Sulfamic acid as a cost-effective and recyclable catalyst for protection of carbonyls to acetals and ketals under mild conditions

Article abstract of DOI:10.1081/SCC-200039314

An efficient H₂NSO₃H-catalyzed protection of various carbonyl compounds at room temperature was investigated. The features of mild conditions, cost-efficient catalyst, simple workup, and the recyclability of the catalyst were represented in this process.

Full text of DOI:10.1081/SCC-200039314

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Sulfamic Acid as a
Cost‐Effective and Recyclable
Catalyst for Protection of
Carbonyls to Acetals and
Ketals Under Mild Conditions
Weizhong Gong a b , Bo Wang a , Yanglong Gu a
Liang Yan a , Liming Yang a & Jishuan Suo a c
a State Key Laboratory for Oxo Synthesis and
,
Selective Oxidation, Lanzhou Institute of Chemical
Physics, Chinese Academy of Sciences, Lanzhou,
730000, China
b Institute of Biology of Gansu Academy
c Chengdu Organic Chemicals Co. Ltd., Chinese
Academy of Sciences, China
Version of record first published: 10 Jan 2011.
To cite this article: Weizhong Gong , Bo Wang , Yanglong Gu , Liang Yan , Liming
Yang & Jishuan Suo (2004): Sulfamic Acid as a Cost‐Effective and Recyclable
Catalyst for Protection of Carbonyls to Acetals and Ketals Under Mild Conditions,
Synthetic Communications: An International Journal for Rapid Communication of
Synthetic Organic Chemistry, 34:23, 4243-4247
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SYNTHETIC COMMUNICATIONSw
Vol. 34, No. 23, pp. 4243–4247, 2004
Sulfamic Acid as a Cost-Effective and
Recyclable Catalyst for Protection of
Carbonyls to Acetals and Ketals
Under Mild Conditions
Weizhong Gong,1,2 Bo Wang,1 Yanglong Gu,1 Liang Yan,1
Liming Yang,1 and Jishuan Suo1,3,
*
1State Key Laboratory for Oxo Synthesis and Selective Oxidation,
Lanzhou Institute of Chemical Physics, Chinese Academy of
Sciences, Lanzhou, China
2Institute of Biology of Gansu Academy
3Chengdu Organic Chemicals Co. Ltd., Chinese Academy of
Sciences, China
ABSTRACT
An efficient H2NSO3H-catalyzed protection of various carbonyl com-
pounds at room temperature was investigated. The features of mild
*
Correspondence: Jishuan Suo, State Key Laboratory for Oxo Synthesis and Selective
Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences,
Lanzhou 730000, China, and Chengdu Organic Chemicals Co. Ltd., Chinese
Academy of Sciences, China; Tel.: þ86-931-8277787; Fax: þ86-931-8277088;
E-mail: jssuo@ns.lzb.ac.cn.
4243
DOI: 10.1081/SCC-200039314
0039-7911 (Print); 1532-2432 (Online)
www.dekker.com
Copyright # 2004 by Marcel Dekker, Inc.

4244
Gong et al.
conditions, cost-efficient catalyst, simple workup, and the recyclability of
the catalyst were represented in this process.
Key Words: Carbonyl compounds; Cost-efficient catalyst; Sulfamic acid.
INTRODUCTION
Protection of carbonyls and deprotection of acetals (or ketals) are two of
the most important reactions in organic chemistry, and many methods have
been developed for these reactions.[1] Although a lot of conventional catalysts,
including acid catalysts,[1,2] have been reported for the protection of carbonyls
into dimethyl acetals, the search for a new catalyst is still actively pursued.[3]
Decaborane was proved to be an effective promoter for protection of carbonyls
using orthoformate as protection reagent, however, its application in organic
synthesis may be limited by the high toxicity of boron-containing com-
pounds.[4] Some organic acids, such as p-toluenesulfonic acid, were also effec-
tive for this transformation, but the reaction rate and product yields are, in
some instances, unsatisfactory.[5]
Sulfamic acid (NH2SO3H; SA) is a stable, nonvolatile, nonhygroscopic,
odorless crystalline solid. Recently, it was shown that SA may prospectively
be used as a substitute for conventional acidic catalytic materials. Last year, it
was used as an efficient heterogeneous acid catalyst for ketal formation or
acetalation[6] and Biginelli reaction.[7] Subsequently, we reported sulfamic
acid catalyzed tetrahydropyranylation of hydroxy compounds,[8] esterification
of cyclic olefins with aliphatic acids under solvent-free conditions,[9] transe-
sterification of b-ketoesters in ionic liquids,[10] and Beckmann rearrangement
of ketoxime.[11] Recently, sulfamic acid has been used as a promoter for intra-
molecular imino Diels–Alder reactions to produce tetrahydroquinolines.[12] In
those homogeneous liquid reactions, SA is recyclable and is easy to handle as
a catalyst owing to its immiscibility with common organic solvents. Unique
catalytic features and the intrinsic zwitterionic property of SA are very differ-
ent from the conventional acidic catalyst. This prompted us to explore further
applications of NH2SO3H as an acidic catalyst in carbon–carbon and carbon–
heteroatom forming reactions. Here, we wish to describe the protection of
carbonyls to acetals using a catalytic amount of sulfamic acid (Scheme 1).
Various aldehydes and ketones were efficiently converted to the corres-
ponding diethyl acetals in the presence of triethyl orthoformate using a cata-
lytic amount of sulfamic acid at room temperature, and the results are shown
in Table 1. Yields of these reactions are almost quantitative in most cases.
Sulfamic acid (5 mol%) was used in all of the cases except for acetophenone
(10 mol%). It was noteworthy that sulfamic acid is insoluble in the

Sulfamic Acid as Cost-Effective Catalyst
4245
Scheme 1.
reaction mixture. Thus, it could be recycled by filtration after reaction and
reused in the next run. In the reaction of benzaldehyde, sulfamic acid could
be reused three times without detectable loss of activity.
In summary, sulfamic acid has proved to be an effective catalyst for
protection of carbonyl compounds using triethyl orthoformate as the protec-
tion reagent. Mild conditions, cost-efficient catalyst, simple workup, and the
recyclability of the catalyst are the features obtained in this method.
Table 1. Sulfamic acid catalyzed protection of carbonyls using triethyl orthoformate.
Time Yield
(h)
Time Yield
(h)
Entry
1
Substrates
(%)
Entry
10
Substrates
(%)
1.0
97
2.0
91
2
1.0
95
11
3.0
90
3
4
5
1.0
2.0
2.5
90
94
96
12
13
14
5.0
6.0
6.0
92
86
89
6
7
8
9
2.0
3.0
4.0
4.0
92
92
94
93
15
16
17
18a
4.0
4.0
85
84
87
96
12.0
1.0
aCatalyst was reused three times.

4246
Gong et al.
Another advantage of the use of sulfamic acid as a novel promoter for this
transformation is its green property, because H2NSO3H is a degradable and
metal-free species. This may be the most attractive for the development of
clean organic transformation and green chemistry. Therefore, the present
catalytic method is useful in organic synthesis.
EXPERIMENTAL
Typical Procedure
To a stirred mixture of carbonyl compounds (10 mmol) and triethyl
orthoformate (15 mmol) in a reaction flask, H2NSO3H (1 mmol) was added.
The mixture was stirred at room temperature (258C), and the progress of the
reaction was monitored by Hewlett-Packard 6890/5793 GC/MS. After
completion of the reaction, the catalyst was recovered from the mixture by
filtration, and was then evaporated to give an almost pure product. Further
purification was achieved through a short column of silica gel (2 cm in
length, 0.5 cm in diameter) with petroleum ether to obtain the pure product.
REFERENCES
1. Greene, T.W.; Wuts, P.G.M. Protective Groups in Organic Synthesis, 3rd
Ed.; John Wiley & Sons: New York, 1991; 188.
2. (a) Perio, B.; Dozias, M.J.; Jacquault, P.; Hamelin, J. Solvent Free Protec-
tion of Carbonyl Group under Microwave Irradiation. Tetrahedron Lett.
1997, 38, 7867–7870; (b) Tateiwa, J.; Horiuchi, H.; Uemura, S. Ce3þ-
Exchanged Montmorillonite (Ce3þ-Mont) as a Useful Substrate-Selec-
tive Acetalization Catalyst. J. Org. Chem. 1995, 60, 4039–4043;
(c) Clerici, A.; Pastori, N.; Porta, O. Efficient Acetalisation of Aldehydes
Catalyzed by Titanium Tetrachloride in a Basic Medium. Tetrahedron
1998, 54, 15679–15690; (d) Karimi, B.; Ashtiani, A.M. 2,3-Dichloro-
5,6-dicyano-p-benzoquinone (DDQ) as a Highly Efficient and Mild
Catalyst for Diethyl Acetalization of Carbonyl Compounds. Chem.
Lett. 1999, 1199–1200.
3. Ishihara, K.; Karumi, Y.; Kubota, M.; Yamamoto, H. Scandium Trifluo-
romethanesulfonimide and Scandium Trifluoromethanesulfonate as
Extremely Active Acetalization Catalysts. Synlett 1996, 839–841.
4. Lee, S.H.; Lee, J.H.; Yoon, C.M. An Efficient Protection of Carbonyls and
Deprotection of Acetals using Decaborane. Tetrahedron Lett. 2002, 43,
2699.

Sulfamic Acid as Cost-Effective Catalyst
4247
5. Bonacorso, H.G.; Martins, M.A.P.; Bittencourt, S.R.T.; Lourega, R.V.;
Zanatta, N.; Flores, A.F.C. Trifluoroacetylation of Unsymmetrical
Ketone Acetals. A Convenient Route to Obtain Alkyl Side Chain
Trifluoromethylated Heterocycles. J. Fluorine Chem. 1999, 99, 177–182.
6. Jin, T.S.; Sun, G.; Li, Y.W.; Li, T.S. An Efficient and Convenient
Procedure for the Preparation of 1,1-Diacetates from Aldehydes
Catalyzed by H2NSO3H. Green Chem. 2002, 255–256.
7. Li, J.T.; Han, J.F.; Yang, J.H.; Li, T.S. An Efficient Synthesis of 3,4-
Dihydropyrimidin-2-ones Catalyzed by NH2SO3H under Ultrasound
Irradiation. Ultrasonics Sonochem. 2003, 10, 119–122.
8. Wang, B.; Yang, L.M.; Suo, J.S. Solvent-Free Tetrahydropyranylation of
Alcohols with Sulfamic Acid as Reusable Catalyst. Synth. Commun.
2003, 33, 3929–3932.
9. Wang, B.; Gu, Y.L.; Yang, L.M.; Suo, J.S. Sulfamic Acid as an Efficient
and Recycling Catalyst for Addition of Aliphatic Acid to Cyclic Olefins.
Catal. Lett. 2004, 96 (1–2), 71–74.
10. Wang, B.; Yang, L.M.; Suo, J.S. Ionic Liquid-Regulated Sulfamic Acid:
Chemoselective Catalyst for the Transesterification of b-Ketoesters.
Tetrahedron Lett. 2003, 44, 5037–5039.
11. Wang, B.; Gu, Y.; Luo, C.; Yang, T.; Yang, L.; Suo, J. Sulfamic Acid as a
Cost-Effective and Recyclable Catalyst for Liquid Beckmann Rearrange-
ment; a Green Process to Produce Amides from Ketoximes Without
Waste. Tetrahedron Lett. 2004, 45, 3369–3372.
12. Nagarajan, R.; Magesh, C.J.; Perumal, P.T. Inter- and Intramolecular
Imino Diels–Alder Reactions Catalyzed by Sulfamic Acid: A Mild and
Efficient Catalyst for a One-Pot Synthesis of Tetrahydroquinolines.
Synthesis 2004, 69–74.
Received in Poland June 20, 2004