Use of N-acyl or N-alkyloxycarbonyl-aminotetrachlorophthalimides for the preparation of alkylhydrazines via the mitsunobu protocol

Article abstract of DOI:10.1081/SCC-120014971

N-acyl and N-alkyloxycarbonyl tetrachloro-aminophthalimides which are best acidic partners in the Mitsunobu reaction and more easily dephthaloylated than their unsubstituted analogs can be used efficiently for the preparation of 1,1-substituted hydrazines.

Full text of DOI:10.1081/SCC-120014971

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USE OF N-ACYL OR N-ALKYLOXYCARBONYL-
AMINOTETRACHLOROPHTHALIMIDES FOR THE
PREPARATION OF ALKYLHYDRAZINES VIA THE
MITSUNOBU PROTOCOL
Maria-Fatima Pinto a , Nicolas Brosse a & Brigitte Jamart-Grégoire b
a MAEM UMR CNRS-UHP n°7567 , Faculté des Sciences , Université H. Poincaré Nancy 1 , Bld.
des Aiguillettes BP 239, Vandoeuvre-lès-Nancy, F-54506, France
b MAEM UMR CNRS-UHP n°7567 , Faculté des Sciences , Université H. Poincaré Nancy 1 , Bld.
des Aiguillettes BP 239, Vandoeuvre-lès-Nancy, F-54506, France
Published online: 16 Aug 2006.
To cite this article: Maria-Fatima Pinto , Nicolas Brosse & Brigitte Jamart-Grégoire (2002) USE OF N-ACYL OR N-
ALKYLOXYCARBONYL-AMINOTETRACHLOROPHTHALIMIDES FOR THE PREPARATION OF ALKYLHYDRAZINES VIA THE MITSUNOBU
PROTOCOL, Synthetic Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry,
32:23, 3603-3610, DOI: 10.1081/SCC-120014971
To link to this article: http://dx.doi.org/10.1081/SCC-120014971
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SYNTHETIC COMMUNICATIONS
Vol. 32, No. 23, pp. 3603–3610, 2002
USE OF N-ACYL OR
N-ALKYLOXYCARBONYL-
AMINOTETRACHLOROPHTHALIMIDES
FOR THE PREPARATION OF
ALKYLHYDRAZINES VIA THE
MITSUNOBU PROTOCOL
Maria-Fatima Pinto, Nicolas Brosse,
*
and Brigitte Jamart-Gregoire
MAEM UMR CNRS-UHP nꢀ7567, Faculte des
Sciences, Universite H. Poincare Nancy 1.,
Bld. des Aiguillettes BP 239 F-54506
Vandoeuvre-les-Nancy, France
ABSTRACT
N-acyl and N-alkyloxycarbonyl tetrachloro-aminophthali-
mides which are best acidic partners in the Mitsunobu
reaction and more easily dephthaloylated than their unsubsti-
tuted analogs can be used efficiently for the preparation of
1,1-substituted hydrazines.
*Corresponding author. Fax: 33 (0)3 83 91 27 48; E-mail: brigitte.jamart@maem.
uhp-nancy.fr
3603
DOI: 10.1081/SCC-120014971
Copyright & 2002 by Marcel Dekker, Inc.
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3604
PINTO, BROSSE, AND JAMART-GREGOIRE
Scheme 1.
N-substituted and N,N-bis-(substituted) hydrazines are very useful
compounds[1] and are notably used for the synthesis of azapeptides,[2]
[4]
heterocyclic compounds[3] and a-hydrazinoacid derivatives.
Recently,
we showed that Na-alkyl Nb-protected hydrazines 2 could be efficiently
obtained starting from N-acyl and N-alkyloxycarbonyl aminophthali-
mides[5,6] via Mitsunobu protocol (Sch. 1).
An ultimate dephthaloylation step using methylhydrazine in THF
allowed the formation of the corresponding Na-alkylhydrazines. Unfortu-
nately, in some cases these conditions failed and compounds 3 were
obtained in poor yields even when a large excess of methylhydrazine was
used.[6] To avoid the harsh procedure needed for phthalimide deprotection
we were interested in the use of tetrachloro analog for nitrogen protection,
the tetrachlorophthaloyl group is known to be removed more easily.[7] In
this paper we compared the results obtained in both Mitsunobu protocol
and dephthaloylation step starting from phthalimide and tetrachloro-
phathlimide derivatives.
PREPARATION OF COMPOUNDS 1 X5Cl
Compounds 1 X¼H and Cl were obtained for R¼OtBu, OCH2Ph and
Ph is respectively 96, 91 and 88% yields by condensing in refluxed toluene
the corresponding and commercially available carbamate or hydrazide onto
the phthalic or tetrachlorophthalic anhydride.
MITSUNOBU REACTION
The results are reported in the Table 1. When starting from the less
sterically hindered compounds 1 R¼OCH2Ph or Ph, the corresponding
compounds 2 were isolated in good to excellent yields whatever the presence
or the absence of chlorine atom on the aromatic ring. Nevertheless, when

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PREPARATION OF ALKYLHYDRAZINES
3605
Table 1.
Assay
X
R
R0
2%a
3%b
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
H
Cl
H
Cl
H
Cl
H
Cl
H
Cl
H
Cl
H
Cl
H
OCH2Ph
OCH2Ph
OtBu
Methyl
Methyl
72
95
0
94
88
–
71
42
91
0
79
0
75
55
84
–
Cyclohexyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
OtBu
33
47
45
80
78
92
80
50
70
0
13c
74
70
0
52c
90
92
OCH2Ph
OCH2Ph
OtBu
OtBu
10-(Propyl)butyl
10-(Propyl)butyl
OCH2Ph
OCH2Ph
OtBu
10-(Propyl)butyl
10-(Propyl)butyl
(CH3)2CHCH2CH2COOBn
(CH3)2CHCH2CH2COOBn
(CH3)2CHCH2COOBn
(CH3)2CHCH2COOBn
(CH3)2CHCH2COOBn
(CH3)2CHCH2COOBn
PhCH2CH2COOBn
PhCH2CH2COOBn
Methyl
OtBu
OtBu
OtBu
–
OCH2Ph
OCH2Ph
OtBu
OtBu
Ph
Ph
35
82
–
–
40
95
Cl
H
Cl
H
Cl
Methyl
b
c
aYields in 2 calculated from 1; Yields in 3 calculated from 2; Reaction time: 24 h.
compounds 1 R¼OCH2Ph, X¼H and X¼Cl were allowed to compete for
4-heptanol, compound 2 R¼OCH2Ph, X¼Cl, R0¼4-heptyl was exclusively
isolated in 78% yield (Sch. 2).
This result is in agreement with those obtained by Fraser-Ried and
Coll,[8] and could be explained by a enhancement of the acidity of the NH
proton in tetrachlorophthalimide derivatives. More interestingly, we found
that the use of tetrachloro compounds 1 X¼Cl instead of unsubstituted
analogs 1 X¼H contributes to enhance the condensation of sterically-
hindered substrates. So, no reaction occurred when the N-tert-butyloxy-
carbonyl-aminophthalimide (1 X¼H, R¼OtBu) was condensed onto the
cyclohexanol (assay 3). In contrast, when using compound 1 X¼Cl,
R¼OtBu instead of its unsubstituted analog we were able to isolate the
corresponding compound 2 X¼Cl, R¼OtBu in 33% yield (assay 4).
The same effect was observed when hindered a-hydroxyesters were used
as alcohol partners (assays 13 and 17 compared respectively to assays 14
and 18). This last result suggests that in our case, the acidity of the NH
proton is not the only factor responsible of the enhancement of these

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3606
PINTO, BROSSE, AND JAMART-GREGOIRE
Scheme 2.
Mitsunobu reactions. The elucidation of the mechanism is under active
investigation.
DEPHTHALOYLATION
The dephthaloylation of compounds 2 X¼Cl and compounds 2 X¼H
were performed respectively by using ethylenediamine (2 eq.) and methylhy-
drazine (1.5 eq.) in THF. As expected, in most of the cases, the tetrachlor-
ophthalimide group was removed more easily than the unsubstituted one,
leading to the formation of compounds 3 in excellent togood yields. As
examples, the assays 7 and 9 showed that the dephthaloylation of com-
pounds 2 X¼H, R¼OCH2Ph, R0¼4-Heptyl and 2 X¼H, R¼OtBu, R0¼4-
Heptyl didn’t occur at all, on the contrary, compounds 3 R¼OCH2Ph,
R0¼4-Heptyl and 3 R¼OtBu, R0¼4-Heptyl (assays 8 and 10) were easily
obtained from the tetrachloro analogs respectively in 75% and 79% yields.
CONCLUSION
We showed that N-alkyloxycarbonyl-aminotetrachlorophthalimides
are better acidic partners in the Mitsunobu reaction than their unsubstituted
analogs. Interestingly, the presence of four atoms of chlorine on the aro-
matic ring enhances also the reaction performed with sterically-hindered
substrates. As expected, the dephthaloylation step was also more effective
when a tetrachloro analog is used.
EXPERIMENTAL SECTION
General: Melting points were obtained on a hot-stage apparatus and
were uncorrected. NMR spectra were recorded on spectrometers operating

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PREPARATION OF ALKYLHYDRAZINES
3607
at 400 MHz or 250 MHz. Mass spectra were performed by the ULIRS Mass
Spectroscopy Facility (the School of Farmacy, London). Tetrahydrofuran
were dried by distilling over sodium-benzophenone.
N-Benzyloxycarbonylaminotetrachlorophthalimide (1 R5OCH2Ph,
X5Cl): (m.p. 210ꢀC); IR (NaCl) ꢀmax/cmÀ1 1800, 1748, 1707; H NMR
1
(400 MHz, DMSO d 6) 10.66–10.51 (m, 1H), 7.48–7.17 (m, 5H), 5.20 (s,
2H); 13C NMR (DMSO d 6) 161.7, 155.7, 140.0, 136.6, 129.8, 129.3, 129.1,
129.0, 126.8, 68.1; HRMS calcd for C16H12N3O4Cl4 ½M+NHþ4 ꢁ m/z
449.9582. Found 449.9579.
N-tert-Butyloxycarbonylaminotetrachlorophthalimide (1 R5OtBu,
X5Cl): (m.p.>260ꢀC); IR (NaCl) ꢀmax/cmÀ1 1799, 1746, 1703; H NMR
1
(400 MHz, DMSO d 6) 10.12 (s, 1H), 1.47 (s, 9H); 13C NMR (DMSO d 6)
162.0, 154.5, 140.0, 129.7, 126.9, 82.3, 28.7; HRMS calcd for
C13H14N3O4Cl4 ½M þ NHþ4 ꢁ m/z 418.0788. Found 418.0792.
N-Benzoylaminotetrachlorophthalimide (1 R5Ph, X5Cl): (m.p.>
260ꢀC); IR (NaCl) ꢀmax/cmÀ1 1799, 1740, 1664; 1H NMR (400 MHz, DMSO
d 6) 8.03–7.91 (m, 2H), 7.63–7.45 (m, 3H); HRMS calcd for C15H10N3O3Cl4
½M+NHþ4 ꢁ m/z 419.9476. Found 419.9448.
General Procedure for the Alkylation of N-Acyl or
N-Alkoxycarbonylaminophthalimide with Alcohols
(Mitsunobu’s Protocol)
To a solution of 1 (5 mmol), PPh3 (7.5 mmol), alcohol (R-OH, 5 mmol),
in dry THF and under Nitrogen was added in one portion DEAD (7.5 mmol)
with stirring at 0–5ꢀC. The resulting solution was stirred at room temperature
(monitored by TLC until completion) and concentrated in vacuo. The residue
was triturated in AcOEt and most of the triphenylphosphine oxide and
diethylhydrazinedicarboxylate was removed by filtration. The filtrate was
evaporated and the residue was chromatographed on silica gel.
1
The observation of two sets of resonance for some graphs in H and
13C NMR spectra suggested that compounds 2 were present as twoisomers.
We already have observed this phenomenon in the preparation of hydrazine
derivatives[5,6] which result from hindered rotation about the nitrogen to
carbonyl bond and permit to distinguish between Z and E forms.
Characteristics of Representatives Compounds
N-Methyl-N-benzyloxycarbonylaminotetrachlorophthalimide (2 R5
OCH2Ph, R05Methyl, X5Cl): (m.p. 176–178ꢀC); IR (NaCl) ꢀmax/cmÀ1

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3608
PINTO, BROSSE, AND JAMART-GREGOIRE
1
1797, 1737; H NMR (400 MHz, DMSO d 6) 7.40–7.15 (m, 5H), 5.23 and
5.12 (2s, 2H), 3.31 and 3.25 (2s, 3H); 13C NMR (DMSO d 6) 160.8, 160.6,
155.0, 154.8, 140.3, 136.2, 130.0, 129.2, 129.0, 128.7, 128.6, 127.8, 126.8,
69.1, 68.5, 38.1, 37.2; HRMS calcd for C17H14N3O4Cl4 ½M+NHþ4 ꢁ m/z
465.9708. Found 465.9698.
N-Cyclohexyl-N-benzyloxycarbonylaminophthalimide (2 R5OCH2Ph,
R05Cyclohexyl, X5H): (m.p. 112ꢀC); IR (NaCl) ꢀmax/cmÀ1 1796, 1740,
1
1721; H NMR (400 MHz, CDCl3) 7.92–7.68 (m, 4H), 7.40–7.00 (m, 5H),
5.24 and 5.08 (2s, 2H), 4.40–4.08 (m, 1H), 2.20–2.00 (m, 2H), 1.84–0.84 (m,
8H); 13C NMR (CDCl3) 166.1, 153.5, 135.8, 134.9, 129.8, 128.5, 128.3,
128.2, 127.8, 127.0, 123.9, 67.8, 58.5, 31.3 and 30.8, 25.5 and 25.2; HRMS
Calcd. for C22H26N3O4 ½M+NH4þꢁ m/z 396.1923. Found 396.1912.
N-Cyclohexyl-N-benzyloxycarbonylaminotetrachlorophthalimide
(2
R5OCH2Ph, R05Cyclohexyl, X5Cl): (m.p. 180ꢀC); IR (NaCl) ꢀmax/cmÀ1
3033, 1797, 1739, 1733; 1H NMR (400 MHz, DMSO d 6) 7.49–6.99 (m, 5H),
5.24 and 5.08 (2s, 2H), 4.25–3.96 (m, 1H), 2.04–0.81 (m, 10H); 13C NMR
(DMSO d 6) 162.3, 140.4, 136.6, 130.0, 129.3, 127.7, 126.7, 68.2, 31.3, 30.7,
25.8, 25.5.
N-10-(Propyl)butyl-N-benzyloxycarbonylaminophthalimide (2 R5
OCH2Ph, R051-(propyl)butyl, X5H): (m.p. 113ꢀC); IR (NaCl) ꢀmax/cmÀ1
1
1797, 1744; H NMR (400 MHz, CDCl3) 7.90–7.84 and 7.80–7.74 (m, 4H),
7.42–7.29 and 7.23, 7.06 (m, 5H), 5.22 and 5.10 (2s, 2H), 4.42 and 4.23 (2
quint, 1H), 1.74–1.29 (m, 8H), 1.00–0.84 (m, 6H); 13C NMR (CDCl3) 167.2
and 166.8, 155.1 and 154.6, 136.2 and 136.0, 135.1, 130.6 and 130.3, 128.9,
128.7, 128.5, 128.2, 127.3, 124.3, 69.1 and 68.3, 60.5 and 59.7, 35.8 and 35.4,
20.3, 14.4; HRMS calcd for C23H30N3O4 ½M+NHþ4 ꢁ m/z 412.2236. Found
412.2216.
N-10-(Propyl)butyl-N-tert-butyloxycarbonylaminotetrachlorophthali-
mide (2 R5OtBu, R051-(propyl)butyl, X5H): (m.p. 121ꢀC); IR (NaCl)
1
ꢀ
max/cmÀ1 1802, 1753, 1727; H NMR (400 MHz, CDCl3) 4.45 and 4.17
(2 quint, 1H), 1.70–1.28 (m, with 2s at 1.49 and 1.31, 17H), 0.99–0.90 (m,
6H); 13C NMR (CDCl3) 163.1 and 162.5, 153.5 and 152.8, 141.3 and
141.1, 130.5, 126.3 and 126.0, 83.4 and 82.6, 60.0 and 58.6, 35.9 and
35.5, 28.5 and 28.3, 20.3, 14.4.
N-tert-Butyloxycarbonyl-N-tetrachlorophthalimidoleucine benzyl (2
P5Boc, R5CH2-CH(CH3)2, R05CH2Ph, X5Cl): [a]D ¼ þ 6.6 (c, 1.01,
CHCl3); IR (NaCl) ꢀmax/cmÀ1 1800, 1748; 1H NMR (400 MHz, CDCl3)
7.46–7.20 (5H, m), 5.23–5.09 and 4.97–4.86 (2m with s at 5.17, 3H),
1.90–1.57 (3H), 1.46 and 1.35 (2s, 9H), 1.03–0.83 (m, 6H); 13C NMR
(CDCl3) 169.8 and 169.6, 162.1 and 161.7 and 161.6 and 161.1, 152.2, 141.3
and 141.1, 135.7, 130.6, 129.0, 128.7, 128.6, 126.1 and 125.8, 84.8 and 83.9,
67.9 and 67.7, 59.7 and 57.8, 38.7, 28.3, 24.9 and 24.8, 23.1 and 22.7.

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PREPARATION OF ALKYLHYDRAZINES
3609
N-Methyl-N-benzoylaminotetrachlorophthalimide (2 R5Ph, R05
Methyl, X5Cl): (m.p. 221ꢀC); IR (KBr) ꢀmax/cmÀ1 1795, 1735; HRMS
Calcd. for C16H8N2O3Cl4 [Mþ] m/z 415.9289. Found 415.9273. This com-
pound being highly insoluble in the usual solvents, we were not able to
perform its NMR spectra.
General Procedure for the Deprotection of the Phthaloyl Group
To a solution of compound 2 X¼H in THF was added at 0ꢀC, 1.5
equivalent of MeNHNH2. The solution was then allowed to warm to room
temperature, stirred for the time indicated in Table 1 and then concentrated
in vacuo. AcOEt was added and the white precipite was filtrated off. The
filtrate was evaporated and the residue was chromatographed on neutral
alumina gel.
General Procedure for the Deprotection of the
Tetrachlorophthaloyl Group
To a solution of compound 2 X¼Cl in THF was added at 0ꢀC,
2 equivalents of ethylenediamine. The solution was then allowed to warm
to room temperature, stirred for the time indicated in Table 1 and then
concentrated in vacuo. The residue was evaporated and chromatographed
on silica gel.
Characteristics of Representative Compounds
N-10-(Propyl)butyl-N-benzyloxycarbonylhydrazine (3 R5OCH2Ph,
R051-(propyl)butyl): (Oil); IR (NaCl) ꢀmax/cmÀ1 3337, 3223, 3033, 1694;
1H NMR (400 MHz, CDCl3) 7.37–7.23 (m, 5H), 5.15 (s, 2H), 3.97 (quint,
1H), 3.79–3.54 (m, 1H), 1.70–1.56 (m, 4H), 1.38–1.10 (m, 4H), 0.96–0.78
(t, 6H); 13C NMR (CDCl3) 159.1, 137.0, 128.8, 128.4, 128.2, 67.9, 57.1, 34.9,
20.0, 14.3.
N-Cyclohexyl-N-benzyloxycarbonylhydrazine
(3
R5OCH2Ph,
R05Cyclohexyl): (Oil); IR (NaCl) ꢀmax/cmÀ1 3110, 3064, 1687; H NMR
(400 MHz, CDCl3) 7.35–7.21 (m, 5H), 5.12 (s, 2H), 4.04 (quint, 1H),
1.83–1.02 (m, 10H); 13C NMR (CDCl3) 152.9, 137.2, 128.8, 128.4, 128.2,
67.4, 58.2, 30.3, 26.1, 25.9; HRMS Calcd. for C14H21N2O2 [MþHþ] m/z
249.1603. Found 249.1596.
1

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3610
PINTO, BROSSE, AND JAMART-GREGOIRE
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Received in the Netherlands November 22, 2001