7/27/2019 Acetato de Manganeso III
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SPOTLIGHT 137
SYNLETT
Spotlight 418
This feature focuses on a re-agent chosen by a postgradu-ate,
highlighting the uses and
preparation of the reagent incurrent research
spotlightManganese(III) Acetate
Compiled by Manoj Mondal
Manoj Mondal was born in Roing, Arunachal Pradesh, India,
in1986. He received his MSc degree in Organic Chemistry in 2010from
Dibrugarh University. He then joined Dr. U. Boras researchgroup at
Dibrugarh University to pursue his PhD studies. His re-search
interests focus on the synthesis of palladium- and copper-based
catalysts for carboncarbon, carbonheteroatom bond-forma-tion
reactions.
Department of Chemistry, Dibrugarh University, Dibrugarh
786004,IndiaE-mail: [email protected]
Dedicated to my honourable mentor Dr. Utpal Bora
Introduction
Manganese(III) acetate [Mn(OAc)3]-mediated free-radi-cal
reactions have emerged as important synthetic meth-
ods. Manganese acetate can be used as an oxidizing
andchlorinating agent1 and in some cases in alkylations1 andinter-
and intramolecular cyclizations.2 Due to the poorsolubility of
Mn(OAc)3 in common organic solvents,Mn(OAc)3-mediated reactions are
often carried out inacetic acid, although other solvents including
toluene, al-cohols, acetonitrile, dichloromethane and
chlorobenzene
can be used.3 Mn(OAc)3 promotes the synthesis of manyalkaloids,4
triterpenes,5 and drugs.6 Mn(OAc)3 is commer-cially available in
form of its dehydrate as a brown pow-der and can be prepared in the
laboratory7 by adding
KMnO4 to a pre-heated mixture of Mn(OAc)2 and glacialacetic acid
(Scheme 1). Addition of acetic anhydride tothe reaction produces
the anhydrous form.8
Scheme 1 Preparation of manganese (III) acetate
Abstracts
Mn(OAc)2 + AcOH + KMnO4
110 CMn(OAc)3 + AcOK + MnO2
20 min
(A) Catalytic amount of manganese acetate in glacial acetic acid
ox-idizes 3-alkyl-substituted 2,4-pyrrolidinediones to their
correspond-
ing 3-hydroperoxy derivatives. This procedure leads to a new
typeof heterocyclic hydroperoxides.9
(B) Manganese acetate-mediated oxidative cyclisation of alkyl
sub-stituted 2-[2-(N-arylamino)-2-oxoethyl]malonates yields the
corre-sponding substituted
4,4-bis(ethoxycarbonyl)-3,4-dihydro-2(1H)-quinolinones in good to
excellent yield (4697%).4c
(C) Manganese acetate generates aryl radicals or cations when
react-ed with aryl boronic acids10a,b or aryl hydrazines10c
preferentially inaromatic solvents (benzene, thiophene) and
subsequently leads tothe formation of biaryls under microwave,10a
room temperature,10b
and reflux10c conditions.
(D) When a catalytic amount of manganese acetate is added to
astirred solution of alkyl- or aryl-substituted alcohol and acetic
acid,acetylation occurs quantitatively (99% yield) within two hours
at re-flux.11
air, 9099%
AcOH, r.t.
N
R1
OHO
R2
N
R1
O
O
R2OOH
R1, R2 = Ar, Alk
Mn(OAc)3
up to 99% yield
+
N O
R2
CO2Et
CO2Et
R1
N O
R2
R1
CO2EtEtO2C
Mn(OAc)3AcOH,
R
B(OH)2
R
Mn(OAc)3 (3 equiv) Mn(OAc)3 (3 equiv)
NHNH2HCl
RPhH PhH
R OHAcOH,
R OAc
Mn(OAc)3
99% yield
SYNLETT2013, 24, 01370138Advanced online publication:
04.12.2012093 6- 5 214 143 7- 20 96DOI: 10.1055/s-0032-1317531; Art
ID: ST-2012-V0425-V
Georg Thieme Verlag Stuttgart New York
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