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Chemistry Letters Vol.38, No.6 (2009)
An Eco-friendly, Convenient, and Practical Conversion of Arylamines to Oxazolidinones
Hang Gong, Nian-Fa Yang,ꢀ Guo-Jun Deng, and Guang-Yi Xu
Key Laboratory of Environment-Friendly Chemistry and Applications of Ministry of Education,
College of Chemistry, Xiangtan University, Xiangtan 411105, P. R. China
(Received April 2, 2009; CL-090330; E-mail: nfyang@xtu.edu.cn)
A one-step procedure for efficient synthesis of oxazolidi-
none only using ethylene carbonate and arylamines in the pres-
ence of 1,4-diazabicyclo[2,2,2]octane (DABCO) was developed.
In most cases, moderate to high yield of products were obtained.
This reaction can be considered a carbon dioxide fixation reac-
tion since ethylene carbonate was synthesized via reaction of
ethylene oxide with carbon dioxide.
Scheme 2. The reaction of dimethyl (Z)-2-butenylene dicarbon-
ate with primary amines in the presence of [Pd(ꢁ3-C3H5)Cl]2
and dppf.
Oxazolidinones, a well-known class of organic compounds,
have many chemical and biological uses. They can be used as
protecting groups in organic synthesis and chiral auxiliaries
(Evans’ chiral auxiliaries) in asymmetric synthesis and as bio-
logically active reagents.1 Usually oxazolidinones are synthe-
sized by reactions of ꢀ-aminoalcohols or other ꢀ-amino com-
pounds with reagents such as phosgene,2 urea,3 dialkyl carbon-
ates,4 or a mixture of carbon monoxide and oxygen via oxidative
carbonylation.5 The synthesis of oxazolidinones by using urea is
limited due to the necessity of high temperature and the forma-
tion of large quantities of polyurea.6 Oxazolidinones can also be
produced from aziridines and carbon dioxide. However, this
route also requires high temperature or has the drawback of poly-
mer formation.7 The synthetic route using phosgene and oxida-
tive carbonylations are not eco-friendly owing to the risk from
using poisonous phosgene or carbon monoxide in the reaction
procedure.2,5 It should be noted that synthesis of dialkyl carbon-
ates also requires such hazardous reagents.8 Recently, Bhanage
and co-workers developed a method which carbon dioxide was
used directly to produce oxazolidinones under high pressure
and high temperature conditions.9
Very recently, the synthesis of oxazolidinones via ethylene
carbonate (EC) and ꢀ-aminoalcohols in the presence of homoge-
nous base catalyst10 or heterogeneous base catalyst11 were re-
ported (Scheme 1). These reactions can be considered as a car-
bon dioxide fixation reaction since EC is synthesized via reac-
tion of ethylene oxide with carbon dioxide.12
Tanimori and Kirihata have reported that the reaction of di-
methyl (Z)-2-butenylene dicarbonate with primary amines in the
presence of [Pd(ꢁ3-C3H5)Cl]2 and 1,10-bis(diphenylphosphino)-
ferrocene (dppf) produced vinyloxazolidone compounds in 70%
yield13 (Scheme 2). However, there are very few reports on the
direct conversion of simple primary amines into oxazolidinones.
Herein, we report a convenient and practical synthesis of
oxazolidinones from EC and aryl amine in the presence of 1,4-
diazabicyclo[2,2,2]octane (DABCO) for the first time. This
Scheme 3. Synthesis of oxazolidinones from EC and aryl amine
in the presence of DABCO.
synthetic method has several advantages: (1) the reaction can
be considered as a carbon dioxide fixation reaction since EC is
synthesized via reaction of ethylene oxide with carbon dioxide;
(2) the oxazolidinones were obtained under mild conditions that
are neither dangerous nor toxic; (3) this reaction is wasteless and
pollution-free; (4) readily available aryl amines are used as sub-
strate; (5) no transition-metal catalyst is necessary. Thus, this
reaction process is environmentally benign and highly atom eco-
nomic (Scheme 3).
To begin our study, the commercially available and inex-
pensive aniline and ethylene carbonate were used as model sub-
strates and DABCO was used as a base catalyst. We found that
the temperature of reaction influences the yield significantly. No
product was observed even if the temperature increased to 60 ꢁC
(Table 1, Entries 1 and 2). A moderate yield of product was ob-
tained when the reaction was carried out at 80 ꢁC (Table 1, Entry
3) and the yield could be improved to 96% by increasing the
temperature to 100 ꢁC in 16 h (Table 1, Entry 4). The reaction
time could be reduced to 5 h which still could give the desired
product in 95% yield (Table 1, Entry 9). Excess DABCO is
required to get a high yield, the yield decreased to 55% when
the amount of DABCO was reduced to one equiv (Table 1, Entry
10). It is worth noting that the reaction should proceeded under
an inert atmosphere of argon to avoid the oxidation of aniline.
With the optimized conditions in hand, the scope of the
reaction with respect to anilines and ethylene carbonate was
investigated. The results are presented in Table 2. The results
showed that aryl amines bearing electron-withdrawing groups
or no substituent at the para- or meta position on the benzene
ring give the corresponding oxazolidinones in high yields
(Table 2, Entries 1 and 2, 4 and 5). Aryl amines with electron-
donating substituents at the para- or meta position on the ben-
zene ring provide the desired products in moderate to good
yields. (Table 2, Entries 8–10). In particular, if there is a sub-
stituent at the ortho position of the benzene ring of the aryl
amine, the reaction yields are much lower (Table 2, Entries 3,
6, 7, and 11). Perhaps the lower yield is partially caused by
the steric effect of the ortho substituent.
Scheme 1. The reaction of ethylene carbonate and ꢀ-aminoal-
cohols in the presence of base catalyst.
Copyright Ó 2009 The Chemical Society of Japan
Gong, Hang
