2, 138.6, 138.9, 139.3 (3 C6H5)
136.6
34.3
33.9
57.9 (NCH2Ph), 71.9 (OCH2Ph), 118.4 (C-2'), 127.1, 127.6, 127.7, 128.3,
128.5, 129.1, 139.2, 139.6 (2 C6H5)
59.2 (NCH2Ph), 71.3 (OCH2Ph), 125.6, 126.7, 127.2, 127.4, 127.8, 128.0,
128.1, 128.7, 129.3, 138.6, 139.3, 140.3 (3 C6H5)
8k
54.7 (OCH3), 59.7 (NCH2Ph), 71.7 (OCH2Ph), 127.1, 127.7, 127.8, 128.3,
128.5, 129.1, 139.2, 140.0 (2 C6H5), 114.0, 130.6, 132.6, 158.5 (C6H4)
9b
9c
9d
9i
64.0
71.1
60.3
65.3
65.5
76.4b
77.0
76.2b
75.9
52.5
52.9
50.8
52.8
52.7
30.2
33.0
13.5
33.1
32.3
14.5 (C-4'), 23.9 (C-3'), 27.0 (C-2')
28.5 [C(CH3)3]
75.2b
76.1b
76.0b
75.1b
75.8b
75.9b
–2.4 [Si(CH3)3]
128.4, 130.2, 130.3, 138.3 (C6H5)
56.0 (OCH3), 115.5, 130.1, 131.4, 160.4 (C6H4)
9k
a Recorded at 62.9 MHz (8a–e, 8i in C6D6, 9b, 9d, 9i in CD3OD) or at 75.5 MHz (8g, 8k in C6D6, 9c, 9k in CD3OD).
bTentative assignments, eventually to be reversed.
Synthesis 1999, No. SI, 1473–1490 ISSN 0039-7881 © Thieme Stuttgart · New York

1484
O. Schwardt et al.
PAPER
(2S,3S,4S)-3,4-Dihydroxy-2-(trimethylsilymethyl)pyrrolidine
Hydrochloride (9d∑HCl)
IR (film): n = 3063, 3029, 2955, 2928, 2857, 2798, 1603, 1495,
1471, 1454, 1361, 1342, 1256, 1125, 1091, 1074, 1029, 1007, 982,
915, 837, 777, 734, 698 cm-1.
The dihydroxypyrrolidine hydrochloride 9d∑HCl was prepared as
described for 9b∑HCl: from 8d (172 mg, 0.466 mmol) with concd
HCl (0.5 mL), 10% Pd/C (50 mg), H2 (4 bar), MeOH (5 mL), r. t.,
5 d. Workup as above, then crystallization of the residue from
MeOH/CH2Cl2 afforded 9d∑HCl as a colourless solid; yield 103 mg
(98%); mp 221–224 °C (dec); [a]D20 –25 (c = 0.30, MeOH).
C31H41NO2Si
(487.8)
calc.
C 76.34
C 76.47
H 8.47
H 8.62
N 2.87
N 2.87
found
(2R,3S,4S)-1-Benzyl-3-(benzyloxy)-4-(tert-butyldimethylsily-
loxy)-2-(4-methoxybenzyl)pyrrolidine (11)
IR (KBr): n = 3379 (OH, NH), 2985, 2542, 2470, 1590, 1416, 1356,
1308, 1242, 1200, 1181, 1149, 1108, 1071, 1038, 1021, 962, 923,
891, 837, 749, 737, 701, 689, 633 cm-1.
As described for 10, a mixture of 8k (370 mg, 0.917 mmol), imida-
zole (125 mg, 1.83 mmol), and TBSCl (207 mg, 1.38 mmol) in
DMF (5 mL) under N2 was stirred for 17 h at 50 °C. After workup
as above the yellowish crude product was purified by flash chroma-
tography on silica (10 g, column 2 cm ¥ 5 cm, petroleum ether/
C8H20ClNO2Si calc.
(225.8) found
C 42.56
C 42.22
H 8.93
H 8.73
N 6.20
N 5.99
20
EtOAc 5:1); yield 465 mg (98%); colourless oil; [a]D –50.6
(c = 1.10, CHCl3).
(2R,3S,4S)-2-Benzyl-3,4-dihydroxypyrrolidine Hydrobromide
(9i∑HBr)
IR (film): n = 3062, 3029, 2953, 2928, 2856, 2797, 1612, 1512,
1496, 1463, 1454, 1300, 1247, 1177, 1126, 1080, 1039, 1007, 982,
914, 836, 777, 736, 699 cm-1.
The hydrobromide 9i∑HBr was prepared as described for 9c∑HBr:
8i (150 mg, 0.402 mmol), 20% Pd(OH)2/C (100 mg), H2 (4 bar),
MeOH (4 mL), r. t., 4 d. Then concd HBr (1 mL) was added and hy-
drogenation continued for 1 d. Workup as above, then crystalliza-
tion of the residue from MeOH/Et2O; 9i∑HBr, colourless solid;
C32H43NO3Si
(517.8)
calc.
C 74.23
C 74.12
H 8.37
H 8.35
N 2.71
N 2.64
found
20
yield 105 mg (95%); mp 202–203 °C; [a]D +6.7 (c = 0.56,
MeOH).
(2R,3S,4S)-2-Benzyl-1-(tert-butoxycarbonyl)-4--(tert-butyldim-
ethylsilyloxy)-3-hydroxypyrrolidine (12)
IR (KBr): n = 3238 (OH, NH), 2928, 2901, 2510, 1572, 1488, 1425,
1386, 1352, 1292, 1262, 1194, 1082, 1009, 951, 906, 891, 758, 730,
687 cm-1.
A solution of 10 (270 mg, 0.554 mmol) and (Boc)2O (181 mg,
0.830 mmol) in dioxane (5 mL) was hydrogenated on 10%
Pd(OH)2/C (150 mg) under H2 (4 bar) at r. t. for 6 d. Concd HOAc
(0.5 mL) was added and hydrogenation was continued for 1 d. The
mixture was then passed through a column filled with Celite, and
the solvents were removed in vacuo (40 °C/ 20 mbar). The yellow-
ish crude product was purified by flash chromatography (silica gel,
12 g, column 2 cm ¥ 6 cm, petroleum ether/EtOAc 5:1) to furnish
12 as an analytically pure, colourless solid; yield 205 mg (91%); mp
89–91 °C; [a]D20 + 8.8 (c = 0.48, CHCl3).
C11H16BrNO2
(274.2)
calc.
C 48.19
C 48.06
H 5.88
H 5.88
N 5.11
N 5.08
found
(2R,3S,4S)-3,4-Dihydroxy-2-(4-methoxybenzyl)pyrrolidine Hy-
drobromide [(+)-Deacetylanisomycin Hydrobromide]
(9k∑HBr)
The dihydroxypyrrolidine hydrobromide 9k∑HBr was prepared as
described for 9c∑HBr: 8k (200 mg, 0.496 mmol), 20% Pd(OH)2/C
(100 mg), H2 (4 bar), MeOH (5 mL), r. t., 2 d. Then concd HBr
(1 mL) was added and hydrogenation continued for 3 d. Workup as
above, then crystallization36 of the remainders from MeOH/Et2O af-
forded 9k∑HBr as a colourless solid; yield 150 mg (99%); mp 222–
224 °C (dec; for hydrochloride: ref.7c 227–229 °C, ref.29 224–
IR (film): n = 3425 (OH), 3029, 2928, 2855, 1655 (C=O), 1495,
1454, 1404, 1366, 1252, 1210, 1164, 1127, 1090, 1042, 1001, 919,
834, 776, 736, 700 cm-1.
C22H37NO4Si
(407.6)
calc.
C 64.82
C 64.97
H 9.15
H 9.09
N 3.44
N 3.38
found
20
226 °C); [a]D +7.2 (c = 1.00, MeOH) {for hydrochloride: ref.7c
[a]D20 +6 (c = 0.7, MeOH)}.
(2R,3S,4S)-1-(tert-Butoxycarbonyl)-4-(tert-butyldimethylsily-
loxy)-3-hydroxy-2-(4-methoxybenzylpyrrolidine (13)
IR (KBr): n = 3410 (OH, NH), 2948, 1605, 1578, 1503, 1431, 1391,
1370, 1296, 1283, 1236, 1169, 1089, 1073, 1020, 953, 890, 830,
818, 802, 789, 743 cm-1.
As described for 12 a mixture of 11 (310 mg, 0.599 mmol) and
(Boc)2O (198 mg, 0.899 mmol) in dioxane (6 mL) was hydrogenat-
ed on 10% Pd(OH)2/C (150 mg) under H2 (4 bar) at r. t. for 3 d.
Concd HOAc (0.5 mL) was added and hydrogenation was contin-
ued for 1 d. After workup as above the yellowish crude product was
purified by flash chromatography (silica gel, 12 g, column
2 cm ¥ 6 cm, petroleum ether/EtOAc 5:1) to furnish 13 as an ana-
C12H18BrNO3
(304.2)
calc.
C 47.38
C 47.65
H 5.96
H 6.10
N 4.60
N 4.43
found
(2R,3S,4S)-1,2-Dibenzyl-3-(benzyloxy)-4-(tert-butyldimethylsi-
lyloxy)pyrrolidine (10)
20
lytically pure, colourless oil; yield 228 mg (87%); [a]D +7.1
(c = 0.48, CHCl3).
To a solution of 8i (750 mg, 2.01 mmol) and imidazole (274 mg,
4.01 mmol) in DMF (10 mL) under N2 was added TBSCl (453 mg,
3.02 mmol) at 0 °C. The mixture was stirred for 20 h at 50 °C, then
quenched with H2O (10 mL) and extracted with Et2O (4 ¥ 30 mL).
The organic layers were combined and dried (Na2SO4). The filtrate
was concentrated (40 °C, 20 mbar) to afford a yellow oil, which was
purified by flash chromatography on silica gel (20 g, column
3 cm ¥ 6 cm, petroleum ether/EtOAc 5:1); yield 918 mg (94%); co-
lourless oil; [a]D20 –48.2 (c = 1.30, CHCl3).
IR (film): n = 3427 (OH), 2930, 2857, 1695, 1667 (C=O), 1613,
1584, 1513, 1463, 1410, 1366, 1300, 1248, 1174, 1124, 1040, 1002,
949, 914, 834, 776 cm-1.
C23H39NO5Si
(437.7)
calc.
C 63.12
C 62.93
H 8.98
H 8.78
N 3.20
N 3.12
found
Synthesis 1999, No. SI, 1473–1490 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Stereoselective Synthesis and Biological Evaluation of Anisomycin and 2-Substituted Analogues
1485
Table 7 1H NMR Data of Compounds 1 and 10–23 Prepareda
Com-
pound
Chemical Shifts, d
2-H
4.21
3.15
3-H
5.10
3.60
4-H
5-HA
5-HB
3.65
3.25
1’-HA 1’-HB
Others
1
4.40 3.24
4.17 2.24
3.02
2.85
3.13
3.04
2.23 (COCH3), 3.82 (OCH3), 6.96, 7.28 (C6H4)
10
–0.03, –0.01 [Si(CH3)2], 0.84 [SiC(CH3)3], 3.42, 3.92 (NCH2Ph),
4.38, 4.56 (OCH2Ph), 7.16–7.34 (3 C6H5)
11
3.09
3.58
4.16 2.23
3.24
2.78
2.97
–0.03, –0.01 [Si(CH3)2], 0.84 [SiC(CH3)3], 3.42, 3.93 (NCH2Ph),
3.78 (OCH3), 4.39, 4.57 (OCH2Ph), 6.77, 7.11, 7.23–7.35 (C6H4,
2 C6H5)
12
13
14
15
16
17
4.22
4.26
4.57
4.55
4.69
4.68
3.68–3.74
3.46–3.51
3.04
3.08
2.94
2.95
3.10
3.09
3.30
3.33
3.26
3.22
3.45
3.42
–0.06, –0.05 [Si(CH3)2], 0.85 [SiC(CH3)3], 1.48 [OC(CH3)3],
7.01–7.13, 7.30–7.33 (C6H5)
3.79
5.02
5.04
5.29
5.32
3.83 3.49
3.96 3.42
3.96 3.43
4.08 3.51
4.10 3.52
3.55
3.49
3.49
3.64
3.65
0.01 [Si(CH3)2], 0.91 [SiC(CH3)3], 1.54 [OC(CH3)3], 3.44
(OCH3), 6.82, 7.30 (C6H4)
–0.03, –0.02 [Si(CH3)2], 0.84 [SiC(CH3)3], 1.47 [OC(CH3)3],
1.67 (COCH3), 7.01–7.22 (C6H5)
–0.03, –0.02 [Si(CH3)2], 0.85 [SiC(CH3)3], 1.48 [OC(CH3)3],
1.71 (COCH3), 3.36 (OCH3), 6.75, 7.14 (C6H4)
–0.03, 0.01 [Si(CH3)2], 0.84 [SiC(CH3)3], 1.50 [OC(CH3)3],
6.93–7.23, 8.08–8.12 (2 C6H5)
0.01, 0.02 [Si(CH3)2], 0.85 [SiC(CH3)3], 1.51 [OC(CH3)3], 3.29
(OCH3), 6.63–6.67, 6.98–7.21, 7.96, 8.10–8.14 (C6H4, C6H5)
18
19
20
21
22
4.17
4.30
4.19
4.13
4.58
5.03
5.25
5.18
3.20
5.34
4.31 3.16
4.44 3.25
4.36 3.19
3.56 3.31
5.14 3.52
3.56
3.67
3.61
2.99
3.09
2.99
3.11
3.22
3.08
2.14 (COCH3), 7.25–7.36 (C6H5)
7.20–7.32, 7.50–7.55, 7.65, 8.11–8.14 (2 C6H5)
3.64 (OCH3), 6.76, 7.09, 7.45, 7.58, 8.07 (C6H4, C6H5)
3.41–3.48 2.96
3.41–3.48 1.47 [OC(CH3)3], 3.40 (OCH3), 6.78, 7.21 (C6H4)
3.68
2.91
3.11
1.47 [OC(CH3)3], 1.58, 1.67 (COCH3), 3.41 (OCH3), 6.81, 7.31
(C6H4)
23
4.01
5.08
5.10 3.33
3.79
3.11
3.21
2.06, 2.22 (COCH3), 3.72 (OCH3), 6.81, 7.13 (C6H4)
Coupling Constants J (Hz)
J2,3
3.4
5.5
5.5
J3,4
0
J4,5A
0
J4,5B
4.5
5.5
5.5
J5A,5B
12.7
10.4
10.4
J2,1’A
8.7
J2,1’B
6.9
Others
1
10
11
J
J
1’A,1’B = 14.2, J3’,4’ = 8.5 (o-, m-H of C6H4)
1’A,1’B = 13.3, JNC H Ph = 13.2, JOC H Ph = 11.8
2.6
2.4
4.6
4.5
5.1
8.8
2
2
5.1
8.9
J
1’A,1’B = 13.6, JNC H Ph = 13.2, JOC H Ph = 11.8, J3’,4’ = 8.5
2 2
(o-, m-H of C6H4)
b
b
b
b
12
13
14
15
16
17
18
19
5.1
5.7
6.2
6.4
5.7
5.6
3.4
3.4
–
–
–
–
8.9
8.8
9.1
8.9
9.3
9.4
8.8
8.5
4.0
4.0
4.1
4.0
4.2
4.0
6.7
7.1
J1’A,1’B = 13.4
4.3
5.1
5.0
4.2
4.2
1.3
1.4
6.5
5.4
5.4
4.7
4.7
1.0
0.8
4.9
4.7
3.9
3.4
3.5
4.5
4.4
11.2
11.3
11.2
11.5
11.5
12.7
12.8
J
J
J
J
J
J
J
1’A,1’B = 13.5, J3’,4’ = 8.6 (o-, m-H of C6H4)
1’A,1’B = 13.6
1’A,1’B = 13.7, J3’,4’ = 8.6 (o-, m-H of C6H4)
1’A,1’B = 13.4
1’A,1’B = 13.5
3,5a = 0.9, J1’A,1’B = 14.2
3,5a = 0.8, J1’A,1’B = 14.0
Synthesis 1999, No. SI, 1473–1490 ISSN 0039-7881 © Thieme Stuttgart · New York

1486
O. Schwardt et al.
PAPER
Table 7 (continued)
Coupling Constants J (Hz)
J2,3
3.5
5.9
6.8
4.5
J3,4
1.7
4.2
5.8
1.2
J4,5A
0
J4,5B
4.2
6.1
6.5
4.7
J5A,5B
12.9
11.2
12.2
13.4
J2,1’A
8.5
J2,1’B
7.2
4.1
4.3
6.3
Others
20
21
22
23
J
J
J
J
1’A,1’B = 14.1, J3’,4’ = 8.3 (o-, m-H of C6H4)
1’A,1’B = 13.5, J3’,4’ = 8.6 (o-, m-H of C6H4)
1’A,1’B = 13.9, J3’,4’ = 8.6 (o-, m-H of C6H4)
1’A,1’B = 14.1, J3’,4’ = 8.5 (o-, m-H of C6H4)
3.6
4.2
0
9.0
8.2
9.0
a Recorded at 300.1 MHz (10, 23 in CDCl3, 1, 18, 19 in CD3OD, and 12–17, 21, 22 in C6D6 at 343 K) or at 500.1 MHz (11 in CDCl3 and 20 in
CD3OD).
b J not resolved.
(2R,3S,4S)-3-Acetoxy-2-benzyl-1-(tert-butoxycarbonyl)-4-(tert-
butyldimethylsilyloxy)pyrrolidine (14)
C29H41NO5Si
(511.7)
calc.
C 68.07
C 67.89
H 8.08
H 7.98
N 2.74
N 2.72
found
To a solution of 12 (200 mg, 0.491 mmol) in anhyd pyridine (4 mL)
under N2 was slowly added Ac2O (92.6 µL, 0.981 mmol) and
DMAP (10 mg) at 0 °C. After stirring the mixture at r. t. for 3 h, the
solvent was removed in vacuo (40 °C, 20 mbar). The residue was
purified by flash chromatography (silica gel, 12 g, column
2 cm ¥ 6 cm, petroleum ether/EtOAc 5:1) to give 14 as an analyti-
(2R,3S,4S)-3-O-Benzoyloxy-1-(tert-butoxycarbonyl)-4-(tert-bu-
tyldimethylsilyloxy)-2-(4-methoxybenzyl)pyrrolidine (17)
As described for 16, a solution of 13 (80.0 mg, 0.183 mmol), Ph-
COCl (92.4 µL, 0.734 mmol), and DMAP (10 mg) in anhyd pyri-
dine (2 mL) under N2 was stirred for 21 h at r. t. After workup as
above and purification by flash chromatography (silica, 10 g, col-
umn 2 cm ¥ 5 cm, petroleum ether/EtOAc 6:1) a slightly impure
(NMR: ca. 5% pyridinium benzoate) colourless oil was isolated;
yield 92.0 mg (93%); [a]D20 –8.1 (c = 0.56, CHCl3).
20
cally pure, colourless oil; yield 215 mg (97%); [a]D +23.5
(c = 1.01, CHCl3).
IR (film): n = 2955, 2931, 2887, 2858, 1748 (C=O), 1697 (C=O),
1497, 1473, 1455, 1393, 1367, 1332, 1251, 1232, 1167, 1123, 1076,
1042, 955, 937, 918, 837, 778, 670 cm-1.
C24H39NO5Si
(449.7)
calc.
C 64.11
C 63.87
H 8.74
H 8.70
N 3.12
N 3.10
IR (film): n = 2954, 2930, 2856, 1792, 1724 (C=O), 1697 (C=O),
1612, 1512, 1452, 1391, 1366, 1268, 1250, 1212, 1173, 1109, 1070,
1035, 834, 778, 710 cm-1.
found
(2R,3S,4S)-3-Acetoxy-1-(tert-butoxycarbonyl)-4-(tert-butyldi-
methylsilyloxy)-2-(4-methoxybenzyl)pyrrolidine (15)
As described for the preparation of 14, a solution of 13 (100 mg,
0.229 mmol), Ac2O (43.2 µL, 0.458 mmol), and DMAP (10 mg) in
anhyd pyridine (2 mL) under N2 was stirred for 3 h at r. t. After
workup as above and purification by flash chromatography (silica
gel, 10 g, column 2 cm ¥ 5 cm, petroleum ether/EtOAc 5:1) a co-
lourless oil was isolated; yield 103 mg (94%); [a]D20 +21 (c = 0.67,
CHCl3).
C30H43NO6Si
(541.8)
calc.
C 66.51
C 67.26
H 8.00
H 7.81
N 2.59
N 2.46
found
(2R,3S,4S)-3-Acetoxy-2-benzyl-4-hydroxypyrrolidine Hydro-
chloride (Demethoxyanisomycin Hydrochloride) (18∑HCl);
Typical Procedure C
A solution of 14 (210 mg, 0.467 mmol) in anhyd. HCl/dioxane (6
M, 5 mL) under N2 was stirred for 3 h at 0 °C. H2O (10 µL, 0.555
mmol) was added and stirring continued at 0 °C for 15 min. The sol-
vent was evaporated (20 mbar, 25 °C) and the solid residue crystal-
lized from MeOH/Et2O; yield 124 mg (98%); colourless needles;
IR (film): n = 2955, 2932, 2858, 1747 (C=O), 1696 (C=O), 1613,
1513, 1464, 1393, 1367, 1300, 1249, 1176, 1124, 1067, 1042, 956,
917, 836, 778 cm-1.
mp 159–161 °C (subl.; ref7b 242 °C); [a]D +7.03 (c = 1.02,
20
MeOH).
C25H41NO6Si
(479.7)
calc.
C 62.60
C 62.77
H 8.61
H 8.66
N 2.92
N 2.90
IR (KBr): n = 3275 (OH, NH), 2870, 2739, 2655, 2530, 2440, 2418,
1749 (C=O), 1386, 1489, 1448, 1398, 1365, 1320, 1210, 1075,
1061, 1019, 956, 921, 869, 760, 728, 693, 681 cm-1.
found
(2R,3S,4S)-3-Benzoyloxy-2-benzyl-1-(tert-butoxycarbonyl)-4-
(tert-butyldimethylsilyloxy)pyrrolidine (16)
C13H18NO3Cl
(271.7)
calc.
C 57.46
C 57.24
H 6.68
H 6.63
N 5.15
N 5.14
To a solution of 12 (160 mg, 0.393 mmol) in anhyd pyridine (4 mL)
under N2 was slowly added PhCOCl (182 µL, 1.57 mmol) and
DMAP (10 mg) at 0 °C. After stirring the mixture at r. t. for 23 h,
the solvent was removed in vacuo (40 °C, 20 mbar). The residue
was purified by flash chromatography (silica gel, 18 g, column
2 cm ¥ 12 cm, petroleum ether/EtOAc 10:1) to give 16 as an analyt-
ically pure, colourless oil; yield 195 mg (97%); [a]D20 –7.87
(c = 1.22, CHCl3).
found
(2R,3S,4S)-3-Acetoxy-4-hydroxy-2-(4-methoxybenzyl)pyrroli-
dine Hydrochloride (Anisomycin Hydrochloride) (1∑HCl)
Typical Procedure C; 15 (85.0 mg, 0.177 mmol), anhyd HCl/diox-
ane (6 M, 2.5 mL), 3 h at 0 °C, water (4.0 µL, 0.22 mmol), 30 min
at 0 °C; colourless solid, recrystallized from MeOH/ether; yield
53.0 mg of 1. HCl (quant.); colourless needles; mp 187–188 °C
IR (film): n = 3087, 3030, 2954, 2930, 2886, 2857, 1726 (C=O),
1696 (C=O), 1602, 1495, 1472, 1453, 1391, 1366, 1333, 1317,
1266, 1166, 1108, 1071, 1028, 918, 835, 778, 711 cm–1.
(ref.6a 187–188 °C); [a]D +4.2 (c = 0.51, MeOH) {ref.6b +3.9
20
(c = 1, MeOH), ref.7a [a]D20 +3.5 (c = 1, MeOH)}.
Synthesis 1999, No. SI, 1473–1490 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Stereoselective Synthesis and Biological Evaluation of Anisomycin and 2-Substituted Analogues
1487
Table 8 13C NMR Chemical Shifts, d of Compounds 1 and 10–23a
Com-
pound
C-2
C-3
C-4
C-5
C-1’
33.4
34.7
Others
1
63.9
67.6
78.5
85.8
73.7
75.0
52.9
60.0
21.0 (COCH3), 56.0 (OCH3), 115.7, 129.3, 131.3, 160.8 (C6H4), 171.1
(COCH3)
10
–4.9, –4.6 [Si(CH3)2], 17.8 [SiC(CH3)3], 25.7 [SiC(CH3)3], 59.7 (NCH2Ph),
72.0 (OCH2Ph), 125.7, 126.8, 127.5, 127.8, 128.1, 128.3, 128.9, 129.3, 138.4,
139.2, 140.4 (3 C6H5)
11
67.8
85.8
74.9
60.0
33.7
–4.9, –4.6 [Si(CH3)2], 17.8 [SiC(CH3)3], 25.7 [SiC(CH3)3], 55.1 (OCH3), 59.7
(NCH2Ph), 71.9 (OCH2Ph), 126.8, 127.5, 127.7, 128.1, 128.2, 128.9, 138.4,
139.2 (2 C6H5), 113.5, 130.1, 132.3, 157.7 (C6H4)
12
13
61.6
61.6
77.4
77.5
75.4
75.3
52.4
52.3
34.5
33.6
–4.7, –4.6 [Si(CH3)2], 18.1 [SiC(CH3)3], 26.0 [SiC(CH3)3], 28.7 [OC(CH3)3],
79.3 [OC(CH3)3], 126.4, 128.6, 130.2, 140.1 (C6H5), 155.3 (NCO2)
–4.7, –4.6 [Si(CH3)2], 18.1 [SiC(CH3)3], 25.9 [SiC(CH3)3], 28.7 [OC(CH3)3],
54.9 (OCH3), 79.1 [OC(CH3)3], 114.5, 131.1, 130.9, 159.1 (C6H4), 155.2
(NCO2)
14
15
16
17
59.5
59.6
60.5
60.7
78.7
78.8
79.3
79.3
72.9
72.9
73.1
73.1
52.2
52.2
53.1
53.1
35.2
34.2
35.1
34.2
–4.9, –4.7 [Si(CH3)2], 18.1 [SiC(CH3)3], 20.2 (COCH3), 25.8 [SiC(CH3)3],
28.6 [OC(CH3)3], 79.4 [OC(CH3)3], 126.5, 128.6, 129.8, 139.2 (C6H5), 155.0
(NCO2), 168.9 (COCH3)
–4.9, –4.7 [Si(CH3)2], 18.1 [SiC(CH3)3], 20.3 (COCH3), 25.8 [SiC(CH3)3],
28.6 [OC(CH3)3], 55.0 (OCH3), 79.4 [OC(CH3)3], 114.4, 130.7, 131.1, 159.1
(C6H4), 155.0 (NCO2), 169.0 (COCH3)
–4.9, –4.7 [Si(CH3)2], 18.1 [SiC(CH3)3], 25.9 [SiC(CH3)3], 28.6 [OC(CH3)3],
79.5 [OC(CH3)3], 126.6, 128.6, 128.7, 129.7, 130.0, 130.7, 133.2, 139.1 (2
C6H5), 155.4 (NCO2), 165.3 (COPh)
–4.9, –4.6 [Si(CH3)2], 18.1 [SiC(CH3)3], 25.9 [SiC(CH3)3], 28.7 [OC(CH3)3],
54.9 (OCH3), 79.5 [OC(CH3)3], 114.5, 128.9, 130.0, 130.6, 130.7, 131.0,
159.1 (C6H5, C6H4), 155.4 (NCO2), 165.4 (COPh)
18
19
20
63.5
63.8
64.0
78.3
78.8
78.8
73.4
73.6
73.6
52.6
52.8
52.8
33.0
33.2
32.4
20.8 (COCH3), 128.6, 130.0, 130.2, 137.3 (C6H5), 171.0 (COCH3)
128.6, 130.0, 130.2, 131.1, 135.1, 137.2 (2 C6H5), 166.2 (COPh)
55.8 (OCH3), 115.5, 128.9, 131.1, 160.6 (C6H4), 130.0, 130.3, 131.0, 135.2
(C6H5), 166.2 (COPh)
21
22
23
61.0
59.4
62.5
76.5
75.9
73.8b
73.7
74.2
73.7b
50.7
49.3
48.9
33.3
34.3
31.1
28.4 [OC(CH3)3], 55.2 (OCH3), 80.2 [OC(CH3)3], 113.7, 130.6, 130.9, 157.9
(C6H4), 155.3 (NCO2)
20.0, 20.1 (2 COCH3), 28.5 [OC(CH3)3], 54.9 (OCH3), 79.7 [OC(CH3)3],
114.5, 130.5, 130.8, 159.2 (C6H4), 154.3 (NCO2), 168.9, 169.3 (COCH3)
20.7, 20.7 (2 COCH3), 55.1 (OCH3), 114.4, 126.8, 129.8, 158.9 (C6H4), 169.0,
169.2 (2 COCH3)
a Recorded at 75.5 MHz (8, 23 in CDCl3; 12-17, 22 in C6D6 at 343 K; 1, 18–20 in CD3OD) or at 125.8 MHz (11, 21 in CDCl3).
b Tentative assignments, eventually to be reversed.
IR (KBr): n = 3370 (OH, NH), 3235, 2890, 2815, 2726, 1742
(C=O), 1603, 1502, 1432, 1388, 1359, 1316, 1291, 1240, 1213,
1162, 1084, 1065, 1015, 953, 866, 818, 796, 741, 620 cm-1.
(7.5 µL, 0.41 mmol), 20 min at 0 °C; solid residue, recrystallized
from MeOH/Et2O; yield 106 mg of 19∑HCl (94%); colourless nee-
dles; mp 150–155 °C (subl.); [a]D20 –45 (c = 0.52, MeOH).
IR (KBr): n = 3280 (OH, NH), 3039, 3005, 2930, 2900, 2840, 1723
(C=O), 1591, 1576, 1484, 1440, 1402, 1372, 1333, 1251, 1165,
1092, 1056, 1009, 960, 820, 806, 787, 730, 688 cm-1.
C14H20NO4Cl
(301.8)
calc.
C 55.72
C 55.86
H 6.68
H 6.74
N 4.64
N 4.56
found
C18H20NO3Cl
(333.8)
calc.
C 64.77
C 64.38
H 6.04
H 6.13
N 4.20
N 4.09
(2R,3S,4S)-3-Benzoyloxy-2-benzyl-4-hydroxypyrrolidine Hy-
drochloride (19∑HCl)
found
Preparation according to Typical Procedure C; 16 (190 mg, 0.371
mmol), anhyd HCl/dioxane (6 M, 4 mL), stirred for 3 h at 0 °C, H2O
Synthesis 1999, No. SI, 1473–1490 ISSN 0039-7881 © Thieme Stuttgart · New York

1488
O. Schwardt et al.
PAPER
(2R,3S,4S)-3-Benzoyloxy-4-hydroxy-2-(4-methoxybenzyl)pyr-
rolidine Hydrochloride (20∑HCl)
In Vitro Cytotoxicity Tests Against Human Cancer Cells; Gen-
eral Procedure37
Typical Procedure C; 17 (90.0 mg, 0.166 mmol), anhyd HCl/diox-
ane (6 M, 3 mL), 3 h at 0 °C, water (4.0 µL, 0.22 mmol), 30 min at
0 °C; solid residue, recrystallized from MeOH/Et2O; yield 59.4 mg
The cells (3.5¥104 cells/mL) were suspended in medium 199 (KB
cells) or EMEM (HBL 100 cells) containing 5% newborn calf se-
rum together with penicillin, streptomycin, and gentamycin as anti-
bacterial agents. The cell suspension was inoculated on 12-well
Costar plates in 2 mL/well, followed by addition of serial dilutions
of the sample in EtOH (from 10-4 mol/L to 10-10 mol/L). The plates
were then incubated at 37 °C in a 95% air/5% CO2 humidified incu-
bator for 3 d. This was followed by overnight incubation in medium
containing 0.002% neutral red,38 extraction of the absorbed vital
dye with sodium dodecylsulfate, and photometric determination at
540 nm. The IC50 was expressed as the dilution concentration caus-
ing 50% cell mortality in comparison with uninoculated control cell
cultures.
20
(98%); colourless needles; mp 203–204 °C; [a]D –46 (c = 0.53,
MeOH).
IR (KBr): n = 3290 (OH, NH), 2932, 2905, 2805, 1720 (C=O),
1603, 1591, 1578, 1503, 1441, 1332, 1305, 1289, 1238, 1164, 1090,
1054, 1009, 960, 818, 790, 740, 691, 663 cm-1.
C19H22NO4Cl
(363.8)
calc.
C 62.72
C 62.70
H 6.09
H 6.15
N 3.85
N 3.80
found
(2R,3S,4S)-1-(tert-Butoxycarbonyl)-3,4-dihydroxy-2-(4-meth-
oxybenzyl)pyrrolidine (21)
A solution of 8k (300 mg, 0.744 mmol) and (Boc)2O (324 mg, 1.49
mmol) in MeOH (6 mL) was hydrogenated with 10% Pd/C
(150 mg)/H2 (4 bar) at r. t. for 4 d. The mixture was passed through
a column filled with Celite and the solvents were removed in vacuo
(30 °C/20 mbar). The crude product was purified by flash chroma-
tography (silica gel, 15 g, column 2 cm ¥ 7 cm, petroleum ether/
EtOAc 1:3) to furnish a colourless solid. Crystallization from
MeOH/Et2O afforded 21 as colourless needles; yield 186 mg
(78%); mp 142 °C; [a]D20 –6.80 (c = 1.02, MeOH).
Acknowledgement
We are grateful to the Deutscher Akademischer Austauschdienst
(DAAD) for a fellowship to O. S. concerning a research stay at Gif,
and to Dr. J. Royer of the ICSN-CNRS, Gif-sur-Yvette, for his kind
hospitality. We thank Dr. U. Bornscheuer, Institut für Technische
Biochemie, Universität Stuttgart, for advice and donations regar-
ding lipase-catalyzed reactions, and Mr. J. Rebell for extensive
NMR measurements. Financial support by the Fonds der Chemi-
schen Industrie and the European Community (HCM network "Ste-
reoselective Organic Synthesis") is gratefully stated.
IR (film/CH2Cl2): n = 3426 (OH), 2927, 1663 (C=O), 1512, 1412,
1366, 1301, 1248, 1175, 1125, 1102, 1076, 1035, 749 cm-1.
C17H25NO5
(322.4)
calc.
C 63.14
C 63.21
H 7.79
H 7.94
N 4.33
N 4.32
References
found
(1) a) Preliminary communication of part of these results: Veith,
U.; Schwardt, O.; Jäger, V. Synlett 1996, 1181.
b) Part of these results have been presented: Schwardt, O.;
Veith, U.; Gaspard, C.; Jäger, V. 2nd Lausanne Conf. on
Bioorg. Chem., Lausanne, Switzerland, 6.-7.3.1997, Abstr. P
26;.
Schwardt, O.; Veith, U.; Gaspard, C.; Jäger, V.., Orchem 98,
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275.
(2R,3S,4S)-3,4-Diacetoxy-1-(tert-butoxycarbonyl)-2-(4-meth-
oxybenzyl)pyrrolidine (22)
To
a solution of the N-Boc-pyrrolidinediol 21 (175 mg,
0.541 mmol) in anhyd pyridine (2 mL) under N2 was slowly added
Ac2O (2.04 mL, 21.6 mmol)/DMAP (10 mg) at 0 °C. After stirring
the mixture at r. t. for 3 h, the solvents were removed in vacuo
(40 °C, 20 mbar) and the residue purified by flash chromatography
(silica gel, 12 g, column 2 cm ¥ 6 cm, petroleum ether/ EtOAc 5:1)
to give 22 as an analytically pure, colourless oil; yield 201 mg
(91%); [a]D20 +54 (c = 0.73, CHCl3).
IR (film): n = 2975, 2935, 2837, 1717 (C=O), 1694 (C=O), 1613,
1584, 1513, 1455, 1393, 1333, 1301, 1216, 1166, 1120, 1043, 960,
904, 857, 771 cm-1.
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Fengler, M.; Jaroskova, L.; Pätzel, M.; LeRoy, P.-Y. Bull.
Soc. Chim. Belg. 1994, 103, 491.
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C21H29NO7
(407.5)
calc.
C 61.90
C 61.84
H 7.17
H 7.17
N 3.44
N 3.16
found
Johnson, J. H.; Phillipson, D. W.; Kahle, A. D. J. Antibiot.
1989, 42, 1184.
Pak, C. S.; Lee, G. H. J. Org. Chem. 1991, 56, 1128.
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(2R,3S,4S)-3,4-O-Diacetyl-3,4-dihydroxy-2-(4-methoxyben-
zyl)pyrrolidine Hydrochloride (4-O-Acetylanisomycin Hydro-
chloride) (23∑HCl)
A solution of 22 (125 mg, 0.307 mmol) in anhyd HCl/dioxane (6 M,
3 mL) under N2 was stirred for 3 h at 0 °C, then the solvent was
evaporated (20 mbar, 25 °C), affording a colourless solid which
was crystallized from MeOH/Et2O; yield 106 mg of 23∑HCl
20
(quant.); colourless needles; mp 82–83 °C; [a]D +25.1 (c = 1.00,
MeOH).
Beier, C.; Schaumann, E. Synthesis 1997, 1296.
de Armas, P.; García-Tellado, F.; Marrero-Tellado, J. J.;
Robles, J. Tetrahedron Lett. 1998, 39, 131.
IR (film/CH2Cl2): n = 3423 (NH), 2933, 2756, 1751 (C=O), 1613,
1585, 1514, 1443, 1372, 1301, 1245, 1182, 1058, 1033, 964, 893,
820, 734 cm-1.
(5) Mathkalikova, S. F.; Malikov, V. M.; Yunusov, S. Yu. Khim.
Prir. Soedin 1969, 5, 30; Chem. Abstr. 1969, 71, 13245z.
Mathkalikova, S. F.; Malikov, V. M.; Yunusov, S. Yu. Khim.
Prir. Soedin 1969, 5, 607; Chem. Abstr. 1970, 73, 25712d.
C16H22NO5Cl
(343.8)
calc.
C 55.90
C 55.93
H 6.45
H 6.58
N 4.07
N 3.80
found
Synthesis 1999, No. SI, 1473–1490 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Stereoselective Synthesis and Biological Evaluation of Anisomycin and 2-Substituted Analogues
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Synthesis 1999, No. SI, 1473–1490 ISSN 0039-7881 © Thieme Stuttgart · New York

1490
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Synthesis 1999, No. SI, 1473–1490 ISSN 0039-7881 © Thieme Stuttgart · New York