Pleuromutilins. Part 1: The identification of novel mutilin 14-carbamates

Article abstract of DOI:10.1016/S0968-0896(00)00338-2

A novel series of mutilin 14-carbamates has been discovered as a result of structure-activity studies on the naturally occurring antibiotic pleuromutilin (1). In particular, the 4-methoxybenzoylcarbamate, SB-222734 (15o) displays potent antibacterial acti

Full text of DOI:10.1016/S0968-0896(00)00338-2

Bioorganic & Medicinal Chemistry 9 (2001) 1221±1231
Pleuromutilins. Part 1:
The Identi®cation of Novel Mutilin 14-Carbamates
Gerald Brooks,a Wendy Burgess,c David Colthurst,c Jeremy D. Hinks,c
Eric Hunt,a Michael J. Pearson,c Burdena Shea,c Andrew K. Takle,a,*
Jennifer M. Wilsonc and Gary Woodnuttb
aSmithKline Beecham Pharmaceuticals Research and Development, Discovery Chemistry Europe, New Frontiers Science Park,
Third Avenue, Harlow, Essex CM19 5AW, UK
bSmithKline Beecham Pharmaceuticals Research and Development, Microbiology Research, 1250 South Collegville Road,
Collegville, PA19426, USA
cSmithKline Beecham Pharmaceuticals Research and Development, Brockham Park, Betchworth, Surrey RH3 7AJ, UK
Received 4 October 2000; accepted 12 December 2000
AbstractÐAnovel series of mutilin 14-carbamates has been discovered as a result of structure±activity studies on the naturally
occurring antibiotic pleuromutilin (1). In particular, the 4-methoxybenzoylcarbamate, SB-222734 (15o) displays potent antibacterial
activity against a number of bacterial pathogens which are resistant to currently used agents and shows enhanced metabolic stabi-
lity when compared to earlier pleuromutilin derivatives. Such derivatives therefore have the potential to provide a new class of
antibacterial agents for human therapy which address the threat of bacterial resistance. # 2001 Elsevier Science Ltd. All rights
reserved.
Introduction
X-ray crystallography.5 Pleuromutilin exerts its anti-
bacterial activity by inhibiting bacterial protein syn-
thesis through an interaction with the prokaryotic
ribosome.6 Although the precise molecular interactions
are not yet known its mode of action appears to be
unique since, in laboratory studies, no clinically relevant
cross-resistance is seen with other classes of anti-
bacterial agents. However, to date, no pleuromutilin
derivative has been successfully developed for human
therapy (Chart 1).
The emergence and spread of resistance to existing
antibiotics (e.g. b-lactams, macrolides, quinolones) is of
major concern world-wide. Although initially viewed as
a problem for the hospital setting, bacterial resistance is
now also an accepted issue for community acquired
infections.1 There is, therefore, an urgent need to iden-
tify and exploit new classes of antibacterial agents, with
modes of action which are distinct from those of estab-
lished classes, in order to circumvent the issue of
bacterial resistance.
One approach to this goal is to re-investigate those
known antibiotics, and their targets, which have so far
found little or no utility in human medicine. One such
under-exploited antibiotic is pleuromutilin (1) which
was ®rst isolated in 1951 from the basidiomycete Pleur-
otus mutilus.2 The unusual tricyclic diterpenoid struc-
ture of the natural product was elucidated in the 1960s
by Arigoni3 and Birch4 and subsequently con®rmed by
*Corresponding author. Tel.: +44-1279-627686; fax: +44-1279-
622550; e-mail: andy_takle-1@sbphrd.com
Chart 1.
0968-0896/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved.
PII: S0968-0896(00)00338-2

1222
G. Brooks et al. / Bioorg. Med. Chem. 9 (2001) 1221±1231
Semi-synthetic pleuromutilins were investigated during
the 1970s and early 1980s by the then Sandoz group.
This work led to a number of publications detailing
some of the intriguing chemistry of the mutilin nucleus,
although details of SAR remained sparse. Those SAR
studies which have been reported consist mainly of
manipulations of the pleuromutilin C14 glycolic acid
side chain.7 As a result of these e€orts, two thioacetate
derivatives, tiamulin (2) and TDM-85,530 (3), were
identi®ed, both of which have improved antibacterial
activity compared to pleuromutilin itself. Tiamulin was
C14 acyloxy group per se, rather than substituted var-
iants thereof. To this end, we targeted a number of
novel C14 ether, carbamate, amide and urea linked
derivatives.
Chemistry
Central to the synthesis of the targeted O-linked ana-
logues (ethers and carbamates) is the skeletally rear-
ranged intermediate, colloquially known as 4-epi-
mutilin (5). 4-epi-Mutilin is readily available in two
steps from pleuromutilin via an acid-catalysed 1,5-
hydride shift9 and serves as a mutilin surrogate in which
the C11 hydroxyl group has been protected, thus
allowing selective functionalisation at the less reactive
C14 hydroxyl group.
successfully developed as
a veterinary antibiotic,
whereas TDM-85,530 entered phase I studies in volun-
teers but was not progressed.8
Semi-synthetic pleuromutilins display many of the
properties appropriate for an oral antibiotic for human
therapy (e.g. appropriate spectrum of activity; ecacy
following oral administration in in vivo infection mod-
els) but su€er from having only moderate potency
against Haemophilus in¯uenzae (an important respira-
tory tract pathogen) and from being rapidly and exten-
sively metabolised in vivo, thus limiting their oral
bioavailability. Here, we describe some of our own
investigations in the pleuromutilin area. These studies
culminated in the discovery of a novel series of mutilin
14-carbamates with potent antibacterial activity,
including activity against strains resistant to current
therapies, and with enhanced metabolic stability over
previous analogues.
C14 ether analogues of pleuromutilin and TDM-85,530
were prepared as shown in Scheme 1. Reaction of
4-epi-mutilin (5) with ethyl diazoacetate in the presence
of a rhodium II catalyst generated the mutilin-oxyace-
tate derivative (6). Subsequent reduction of this keto-
ester with lithium aluminium hydride resulted in a 3:2
mixture of the desired keto-alcohol (7) and the diol (12),
as a result of the steric protection a€orded to the C11
ketone. Treatment of 7 with a saturated solution of zinc
chloride in concentrated hydrochloric acid then e€ected
a reverse 1,5-hydride shift9 regenerating the mutilin
con®guration and, in this particular case, the pleur-
omutilin ether analogue (10). The 19,20 didehydro-ether
analogue of TDM-85,530 (11) was also prepared from
the keto-alcohol (7) via the 4-epi-mutilin derivatives (8)
and (9).
Results and Discussion
The early studies by the Sandoz group had demon-
strated that a C14 side chain was essential for anti-
bacterial activity; the tricyclic diol, mutilin (4), did not
inhibit protein synthesis on isolated Escherichia coli
ribosomes and was devoid of useful antibacterial activi-
ty.7b We wished to further explore the SAR associated
with this side chain so as to assess the importance of the
The C14-carbamate derivatives were prepared by one of
two routes shown in Scheme 2. In route A, 4-epi-mutilin
(5) was reacted with an isocyanate or a carbamoyl
chloride to form a 4-epi-mutilin 14-carbamate derivative
(13). Unactivated isocyanates and carbamoyl chlorides
reacted very slowly with 4-epi-mutilin, requiring 5 to 7
days at room temperature for complete reaction. The
Scheme 1. Synthesis of mutilin 14-ether derivatives. Reagents and conditions: (i) ethyl diazoacetate, Rh2(OAc)4, dichloromethane; (ii) lithium alu-
minium hydride, diethyl ether; (iii) methanesulphonyl chloride, pyridine, dichloromethane; (iv) 3-Amino-5-mercapto-1,2,4-triazole, sodium meth-
oxide, acetone/methanol; (v) zinc chloride, conc. hydrochloric acid, dioxane; (vi) conc. hydrochloric acid, dioxane.

G. Brooks et al. / Bioorg. Med. Chem. 9 (2001) 1221±1231
1223
Scheme 2. Synthesis of mutilin 14-carbamates. Reagents and conditions: (i) R1NCO or R1R2NCOCl, THF; (ii) trichloromethyl chloroformate,
triethylamine, THF; (iii) R1R2NH, dichloromethane; (iv) zinc chloride, conc. hydrochloric acid, dioxane; (v) conc. hydrochloric acid, dioxane.
Scheme 3. Synthesis of 14-acylamino mutilin derivatives. Reagents and conditions: (i) potassium tert butoxide, DMF; (ii) sodium azide, DMF,
150 ꢀC; (iii) hydrogen gas, 10% palladium on charcoal, THF; (iv) phenylacetyl chloride, triethylamine, chloroform; (v) sodium hydroxide, ethanol;
(vi) benzoylisocyanate, dichloromethane.
reaction with activated sulphonyl- or acylisocyanates,10
on the other hand, was complete within minutes. The
alternative, three-step process, route B, proceeds via the
stable, crystalline 4-epi-mutilin 14-chloroformate (14)
which is formed by treatment of 4-epi-mutilin with tri-
chloromethyl chloroformate. Reaction of the chloro-
formate (14) with primary or secondary amines then
leads to a variety of 4-epi-mutilin 14-carbamate deriva-
tives, in high yield. The later route has the advantage
Figure 1.
over route A, in that it allows access to a more diverse
range of carbamates due to the ready availability of
primary and secondary amines. Once more, strong
acid treatment e€ects rearrangement of the 4-epi-
mutilin 14-carbamates (13) to the corresponding
mutilin derivatives (15).
Table 1. Antibacterial activity of novel mutilin derivatives
MIC (mg/mL)a
Compound IVTb S.a. 1
S.a. 2
S.p
H.i.
M.c.
E.c.
In contrast to the ether and carbamate derivatives pre-
viously discussed, the synthesis of the N-linked ana-
logues proved far more taxing (Scheme 3). Substitution,
as opposed to functionalisation, of the mutilin C14
hydroxyl group is extremely dicult; the appropriate
trajectory for an incoming nucleophile during SN2 dis-
placement of the C14 hydroxyl group (or other leaving
group) is blocked by C10 and attempts to introduce
substituents by an SN1 type mechanism are thwarted by
another transannular 1,5-hydrogen shift from C10 to
C14 (Fig. 1) which results in expulsion of the C14 leaving
group.11 In an attempt to circumvent these problems, we
proposed to make use of yet another of the vagaries of
mutilin chemistry, namely the 4,14-cyclopropane (17),12
1
2
3
71
77
65
0.5
0.25
0.25
0.25
0.125
0.125
2
1
8
4
0.25
ꢁ0.06
0.125
2
8
8
0.125
0.25
32
32
>4
>4
10
11
19
20
nd >64
>64
>64 64
>64 32
>64 >4
>64 >4
>64
>64
>64
>64
18
29
0
64
>4
>4
32
>4
>4
aS.a. 1, Staphylococcus aureus Oxford (methicillin sensitive). S.a. 2,
Staphylococcus aureus V573 (methicillin resistant); S.p., Streptococcus
pneumoniae ERY2 (macrolide resistant); H.i., Haemophilus in¯uenzae
WM493 (penicillin resistant); M.c., Moraxella catarrhalis Ravasio
(penicillin resistant); E.c,. Escherichia coli DC2, permeability mutant.
bIVT, percent inhibition of in vitro protein synthesis (poly Phe) in
presence of 1 mM drug. nd, not determined.

1224
G. Brooks et al. / Bioorg. Med. Chem. 9 (2001) 1221±1231
since such conjugated cyclopropanes are known to be
susceptible to nucleophilic ring opening.13 The cyclo-
propane (17) was conveniently prepared in 32% yield by
treatment of mutilin 11,14-diacetate (16) with potassium
tert-butoxide in DMF. However, this cyclopropane
proved stubbornly resistant to a variety of ring opening
conditions. Only treatment with sodium azide in DMF
at 150 ꢀC proved successful, generating the C14-azide
(18) in low yield. This enabled us to complete the
synthesis of the desired C14 amino derivatives by
reduction of the azide, along with concomitant reduc-
tion of the 19,20 double bond, followed by acylation
of the resultant amine and saponi®cation of the 11-
acetate.
or signi®cantly reduced, activity in an in vitro transla-
tion assay.
The carbamate derivatives (15), on the other hand, dis-
play potent antibacterial activity against Gram-positive
and the more permeable Gram-negative bacteria, in
some cases surpassing that of the standard agents. The
activity of a representative selection of such derivatives
is shown in Table 2, thus demonstrating the SAR
observed for this series. The N-aryl and N-arylalkyl
carbamates (15a±d) display good to excellent anti-
Gram-positive activity, including activity against strains
of methicillin-resistant Staphylococcus aureus and mac-
rolide resistant Streptococcus pneumoniae. Within the
series of N-aryl derivatives, electron donating sub-
stituents are advantageous whereas electron with-
drawing substituents have a deleterious e€ect on
antibacterial activity. The N-alkyl carbamates (15e,f)
display broad-spectrum activity but are in general less
potent than the N-aryl derivatives against the Gram-
positive pathogens. N,N-disubstituted carbamates
(15g,h), including cyclic derivatives (15i), are in all cases
less potent than the corresponding mono-substituted
Biological results
The antibacterial activity of the ethers (10 and 11),
amide (19) and acylurea (20) mutilin derivatives are
shown in Table 1, with pleuromutilin, tiamulin and
TDM-85,530 included for comparative purposes. These
novel derivatives all display considerably reduced anti-
bacterial activity, which is also re¯ected in the lack of,
Table 2. Antibacterial activity of mutilin-14-carbamates
MIC (mg/mL)a
Compound
R1
R2
Route
S.a. 1
S.a. 2
S.p
H.i.
M.c.
E.c.
15a
15b
15c
15d
15e
15f
15g
15h
15i
15j
15k
15l
15m
15n
15o
Ph
4-MeO.Ph
4-NO2.Ph
PhCH2
Me
(CH2)2OH
Ph
Me
H
H
H
H
H
H
Me
Me
A
A
A2
A
A0.5
B
B
B
B
Ab
B
ꢁ0.06
ꢁ0.06
2
ꢁ0.06
ꢁ0.06
64
2
0.5
>64
0.25
8
2
8
4
4
64
>64
64
8
0.5
16
>64
>64
>64
4
2
8
16
8
1
1
4
64
>64
>64
0.125
16
1
16
4
8
0.125
0.25
0.25
0.5
ꢁ0.06
ꢁ0.06
4
0.5
2
1
1
4
1
1
2
4
8
>64
>64
>64
2
CH2CH2OCH2CH2
H
HO
4
H
H
H
H
H
H
0.5
0.5
0.5
1
0.125
0.25
0.25
0.5
0.5
1
1
0.5
Me2N
B
B
A
A
1
nd
32
1
MsNH
PhSO2
4-MeO.PhCO
4
ꢁ0.06
ꢁ0.06
0.5
ꢁ0.06
1
ꢁ0.06
ꢁ0.06
ꢁ0.06
aSee footnote to Table 1 for abbreviations.
b15j was prepared by the reaction of 4-epi-mutilin with trichloroacetyl isocyanate followed by hydrolysis of the trichloroacetylcarbamate.
Table 3. Antibacterial activity of mutilin 14-(4-methoxybenzoyl)carbamate (15o, SB-222734)a
MIC (mg/mL)
15o
Amoxycillin
Clarithromycin
Chloramphenicol
S. aureus (n=40)
MIC90
MIC50
MIC range
0.06
ꢁ0.015
>128
64
>64
>64
16
8
ꢁ0.015±4
ꢁ0.125±>128
ꢁ0.06±>64
0.06±>32
S. pneumoniae (n=40)
H. in¯uenzae (n=40)
MIC90
MIC50
MIC range
0.5
0.25
0.03±0.5
No data
No data
No data
>512
0.06
16
4
2±16
ꢁ0.03±>512
MIC90
MIC50
MIC range
2
1
64
4
32
16
8
0.5
0.25±16
0.125±4
0.125±>64
4±64
aThe extended panel of organisms have the following resistance pro®les. S. aureus: macrolide, fusidic acid and cipro¯oxacin resistant strains, many
with multi-resistant characteristics, including 22 methicillin-resistant organisms. S. pneumoniae: 18 penicillin, 16 clarithromycin, 17 chloramphenicol
and six o¯oxacin resistant strains including many with multi-resistant pro®les. H. in¯uenzae: 12 b-lactamase producers, 11 clarithromycin and six
tetracycline resistant strains.

G. Brooks et al. / Bioorg. Med. Chem. 9 (2001) 1221±1231
1225
The novel mutilin 14-carbamates described have potent
antibacterial activity, displaying a spectrum of activity
which encompasses the major respiratory tract patho-
gens. The 4-methoxybenzoyl carbamate (15o) is partic-
ularly impressive, demonstrating potent activity against
a panel of organisms which are refractory to treatment
with established antibacterial agents. Furthermore, 15o
also displays improved stability to mouse liver micro-
somes, when compared to previous semi-synthetic deri-
vatives.
Experimental
General conditions
Figure 2. Comparative disappearance curves for SB-222734 (15o,
closed circles) and tiamulin (open circles) in a mouse liver microsome
preparation.
NMR spectra were recorded on a Bruker AC250 or
AM250 spectrometer in CDCl3 (unless otherwise stated)
with tetramethylsilane as an internal standard. Infra-red
spectra were recorded in dichloromethane solution on a
Perkin-Elmer 1600 series FTIR. Mass spectra were
recorded on either a Finnigan TSQ700, VG ZAB1F or
VG Trio-2 spectrometer in electron impact (EI), elec-
trospray (ESI), chemical ionisation (NH3DCI) or fast
atom bombardment (FAB) modes. Chromatography
was performed on Merck silica 60, (230±400 mesh)
eluting with ethyl acetate/hexane mixtures, unless
otherwise speci®ed.
derivatives. The primary carbamate (15j) and those
derivatives bearing small polar substituents (15k±m) on
the other hand, show improved potency against
Haemophilus in¯uenzae but at the expense of some of
the anti-Gram-positive activity displayed by the aryl
derivatives. However, the N-arylsulphonyl (15n) and, in
particular, the N-aroyl carbamates (15o, SB-222734)
combine the best features of all of the derivatives pre-
viously discussed, displaying excellent broad-spectrum
activity. The activity of this latter derivative was further
challenged through evaluation against an expanded
selection of bacteria with di€ering susceptibilities to
existing agents (Table 3). The novel aroyl carbamate
(15o) was shown to possess potent in vitro antibacterial
activity against S. aureus, S. pneumoniae and H. in¯u-
enzae and was clearly superior to the comparator agents
used in the study.
(3R)-3-Deoxo-11-deoxy-14-O-(ethoxycarbonylmethyl)-3-
methoxy-11-oxo-4-epi-mutilin (6). Ethyl diazoacetate
(2.5 mL, 22.8 mmol) in dichloromethane (20 mL) was
slowly added, over 6 h, to a mixture of (5, 2.0 g, 6 mmol)
and rhodium acetate dimer (8 mg) in dichloromethane
(5 mL) under argon. The reaction mixture was then
concentrated and the residue puri®ed by silica gel chro-
matography, eluting with dichloromethane, to give (6,
1
1.1 g, 42%); nmax 1753, 1697 cmÀ1; H NMR 0.97 (3H,
As previously mentioned, pleuromutilins such as tia-
mulin are rapidly eliminated in vivo by cytochrome
P450-mediated hydroxylation of the tricyclic nucleus.
The rate of metabolism of the novel N-aroylcarbamate
(15o) was therefore compared to that of tiamulin, in an
in vitro mouse live microsome preparation (Fig. 2). This
study demonstrated that, in addition to its superior
antibacterial activity, 15o was signi®cantly more stable,
being eliminated at one tenth of the rate of tiamulin.
d, J=6.7 Hz), 0.98 (3H, d, J=6.4 Hz), 1.23 (3H, s), 1.24
(3H, s), 1.29 (3H, t, J=7.2 Hz), 1.03±1.34 (4H, m), 1.47
(2H, m), 1.67 (1H, d, J=15.8 Hz), 1.70 (1H, d,
J=11.2 Hz), 1.97 (2H, m), 2.18 (1H, m), 2.42 (1H, dd,
J=15.8, 9.5 Hz), 2.86 (1H, q, J=6.4 Hz), 3.21 (3H, s),
3.48 (1H, ddd, J=11.2, 8.0, 5.2 Hz), 3.92 (1H, d,
J=15.2 Hz), 4.08 (1H, d, J=9.5 Hz), 4.15 (1H, d,
J=15.2 Hz), 4.21 (2H, dq, J=5.8, 7.1 Hz), 5.10 (1H, d,
J=17.4 Hz), 5.27 (1H, d, J=10.7 Hz), 6.14 (1H, dd,
J=17.4, 10.7 Hz); MS (NH3DCI) m/z 421 (MH+).
(3R)-3-Deoxo-11-deoxy-14-O-(2-hydroxyethyl)-3-meth-
oxy-11-oxo-4-epi-mutilin (7). Asolution of ( 6, 520 mg,
1.24 mmol) in THF (7 mL) was added to an ice-cooled
suspension of lithium aluminium hydride (70 mg,
1.84 mmol) in THF (3 mL) under an argon atmosphere.
After 4 h, the reaction was carefully quenched by the
addition of water (0.1 mL), 15% sodium hydroxide
(0.1 mL) and water (0.3 mL) and the mixture rapidly
stirred until a ®ne suspension formed. The mixture was
®ltered and the residue washed with brine, dried (mag-
nesium sulphate) concentrated and puri®ed by silica gel
chromatography, eluting with 1/19 ethyl acetate/di-
chloromethane, to give (7, 170 mg, 36%); nmax 2930,
Conclusion
Our studies have thus extended knowledge of the SAR
associated with the pleuromutilins as a class and, as a
result, identi®ed a novel series of potent antibacterials.
In doing so, we have also demonstrated that the nature
of the mutilin C14 substituent is crucial to the activity of
such derivatives. Clearly the carbonyl group is an
essential feature of this C14 substituent, since both the
pleuromutilin and TDM-85,530 ether analogues (10 and
11) are devoid of activity. However, the linker atom also
appears to be of signi®cance since both the amide and
acylurea derivatives are inactive, whereas the ester and
carbamates are active.
1
1697 cmÀ1; H NMR 0.97 (6H, d, J=6.5 Hz), 1.17 (3H,

1226
G. Brooks et al. / Bioorg. Med. Chem. 9 (2001) 1221±1231
s), 1.23 (3H, s), 1.02±1.37 (5H, m), 1.47 (1H, m), 1.66
(1H, d, J=15.6 Hz), 1.69 (1H, d, J=11.3 Hz), 1.98 (3H,
m), 2.18 (1H, m), 2.37 (1H, dd, J=15.6, 9.5 Hz), 2.87
(1H, q, J=6.5 Hz), 3.32 (3H, s), 3.34 (1H, m), 3.52 (1H,
ddd, J=11.3, 5.1, 2.6 Hz), 3.67 (3H, m), 4.02 (1H, d,
J=9.5 Hz), 5.09 (1H, d, J=17.5 Hz), 5.27 (1H, d,
J=10.8 Hz), 6.19 (1H, dd, J=17.5, 10.8 Hz); MS
(NH3DCI) m/z 379 (MH+).
14-O-(2-Hydroxyethyl)-mutilin (10). Asolution of
(7,34 mg, 0.09 mmol) in dioxane (2 mL) was treated with
Lukas reagent (concentrated hydrochloric acid satu-
rated with zinc chloride, 0.5 mL) and stirred at room
temperature for 3 h. The reaction mixture was then
partitioned between ethyl acetate and brine and the
aqueous phase re-extracted with ethyl acetate. The
combined organic extracts were washed with water,
dried (magnesium sulphate) concentrated and the resi-
due puri®ed by silica gel chromatography to give (10,
Also formed was (3R)-3-deoxo-14-O-(2-hydroxyethyl)-
1
3-methoxy-4-epi-mutilin (12, 21%); nmax 2930 cmÀ1; H
21 mg, 64%); nmax 1733 cmÀ1; H NMR 0.89 (6H, d,
1
NMR 0.86 (3H, d, J=6.3 Hz), 1.07 (3H, d, J=6.8 Hz),
1.09 (3H, s), 1.13 (3H, s), 1.05±1.52 (6H, m), 1.71 (1H,
d, J=11.2 Hz), 1.92 (1H, m), 2.05 (3H, m), 2.26 (1H,
m), 2.64 (1H, dd, J=15.9, 7.5 Hz), 3.16 (1H, m), 3.31 (3H,
s), 3.61 (5H, m), 4.63 (1H, ddd, J=11.2, 7.3, 5.3 Hz), 5.05
(1H, d, J=17.7 Hz), 5.12 (1H, d, J=11.1 Hz), 6.07 (1H,
dd, J=17.7, 11.3 Hz); MS (NH3DCI) m/z 398 (MNH+4 ).
J=7.0 Hz), 1.19 (1H, m), 1.24 (3H, s), 1.37 (3H, s),
1.35±1.49 (4H, m), 1.62±1.85 (5H, m), 1.97 (1H, dd,
J=16.1, 8.3 Hz), 2.10 (1H, brs), 2.25 (3H, m), 3.23 (1H,
ddd, J=9.1, 5.3, 3.6 Hz), 3.39 (1H, dd, J=9.3, 6.8 Hz),
3.53 (1H, ddd, J=9.2, 6.1, 3.3 Hz), 3.65 (2H, br), 3.46
(1H, m), 3.84 (1H, d, J=8.3 Hz), 5.33 (1H, d, J=17.3,
1.3 Hz), 5.39 (1H, dd, J=11.5, 1.3 Hz), 6.20 (1H, dd,
J=17.4, 11.1 Hz); MS (NH3DCI) m/z 382 (MNH+4 ),
C22H36O4.
(3R)-3-Deoxo-11-deoxy-14-O-(2-methanesulphonyloxy-
ethyl)-3-methoxy-11-oxo-4-epi-mutilin (8). Methanesul-
phonyl chloride (0.15 mL, 1.94 mmol) was added to an
ice-cooled solution of (7, 133 mg, 0.35 mmol) and pyri-
dine (0.3 mL, 3.7 mmol) in dichloromethane (15 mL)
and the resultant solution stirred at room temperature
for 18 h. The reaction mixture was then washed with
1 M hydrochloric acid and brine. The organic phase was
then dried (magnesium sulphate), concentrated and the
residue puri®ed by silica gel chromatography, eluting
with 1/19 ethyl acetate/dichloromethane, to give (8,
14-O-[2-(3-Amino-1,2,4-triazol-5-yl-thio)-ethyl]-mutilin
(11). Concentrated hydrochloric acid (0.5 mL) was
added to a solution of (9, 38.6 mg, 0.08 mmol) in diox-
ane (2 mL) and the resultant solution stirred at room
temperature for 20 h. The reaction mixture was then
partitioned between ethyl acetate and water and the
mixture basi®ed with saturated sodium hydrogen car-
bonate solution. The aqueous phase was re-extracted
with ethyl acetate and the combined organic fractions
washed with water, dried (magnesium sulphate) and
concentrated. The resulting residue was puri®ed by
silica gel chromatography, eluting with ethyl acetate, to
1
136 mg, 85%); nmax 1698 cmÀ1; H NMR 0.95 (3H, d,
J=6.7 Hz), 0.96 (3H, d, J=6.4 Hz), 1.14 (3H, s), 1.23
(3H, s), 1.02±1.36 (4H, m), 1.48 (2H, m), 1.60 (1H, d,
J=15.6 Hz), 1.68 (1H, d, J=11.3 Hz), 1.98 (2H, m),
2.17 (1H, m), 2.37 (1H, dd, J=15.6, 9.5 Hz), 2.84 (1H,
q, J=6.5 Hz), 3.04 (3H, s), 3.21 (3H, s), 3.48 (2H, m),
3.81 (1H, ddd, J=10.5, 6.8, 3.3 Hz), 3.99 (1H, d,
J=9.4 Hz), 4.28 (1H, ddd, J=11.2, 5.1, 3.1 Hz), 4.36
(1H, ddd, J=11.2, 6.7, 3.1 Hz), 5.10 (1H, d,
J=17.5 Hz), 5.27 (1H, d, J=10.8 Hz), 6.15 (1H, dd,
J=17.5, 10.8 Hz); MS (NH3DCI) m/z 457 (MH+).
1
give (11, 18 mg, 48%); nmax 1733 cmÀ1; H NMR 0.87
(3H, d, J=6.8 Hz), 0.88 (3H, d, J=7.0 Hz), 1.20 (3H, s),
1.36 (3H, s), 1.33±1.48 (6H, m), 1.66 (3H, m), 1.96 (1H,
dd, J=16.0, 8.3 Hz), 2.07 (1H, brs), 2.20 (3H, m), 3.15
(2H, m), 3.38 (1H, d, J=6.4 Hz), 3.48 (1H, m), 3.66
(1H, m), 3.80 (1H, d, J=8.2 Hz), 4.60 (2H, br), 5.28
(1H, d, J=17.6 Hz), 5.34 (1H, d, J=11.3 Hz), 6.15 (1H,
dd, J=17.3, 11.3 Hz); MS (NH3DCI) m/z 463 (MH+),
C24H38N4O3S.
(3R)-14-O-[2-(3-Amino-1,2,4-triazol-5-yl-thio)-ethyl]-3-
deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-mutilin (9). A
solution of 3-amino-5-mercapto-1,2,4-triazole (50 mg,
0.43 mmol) in 1 M sodium methoxide in methanol
(0.6 mL, 0.6 mmol) was added to an ice-cooled solution
of (8, 133 mg, 0.29 mmol) in acetone (4 mL). The cooling
bath was then removed and the reaction mixture stirred
at room temperature for 24 h before being concentrated
to dryness. The residue was then partitioned between
ethyl acetate and water, dried (magnesium sulphate),
concentrated and puri®ed by silica gel chromatography,
eluting with ethyl acetate, to give (9, 41 mg, 30%); nmax
4-epi-mutilin 14-carbamates (13): route A
(3R)-3-Deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-mutilin
14-(N-phenylcarbamate) (13a). Asolution of ( 5, 1 g,
3 mmol) in dry dichloromethane (3 mL) was treated
with phenyl isocyanate (0.65 mL, 6 mmol) and N,N-di-
isopropylethylamine (1 drop) and the solution was stir-
red at room temperature, with exclusion of moisture,
for 7 days. The solution was then diluted with ethyl
acetate and was washed with 1 M hydrochloric acid,
water and saturated sodium hydrogen carbonate solu-
tion. The solution was then dried (sodium sulphate) and
concentrated to a colourless oil which was puri®ed by
silica gel chromatography yielding (13a, 1.25 g, 92%);
1
1697 cmÀ1; H NMR 0.96 (6H, d, J=6.5 Hz), 1.12 (1H,
m), 1.20 (3H, s), 1.21 (3H, s), 1.31 (3H, m), 1.47 (2H,
m), 1.65 (1H, d, J=15.6 Hz), 1.68 (1H, d, J=11.2 Hz),
1.94 (2H, m), 2.17 (1H, m), 2.38 (1H, dd, J=15.5,
9.7 Hz), 2.83 (1H, q, J=6.3 Hz), 3.20 (3H, s), 3.21 (2H,
m), 3.46 (1H, m), 3.62 (1H, m), 3.82 (1H, m), 4.00 (1H,
d, J=9.4 Hz), 4.64 (2H, br), 5.07 (1H, d, J=17.5 Hz),
5.25 (1H, d, J=10.7 Hz), 6.15 (1H, dd, J=17.5,
10.7 Hz); MS (NH3DCI) m/z 477 (MH+).
n
max 1724, 1695 cmÀ1; 1H NMR 0.89 (3H, d, J=6.9 Hz),
1.00 (3H, d, J=6.4 Hz), 1.20 (3H, s), 1.25 (3H, s), 1.07±
1.37 (5H, m), 1.49 (1H, m), 1.70 (1H, d, J=15.3 Hz),
1.73 (1H, d, J=11.3 Hz), 2.01 (2H, m), 2.21 (1H, m),
2.48 (1H, dd, J=15.2, 10.0 Hz), 2.97 (1H, q,
J=6.4 Hz), 3.24 (3H, s), 3.48 (1H, ddd, J=11.3, 8.1,

G. Brooks et al. / Bioorg. Med. Chem. 9 (2001) 1221±1231
1227
5.2 Hz), 5.02 (1H, d, J=17.5 Hz), 5.32 (1H, d,
J=10.2 Hz), 5.79 (1H, d, J=9.9 Hz), 6.56 (1H, brs),
6.75 (1H, dd, J=17.5, 10.2 Hz), 7.08 (1H, t, J=7.1 Hz),
7.32 (2H, m), 7.42 (2H, m); MS (ESIÀve ion) m/z 452
((MÀH)À).
(3R)-3-Deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-mutilin
14-(N-phenylsulphonyl carbamate) (13n). In 71% yield
from (5, 1 mmol) and benzenesulphonyl isocyanate
1
(2 mmol); nmax 1745, 1698 cmÀ1; H NMR 0.62 (3H, d,
J=6.9 Hz), 0.95 (3H, d, J=6.4 Hz), 1.10 (3H, s), 1.15
(3H, s), 1.48±1.02 (7H, m), 1.67 (1H, d, J=11.3 Hz),
1.99 (2H, m), 2.16 (1H, m), 2.32 (1H, dd, J=15.3,
10.0 Hz), 2.77 (1H, q, J=6.4 Hz), 3.21 (3H, s) 3.37 (1H,
ddd, J=11.1, 8.3, 5.1 Hz), 4.96 (1H, d, J=17.5 Hz), 5.25
(1H, d, J=10.7 Hz), 5.67 (1H, d, J=10.0 Hz), 6.42 (1H,
dd, J=17.5, 10.7 Hz), 7.57 (2H, m), 7.68 (1H, t,
J=7.3 Hz), 8.05 (2H, d, J=7.1 Hz); MS(EI) m/z 517
(M+).
The following compounds were prepared using the
above method (5) and the appropriate isocyanate.
(3R)-3-Deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-mutilin
14-(N-4-methoxyphenyl carbamate) (13b). In 95% yield
from (5, 3 mmol) and 4-methoxyphenyl isocyanate
1
(6 mmol); nmax 1722, 1697 cmÀ1; H NMR 0.89 (3H, d,
J=6.1 Hz), 0.99 (3H, d, J=6.4 Hz), 1.07±1.29 (5H, m),
1.20 (6H, s), 1.34±1.37 (1H, m), 1.70 (1H, d,
J=15.2 Hz), 1.73 (1H, d, J=11.3 Hz), 1.94±2.05 (2H,
m), 2.15±2.24 (1H, m), 2.46 (1H, dd, J=15.2, 10.0 Hz),
2.96 (1H, q, J=6.4 Hz), 3.23 (3H, s), 3.47 (1H, m), 3.80
(3H, s), 5.01 (1H, d, J=17.5 Hz), 5.31 (1H, d,
J=10.6 Hz), 5.77 (1H, d, J=10.0 Hz), 6.43 (1H, broad
s), 6.75 (1H, dd, J=17.5, 10.6 Hz), 6.86 (2H, d,
J=8.9 Hz), 7.31 (2H, broad d); MS (ESI±ve ion) m/z
482 ((MÀH)À).
(3R)-3-Deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-mutilin
14-[N-(4-methoxybenzoyl) carbamate] (13o). Asuspen-
sion of (5, 335 mg, 1.0 mmol), 4-methoxybenzoyl-
chloride (682 mg, 4.0 mmol), and silver cyanate (689 mg,
4.6 mmol) in dry dichloromethane (50 mL) was stirred
for 1 h at room temperature under an atmosphere of
argon. The reaction mixture was then diluted with di-
chloromethane, ®ltered and the ®ltrate washed with 1M
hydrochloric acid, water and saturated sodium chloride
solution. After drying (magnesium sulphate) the crude
material was puri®ed by silica gel chromatography to
(3R)-3-Deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-mutilin
14-(N-4-nitrophenylcarbamate) (13c). In 47% yield from
(5, 3 mmol) and 4-nitrophenyl isocyanate (6 mmol); nmax
1733, 1698 cmÀ1; 1H NMR 0.87 (3H, d, J=6.9 Hz), 1.01
(3H, d, J=6.4 Hz), 1.10±1.90 (6H, m), 1.21 (3H, s), 1.26
(3H, s), 1.68 (1H, d, J=15.2 Hz), 1.75 (1H, d,
J=11.5 Hz), 1.94±2.06 (2H, m), 2.16±2.25 (1H, m), 2.51
(1H, dd, J=15.2, 10.1 Hz), 2.94 (1H, q, J=6.3 Hz), 3.23
(3H, s), 3.47±3.49 (1H, m), 5.04 (1H, d, J=17.5 Hz),
5.32 (1H, d, J=10.6 Hz), 5.82 (1H, d, J=10.1 Hz), 6.70
(1H, dd, J=17.5, 10.6 Hz), 6.93 (1H, broad s), 7.61 (2H,
d, J=9.1 Hz), 8.22 (2H, d, J=9.1 Hz); MS (NH3DCI)
m/z 499 (MH+), m/z 516 (MNH+4 ).
give (13o, 488 mg, 95%); nmax 1774, 1697 cmÀ1 1H
;
NMR 0.90 (3H, d, J=6.9 Hz), 1.00 (3H, d, J=6.4 Hz),
1.07±1.56 (12H, m), 1.20 (3H, s), 1.32 (3H, s), 1.72 (1H,
d, J=15.3 Hz), 1.74 (1H, d, J=11.2 Hz), 1.94±2.04 (2H,
m), 2.16±2.24 (1H, m), 2.53 (1H, dd, J=15.2, 10.1 Hz),
2.91 (1H, q, J=6.2 Hz), 3.23 (3H, s), 3.42±3.50 (1H, m),
3.87 (3H, s), 5.00 (1H, d, J=17.5 Hz), 5.29 (1H, d,
J=10.7 Hz), 5.84 (1H, d, J=9.9 Hz), 6.73 (1H, dd,
J=17.5, 10.7 Hz), 6.97 (2H, d, J=8.9 Hz), 7.81 (2H, d,
J=8.9 Hz); MS (EI) m/z 511 (MH+); (NH3DCI) m/z
512 (MH+).
(3R)-3-Deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-mutilin
14-(N-trichloroacetyl carbamate) precursor to (3R)-3-
Deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-mutilin 14-car-
bamate, (13j). In quantitative yield from (5, 1 mmol)
and trichloroacetyl isocyanate (3.3 mmol); nmax 1737,
(3R)-3-Deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-mutilin
14-(N-benzylcarbamate) (13d). In 95% yield from (5,
3 mmol) and benzyl isocyanate (6 mmol); nmax 1711,
1
1698 cmÀ1; H NMR 0.87 (3H, d, J=6.8 Hz), 0.98 (3H,
d, J=6.4 Hz), 1.18 (3H, s), 1.19 (3H, s), 1.02±1.54 (6H,
m), 1.67 (1H, d, J=15.2 Hz), 1.70 (1H, d, J=11.3 Hz),
1.93±2.04 (2H, m), 2.15±2.23 (1H, m), 2.42 (1H, dd,
J=15.1, 10.0 Hz), 2.95 (1H, q, J=6.4 Hz), 3.22 (3H, s),
3.42±3.51 (1H, m), 4.32 (1H, dd, J=14.9, 5.5 Hz), 4.52
(1H, dd, J=14.9, 6.4 Hz), 4.95 (1H, broad s), 5.01 (1H,
d, J=17.6 Hz), 5.32 (1H, d, J=10.7 Hz), 5.69 (1H, d,
J=9.8 Hz), 6.79 (1H, dd, J=17.6, 10.7 Hz), 7.26±7.37
(5H, m); MS(EI) m/z 467 (M+).
1698 cmÀ1 1H NMR (acetone-d6) 0.85±0.91 (3H, m),
;
1.02 (3H, d, J=6.4 Hz), 1.11±1.79 (14H, m), 1.90±2.23
(3H, m),2.42±2.63 (1H, m), 3.01 (1H, q, J=6.4 Hz),
3.18±3.27 (5H, m), 3.50±3.59 (1H, m), 4.04±4.18 (2H,
m), 4.99 (1H, d, J=17.6 Hz), 5.30 (1H, d, J=10.8 Hz),
5.83±5.87 (1H, m), 6.82±7.91 (4H, m); MS (NH3DCI)
m/z 521 (MH+), m/z 539 (MNH+4 ).
(3R)-3-Deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-mutilin
14-(N,N-dimethylcarbamate) (13h). Asolution of ( 5,
336 mg, 1.0 mmol) and N,N-dimethylcarbamoyl chlo-
ride (0.12 mL, 1.3 mmol) in pyridine (10 mL) was heated
to re¯ux under an atmosphere of argon. Further por-
tions of N,N-dimethylcarbamoyl chloride (0.12 mL,
1.3 mmol) were added to the reaction at daily intervals
during its duration. After 14 days at re¯ux, the reaction
was allowed to cool and then partitioned between ethyl
acetate and 1 M hydrochloric acid. The organic phase
was separated and washed with water followed by satu-
rated sodium chloride solution. After drying (mag-
nesium sulphate) the crude material was puri®ed by
(3R)-3-Deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-mutilin
14-(N-methylcarbamate) (13e). In 37% yield from (5,
1 mmol) and methyl isocyanate (2 mmol); nmax
1
1711 cmÀ1; H NMR 0.85 (3H, br d, J=6.9 Hz), 0.99
(3H, d, J=6.4 Hz), 1.20 (6H, s), 1.00±1.30 (4H, m), 1.47
(1H, m), 1.65 (3H, m), 2.02 (2H, m), 2.20 (1H, m), 2.40
(1H, dd, J=15.3, 9.8 Hz), 2.83 (3H, br d, J=4.8 Hz),
2.95 (1H, q, J=6.4 Hz), 3.23 (3H, s), 3.46 (1H, m), 4.55
(1H, br), 5.01 (1H, d, 17.5 Hz), 5.31 (1H, d, J=10.5 Hz),
5.65 (1H, d, J=9.9 Hz), 6.79 (1H, dd, J=17.5, 10.5 Hz);
MS(EI) m/z 391 (M+).

1228
G. Brooks et al. / Bioorg. Med. Chem. 9 (2001) 1221±1231
silica gel chromatography to give (13h, 158 mg, 40%);
1
(3R)-3-Deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-mutilin
14-(N-methyl-N-phenylcarbamate) (13g). In 81% yield
from (14, 0.75 mmol) and N-methylaniline (2.32 mmol);
nmax 1693 cmÀ1; H NMR 0.87 (3H, d, J=6.7 Hz), 0.98
(3H, d, J=6.4 Hz), 1.07±1.74 (6H, m), 1.20 (3H, s), 1.26
(3H, s), 1.99±2.04 (2H, m), 2.16±2.24 (1H, m), 2.82 (3H,
s), 2.92 (3H, s), 2.92 (1H, m), 3.21 (3H, s), 3.23 (3H, s),
3.46±3.56 (1H, m), 4.28 and 4.76 (ABq, J=15.2 Hz)
with 4.32 and 4.76 (ABq, J=15.7 Hz) (total 2H), 5.01
(1H, d, J=17.6 Hz), 5.32 (1H, d, J=10.2 Hz), 5.72 (1H,
d, J=9.9 Hz), 6.79±6.90 (1H, m), 7.22±7.31 (5H, m);
MS(EI) m/z 405 (M+).
1
nmax 1693 cmÀ1; H NMR 0.82 (3H, m), 0.97 (3H, d,
J=6.4 Hz), 1.02±1.38 (11H, m), 1.58±1.74 (3H, m), 1.99
(2H, m), 2.18 (1H, m), 2.41 (1H, m), 2.92 (1H, m), 3.19
(3H, s), 3.32 (3H, s), 3.45 (1H, m), 5.00 (1H, d,
J=17.5 Hz), 5.30 (1H, d, J=10.7 Hz), 5.69 (1H, m),
6.83 (1H, m), 7.24 (3H, m), 7.37 (2H, m); MS(EI) m/z
467 (M+).
(3R)-3-Deoxo-11-deoxy-3-methoxy-11-oxo-14-O-(mor-
pholinocarbonyl)-4-epi-mutilin (13i). In 57% yield from
(14, 0.75 mmol) and morpholine (2.3 mmol); nmax
4-epi-Mutilin 14-carbamates: route B
1
(3R)-3-Deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-mutilin
14-chloroformate (14). Trichloromethylchloroformate
(0.215 mL, 1.48 mmol) followed by triethylamine
(0.495 mL, 3.56 mmol) were added to an ice-cooled
solution of (5, 1.0 g, 2.97 mmol) in THF (10 mL) under
an atmosphere of argon. The heterogeneous mixture
was stirred at room temperature for 2 h and then treated
with further quantities of trichloromethylchloroformate
(0.215 mL, 1.48 mmol) and triethylamine (0.495 mL,
3.56 mmol). After a further 2 h, the reaction was diluted
with ethyl acetate and washed with saturated sodium
chloride solution. The organic phase was then dried
(magnesium sulphate) and concentrated to a€ord (14,
1.42 g, quant) as a yellow oil which crystallised on
standing. The chloroformate (14) was generally used
without further puri®cation, although this could be
readily achieved by silica gel chromatography; nmax
1691 cmÀ1, H NMR 0.89 (3H, d, J=6.9 Hz), 0.98 (3H,
d, J=6.4 Hz), 1.09 (1H, m), 1.20 (3H, s), 1.23 (3H, s),
1.20±1.52 (5H, m), 1.63 (1H, d, J=15.2 Hz), 1.72 (1H,
d, J=11.3 Hz), 1.99 (2H, m), 2.20 (1H, m), 2.43 (1H, dd,
J=15.2, 10.0 Hz), 2.93 (1H, q, J=6.4 Hz), 3.22 (3H, s),
3.49 (5H, m), 3.66 (4H, m), 5.01 (1H, d, J=17.6 Hz),
5.31 (1H, d, J=10.7 Hz), 5.86 (1H, d, J=9.9 Hz),
6.79 (1H, dd, J=17.6, 10.7 Hz); MS(EI), m/z 447
(M+).
(3R)-3-Deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-mutilin
14-(N-hydroxycarbamate) (13k). In 54% yield from (14,
0.38mmol) and hydroxylamine hydrochloride (0.72
1
mmol); nmax 1720, 1698 cmÀ1; H NMR 0.84 (3H, d,
J=6.9 Hz), 0.99 (3H, d, J=6.4 Hz), 1.19 (6H, s), 1.03±
1.35 (4H, m), 1.49 (2H, m), 1.62 (1H, d, J=15.2 Hz),
1.72 (1H, d, J=11.3 Hz), 1.99 (2H, m), 2.19 (1H, m),
2.45 (1H, dd, J=15.2, 10.1 Hz), 2.89 (1H, q, J=6.4 Hz),
3.21 (3H, s), 3.44 (1H, ddd, J=11.2, 8.0, 5.4 Hz), 5.02
(1H, d, 17.5 Hz), 5.29 (1H, d, J=10.7 Hz), 5.73 (1H, d,
J=9.9 Hz), 6.67 (2H includes 1H, dd, J=17.5, 10.6 Hz),
7.18 (1H, s); MS(FAB) m/z 416 (MNa+).
;
1765, 1732, 1699 cmÀ1 1H NMR 0.92 (3H, d,
J=6.8 Hz), 1.00 (3H, d, J=6.4 Hz), 1.12 (1H, m), 1.22
(3H, s) 1.26 (3H, s), 1.22±1.41 (4H, m), 1.73 (2H, m),
1.98 (1H, m), 2.01 (2H, m), 2.19 (1H, m), 2.58 (1H, dd,
J=15.4, 10.3 Hz), 2.77 (1H, q, J=6.4 Hz), 3.22 (3H, s),
3.44 (1H, ddd, J=11.3, 8.0, 5.3 Hz), 5.04 (1H, d,
J=17.5 Hz), 5.31 (1H, d, J=10.7 Hz), 5.76 (1H, d,
J=10.2 Hz), 6.45 (1H, dd, J=17.5, 10.7 Hz).
(3R)-3-Deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-mutilin
14-(N-dimethylamino carbamate) (13l). In 73% yield
from (14, 0.42 mmol) and 1,1-dimethylhydrazine
1
(3R)-3-Deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-mutilin
14-[N-(2-hydroxyethyl)carbamate] (13f). Ethanolamine
(0.14 mL, 2.25 mmol) was added to a solution of (14,
300 mg, 0.75 mmol) in dichloromethane (5 mL) under an
atmosphere of argon. After stirring for 1 h, the solution
was diluted with dichloromethane and washed with 1M
hydrochloric acid, water and saturated sodium chloride
solution. The solution was then dried (magnesium sul-
phate), concentrated and the crude residue puri®ed by
silica gel chromatography to a€ord (13f, 323 mg,
(0.52 mmol); nmax 1729, 1696 cmÀ1, H NMR 0.84 (3H,
d, J=6.9 Hz), 0.98 (3H, d, J=6.4 Hz), 1.18 (6H, s),
1.05±1.53 (5H, m), 1.64 (3H, m), 1.98 (2H, m), 2.18 (1H,
m), 2.40 (1H, dd, J=14.9, 10.2 Hz), 2.58 (6H,s), 2.92
(1H, q, J=6.4 Hz), 3.21 (3H, s), 3.46 (1H, ddd, J=11.2,
4.7, 2.9 Hz), 4.98 (1H, d, 17.5 Hz), 5.26 (1H, d,
J=10.7 Hz), 5.54 (1H, br s), 5.66 (1H, d, J=9.9 Hz),
6.78 (1H, dd, J=17.5, 10.7 Hz); MS(EI) m/z 420
(M+).
1
100%); nmax 1699 cmÀ1; H NMR (CDCl3) 0.85 (3H, d,
(3R)-3-Deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-mutilin
14-[N-(methanesulphonylamino) carbamate] (13m). In
89% yield from (14, 0.43 mmol) and methanesulphonyl
J=6.9 Hz), 0.95±1.72 (7H, m), 0.98 (3H, d, J=6.4 Hz),
1.23 (6H, s), 1.61 (1H, brs) 1.93±2.04 (2H, m), 2.14±2.36
(1H, m), 2.41 (1H, dd, J=15.2, 10.1 Hz), 2.93 (1H, q,
J=6.4 Hz), 3.22 (3H, s), 3.37±3.48 (3H, m), 3.72 (2H,
m), 5.00 (1H, d, J=17.6 Hz), 5.04 (1H, broad s) 5.29
(1H, d, J=10.6 Hz), 5.69 (1H, d, J=9.9 Hz), 6.73 (1H,
dd, J=17.6, 10.6 Hz); MS (NH3DCI) m/z 422 (MH+),
m/z 439 (MNH+4 ).
1
hydrazide (0.85 mmol); nmax 1716, 1698 cmÀ1, H NMR
0.87 (3H, d, J=6.9 Hz) 1.00 (3H, d, J=6.4 Hz), 1.05±
1.54 (6H, m), 1.21 (3H, s), 1.33 (3H, s), 1.67 (1H, d,
J=15.3 Hz), 1.76 (1H, d, J=11.3 Hz), 2.00 (2H, m),
2.21 (1H, m), 2.57 (1H, dd, J=15.3, 10.1 Hz), 2.87 (1H,
q, J=6.4 Hz), 3.22 (3H, s), 3.33 (3H, s), 3.47 (1H, ddd,
J=11.3, 8.1, 5.3 Hz), 4.32 (2H, s), 5.03 (1H, d,
17.5 Hz), 5.31 (1H, d, J=10.7 Hz), 5.85 (1H, d,
J=10.1 Hz), 6.63 (1H, dd, J=17.5, 10.7 Hz); MS(EI)
m/z 470 (M+).
The following compounds were prepared using the
above method from (14) and the appropriate amine, or
amine hydrochloride.

G. Brooks et al. / Bioorg. Med. Chem. 9 (2001) 1221±1231
1229
Mutilin 14-carbamates
3.34 (1H, dd, J=11.0, 6.7 Hz), 4.47 (1H, br), 5.21 (1H,
dd, J=17.4, 1.6 Hz), 5.37 (1H, br d, J=11.0 Hz), 5.64
(1H, d, J=8.4 Hz), 6.61 (1H, dd, J=17.4, 11.0 Hz);
MS(EI) m/z 377 (M+), C22H35NO4.
Mutilin 14-(N-phenylcarbamate) (15a). Asolution of
(13a, 160 mg) in dioxane (3 mL) was treated with a
saturated solution of zinc chloride in concd hydrochlo-
ric acid (1.2 mL) and the solution was stirred at room
temperature for 3.5 h. The mixture was partitioned
between ethyl acetate and saturated sodium chloride
solution then the organic phase washed with sodium
hydrogen carbonate solution. The solution was dried
(magnesium sulphate), concentrated and the crude resi-
due puri®ed by silica gel chromatography to give (15a,
Mutilin 14-[N-(2-hydroxyethyl)carbamate] (15f). In 47%
1
yield from (13f); nmax 1733, 1712 cmÀ1; H NMR 0.76
(3H, d, J=6.4 Hz), 0.86 (3H, d, J=7.0 Hz), 1.08±1.81
(10H, m) 1.16 (3H, s), 1.40 (3H, s), 2.0 (1H, m), 2.08
(1H, broad s), 2.18±2.24 (2H, m), 2.39 (1H, quintet,
J=6.9 Hz), 3.31±3.38 (3H, m), 3.68 (2H, m), 4.98 (1H,
m), 5.20 (1H, dd, J=17.5, 1.5 Hz), 5.35 (1H, dd,
J=11.3, 1.5 Hz), 5.64 (1H, d, J=8.3 Hz), 6.56 (1H,
dd, J=17.5, 11.3 Hz); MS(EI) m/z 407 (M+),
C23H37NO5.
145 mg, 93%); nmax 1726 cmÀ1; H NMR 0.78 (3H, d
1
J=6.2 Hz), 0.89 (3H, d, J=7.0 Hz), 1.14 (1H, m), 1.19
(3H, s), 1.34±1.52 (4H, m), 1.46 (3H, s), 1.72 (4H, m)
2.12 (2H, m), 2.24 (2H, m), 2.41 (1H, quint, J=6.9 Hz),
3.37 (1H, dd, J=10.9, 6.6 Hz), 5.22 (1H, dd, J=17.5,
1.5 Hz), 5.37 (1H, dd, J=11.0, 1.5 Hz), 5.79 (1H, d,
J=8.3 Hz), 6.50 (1H, s), 6.60 (1H, dd, J=17.4, 11.0 Hz),
7.06 (1H, t, J=7.1 Hz), 7.33 (4H, m); MS(EI) m/z 439
(M+), C27H37NO4.
Mutilin 14-(N-methyl-N-phenyl)-carbamate (15g). In
1
66% yield from (13g); nmax 1734, 1691 cmÀ1; H NMR
0.74 (3H, m), 0.85 (3H, d, J=7.0 Hz), 1.07±1.78 (9H,
m), 1.18 (3H, s), 1.58 (3H, s), 2.05±2.38 (5H, m), 3.28
(3H, s), 3.33 (1H, dd, J=11.2, 6.7 Hz), 5.23 (1H, d,
J=17.6 Hz), 5.38 (1H, d, J=10.7 Hz), 5.71 (1H, m),
6.64 (1H, dd, J=17.6, 10.7 Hz), 7.20 (3H, m), 7.34 (2H,
m); MS(EI) m/z 453 (M+), C28H39NO4.
The following compounds were prepared using the
general procedure described above.
Mutilin 14-[N-(4-methoxyphenyl)]-carbamate (15b). In
1
Mutilin 14-(N,N-dimethyl)-carbamate (15h). In 49%
1
86% yield (13b); nmax 1725 cmÀ1; H NMR 0.79 (3H,
yield from (13h); nmax 1734, 1692 cmÀ1; H NMR 0.73
broad d), 0.87 (3H, d, J=7.0 Hz), 1.18 (3H, s), 1.14±
1.82 (13H, m), 2.04±2.26 (3H, m), 2.37 (1H, quint,
J=6.9 Hz), 3.36 (1H, dd, J=10.9, 6.7 Hz), 3.78 (3H, s),
4.81 (1H, dd, J=17.4, 1.6 Hz), 5.36 (1H, dd, J=10.9,
1.4 Hz), 5.73 (1H, d, J=8.3 Hz), 6.39 (1H, broad s), 6.59
(1H, dd, J=17.4, 10.9 Hz), 6.85 (2H, d, J=8.9 Hz), 7.26
(2H, broad d); MS (EI) m/z 469 (M+), C28H39NO5.
(3H, d, J=6.4 Hz), 0.84 (3H, d, J=7.1 Hz), 1.08±1.80
(5H, m), 1.16 (3H, s), 1.36 (1H, d, J=16.0 Hz), 1.45
(3H, s) 2.00±2.10 (2H, m), 2.18±2.26 (2H, m), 2.37 (1H,
quintet, J=6.9 Hz), 2.86 (3H, s), 2.90 (3H, s), 3.34 (1H,
dd, j=11.3, 6.6 Hz), 5.20 (1H, dd, J=17.4, 1.7 Hz), 5.36
(1H, dd, J=11.0, 1.6 Hz), 5.67 (1H, d, J=8.4 Hz), 6.65
(1H, dd, J=17.4, 11.0 Hz); MS(EI) m/z 391 (M+); MS
(NH3DCI) m/z 392 (MH+), C23H37NO4.
Mutilin 14-[N-(4-nitrophenyl)]-carbamate (15c). In 82%
yield from (13c); nmax 1733 cmÀ1; 1H NMR 0.78 (3H, d,
J=6.5 Hz), 0.92 (3H, d, J=7.0 Hz), 1.20±1.84 (10H, m),
1.20 (3H, s), 1.46 (3H, s), 2.09±2.28 (3H, m), 2.39 (1H,
quintet, J=7.0 Hz), 3.38 (1H, dd, J=10.7, 6.6 Hz), 5.23
(1H, dd, J=17.5, 1.4 Hz), 5.39 (1H, dd, J=10.9,
1.4 Hz), 5.80 (1H, d, J=9.3 Hz), 6.56 (1H, dd, J=17.4,
10.9 Hz), 6.88 (1H, broad s), 7.56 (2H, d, J=9.2 Hz),
8.20 (2H, d, J=9.2 Hz); MS (EI) m/z 484 (M+),
C27H36N2O6.
14-O-(Morpholinocarbonyl)-mutilin (15i). In 55% yield
from (13i); nmax 1733, 1689 cmÀ1, 1H NMR 0.74 (3H, d,
J=6.5 Hz), 0.86 (3H, d, J=7.0 Hz), 1.17 (3H, s), 1.19
(1H, m), 1.43 (3H, s), 1.34±1.54 (4H, m), 1.57±1.81 (4H,
m), 2.04 (1H, m), 2.10 (1H, br), 2.22 (2H, m), 2.36 (1H,
quintet, J=7.0 Hz), 3.35 (1H, dd, J=11.2, 6.6 Hz), 3.43
(4H, m), 3.62 (4H, m), 5.21 (1H, dd, J=17.4, 1.6 Hz),
5.37 (1H, dd, J=11.0, 1.6 Hz), 5.70 (1H, d, J=8.4 Hz),
6.62 (1H, dd, J=17.4, 11.0 Hz); MS(EI) m/z 433 (M+),
C25H39NO5.
Mutilin 14-(N-benzyl)-carbamate (15d). In 82% yield
1H NMR 0.77 (3H, d,
from (13d); nmax 1718 cmÀ1
;
Mutilin 14-(N-hydroxy)-carbamate (15k). In 68% yield
1
J=5.9 Hz), 0.86 (3H, d, J=7.0 Hz), 1.08±1.80 (8H, m),
1.17 (3H, s), 1.39 (1H, s) 1.99±2.07 (3H, m), 2.17±2.24
(2H, m), 2.39 (1H, quintet., J=6.9 Hz), 3.35 (1H, dd,
J=10.8, 6.7 Hz), 4.31 (1H, dd, J=16.0, 5.9 Hz), 4.41
(1H, dd, J=16.0, 6.2 Hz), 4.90 (1H, broad t), 5.20 (1H,
d, J=17.3 Hz), 5.36 (1H, d, J=10.9 Hz), 5.69 (1H, d,
J=8.4 Hz), 6.61 (1H, dd, J=17.3, 10.9 Hz), 7.24±7.43
(5H, m); MS (EI) m/z 391 (M+); MS (NH3DCI) m/z
454 (MH+), C28H39NO4.
from (13k); nmax (KBr) 1728 cmÀ1, H NMR 0.67 (3H,
br d, J=5.7 Hz), 0.81 (3H, d, J=6.8 Hz), 1.06 (4H,
includes 3H, s), 1.26 (3H, m), 1.33 (3H, s), 1.49 (2H, m),
1.65 (2H, m), 2.09 (4H, m), 2.36 (1H,br s), 3.40 (1H,
m,), 4.46 (1H, d, J=6.1 Hz), 5.04 (1H, dd, J=11.1,
1.8 Hz), 5.11 (1H, dd, J=17.7, 1.8 Hz), 5.46 (1H, d,
J=8.0 Hz), 6.24 (1H, dd, J=17.7, 11.1 Hz), 8.59 (1H, s),
9.38 (1H, s); MS(NH3DCI) m/z 397 (MNH+4 ),
C21H33NO5.
Mutilin 14-(N-methyl)-carbamate (15e). In 69% yield
from (13e); nmax 1732, 1714 cmÀ1; 1H NMR 0.76 (3H, d,
J=6 Hz), 0.86 (3H, d, J=7.0 Hz), 1.23 (3H, s), 1.42
(6H, m), 1.70 (4H, m), 2.02 (2H, m), 2.21 (4H, m), 2.37
(1H, quintet, J=6.8 Hz), 2.78 (3H, br d, J=4.8 Hz),
Mutilin 14-(N-dimethylamino)-carbamate (15l). In 89%
1
yield from (13l); nmax 1732 cmÀ1, H NMR 0.76 (3H, d,
J=6.2 Hz), 0.87 (3H, d, J=7.0 Hz), 1.12 (1H, m), 1.16
(3H, s), 1.42 (7H, m), 1.59±1.81 (4H, m), 2.03 (2H, m),
2.22 (2H, m), 2.36 (1H, quintet, J=6.9 Hz), 2.55 (6H, s),

1230
G. Brooks et al. / Bioorg. Med. Chem. 9 (2001) 1221±1231
3.34 (1H, dd, J=10.9, 6.6 Hz), 5.19 (1H, dd, J=17.4,
1.5 Hz), 5.34 (1H, dd, J=11.0, 1.5 Hz), 5.41 (1H, br s),
5.65 (1H, d, J=8.4 Hz), 6.60 (1H, dd, J=17.4, 11.0 Hz);
MS(EI) m/z 406 (M+), C23H38N2O4.
1.5 Hz), 5.62 (1H, d, J=8.5 Hz) 6.57 (1H, dd,
J=17.4, 11.0 Hz); MS(NH3DCI) m/z 364 (MH+),
C21H33NO4.
4,14-Cyclomutilin-11-acetate (17). An ice-cooled solu-
tion of (16, 12.1 g, 30 mmol) in DMF (120 mL) was
purged with argon before treatment with potassium
tert-butoxide (5 g, 50 mmol). The mixture was then stir-
red for 2 h, whilst warming to room temperature, dilu-
ted with ethyl acetate and washed with water. The
organic fraction was dried (magnesium sulphate), con-
centrated and puri®ed by silica gel chromatography to
Mutilin 14-(N-methanesulphonylamino)-carbamate (15m).
1
In 85% yield from (13m); nmax 1733 cmÀ1, H NMR
0.77 (3H, d, J=6.8 Hz), 0.89 (3H, d, J=7.0 Hz), 1.17
(1H, m), 1.19 (3H, s), 1.41±1.81 (8H, m), 1.59 (3H, s),
2.12 (1H, br s), 2.24 (4H, m), 3.29 (3H, s), 3.37 (1H, dd,
J=10.6, 6.7 Hz), 4.28 (2H, s), 5.23 (1H, dd, J=17.4,
1.4 Hz), 5.37 (1H, dd, J=11.0, 1.4 Hz), 5.81 (1H, d,
J=8.6 Hz), 6.48 (1H, dd, J=17.4, 11.0 Hz);
MS(NH3DCI) m/z 474 (MNH+4 ), C22H36N2O6S.
1
give (17, 3.35 g, 32%); nmax 1725, 1697 cmÀ1; H NMR
0.78 (3H, d, J=7.1 Hz), 0.90 (3H, s), 0.94 (3H, d,
J=6.4 Hz), 0.95±1.2 (3H, m), 1.25±1.55 (5H, m), 1.68±
1.8 (2H, m), 1.90 (1H, dd, J=13.4, 1.4 Hz), 2.0±2.2 (5H,
m), 2.2±2.4 (2H, m), 2.6±2.8 (1H, m), 4.53 (1H, d,
J=8.9 Hz), 5.1±5.25 (2H, m), 6.04 (1H, dd, J=17.5,
11.3 Hz); MS(NH3DCI) m/z 345 (MH+).
Mutilin 14-(N-benzenesulphonyl)-carbamate (15n). In
1
88% yield from (13n); nmax 1736 cmÀ1; H NMR 0.51
(3H, d, J=6.7 Hz), 0.85 (3H, d, J=7.0 Hz), 1.07 (3H, s),
1.08 (1H, m), 1.23±1.75 (8H, m), 1.33 (3H, s), 1.95 (2H,
m), 2.19 (3H, m), 3.18 (1H, dd, J=10.1, 6.7 Hz), 5.07
(1H, dd, J=17.5, 1.3 Hz), 5.23 (1H, dd, J=11.0,
1.3 Hz), 5.61 (1H, d, J=8.4 Hz), 6.26 (1H, dd, J=17.5,
11.0 Hz), 7.54 (2H, d, J=7.5 Hz), 7.65 (1H, t,
J=7.4 Hz), 8.00 (2H, d, J=7.4 Hz); MS(EI) m/z 503
(M+), C27H37NO6S.
14-Azido-14-deoxy-mutilin 11-acetate (18). Asuspension
of (17, 2.54 g, 7.4 mmol) and sodium azide (2 g,
30.7 mmol) in DMF (30 mL) was heated under argon at
150 ꢀC for 20 h. After cooling the mixture was diluted
with ethyl acetate and washed with water. The organic
fraction was dried (magnesium sulphate), concentrated
and puri®ed by silica gel chromatography to give (18,
Mutilin 14-[N-(4-methoxybenzoyl)]-carbamate (15o). In
33% yield from (13o); nmax 1776, 1733, 1710 cmÀ1; H
125 mg, 4.5%); nmax 2098, 1728 cmÀ1 1H NMR 0.83
;
1
NMR 0.81 (3H, d, J=6.6 Hz), 0.88 (3H, d, J=7.0 Hz),
1.10±1.81 (9H, m), 1.15 (3H, s), 1.51 (3H, s), 2.09±2.26
(2H, m), 2.12 (1H, bs), 2.35 (1H, quintet J=6.9 Hz),
3.36 (1H, dd, J=11.0, 6.6 Hz), 3.86 (3H, s), 5.22 (1H,
dd, J=17.3, 1.5 Hz), 5.37 (1H, dd, J=11.0, 1.5 Hz), 5.83
(1H, d, J=8.5 Hz), 6.56 (1H, dd, J=17.3, 11.0 Hz), 6.95
(2H, d, J=8.8 Hz), 7.77 (2H, d, J=8.8 Hz), 7.88 (1H,
bs); MS(NH3DCI) m/z 498 (MH+), C29H39NO6.
(3H, d, J=7.1 Hz), 0.94 (3H, d, J=7.3 Hz), 1.08 (3H, s),
1.15 (1H, m), 1.35 (3H, s), 1.36±1.45 (3H, m), 1.65±1.75
(2H, m), 1.85±1.95 (2H, m), 2.0±2.1 (1H, m), 2.11 (3H,
s), 2.13±2.23 (2H, m), 2.25±2.35 (1H, m), 3.93 (1H, d,
J=6.9 Hz), 4.89 (1H, d, J=6.9 Hz), 5.3±5.4 (2H, m),
6.13 (1H, dd, J=18.1, 11.4 Hz); MS(NH3DCI) m/z 405
(MNH+4 ).
N-(14-Amino-14-deoxy-19,20-dihydromutilin) 11-acetate-
14-phenylacetamide. Asolution of
Mutilin 14-(N-trichloroacetylcarbamate). In 60% yield
from (3R)-3-deoxo-11-deoxy-3-methoxy-11-oxo-4-epi-
mutilin 14-(N-trichloroacetylcarbamate); nmax 1803,
(
18, 30 mg,
0.08 mmol) in THF (2 mL) was treated with 10% palla-
dium on charcoal (50 mg) and shaken under an atmo-
sphere of hydrogen for 2 h. The mixture was then
®ltered through kieselguhr and concentrated. The resi-
due was then dissolved in chloroform, cooled in an ice-
bath and treated with triethylamine (0.02 mL,
0.16 mmol) and phenylacetyl chloride (0.02 mL,
0.16 mmol). After 2 h, the solution was washed with
saturated sodium hydrogen carbonate, dried (mag-
nesium sulphate) and concentrated. The residue was
then puri®ed by silica gel chromatography to give N-
(14-amino-14-deoxy-19,20-dihydromutilin) 11-acetate-
14-phenylacetamide (25 mg, 68%); nmax 1725,
1664 cmÀ1; 1H NMR 0.6±0.9 (12H, m), 0.9±1.2 (5H, m),
1.2±1.4 (2H, m), 1.5±2.0 (7H, m), 2.07 (3H, s), 2.1±2.3
(3H, m), 2.7 (1H, m), 3.49 (2H, d, J=16 Hz), 4.7±4.9
(2H, m), 5.49 (1H, d, J=10.2 Hz), 7.1±7.4 (5H, m);
MS(EI) m/z 481 (MH+).
1736 cmÀ1
;
1H NMR (acetone-d6) 0.89 (3H, d,
J=6.8 Hz), 1.01 (3H, d, J=6.4 Hz), 1.11±2.22 (17H, m),
2.55 (1H, dd, J=15.4, 10.1 Hz), 2.91±2.96 (1H, m), 3.19
(3H, s), 3.45±3.55 (1H, m), 5.00 (1H, d, J=17.6 Hz),
5.31 (1H, d, J=10.7 Hz), 5.88 (1H, d, J=10.0 Hz), 6.74
(1H, dd, J=17.6, 10.7 Hz), 10.59 (1H broad s); MS
(ESIÀve ion) m/z 506 ((MÀH)À).
Mutilin 14-carbamate (15j). Mutilin 14-(N-tri-
chloroacetylcarbamate) (300 mg, 0.59 mmol) was dis-
solved in dichloromethane (2 mL) and methanol (2 mL)
then treated with potassium carbonate (122 mg,
0.9 mmol). The reaction was stirred at rt for 4 h before
diluting with dichloromethane. The organic phase was
washed with water followed by saturated sodium chlo-
ride solution, dried (magnesium sulphate), concentrated
and triturated with diethyl ether to give (15j, 179 mg,
85%); nmax 1725 cmÀ1
;
1H NMR 0.79 (3H, d,
N-(14-Amino-14-deoxy-19,20-dihydromutilin) 14-phenyl-
acetamide (19). Asolution of N-(14-amino-14-deoxy-
19,20-dihydromutilin) 11-acetate-14-phenylacetamide
(23 mg, 0.048 mmol) in ethanol (1 mL) was treated with
10 M sodium hydroxide (0.1 mL, 1 mmol) and heated to
re¯ux for 5 h. After cooling, the mixture was diluted
J=6.4 Hz), 0.86 (3H, d, J=7.0 Hz), 1.17 (3H, s), 1.39
(3H, s), 1.38±1.79 (10H, m), 2.14 (1H, d, J=8.6 Hz),
2.09 (1H, broad s), 2.17±2.31 (2H, m), 2.36 (1H, quint,
J=6.9 Hz), 3.35 (1H, broad t), 4.52 (2H, broad s), 5.21
(1H, dd, J=17.4, 1.5 Hz), 5.36 (1H, dd, J=11.0,

G. Brooks et al. / Bioorg. Med. Chem. 9 (2001) 1221±1231
1231
with ethyl acetate and washed with water. The organic
phase was then dried (magnesium sulphate), con-
centrated and puri®ed by silica gel chromatography to
In vitro translation assay (IVT)
Poly(U)-dependent 3H-poly(Phe) synthesis directed by
E. coli ribosomes was used to determine the e€ect of
novel pleuromutilin analogues on in vitro translation.
Results are expressed as percent inhibition relative to
untreated control calculated from the trichloroacetic
1
give (19, 7.5 mg, 35%); nmax 1732, 1664 cmÀ1; H NMR
0.7±0.8 (6H, m), 0.8±1.9 (21H, m), 2.04 (1H, s), 2.1±2.25
(2H, m), 2.61 (1H, quintet, J=6.9 Hz), 3.32 (1H, d,
J=6.2 Hz), 3.48 (2H, d, J=16 Hz), 4.73 (1H, dd,
J=9.5, 6.7 Hz), 5.44 (1H, d, J=10.2 Hz), 7.15±7.4 (5H,
m); MS(EI) m/z 439 (MH+), C28H41NO3.
3
acid precipitated H-poly(Phe) produced.
Acknowledgements
14-Azido-14-deoxymutilin
Asolution of 14-azido-14-deoxy-mutilin 11-acetate
(100 mg, 0.26 mmol) in ethanol (1 mL) was treated with
an ethanolic solution of potassium hydroxide. After
stirring at rt for 18 h, the mixture was partitioned
between ethyl acetate and water. The organic phase was
then dried (magnesium sulphate), concentrated and the
residue puri®ed by silica gel chromatography to give 14-
azido-14-deoxy-mutilin (87 mg, 98%); nmax 2098,
The authors wish to thank Mrs. J. White, Mr. J. W.
Tyler and Mr. D. A. Tolson for the provision of NMR
and mass spectral data.
References and Notes
1. Cohen, M. L. Trends Microbiol. 1994, 2, 422.
2. Kavanagh, F.; Hervey, A.; Robbins, W. J. Proc. Natl.
Acad. Sci. U.S.A. 1951, 37, 570.
3. Arigoni, D. Gazz. Chim. Ital. 1962, 92, 884.
4. Birch, A. J.; Holzapfel, C. W.; Rickards, R. W. Tetrahedron
1996, 8 (part II), 359.
5. (a) Bonavia, G. Ph.D. Thesis, ETH Zurich, 1968, No. 4189.
(b) Dobler, M.; Durr, G. G. Cryst. Struct. Commun. 1975, 4, 259.
6. Hogenauer, G. In Antibiotics; Hahn, F. E. Ed.; Springer-
Verlag, 1979; Vol. V, part I, pp 344±360.
1
1735 cmÀ1; H NMR 0.94 (3H, d, J=7.1 Hz), 0.97 (3H,
d, J=7.3 Hz), 1.05±1.25 (4H, m), 1.32 (3H, s), 1.35±1.85
(9H, m), 1.95±2.1 (2H, m), 2.15±2.3 (2H, m), 3.44 (1H, t,
J=6.5 Hz), 4.03 (1H, d, J=7.2 Hz), 5.30±5.45 (2H, m),
6.16 (1H, dd, J=17.7, 11.4 Hz); MS(NH3DCI) m/z 346
(MNH+4 ).
7. (a) Egger, H.; Reinshagen, H. J. Antibiot. 1976, 29, 915. (b)
J. Antibiot. 1976, 29, 923.
8. Proceedings of the 13th International Congress of Chemo-
therapy, Vienna, 28 August 1983, Abstracts PS 4.6/2-1±PS 4.6/
2-14.
9. Berner, H.; Schultz, G.; Schneider, H. Tetrahedron 1980,
36, 1807: The acid catalysed interconversion of the mutilin and
4-epi-mutilin con®gurations is a reversible process. When the
reaction is carried out in the presence of trimethyl orthoformate,
the resultant O-methyl-oxonium intermediate (R1=Me) serves
to trap the 4-epi-mutilin con®guration. The reverse transforma-
tion is carried out in the presence of aqueous acid
N-(14-Amino-14-deoxy-19,20-dihydromutilin)-N-(4-meth-
oxybenzoyl)-urea (20). Asolution of 14-azido-14-deoxy-
mutilin (40 mg, 0.116 mmol) in THF (3 mL) was treated
with 10% palladium on charcoal (50 mg) and shaken
under an atmosphere of hydrogen for 2 h. The mixture
was then ®ltered through kieselguhr and concentrated
before being redissolved in dichloromethane (1.5 mL).
The solution was then added to an ice-cooled solution
of 4-methoxybenzoyl isocyanate (generated from 4-
methoxybenzoyl chloride (341 mg, 2 mmol) and silver
cyanate (345 mg, mmol)) then stirred at rt for 15 min.
After washing with saturated sodium hydrogen carbon-
ate solution, the reaction mixture was dried (magnesium
sulphate), concentrated and the residue puri®ed by silica
gel chromatography to give (20, 45 mg, 77%); nmax
;
1732, 1705, 1686 cmÀ1 1H NMR 0.65 (3H, d,
J=7.4 Hz), 0.80 (3H, d, J=6.4 Hz), 0.85±0.95 (6H, m),
1.0±1.19 (15H, m), 2.0±2.3 (3H, m), 2.45 (1H, quintet,
J=6.7 Hz), 3.38 (1H, m), 3.86 (3H, s), 4.69 (1H, dd,
J=9.3, 6.5 Hz), 6.94 (2H, d, J=8.9 Hz), 8.05 (2H, d,
J=8.9 Hz), 9.27 (1H, d, J=9.3 Hz), 10.01 (1H, s); MS
(NH3DCI) m/z 499 (MNH+4 ), C29H42N2O5.
10. Acyl isocyanates were prepared in situ by analogy to the
.
method described by: Arcus, C.L.; Prydal, B.S. J. Chem. Soc.,
1954, 4018.
11. Berner, H.; Vyplel, H.; Schultz, G. Monatsh. Chem. 1983,
114, 501.
12. Similar 4,14-cyclopropylmutilin derivatives have been
reported by the Sandoz group: Berner, H.; Vyplel, H.; Schultz,
G. Tetrahedron 1987, 43, 765.
13. (a) Danishefsky, S. Acc. Chem. Res. 1979, 12, 66. (b)
Miller, R. D.; McKean, D. R. J. Org. Chem. 1981, 46, 2412.
14. National Committee for Clinical Laboratory Standards
1993. Methods for Dilution Antimicrobial Susceptibility Tests
for Bacteria that Grow Aerobically. Approved standard M7-A4.
National Committee for Clinical Laboratory Standards,
Wayne, PA, 1993.
Antibacterial activity
The susceptibility of the strains used in this study were
measured by a broth microdilution assay in accordance
with the procedures recommended by the National
Committee for Clinical Laboratory Standards.14 Data
are presented as the minimum inhibitory concentration
(MIC in mg/mL) required to inhibit the growth of the
stated organism.