Triton-B-catalyzed, efficient, one-pot synthesis of carbazates through alcoholic tosylates

Article abstract of DOI:10.1080/00397910802269259

A quick, efficient, one-pot synthesis of carbazates was accomplished in high yields by the reaction of various tosylates of primary, secondary, and tert alcohols, with a variety of substituted hydrazines using the benzyltrimethylammonium hydroxide (Triton-B)/CO2 system. The reaction conditions are mild with simpler workup procedures than the reported methods. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397910802269259

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Triton-B-Catalyzed, Efficient,
One-Pot Synthesis of
Carbazates Through Alcoholic
Tosylates
Devdutt Chaturvedi a , Amit K. Chaturvedi b , Nisha
Mishra b & Virendra Mishra b
a Bio-organic Chemistry Division , Indian Institute of
Integrative Medicine , Jammu-Tawi , India
b Synthetic Research Laboratory, Department of
Chemistry, B.S.A.P.G. College , Mathura , India
Published online: 20 Oct 2008.
To cite this article: Devdutt Chaturvedi , Amit K. Chaturvedi , Nisha Mishra &
Virendra Mishra (2008) Triton-B-Catalyzed, Efficient, One-Pot Synthesis of Carbazates
Through Alcoholic Tosylates, Synthetic Communications: An International Journal
for Rapid Communication of Synthetic Organic Chemistry, 38:22, 4013-4022, DOI:
10.1080/00397910802269259
To link to this article: http://dx.doi.org/10.1080/00397910802269259
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Synthetic Communications1, 38: 4013–4022, 2008
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910802269259
Triton-B-Catalyzed, Efficient, One-Pot Synthesis
of Carbazates Through Alcoholic Tosylates
Devdutt Chaturvedi,1 Amit K. Chaturvedi,2 Nisha Mishra,2
and Virendra Mishra2
1Bio-organic Chemistry Division, Indian Institute of Integrative Medicine,
Jammu-Tawi, India
2Synthetic Research Laboratory, Department of Chemistry,
B.S.A.P.G. College, Mathura, India
Abstract: A quick, efficient, one-pot synthesis of carbazates was accomplished in
high yields by the reaction of various tosylates of primary, secondary, and tert
alcohols, with a variety of substituted hydrazines using the benzyltrimethylammo-
nium hydroxide (Triton-B)=CO2 system. The reaction conditions are mild with
simpler workup procedures than the reported methods.
Keywords: Alcoholic tosylates, benzyltrimethylammonium hydroxide, carba-
zates, carbon dioxide, substituted hydrazines
INTRODUCTION
Organic carbazates have unique applications in the fields of pharmaceu-
ticals[1] and agrochemicals,[2] as intermediates in organic synthesis,[3] for
protection of amino groups in peptide synthesis,[4] as linkers in solid-
phase organic synthesis,[5] and as donor ligands in complexation reac-
tions with transition metals.[6] To satisfy demand, their synthesis has been
changed from the use of costly and toxic chemicals such as phosgene[7]
and its derivatives,[8] directly or indirectly, to the abundantly available
cheap and safe reagents such as CO2. However, their formation using
Received April 23, 2008.
Address correspondence to Devdutt Chaturvedi, Bio-organic Chemistry
Division, Indian Institute of Integrative Medicine, Canal Road, Jammu-
Tawi180001, India. E-mail: ddchaturvedi002@yahoo.co.in
4013

4014
D. Chaturvedi et al.
CO2 employed harsh reaction conditions, such as use of strong bases,
higher reaction temperatures, and longer reaction times.[9] Thus, we were
prompted to embark on improved procedures. Our group[10] has been
engaged during the past several years with the development of new meth-
odologies for the preparation of carbamates, dithiocarbamates, and
related compounds using cheap, abundantly available, and safe reagents
such as CO2 and CS2. Recently,[11] we found that benzyltrimethyl
ammonium hydroxide (Triton-B) is the best catalyst for the synthesis
of carbamates, dithiocarbamates, and dithiocarbonates (xanthates). We
report here an efficient, one-pot synthesis of carbazates from a variety
of alcoholic tosylates of primary, secondary, and tertiary alcohols and
substituted hydrazines using the Triton-B=CO2 system. The alcoholic
tosylates of various alcohols were prepared from the corresponding
alcohols using p-toluene sulfonyl chloride following the standard
procedure.[12]
RESULTS AND DISCUSSION
Substituted hydrazine was taken in dry dimethylsulfoxide (DMSO) and
purified CO2 gas was bubbled in it at 60 ꢀC for 30 min with constant
stirring. Triton-B was slowly added with constant stirring. The reaction
continued for another 30 min, and then corresponding alcoholic tosylate
was added. The reaction was further continued until complete as checked
by Thin-Layer Chromatography (TLC; see Table 1). It is proposed that
the Oꢁ of the carbazate ion produced will attack the electrophilic carbon
of the respective alcoholic tosylates to afford carbazates in high yields
(80–98%) at room temperature in 2–4 h, as mentioned in Table 1. The
reaction proved to be successful, and the desired products were isolated
and their structures confirmed by various spectroscopic and analytical
techniques. Thus, various substituted hydrazines were reacted with a vari-
ety of alcoholic tosylates of primary, secondary, and tertiary alcohols
using the Triton-B=CO2 system to afford the corresponding carbazates
in good to excellent yields (Table 1). The reaction conditions are shown
in Scheme 1.
We have screened several solvents such as n-heptane, n-hexane,
acetonitrile, benzene, toluene, methanol, dichloromethane, chloroform,
DMSO, dimethylformamide, and hexamethylphosphoric triamide, of which
dry DMSO proved to be the most suitable at room temperature.
In conclusion, we developed a convenient and efficient protocol for
the one-pot, three-component coupling of various substituted hydrazines
with a variety of alcoholic tosylates of primary, secondary, and tertiary
alcohols via a CO2 bridge using Triton-B. This method generates the

One-Pot Carbazates Synthesis
4015
Table 1. Conversion of alcoholic toylates into carbazates of formula 1–16
Entry
R1
R2
R3
R
Time (h)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
n-C3H7
PhCH2CH2
PhCH2
Ph
H
H
H
H
Me
H
H
H
H
C4H9
C4H9
H
H
H
H
H
H
H
H
H
H
H
H
H
C4H9
H
H
H
4-MeO-Ph
Ph
Ph
3
3
4
Bn
Bn
4.5
4.5
4.5
4.5
5
4.5
4.5
4.5
3
3
3
4.5
5
C2H5
Ph-4-MeO
C3H7
C3H7
C3H7
C4H9
C4H9
C5H11
C7H15
C9H19
C3H7
Ph-3-NO2
Ph-4-NO2
Ph-2,4-NO2
Naphthyl
Ph
Ph
n-C4H9
Ph
n-C4H9
Ph
Ph
C3H7
CH3
H
H
Ph
aAll the products were characterized by IR, NMR, and mass spectroscopic
data.
bIsolated yields.
corresponding carbazates in good to excellent yields. Furthermore, this
method exhibits substrate versatility, mild reaction conditions, and
experimental convenience. This synthetic protocol is believed to offer a
more general method for the formation of the carbon–oxygen bonds
essential to numerous organic syntheses.
EXPERIMENTAL
Chemicals were procured from Merck, Aldrich, and Fluka chemical
companies. Reactions were carried out under an atmosphere of argon.
IR spectra (4000–200 cmꢁ1) were recorded on a Bomem MB-104 Fourier
Scheme 1.

4016
D. Chaturvedi et al.
transform infrared (FTIR) spectrophotometer using the neat technique,
whereas NMRs were scanned on an AC-300F NMR (300-MHz), instru-
ment using CDCl3 and some other deutrated solvents and TMS as
internal standard. Elemental analyses were conducted by means of a
Carlo-Erba EA 1110-CNNO-S analyzer and agreed favorably with
calculated values.
Typical Experimental Procedure
To a stirred solution (under Ar) of 3 mmol of substituted hydrazine in
5 cm3 of anhyd. DMSO, 2 cm3 Triton-B were slowly added and carbon
dioxide was continuously bubbled in it at 60 ꢀC. Then the mixture was
stirred for 0.5 h, at which point 3 cm3 of the required alkyl halide was
added over a period of 5 min. The stirring was further continued until
the completion of the reaction (cf. Table 1). The reaction mixture was
poured into 20 cm3 of water, and the organic layer was extracted with
3 ꢂ 10 cm3 EtOAc. The organic layer was washed with 20 cm3 of 0.1 N
HCl, 25 cm3 of saturated solution of NaHCO3, and 30 cm3 of brine,
and then dried (Na2SO4) and concentrated to get the desired compound.
Data
N0-(4-Methoxyphenyl) Hydrazine Carboxylic Acid Butyl Ester
(1, C12H18N2O3)
Yield: 94%; mp: oil; IR (neat) t ¼ 1680 cmꢁ1; 1H NMR (CDCl3) d ¼ 0.96
€
(t, 3H, J ¼ 7.3 Hz), 1.34 (m, 2H), 1.86 (m, 2H), 3.73 (s, 3H), 4.12 (t, 2H),
4.85 (m, NH), 6.74–7.66 (m, 4H), 8.0 (br, NH); 13C NMR (CDCl3)
d ¼ 13.7, 19.5, 32.5, 63.5, 112.5, 114.9, 134.5, 152.4, 160.6 (C¼O) ppm;
MS (EI): m=z ¼ 238.
N0-Phenyl Hydrazine Carboxylic Acid 3-Phenyl Propyl Ester
(2, C16H18N2O2)
Yield: 96%; mp: oil; IR (neat) t ¼ 1685 cmꢁ1; 1H NMR (CDCl3) d ¼ 1.92
€
(m, 2H), 2.56 (t, 2H, J ¼ 7.2 Hz, Ph.CH2), 4.10 (t, 2H), 4.67 (br, NHPh),
6.66–7.12 (m, 10H, Ar-H), 8.0 (br, NH); 13C NMR (CDCl3), d ¼ 32.4,
34.4, 63.5, 112.6, 119.4, 125.7, 128.8, 129.6, 138.7, 161 (C¼O) ppm;
MS: m=z ¼ 270.

One-Pot Carbazates Synthesis
4017
N0-Phenyl Hydrazine Carboxylic Acid Phenethyl Ester (3, C15H16N2O2)
Yield: 87%; mp: oil; IR (neat) t ¼ 1681 cmꢁ1; 1H NMR (CDCl3) d ¼ 2.83
€
(2H, t, J ¼ 6.7 Hz, Ph.CH2CH2O), 4.42 (t, 2H, J ¼ 7.2 Hz, PhCH2O), 4.77
(br, H, PhNH), 6.69–7.15 (m, 10H, Ar-H), 8.05 (br, NH); 13C NMR
(CDCl3), d ¼ 35.5, 65.9, 112.3, 118.6, 128.5, 129.5, 140.3, 142.5, 165.4
(C¼O) ppm; MS: m=z ¼ 256.
N0-Butyl Hydrazine Carboxylic Acid Benzyl Ester (4, C12H18N2O2)
Yield: 92%; mp: oil; IR (neat) t ¼ 1680 cmꢁ1; 1H NMR (CDCl3) d ¼ 0.99
€
(t, 3H, CH3), 1.34 (m, 2H, CH2CH3), 1.56 (m, 2H, CH2 ꢃ CH2CH3), 2.15
(br, NH), 2.66 (m, 2H, NHCH2), 5.13 (s, 2H, PhCH2), 7.10–7.19 (m, 5H,
Ar-H), 8.0 (br, NH); 13C NMR (CDCl3), d ¼ 13.8, 20.3, 31.6, 51.2, 69.3,
126.8, 127.6, 128.5, 141.8, 158 (C¼O) ppm; MS: m=z ¼ 222.
N0-Butyl Hydrazine Carboxylic Acid Sec-butyl Ester (5, C9H20N2O2)
Yield: 90%; mp: oil; IR (neat) t ¼ 1681 cmꢁ1; 1H NMR (CDCl3) d ¼ 0.98
€
(t, 3H, CH3), 1.15 (t, 3H, CH3), 1.38 (m, 2H, CH2 ꢃ CH3), 1.42 (d, 3H,
CHCH3), 1.56 (m, 2H, CH3CH2CH2), 2.0 (br, H, NH), 2.66 (m, 2H,
NHCH2), 4.20 (m, CHCH3), 8.0 (br, NH); 13C NMR (CDCl3) d ¼ 8.2,
13.8, 19.2, 20.5, 29.3, 71.4, 156.9 (C¼O) ppm; MS: m=z ¼ 188.
N0-(3-Nitrophenyl)-hydrazine Carboxylic Acid 4-Methoxy Benzyl Ester
(6, C15H15N3O5)
Yield: 85%; mp: oil; IR (neat) t ¼ 1682 cmꢁ1; 1H NMR (CDCl3) d ¼ 3.73
€
(s, 3H, OCH3), 4.05 (br, H, NHPh ꢃ OMe), 5.34 (s, 2H), 6.66–7.69 (m, 8H,
Ar-H), 8.1 (br, NH); 13C NMR (CDCl3) d ¼ 69.3, 107.6, 114.8, 118.8,
128.5, 129.9, 133.6, 143.6, 148.7, 160.6 (C¼O) ppm; MS: m=z ¼ 317.
N0-(4-Nitrophenyl)-hydrazine Carboxylic Acid Butyl Ester
(7, C11H15N3O4)
Yield: 85%; mp: oil; IR (neat) t ¼ 1682 cmꢁ1; 1H NMR (CDCl3) d ¼ 0.99
€
(t, 3H, CH3), 1.36 (m, 2H, CH2CH3), 1.57 (m, 2H, OCH2 ꢃ CH2), 4.04 (br,
N, NHArNO2), 6.92–8.15 (m, 4H, Ar-H), 8.0 (br, NH); 13C NMR
(CDCl3) d ¼ 13.8, 21.7, 32.3, 63.7, 113.5, 124.6, 138.8, 143.3, 159
(C¼O) ppm; MS: m=z ¼ 253.

4018
D. Chaturvedi et al.
N0-(2,4-Dinitro-phenyl)hydrazinecarboxylic Acid Butyl Ester
(8, C11H14N4O6)
Yield: 80%; mp: oil; IR (neat) t ¼ 1681 cmꢁ1; 1H NMR (CDCl3) d ¼ 0.98
€
(t, 3H, CH3), 1.36 (m, 2H, CH2CH3), 1.59 (m, 2H, SCH2 ꢃ CH2), 4.08 (br,
N, NHArNO2), 7.19–9.50 (m, 3H, Ar-H), 8.10 (br, NH); 13C NMR
(CDCl3) d ¼ 13.8, 19.3, 31.8, 63.8, 113.6, 119.2, 130.2, 132.8, 139.7,
143.3, 160 (C¼O) ppm; MS: m=z ¼ 298.
N0-Naphthalen-2-yl Hydrazine Carboxylic Acid Butyl Ester
(9, C15H18N2O2)
Yield: 83%, mp: oil; IR (neat) t ¼ 1681 cmꢁ1; 1H NMR (CDCl3) d ¼ 0.96
€
(t, 3H, CH3), 1.36 (m, 2H, CH2CH3), 1.57 (m, 2H, OCH2 ꢃ CH2), 4.05 (br,
H, Ar-NH), 4.12 (t, 2H), 6.76–7.55 (m, 7H, Ar-H), 8.02 (br, NH); 13C
NMR (CDCl3) d ¼ 13.9, 22.1, 32.5, 33.9, 107.4, 117.2, 121.3, 124.5,
126.6, 127.2, 133.5, 142.6, 161 (C¼O) ppm; MS: m=z ¼ 258.
N0-Phenyl-hydrazine Carboxylic Acid 1-Butyl Pentyl Ester
(10, C16H26N2O2)
Yield: 89%; mp: oil; IR (neat) t ¼ 1682 cmꢁ1; 1H NMR (CDCl3) d ¼ 0.99
€
(t, 6H, CH3), 1.33 (m, 4H, CH2CH2CH), 1.38 (m, 4H, CH2CH3), 1.54 (m,
4H, CHCH2), 3.95 (t, H, OCH), 4.15 (br, H, NHAr), 6.66–7.18 (m, 5H,
Ar-H), 8.0 (br, NH); 13C NMR (CDCl3) d ¼ 14.3, 23.1, 28.5, 36.2, 72.7,
112.2, 119.3, 129.0, 142.4, 158 (C¼O) ppm; MS: m=z ¼ 278.
N0-Phenyl-hydrazine Carboxylic Acid 1,1-Dibutyl Pentyl Ester
(11, C20H34N2O2)
Yield: 88%; mp: oil; IR (neat) t ¼ 1684 cmꢁ1; 1H NMR (CDCl3) d ¼ 0.96
€
(t, 9H, CH3), 1.29 (m, 4H, CH2CH2C), 1.33 (m, 4H, CH2CH3), 1.50 (m,
4H, CHCH2), 4.0 (br, H, NH-Ar), 6.67–7.19 (m, 5H, Ar-H), 8.0 (br, NH);
13C NMR (CDCl3) d ¼ 14.3, 23.5, 26.8, 39.8, 72.4, 112.5, 119.3, 129.6,
142.2, 162 (C¼O) ppm; MS: m=z ¼ 334.
N0-Butyl-hydrazine Carboxylic Acid Hexyl Ester (12, C11H24N2O2)
Yield: 96%; mp: oil; IR (neat) €t ¼ 1684 cmꢁ1; 1H NMR (CDCl3) d ¼ 0.98
(t, 6H, CH3), 1.30 (m, 4H, CH2CH2CH2CH3), 1.36 (t, 2H, CH2CH3),

One-Pot Carbazates Synthesis
4019
1.58 (m, 2H, NHCH2CH2), 1.63 (t, 2H, CH2N), 2.0 (br, 2H, NH), 2.66
(t, 2H, NHCH2), 4.10 (t, 2H, OCH2), 8.0 (br, NH); 13C NMR (CDCl3)
d ¼ 13.7, 14.1, 20.2, 23.1, 28.6, 31.5, 32.6, 69.5, 164.5 (C¼O) ppm; MS:
m=z ¼ 216.
N0-Phenyl-hydrazine Carboxylic Acid n-Octyl Ester (13, C15H24N2O2)
Yield: 96%; mp: oil; IR (neat) €t ¼ 1685 cmꢁ1
;
1H NMR (CDCl3)
d ¼ 0.96 (t, 3H, CH3), 1.30 (m, 8H, CH2), 1.35 (m, 2H, CH2CH3), 1.63
(m, 2H, OCH2CH2), 4.0 (br, H, Ph.NH), 4.12 (t, 2H, OCH2), 6.66–7.25
(m, 5H, Ar-H), 8.0 (br, NH); 13C NMR (CDCl3) d ¼ 14.5, 23.10, 27.5,
30.5, 32.5, 63.6, 112.2, 129.6, 118.9, 142.2, 163 (C¼O) ppm; MS:
m=z ¼ 264.
N0-Butyl Hydrazine Carboxylic Acid Decyl Ester (14, C15H32N2O2)
Yield: 98%; mp: oil; IR (neat) t ¼ 1683 cmꢁ1; 1H NMR (CDCl3), d ¼ 0.97
€
(s, 3H, CH3), 0.99 (s, 3H, CH3), 1.29 (m, 12H, CH2), 1.34 (m, 4H,
CH2CH3), 1.57 (m, 2H, CH2CH2CH3), 2.0 (br, NH), 2.65 (m, 2H,
NHCH2), 4.12 (t, 2H, OCH2), 8.0 (br, NH); 13C NMR (CDCl3)
d ¼ 13.7, 14.5, 20.3, 23.1, 28.9, 30.6, 30.9, 31.5, 32.5, 63.5, 160 (C¼O)
ppm; MS: m=z ¼ 272.
N0-Phenyl Hydrazine Carboxylic Acid 1-Propyl Butyl Ester
(15, C14H22N2O2)
Yield: 86%; mp: oil; IR (neat) t ¼ 1680 cmꢁ1; 1H NMR (CDCl3) d ¼ 0.97
€
(s, 3H, CH3), 1.33 (m, 4H, CH2CH3), 1.54 (m, 4H, CHCH2), 3.95 (m, H,
CH-O), 4.1 (br, H, NH-Ar), 6.66–7.22 (m, 5H, Ar-H), 8.0 (br, NH); 13C
NMR (CDCl3) d ¼ 14.5, 20.1, 38.4, 72.8, 112.5, 118.3, 129.6, 143.3, 160
(C¼O) ppm; MS: m=z ¼ 250.
N0-Phenyl Hydrazine Carboxylic Acid 1-Phenyl Ethyl Ester
(16, C15H16N2O2)
ꢁ1
;
1H NMR (CDCl3)
€
Yield: 82%; mp: oil; IR (neat) t ¼ 1682 cm
d ¼ 1.69 (d, 3H, CH3), 4.2 (br, H, NH-Ph), 5.42 (m, H, CH-O), 6.66–
7.22 (m, 10H, Ar-H), 8.0 (br, NH); 13C NMR (CDCl3) d ¼ 23.4, 74.2,
112.5, 118.9, 126.5, 128.5, 129.7, 141.3, 142.5, 163.5 (C¼O) ppm;
MS: m=z ¼ 256.

4020
D. Chaturvedi et al.
ACKNOWLEDGMENT
Authors thank the SIAF division of Central Drug Research Institute for
providing spectroscopic and analytical data.
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One-Pot Carbazates Synthesis
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