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92 Chemistry and Biology of Beta-Lactams
Ph
O OMe
OMOM
O
NHAc
O
H
TBS
3
2
R
O
O
ClO
3
https://t.me/med1917
O
2
H
Et
OMOM
N
Me
N
Ph
O
O
NH
3
O
MeSO
K
CO
2
Me
BBu
O
N
Et
O
Cl
,
pyridine
2
3
SCHEME 3.41 Synthesis of Carbapenem Antibiotics.
H2N
H
OH
O
C
3
X
O
K
CO
2
3
Cl
trimethylaluminum
OTBS
H
C
3
N
O OMe
OTBS
H
C
3
N
O
CO
SCH2CH
H
TBSO
H
C
3
O
2NH2
OH
NHCOCH
NH
OEtOH
CH
/Li
3
H2N
H
OMOM
Et
NH
O
MeSO2Cl
,
2
3
pyridine
OTBS
H
C
3
O
Cl
trimethylaluminum
OMOM
TBSO
H
3
NH
C
O
RuO
MeO
NHCOCH
CH
,
4
OH
2N2
OEtOH
N
H
Et
CH
O
3
N
2
H
3
CO2CH2OMe
OTBS
C
O
OMOM
SCH2CH
NH
2
COCH
SCHEME 3.42 Synthesis of Optically Active Thienamycin.
0
N
R
N
1
Et
2
3
,
DCM,
H2N
-78
C-0
0
3-4h
C,
H2N
O
H H
R
2
N
R
1
H2N
O
H H
N
R
ClO
O
CH
3
N
CH
R
SCHEME 3.43 Chiral Synthesis of β-Lactams Using Epoxides.
O-t-butyldimethylsilyl-hydroxylamine was employed to deblock the chiral part. The hydroxamate was
employed for the synthesis of O-pivaloyl hydroxamate (Scheme 3.49). A few subsequent chemical reac-
3
H2N
N
Et
3
H2N
O
H H
O
CH
3
CH
3
N
R
H2N
O
H H
N
R
tions gave trans-β-lactam.
An addition of benzylamine to furanone was identied by Feringa et al.87 This reaction gave trans-βamino lactone (Scheme 3.50). A ring rupture method was performed. This step proceeded via a transesterication-transacetalization reaction. This process helped to prepare γ-substituted β-amino esters. A
direct lactamization was not convenient. A lactamization through the β-amino acids was studied.
The β-amino acid obtained from the ester was cyclized. An indirect method was used for the determination of enantiomeric excess of β-lactam. This result demonstrated that the stereochemical relationship
at the β-carbon is xed during the reaction of amino lactones into β-lactams.
O
R
2
1
O
CH
CH
3
93Polycyclic Beta-Lactams
H
O
pTolSO
2
O
pTolSO
pTolSO
2
OH
Me
Me
MeMe
2
R
1
O
Ph
O
2
Ph
CO
Et
Me
Ph
Ph
https://t.me/med1917
Me
N
H
O
Ph
O
H2N
H
Cl
N-hydroxybenzotriazole
Ethanedithiol,
BF
3
OEt
Potassium
MeOHN
2
hypochlorite
O OH
H
O
HO
S
S
DEAD
HgO,
BF
H
3
and
OE
H
PPh
,
2
N
O
3
THF-H
2
Me
Ph
O
2
H
O
R=
R=CHO
R=
Me
H
N
CH
SCHEME 3.44 Synthesis of β-Lactams from Norephedrine-derived Oxazolidines.
O
N
O
6N
N
HCl
Ph
Ph
Ph
LHMDS
RX
H2N
H NH
CH
3
COOH
.2HCl
Ph
O
N
O
LiAlH
O
H
R
Ph
N
Ph
4
Ph
Li/NH
H2N
(R)
H
,Pd/C
2
(S)
H NH
CuLi
2
R
OMe
HC
3
CH
2
OH
O
OH
R
H
=
R
OH
=
R
MeONH
NaBH
4
S
S
O
N
2
Me
N
O
Ph
H
H
NH
O
O
H
R
Ph
NH
O
3
OH
SCHEME 3.45 Synthesis of Optically Active β-Lactams Using Chiral Systems.
2
Si
N
Si
CH2COOR
*
LDA
R
N
1
R
H2N R
**
N
SCHEME 3.46 Synthesis of Chiral β -Lactams By Enolate Condensation.
O
2
OCH
Et
CO
2
O
N
H
CH2COOH
3
OMOM
CF
(
OH O
HO
O
L
tartaric acid
(+)
O
O O
N
CH2COOH
OH
OMe
+
OH
O
OMOM
N
CH2COOH
+
MeO
H
TEA
O,
2
3
benzalaniline
CO
3
O O
OCH
N
CH2COOR
R
1
O
3
*
*
N
SCHEME 3.47 Synthesis of β-Lactams Using Tartaric Acid Derivative.
Galvez et al.88 described the preparation of chiral β-lactam from the isobornyl cyanopropenoate
(Scheme 3.51). Alkylation of the enolate with halides led to isobornyl 2-alkyl derivatives. These molecules were cyclized to β-amino esters and then to β-lactams. Hydrogenation and another cyclization
produced disubstituted β-lactams.
94 Chemistry and Biology of Beta-Lactams
OAc
3
3
OH
3
OCOC(CH3)
RHN
NHR
O
OH
NHR
O
O
*RO
O
H
/Rh,
Al
O
,
N(Cy)
https://t.me/med1917
OAc
O
AcO
Ph
(COCl)
2.
N
Et
3
OCH
3
O CO
Cat.
DMF,
Bn
2
AcO
AcO
H
Pd/C
,
2
O
O
O
AcO
AcO
OAc
O
OAc
O
O CO
HO CO
BF
Et
3.
H
2
+
Bn
2
O
2
N
SCHEME 3.48 Synthesis of β-Lactams Using Glucose Derivatives.
OH
NH
O-Si(tBu)Ph
2
O
Xc
DMAP
OH
Br
CO
2/K2
3
2
O
NHOSi(tBu)Ph
Br
N
O
3
SCHEME 3.49 Synthesis of Thienamycin β-Lactams.
N
2
OAc
O
AcO
Ph
OCH
TBAF
ClCOC(CH
O CO
AcOH,
3)3
H
2
THF-H
HO
O
2
OH
O
NHOCOC(CH3)
Ph
N
O
OCH
M*O
RNH
O
O
-
N
Cl
I
Me
N
Et
3
2
MeO
O
M*O
OMe
H
N
R
p-TsOH
O
MeO
OMe
OMe
SCHEME 3.50 Synthesis of β-Lactams by Cyclization of Amino Acids.
2
2
3
CH
H2NH
*RO
3
O
MgBr
C
2
(R)
SO
O
2
CN
N(Cy)
O
Ph
R
2
O
2
LDA, THF,
CN
Ph
H
NH
HMPA
/Rh,
2
3
NC
R
NH
3
*RO
Al
O
,
2
3
Ph
(R)
O
R
2CH2NH2
O
R
3
O
2
SO
2
SCHEME 3.51 Synthesis of Chiral β-Lactam from Isobornyl Cyanopropenoate.
NaOH
MeO
OMe
R
Ph
CH
MgBr
3
Ph
NH
R
3
O
R
2
NH
OH O
H
OH O
)
2
tBuO
Ph
O
H
Ph
n-BuLi,
H
OH
Ar
Ph
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EtOH
/Pd-C,
OAnp
tBuMe
2
95%
SiCl,
OBn
2
BnoNH
2
tBu
CAN,
CH
N
Et
3
O(pAn)
N
O
SiMe
OAnp
3
Pyridine
CN,
H
NHOBn
O
2
O
N
DEAD,
OR
R
2
PPh
1
SCHEME 3.52 Synthesis of β-Lactam Antibiotics Intermediates.
THF
LDA,
SiMe
TBDMSiCl
Imidazole
3
OTr
C
2
LiN
OSMDBT
tBuO2C
OTr
NH
Ph
SCHEME 3. 53 Synthesis of β-Lactams Through Aldol Reaction.
O
C
3
CH
SPy
3
BCl3SMe
Base
Ph
2
Ph
3
Ethylmagnesium
bromide
CH
3
NMe
2
N
95Polycyclic Beta-Lactams
H
Pd-C
,
O(pAn)
N
OBnO
H
H
C
3
O
2
TiCl
3
TBDMSO
O(pAn
NH
O
OTr
HH
N
O
H
C
3
N
Ar
SCHEME 3.54 Synthesis of β-Lactams Using Chiral Amino Alcohol.
Guanti et al.89 prepared hydrocamate, which after biometic reaction afforded β-lactam (Scheme 3.52).
In DMF media, side products were formed. A good yield was obtained in THF. Removal of benzyloxy
and p-anisyl groups afforded 4-(hydroxymethyl) azetidinone. This molecule is a key material for the
preparation of thienamycin, isoclavams, and some β-lactam antibiotics.
Yamamoto et al.90 reported an aldol condensation to produce the desired diastereoisomer (Scheme
3.53), which was converted to azetidinone.
Yamamoto et al.91 described the use of optically active amino alcohol as a ligand and as a tertiary
amine for the preparation of β-lactam (Scheme 3.54). Ancillary studies carried out with ephedrine and
N-dimethylephedrine identied the importance of the tertiary amino and the hydroxyl functionalities.
This result showed the unique function of the use of BC13 and amino alcohols in an enantioselective
synthesis of β-lactam.
Miller et al.92 studied the reactions of optically active Schiff bases and threonine derivatives to cissubstituted β-lactams. Reductive, oxidative, or photolytic methods were able to remove the ox group.
This reaction gave cis-β-lactams. A big size of the protecting group on the threonine improved diastereoselectivity. For example, reaction with O-TBDMS-protected threonine esters with oxglycyl chloride
gave cis-β-lactams (Scheme 3.55).
An imine was prepared from D-threonine through its reaction with D-glyceraldehyde acetonide.
Reaction of this imine produced diastereomeric β -lactams.
Braun et al.93 identied an asymmetric synthetic route for both cis- and trans-2-azeditinones using
chiral propionates obtained from R-triphenylglycol. The alcohol ester was deprotonated using LiNiPr2
(Scheme 3.56). The resulting dianion was reacted with imines. The β-lactams were formed in good yield.
The stereochemistry was conrmed by 1H-NMR spectroscopy by comparing coupling constants of the
96 Chemistry and Biology of Beta-Lactams
O
Ph
Ph
Ph
1
OLi
Ph
R
https://t.me/med1917
OHHO
H2N
COC
3
PN
+
X
O
TBDMSCI,
H
H
+
Ox
OH
DMF
O
H H
H
N
O
H
CO2C
3
CH
3
N
R
CO
2
3
H
OH
H H
3
N
CO2C
HCl
H
O
O
H
H
OTBS
HCI,
CH
Ox
O
H2N
HO2C
OxCH
PN
O OH
H
H
OH
COCI,TEA
2
SCHEME 3.55 Synthesis of β-Lactams Using Threonine.
Me
O
O
OH
Ph
O
H
OTBS
LDA
O
O
H
CH
3
H
N
R
O
1
R
CO
2
O
O
H
H
H
H2N
COC
3
Ox
OTBS
H
H
N
O
H
CO2C
3
H
+
H
OTBS
OHC
MgSO
Ox
4
Ph Ph
=
O
TBSO
N
O
O
H
H
N
CO2CH
3
Ph
O
OLi
Ph
OLi
R
G
N
R
R
G
N
Me
G
N
O
Ph
Ph
O
OR
1
LDA
Me
Me
O
G
N
O
Ph
Ph
O
OR
Ph
SCHEME 3.56 Synthesis of β-Lactams Using Chiral Propionates.
hydrogens at C3 and C4. Based on the observations, trans-isomers were formed in major amounts. In
particular examples, the imine condensation provided high enantioselectivity.
The protection of the tertiary hydroxyl group of the propionate as silyl ether or methyl ether helped to
reverse the stereochemical outcome. A monodeprotonation of esters and reaction of the enolate formed
delivered cis-2-azetidinones in some examples.
Shankar et al.94 reacted chiral alcohols with bromoacetyl chloride to prepare esters. Reaction of these
bromoacetates and imine with zinc produced a mixture of β-amino esters. A subsequent Grignard reaction afforded β-lactam (Scheme 3.57).
3-Benzylideneamino-β-lactams were synthesized by Ojima et al.95 These were prepared by reaction
of azidoketene with imino ester. A reduction of the azido group and imine formation was followed.
3-Benzylideneamino-β-lactam was transformed into the bis-β -lactam (Scheme 3.58). The stereochemistry was identied by 1H-NMR, and the conguration was available by converting the compounds to
tripeptides.
I
OBn
F
RO
Me
Ph
N
Ph
N
Ph
N
2
https://t.me/med1917
;
Zn;
2
Dioxanem
H
RO
Br
O
)))
N
BnO
RO
F
O
SCHEME 3.57 Synthesis of β-Lactams by Reformatsky Reaction.
HN
OBn
F
EtMgBr/THF
97Polycyclic Beta-Lactams
N
O
+
CH2COCl
3
N
Et
3
3
N
CO
Me
N
O
Bu
2
3
t
Ph
N Ph
N
O
CO
Me
t
Bu
2
O
N
CH2COCl
3
Et
CH
N,
2Cl2
3
CO
t
Bu
2
N
3
N
CO
Me
t
Bu
2
O
Ph
Ph
3
N
CO
Me
Bu
2
O
H
(1 atm)
2
Pd-C
5%
PhCHO
t
N Ph
N
O
CO
Me
2
Bu
N
t
XHN Ph
O
N Ph
N
O
CO
Me
Bu
Ph
Pd-C
AcHN
H
N
O
t
O
Ph
Me
CO
t
Bu
2
N
H
SCHEME 3.58 Synthesis of β-lactams using Azidoketenes.
The use of (+)-tartaric acid derivative as the ketene precursor toward the synthesis of β-lactams was
demonstrated by Ojima et al.95 (Scheme 3.59). The use of ephedrine-derived chiral ketene afforded product with 90% diastereoselectivity.
An enantiopure 3-siloxy-β-lactam was synthesized using ester enolate-imine reactions by Ojima et
al.96 Because of the acidity of the benzylic protons of the aldimine, the 4-benzyl-β-lactam was not produced. However, it was synthesized from 4-isobutenyl β-lactam (Scheme 3.60).
Ojima et al.97 showed a reaction of styryl β-lactam with m-chloroperoxybenzoic acid in the formation of isomeric epoxides. In addition, the reaction of hydroxyl β-lactam with the same reagent afforded
a single epoxide (Scheme 3.68). N-t-Boc-oxanorstatine methyl ester was produced by ring opening of
epoxide with methanol. Thus, the asymmetric preparation of a cyclopropane or an epoxide system was
available with stereochemical control (Scheme 3.61).
The reaction of chiral ketenes with methylcopper and a quenching with imine were investigated by
Palomo et al.98 The reaction gave the β-lactam. The best outcome was obtained with Gilman reagents.
Some differences were observed when enolates were evaluated with respect to metal enolates obtained
by a deprotonation method. For example, camphorsultam on reaction with LDA and imine produced
β-lactam in low yield (Scheme 3.62). The product was a mixture of two compounds. Interestingly, no
β-lactam was formed in the absence of CuI. This three-component coupling to β-lactam was extended by
the synthesis of a compound that has three contiguous stereogenic parts. The rst step was investigated
H
5%
2
(1 atm)
Pd-C
Ac
O
2
NMM
98 Chemistry and Biology of Beta-Lactams
PhOC
Ph
Ph
Ar
TIPSO
O
PMP
O
Ph
TIPS
t
O
https://t.me/med1917
PhOCO
O
N
O
OH
O
O
N
base
Ar
PhOCO
OCOPh
N
O
O
Ph
O
Ph
base
N
Ar
Me
O
N
N
O
Ar
Ph
O
O
N
OH
O
Me
SCHEME 3.59 Synthesis of β-Lactams Using Tartaric Acid Derivatives.
O
3
N
PMP
O
PhMgBr
Ac
TIPSO
O
2
O
Ph
N
H
2
EtOAc
SCHEME 3.60 Synthesis of β-Lactams Using Ester-Enolate Reaction.
O
N
Bu-t
O
CO
2
m
-CPBA
(3eq.)
TIPSO
H
N
O CO
O
+
Bu-t
2
TIPSO
H
N
O CO
O
Bu-t
2
O
N
Ar
TIPSO
HF/Py
CH
Ph
O
CN/Py
3
Ph
N
Ph
PMP
OHOCO
Ph
N
PhOCO
Me
CAN
(t-Boc)
Bu-t
2
OCOPh
O
N
O
O
N
O
N
O
Ar
O
Ph
N
TIPSO
O
HO
O CO
N
Boc
H
N
Bu-
2
m
O
2
-CPBA
Et
N
3
-tBuO2C-HN
O
OMe
O
OH
SCHEME 3.61 Synthesis of β-Lactams Fused with Cyclopropane.
following the method of Hruby et al.98 The enolate on reaction with an imine gave the product (Scheme
3.62).
An asymmetric synthesis of β-lactam employing chiral ester enolate-imine condensation was performed by Ojima et al.99 Importantly, a TIPS group was required for a highly efcient enantioselective
condensation. The deprotection of the TIPS group and a reaction with chlorodimethylphenylsilane or
chlorotriethylsilane afforded the product. Alkylation was carried out by reacting the β-lactams with
LDA, adding methyl iodide or allyl bromide to give 3-alkyl-ß-lactams as the single isomer (Scheme
3.63).
The removal of the p-anisyl group with ceric ammonium nitrate afforded the desired compound with
desilylated product. The reaction of β-lactams with hydrochloric acid produced α-alkylisoserine derivative. Protection of the β-lactam gave carbonate. Methanolysis produced desilylated α-alkylisoserine
methyl esters. The N-protected α-alkyl compound was used as building blocks for the preparation of
enzyme inhibitors.
A number of cyclic imines (diazeptines and phenantridine) were cyclized with ketene to give polycyclic ß-lactams as trans-isomers
Ohtake et al.
101
identied a condensation method for the preparation of β-lactam that is a main com-
100
(Scheme 3.64).
pound for the preparation of antibiotics. Another approach to the same β-lactam was conducted using
N-methylidenebenzylamine N-oxide. The reaction of silyl enol ether with nitrone and a treatment
with acid produced N-hydroxy-β-amino ester. Hydrogenation and HCl treatment gave β-amino ester
99Polycyclic Beta-Lactams
R
OH
R
1
TIPSO
P
Ph
R
1
O
1
O
Ph
H H
HH
O
Me
https://t.me/med1917
O
*X
[RM]
PMP-N=CHCO
R
Me
2
O
O
X*:
N
S
O
O
X*:
O
O
N
S
O
LDA
PMP-N=CHCO
2
Me
SCHEME 3.62 Synthesis of β-Lactams with Chiral Ketenes.
2
R
N
Et
3
(tBoc)
O
O,
2
N
O
PMP
(NH4Ce(NO3)
6
HF/Pyridine
DMPSiCl
3
R
2
R
O
O
or
NH
TESCl,
1
R
O
N
Ph
Me
Me
3
N
CO
N
PMP
Me
1
R
COOBu
2
R
O
t
HH
N
2
R
O
O
CO
PMP
3
R
2
1
R
N
PM
Me
CO
2
N
PMP
R
H H
O
1
R
N
PMP
Et
N,
3
R
O
Me
CO
2
N
PMP
LDA
MeI or allyl bromide
R
2
R
O
O
HCl
1
R
O
H2N
HCl
.
OH
3
OH
R
SCHEME 3.63 Synthesis of β-Lactams Employing Enolate-Imine Method.
O
O
N
Et
N
O
O
+
N
N
ClO
CO
R
2
N
+
N
3
2
N
Et
3
ClO
Ph
Ph
O
N
O
O
N
O
H H
H H
SCHEME 3.64 Synthesis of β-Lactams Employing Cyclic Imines.
N
Et
HF
3
1
R
O
t
Bu
OCOHN OMe
3
O
1
R
+
N
N
2
R
CO
2
Ph
H H
N
O
R
N
N
2
R
CO
2
O
N
100 Chemistry and Biology of Beta-Lactams
BnH
C
OSiEt
O
OAc
NMe2NMe
Me
EtOOC
R
Ph
O
SP
base
2H5
H
SP
catalyst
https://t.me/med1917
2
+
N
-
O
(TMS)
2
t-BuMgCl
NH,
TMSCl;
Et
3
MeO
SiO
OSiEt
OH
O
ZnI
3
2
AcOH
H
NH
SCHEME 3.65 Synthesis of Chiral β-Lactams.
O
Cl
BQ
R
O
BQ
H R
H
N
NMe
2
Cl
2
O
BQ
H R
(cat.)
t-BuMe
HCl
Ts
H
SiCl
2
(R)
MeO2C
COOEt
(S)
3
NBn
OH
OSiMe
O
H
Pd/C
,
2
HCl
Bu-t
CH3COOH/
2
H
NH
2
Ru
(cat.)
OH
CO
NH
Me
2
OSiMe
H
2.
NH
HCl
Bu-t
2
OMe
N
N
H
OO
O
Ts
N
BQ-Catalyst
SCHEME 3.66 Synthesis of β-Lactams Using Catalyst.
ClO
H
Ph
H
Ts
Ph
N
COOC
Ts
C
OOC
2H5
O
N
Ph
SCHEME 3.67 Asymmetric Synthesis of β-Lactams.
hydrochloride. The β-lactam was then obtained by ring closure and silylation. An oxidative reaction was
performed by ruthenium-catalyzed reaction or using acetaldehyde and O2 to produce a key intermediate
(Scheme 3.65).
An enantiospecic synthesis of β-lactam using a nucleophile reaction of electron-decient ketenes
and imines was reported by Lectka et al.
catalyst, and this afforded a racemic compound. A strong base “proton sponge” was employed as a non-
102
Hünig’s base was used to generate phenylketene with BQ
nucleophilic deprotonating partner. But an initial reaction with it did not produce the ketene. Despite a
strong thermodynamic basic character, it failed to deprotonate carbon-based acids. It was interesting
that toluene precipitates salts and affords the monoketenes. Importantly, BQ served as a shuttle base.
The addition of BQ to phenylacetyl chloride helped to form ketene, and the reaction of the imino ester
produced cis-β-lactam. Therefore, BQ had double catalytic roles as a dehydrohalogenating and a nucleophilic catalyst (Scheme 3.66).
A novel column asymmetric catalysis for the synthesis of β-lactams using catalytic solid-phase base
and solid-phase catalyst was demonstrated by Lectka et al.
103
(Scheme 3.67).
101Polycyclic Beta-Lactams
R
R
1
Ph
O
G
OH
https://t.me/med1917
Sakamoto et al.
104
investigated the mechanism involved in the reaction of thietane formation. The
formation of a six-membered biradical was speculated. Two methods of cyclization to thietane were possible, and they gave enantiomeric products (Scheme 3.68).
A DABCO-induced reaction of vinyl substrates with 4-oxoazetidine-2-carbaldehydes was studied by
Alcaide et al.
105
The presence of bulky group at N1 was able to decrease the efciency of the process. The
carbaldehyde group was not accessible properly to the activated alkene because of steric reasons. The
3-phenoxy group on the β-lactam system ensured a high selectivity, while some other groups dropped
it. A methoxy group lowered the stereoselectivity. The Felkin-Ahn model was used to understand the
origins of the stereochemistry. The large group was assigned to stay perpendicularly to the carbonyl
functionality. The reactive olen attacked the carbonyl group with a favored conformation giving the syn
products (Scheme 3.69).
Palomo et al.
106
synthesized 4-alkenyl β-lactam and reacted it with osmium-catalyzed dihydroxylation.
The conguration between the carbons at the C4 position of the ring and at the side chain was identied. This was necessary to establish the conguration of the product amino acid. The dihydroxylation
1
1
2
R
Me
Ph
S
N
3
R
v
h
O
Ph
S
H
C
2
N
Ph
hv
solid
state
O
S
2
PhR
N
R
O
S
OH
2
b
Me
a
O
Path a
R
H
S
N
2
3
R
b
Ph
a
N
Me
Me
O
Ph
Path b
Me
Ph
S
N
Ph
Ph
Ph
Me
S
N
O
SCHEME 3.68 Synthesis of Thietane β-Lactams.
H H
2
R
O
O
H
2
R
O
H
O
O
N
1
R
Nu
EWG
H
O
N
1
R
DABCO
2
R
O
O
H H
2
R
O
N
O
EW
1
R
OH
EWG
N
1
R
SCHEME 3.69 Synthesis of β-Lactams Derivatives by Catalytic Methods.
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