CAN catalyst in Organic Chemistry

CERIUM(IV) AMMONIUM NITRATE AS A
CATALYST IN ORGANIC SYNTHESIS
Prepared By:-
MOHD UMAR KHAN
En. No. GD 5010
Roll No.6020097

CONTENTS
 INTRODUCTION
 MECHANISTIC PATHWAYS
 APPLICATIONS
 CONCLUSION
 REFERENCES

INTRODUCTION
 Commercially available , use as one-electron
oxidants
 Low toxicity , inexpensive
 Reasonably soluble in many organic media
 Air- stable, easily handled, experimental simplicity
 Current goal is use of catalytic amounts of CAN
 Superior to manganese triacetate for the generation
of radicals

MECHANISTIC PATHWAYS
Various pathways are involved and different
intermediates are formed
I. Generation of radical and radical- cation species
II. Reduction of Ce(IV) to Ce(III)
III. Concomitant regeneration of Ce(IV) by an
external oxidant
IV. Lewis acid catalysis

APPLICATIONS
(A) OXIDATION OF ALCOHOLS
 oxidation of some primary or secondary benzylic alcohols to the
corresponding aldehydes or ketones in the presence of the NaBrO
3

THE YIELD OF THE REACTIONS IS HIGHLY IMPROVED

• THE AEROBIC CATALYTIC OXIDATION OF BENZYLIC AND ALLYLIC
ALCOHOLS USING A CATALYTIC SYSTEM COMPOSED OF CAN AND
2,2,6,6-TETRAMETHYLPIPERIDINYL-1-OXYL (TEMPO)
 Milder conditions and in shorter time with efficient yields

(B)OXIDATION OF ACTIVE METHYLENE
COMPOUNDS
 Direct transformation of diethyl malonate into diethyl ketomalonate by
molecular oxygen
 Optimal reaction conditions involved bubbling oxygen through a
solution of the reactants in acetic acid-acetonitrile

(C) REACTIONS INVOLVING THE GENERATION
OF
CARBON-CARBON BONDS
 Most essential maneuver in synthetic organic chemistry.
 The CAN- induced generation of C-C bonds has been for some time an
important aspect of the synthetic application of Ce(IV) species
(a)Allylation of carbonyl compounds with allyltrimethylsilane:-

(D)ALLYLATION OF 1,3-DIOXO COMPOUNDS
• 1,3-Diketones, such as diethyl malonate, can also be converted to the
corresponding monoallylated products in 74–98% yields under the
same conditions

(E)REMOVAL OF PROTECTING GROUPS
 An efficient reagent for removal of commonly used protecting
groups
 Markó et al. applied CAN as a catalyst in the deprotection of
acetals to give the parent ketones

(F) SYNTHESIS OF BENZOTHIAZOLES
 CAN catalyzes the reaction between o-mercaptoaniline and aromatic
aldehydes at room temperature to give 2-arylbenzothiazoles
 The mechanism of this transformation involves CAN acting both as a
Lewis acid and as an oxidant

CONCLUSION
 Excellent, multipurpose catalyst that can be used to promote a wide
range of synthetically relevant reactions that go well beyond its
traditional role as an oxidant
 The reactions are characterized by their experimental simplicity and
mild reaction conditions.
 Reactions may proceed via processes initiated by a one-electron
oxidation, or alternatively CAN may act as a Brønsted acid catalyst, or
as a Lewis acid
 Low cost and air stability of CAN may make it a useful alternative to
the expensive

REFERENCES
 Ho, T. L. Synthesis 1978, 936.
 Kim, S. S.; Jung, H. C. Synthesis 2003, 2135
 Ho, T. L. Synth. Commun. 1979, 9, 237.
 Zeng, X.-F.; Ji , S.J.; Wang, S.-Y. Tetrahedron 2005, 61, 10235.
 Aggarwal, V. K.; Vennall, G. P. Synthesiett. 2009, 19, 4501.
 Al - Qalaf, F.; Mekheimer, R. A.; Sadek, K. U. Molecules 2008, 13,
2908.
 More, S. V.; Sastry, M. N. V.; Yao, C.-F. s 1998, 1822.
 Sujatha, K.; Shanthi, G.; Selvam, N. P.; Manohara, S.; Perumal, P. T.; Rajendran, M.
Bioorg. Med. Chem. LGreen Chem. 2006, 8, 91.
 Shaabani, A.; Maleki, A. Chem. Pharm. Bull. 2008, 56, 79

CAN catalyst in Organic Chemistry

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CAN catalyst in Organic Chemistry