Synthesis and characterization of 2,2-disubstituted-5-(2-phenothiazin-10-ylethyl)-2,3-dihydro-1,3,4-oxadiazoles

Article abstract of DOI:10.1081/SCC-120015570

A variety of heterocyclic hybrids 3 linking 2,3-dihydro-1,3,4-oxadiazoles and phenothiazine has been successfully prepared by cyclization of the corresponding acylhydrazones 2.

Full text of DOI:10.1081/SCC-120015570

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Synthesis and Characterization of 2,2-Disubstituted-5-
(2-phenothiazin-10-ylethyl)-2,3-dihydro-1,3,4-
oxadiazoles
Elena Bâcu a , Axel Couture b & Pierre Grandclaudon b c
a Department of Organic Chemistry , Faculty of Chemistry , University Al. I. Cuza , Iasi,
Romania
b Laboratoire de Chimie Organique Physique , UPRES A CNRS 8009 , Université des Sciences
et Technologies de Lille 1 , Villeneuve d’Ascq Cedex, France
c Laboratoire de Chimie Organique Physique , UPRES A CNRS 8009 , Université des Sciences
et Technologies de Lille 1 , Bâtiment C3(2), 59655 Villeneuve d’Ascq Cedex, France
Published online: 29 Jun 2011.
To cite this article: Elena Bâcu , Axel Couture & Pierre Grandclaudon (2003) Synthesis and Characterization of 2,2-
Disubstituted-5-(2-phenothiazin-10-ylethyl)-2,3-dihydro-1,3,4-oxadiazoles, Synthetic Communications: An International
Journal for Rapid Communication of Synthetic Organic Chemistry, 33:1, 143-151, DOI: 10.1081/SCC-120015570
To link to this article: http://dx.doi.org/10.1081/SCC-120015570
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SYNTHETIC COMMUNICATIONSÕ
Vol. 33, No. 1, pp. 143–151, 2003
Synthesis and Characterization of
2,2-Disubstituted-5-(2-phenothiazin-10-ylethyl)-
2,3-dihydro-1,3,4-oxadiazoles
Elena Bacu,1 Axel Couture,2
and Pierre Grandclaudon2,
*
1Department of Organic Chemistry, Faculty of Chemistry,
University Al. I. Cuza, Iasi, Romania
2Laboratoire de Chimie Organique Physique, UPRES A CNRS
8009, Universite des Sciences et Technologies de Lille 1,
Villeneuve d’Ascq Cedex, France
ABSTRACT
A variety of heterocyclic hybrids 3 linking 2,3-dihydro-1,3,4-oxadia-
zoles and phenothiazine has been successfully prepared by cyclization
of the corresponding acylhydrazones 2.
Key Words: Phenothiazine; Acylhydrazones; Cyclization; Oxadi-
azolines.
*Correspondence: Pierre Grandclaudon, Laboratoire de Chimie Organique
Physique, UPRES A CNRS 8009, Universite des Sciences et Technologies de
Lille 1, Batiment C3(2), 59655 Villeneuve d’Ascq Cedex, France; Fax: +33 (0)3
20 33 63 09; E-mail: pierre.grandclaudon@univ-lille1.fr.
143
DOI: 10.1081/SCC-120015570
0039-7911 (Print); 1532-2432 (Online)
www.dekker.com
Copyright & 2003 by Marcel Dekker, Inc.

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144
Bacu, Couture, and Grandclaudon
In the framework of our systematic studies dealing with the
synthesis[1,2] and the biological evaluation[3] of five-membered nitrogen
containing heterocycles connected to the N atomof a phenothiazine
unit through a two carbon atomchain, we planned to synthesize
the heterocyclic hybrids 3 linking 2,3-dihydro-1,3,4-oxadiazoles and
phenothiazine. Interestingly
a
variety of differently substituted
oxadiazole and oxadiazoline derivatives have been found to exhibit
H2 antagonistic properties[4] as well as moderate or low antimicrobial
activities.[5–10] Generally the oxadiazoline framework is built via the
cyclization of the corresponding acylhydrazones by refluxing in acid
anhydrides or chlorides[11–13] and most of the acylhydrazone derivatives
are prepared by condensation of hydrazides with aldehydes.
In order to achieve the construction of 2,2-disubstituted or spiro
union containing oxadiazolines, hydrazide 1, deriving from3-(10 H-phe-
nothiazin-10-yl)propionic acid,[14] was initially condensed with a variety
of aliphatic and aromatic ketones to give rise to acylhydrazones 2a–f.
Acetic anhydride in pyridine was successfully used as the electrophilic
agent to ensure the ring closure of aliphatic ketone hydrazones 2a–d
thus delivering the desired oxadiazolines 3a–d. Under similar conditions
the acetophenone hydrazone 2e was converted into the diacylhydrazone
4e but treatment of 2e in refluxing neat acetyl chloride afforded the
expected oxadiazoline 3e (Sch. 1, Table 1).
1H NMR and 13C NMR spectra showed 2a–f as a mixture of two
rotational isomers. The two proton resonances in the ꢀ 2.5–3.2 ppm
and the ꢀ 10.0–11.0 ppmregion were attributed to the CH CO protons
2
and NH proton, respectively. 13C NMR displayed two C¼O and two
C¼N characteristic resonances in the ꢀ 165–175 ppmand ꢀ 147–160 ppm
region, respectively.
The structure of 3a–e was mainly supported by 13C NMR data. Besides
the characteristic patterns of the carbon atoms present in the pheno-
thiazine framework, spectra displayed the O–C¼N resonance of the oxa-
diazoline ring in the ꢀ 154–155 ppmregion and the O–C–N resonance in
[9,13]
the ꢀ 99–102 ppmregion in accordance with the literature reports.
EXPERIMENTAL
Melting point determinations were carried out on a Reichert–
Thermopan apparatus and were recorded uncorrected. 1H and 13C spectra
were measured at 300 MHz and 75 MHz, respectively on a Bruker AM 300
spectrometer as solutions in DMSO-d6 with TMS as internal standard. IR

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2,3-Dihydro-1,3,4-oxadiazoles
145
Scheme 1.
Table 1. Data of acylhydrazones 2a–f, oxadiazolines 3a–e and diacylhydrazone
4e prepared.
Product
R1
R2
M.p. (ꢀC)
Yield (%)
2a
2b
2c
2d
2e
2fa
3a
3b
3c
3d
3e
4e
CH3
CH3
C6H5CH2
–(CH2)5 –
CH3
C6H5
CH3
CH3
C6H5CH2
–(CH2)5 –
CH3
CH3
CH3CH2
C6H5CH2
188–189
172–173
97–98
93
80
82
79
62
59
78
52
56
65
55
82
137–138
C6H5
C6H5
CH3
CH3CH2
C6H5CH2
175–176, Lit.[15] 172–173
158–159, Lit.[15] 161–162
120–121
85–86
165–166
117–118
162–163
138–139
C6H5
C6H5
CH3
aAttempts to obtain 3f were unsuccessful.

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146
Bacu, Couture, and Grandclaudon
spectra were recorded on a Perkin–Elmer 881 spectrometer. Elemental
analyses were determined by the CNRS microanalysis centre. For flash
chromatography, Merck silica gel 60 (0.063–0.200 mm) was used.
Synthesis of 3-(10H-Phenothiazin-10-yl)propionic Acid
Alkylidenehydrazides (2a–f ). General Procedure
A solution of 3-(10H-phenothiazin-10-yl)propionic acid hydrazide 1
(1 g, 3.5 mmol) and an appropriate ketone (4.0 mmol) in EtOH (10 mL)
was refluxed for 2 h. The solid obtained after cooling of the mixture was
filtered, washed with cold EtOH and recrystallized fromacetone–EtOH.
3-(10H-Phenothiazin-10-yl)propionic acid isopropylidenehydrazide 2a:
White crystals. 1H NMR (mixture of two rotational isomers 60:40) ꢀ
(ppm) 1.79 and 1.83 (3H, 2 Â s, CH3C¼), 1.82 and 1.90 (3H, 2 Â s,
CH3C¼), 2.70 and 2.95 (2H, 2 Â t, J ¼ 7.0 and 7.2 Hz, CH2CO), 4.14
(2H, m, CH2N), 6.92–6.98 (2H, m, Harom), 7.05–7.35 (6H, m, Harom),
10.04 and 10.18 (1H, 2 Â s, NH); 13C NMR (mixture of two rotational
isomers) ꢀ (ppm) 17.1 and 17.5 (CH3), 24.9 and 25.1 (CH3), 30.6 and 32.1
(CH2), 42.5 and 42.9 (CH2), 115.3 and 115.5 (CHpheno), 122.5 (CHpheno),
123.0 and 123.3 (Cpheno), 127.1 (CHpheno), 127.6 (CHpheno), 144.3
and 144.4 (Cpheno), 150.6 and 155.1 (C¼N), 166.5 and 172.3 (C¼O).
IR (KBr) ꢁ (cmÀ1) 3178, 1670. Anal. calcd for C18H19N3OS: C, 66.43;
H, 5.88; N, 12.91. Found: C, 66.34; H, 5.99; N, 12.72.
3-(10H-Phenothiazin-10-yl)propionic acid sec-butylidenehydrazide 2b:
White crystals. 1H NMR (mixture of two rotational isomers 60:40) ꢀ
(ppm) 0.92 and 1.00 (3H, 2 Â t, J ¼ 7.4 and 7.5 Hz, CH3), 1.78 and 1.80
(3H, 2 Â s, CH3C¼), 2.12 and 2.21 (2H, 2 Â q, J ¼ 7.4 and 7.5 Hz,
CH2C¼), 2.70 and 2.97 (2H, 2 Â t, J ¼ 7.1 Hz, CH2CO), 4.14 (2H, t,
J ¼ 7.1 Hz, CH2N), 6.89–6.96 (2H, m, Harom), 7.03–7.24 (6H, m,
H
arom), 9.99 and 10.18 (1H, 2 Â s, NH); 13C NMR (mixture of two rota-
tional isomers) ꢀ (ppm) 10.5 and 10.8 (CH3), 15.8 and 15.9 (CH3), 30.5
and 31.4 (CH2), 31.5 and 32.1 (CH2), 42.5 and 42.9 (CH2), 115.3 and
115.5 (CHpheno), 122.4 and 122.5 (CHpheno), 123.0 and 123.2 (Cpheno),
127.1 (CHpheno), 127.6 and 127.7 (CHpheno), 144.3 and 144.4 (Cpheno),
154.2 and 158.5 (C¼N), 166.5 and 172.5 (C¼O). IR (KBr) ꢁ (cmÀ1
)
3172, 1668. Anal. calcd for C19H21N3OS: C, 67.23; H, 6.24; N, 12.38.
Found: C, 67.01; H, 6.40; N, 12.49.
3-(10H-Phenothiazin-10-yl)propionic acid (1-benzyl-2-phenyl-ethylide-
ne)hydrazide 2c: White crystals. 1H NMR (mixture of two rotational
isomers 60:40) ꢀ (ppm) 2.75 and 3.02 (2H, 2 Â t, J ¼ 6.8 and 7.0 Hz,

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2,3-Dihydro-1,3,4-oxadiazoles
147
CH2CO), 3.35 and 3.43 (2H, 2 Â s, CH2C¼), 3.58 and 3.65 (2H, 2 Â s,
CH2C¼), 4.16 (2H, m, CH2N), 6.90–6.97 (2H, m, Harom), 7.02–7.33
(16H, m, Harom), 10.53 and 10.72 (1H, 2 Â s, NH); 13C NMR (mixture
of two rotational isomers) ꢀ (ppm) 30.8 and 32.2 (CH2), 34.1 and 34.3
(CH2), 42.2 and 42.3 (CH2), 42.5 and 42.8 (CH2), 115.4 and 115.6
(CHpheno), 122.6 (CHpheno), 123.2 and 123.3 (Cpheno), 126.5 and
126.6 (CHPh), 127.1 (CHpheno), 127.6 (CHpheno), 128.3, 128.6, 128.7,
and 128.9 (CHPh), 135.7 (CPh), 137.1(CPh), 144.4 (Cpheno), 152.0 and
156.5 (C¼N), 167.1 and 173.0 (C¼O). IR (KBr) ꢁ (cmÀ1) 3165, 1673.
Anal. calcd for C30H27N3OS: C, 75.44; H, 5.70; N, 8.80. Found: C,
75.68; H, 5.81; N, 9.07.
3-(10H-Phenothiazin-10-yl)propionic acid cyclohexylidenehydrazide
1
2d: White crystals. H NMR (mixture of two rotational isomers 60:40)
ꢀ (ppm) 1.42–1.55 (6H, m, 3 Â CH2), 2.03–2.36 (4H, m, 2 Â CH2C¼), 2.67
and 2.95 (2H, 2 Â t, J ¼ 6.9 Hz, CH2CO), 4.13 (2H, t, J ¼ 6.9 Hz, CH2N),
6.90–6.97 (2H, m, Harom), 7.04–7.24 (6H, m, Harom), 10.17 and 10.36 (1H,
2 Â s, NH); 13C NMR (mixture of two rotational isomers) ꢀ (ppm) 25.1
(CH2), 25.6 and 25.7 (CH2), 26.5 and 26.8 (CH2), 26.8 and 27.2 (CH2),
30.5 and 32.1 (CH2), 34.9 and 35.1 (CH2), 42.5 and 42.9 (CH2), 115.3 and
115.5 (CHpheno), 122.5 (CHpheno), 122.9 and 123.2 (Cpheno), 127.1
(CHpheno), 127.6 and 127.7 (CHpheno), 144.3 and 144.4 (Cpheno), 155.9
and 160.9 (C¼N), 166.6 and 172.5 (C¼O). IR (KBr) ꢁ (cmÀ1) 3186,
1675. Anal. calcd for C21H23N3OS: C, 69.01; H, 6.34; N, 11.50. Found:
C, 68.88; H, 6.09; N, 11.57.
3-(10H-Phenothiazin-10-yl)propionic acid (1-phenyl-ethylidene)hydra-
zide 2e: White crystals. 1H NMR (mixture of two rotational isomers
60:40) ꢀ (ppm) 2.22 and 2.23 (3H, 2 Â s, CH3C¼), 2.84 and 3.13 (2H,
2 Â t, J ¼ 6.9 Hz, CH2CO), 4.21 (2H, t, J ¼ 6.9 Hz, CH2N), 6.88–6.99 (2H,
m , Harom), 7.07–7.30 (6H, m, Harom), 7.32–7.45 (3H, m, Harom), 7.57–7.61
and 7.76–7.80 (2H, 2 Â m , Harom), 10.42 and 10.65 (1H, 2 Â s, NH);
13C NMR (mixture of two rotational isomers 60:40) ꢀ (ppm) 13.9 and
14.1 (CH3), 30.5 and 32.3 (CH2), 42.7 and 42.8 (CH2), 115.4 and 115.6
(CHpheno), 122.6 (CHpheno), 123.1 and 123.3 (Cpheno), 126.0 and 126.3
(CHPh), 127.1 (CHpheno), 127.6 and 127.7 (CHpheno), 128.3 (CHPh),
128.9 and 129.2 (CHPh), 138.2 (CPh), 144.3 and 144.5 (Cpheno), 147.9
and 151.2 (C¼N), 167.2 and 173.2 (C¼O). IR (KBr) ꢁ (cmÀ1) 3166, 1671.
3-(10H-Phenothiazin-10-yl)propionic acid benzhydrylidenehydrazide 2f:
1
White crystals. H NMR (mixture of two rotational isomers 60:40) ꢀ (ppm)
2.68 and 3.22 (2H, 2 Â t, J ¼ 6.8 and 6.7 Hz, CH2CO), 4.14 and 4.25 (2H,
2 Â t, J ¼ 6.7 and 6.8 Hz, CH2N), 6.90–7.60 (18H, m, Harom), 9.37 and 10.07
(1H, 2 Â s, NH); 13C NMR (mixture of two rotational isomers 60:40) ꢀ (ppm)

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148
Bacu, Couture, and Grandclaudon
30.4 and 32.3 (CH2), 42.6 and 42.8 (CH2), 115.5 (CHpheno), 122.6 (CHpheno),
123.3 (Cpheno), 127.1 (CHpheno), 127.5 and 127.7 (CHpheno), 128.3, 128.4,
128.5, 128.7, 129.2, and 129.5 (CHPh), 131.8 and 132.5 (CPh), 137.1 and
137.8 (CPh), 144.4 (Cpheno), 150.2 and 152.7 (C¼N), 167.5 and 172.4
(C¼O). IR (KBr) ꢁ (cmÀ1) 3321, 1679.
Synthesis of 1-{2,2-Disubstituted-5-[2-(10H-phenothiazin-10-
yl)ethyl]-1,3,4-oxadiazol-3-yl}ethanones (3a–e). General Procedure
A mixture of 2a–e (1 g) acetic anhydride (1 g) and pyridine (2 g) was
stirred at 100ꢀC for 2 h. After concentration under vacuumthe oily resi-
due was poured into water and Na2CO3 was added (pH ¼ 8). After
extraction (Et2O, 10 Â 20 mL), drying (MgSO4) and evaporation of the
solvent, the crude product was purified by chromatography over a pad of
silica (10 cm) with hexanes/acetone (1:1) as eluent and recrystallized from
acetone–ethanol to afford oxadiazolines 3a–d or diacylhydrazone 4e.
Ring closure giving rise to oxadiazoline 3e was achieved by refluxing 2e
(1 g) in neat acetyl chloride (5 mL) for 2 h and subsequent treatment as
previously described.
1-{2,2-Dimethyl-5-[2-(10H-phenothiazin-10-yl)ethyl]-1,3,4-oxadiazol-
3-yl}ethanone (3a): White crystals. 1H NMR ꢀ (ppm) 1.49 (6H, s, CH3C),
1.89 (3H, s, CH3C¼O), 2.70 (2H, t, J ¼ 6.0 Hz, CH2C¼N), 4.21 (2H, t,
J ¼ 6.0 Hz, CH2N), 6.94 (2H, t, J ¼ 7.3 Hz, Harom), 7.05–7.31 (6H, m,
H
arom); 13C NMR ꢀ (ppm) 21.9 (CH3), 23.7 (CH2), 23.9 (CH3), 42.6
(CH2), 98.8 (O–C–N), 115.9 (CHpheno), 122.7 (CHpheno), 124.2 (Cpheno),
127.1 (CHpheno), 127.6 (CHpheno), 144.2 (Cpheno), 154.3 (C¼N), 165.3
(C¼O). IR (KBr) ꢁ (cmÀ1) 1655. Anal. calcd for C20H21N3O2S: C,
65.37; H, 5.76; N, 11.43. Found: C, 65.30; H, 5.88; N, 11.62.
1-{2-Ethyl-2-methyl-5-[2-(10H-phenothiazin-10-yl)ethyl]-1,3,4-oxadia-
zol-3-yl}ethanone 3b: White crystals. 1H NMR ꢀ (ppm) 0.60 (3H, t,
J ¼ 7.3 Hz, CH3), 1.47 (3H, s, CH3C¼O), 1.74 (1H, dq, J ¼ 14.5,
7.3 Hz, CH2), 1.97 (3H, s, CH3), 2.20 (1H, dq, J ¼ 14.5, 7.3 Hz, CH2),
2.72 (2H, t, J ¼ 6.0 Hz, CH2C¼N), 4.20 (2H, t, J ¼ 6.0 Hz, CH2N), 6.94
(2H, t, J ¼ 7.1 Hz, Harom), 7.02–7.24 (6H, m, Harom); 13C NMR ꢀ (ppm)
6.6 (CH3), 21.8 (CH3), 22.7 (CH3), 23.6 (CH2), 29.1 (CH2), 42.6 (CH2),
101.3 (O–C–N), 115.9 (CHpheno), 122.6 (CHpheno), 124.3 (Cpheno), 127.1
(CHpheno), 127.6 (CHpheno), 144.2 (Cpheno), 154.7 (C¼N), 165.1 (C¼O).
IR (KBr) ꢁ (cmÀ1) 1660. Anal. calcd for C21H23N3O2S: C, 66.12; H, 6.08;
N, 11.01. Found: C, 66.41; H, 5.87; N, 11.16.

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2,3-Dihydro-1,3,4-oxadiazoles
149
1-{2,2-Dibenzyl-5-[2-(10H-phenothiazin-10-yl)ethyl]-1,3,4-oxadiazol-3-yl}-
1
ethanone 3c: White crystals. H NMR ꢀ (ppm) 1.88 (3H, s, CH3C¼O), 2.34
(2H, t, J ¼ 6.7 Hz, CH2C¼N), 3.75 (2H, t, J ¼ 6.7 Hz, CH2N), 3.83 (4H, s,
CH2Ph), 6.95 (2H, t, J ¼ 6.3 Hz, Harom), 7.02–7.28 (16H, m, Harom); 13C NMR
ꢀ (ppm) 21.9 (CH3), 22.7 (CH2), 42.4 (CH2), 48.4 (CH2), 102.6 (O–C–N), 115.6
(CHpheno), 122.6 and 122.7 (CHpheno), 124.1 and 124.2 (Cpheno), 126.5–127.9
(m, CHpheno and CHPh), 128.9 (CHPh), 130.3 (CHPh), 134.3 and 134.6 (CPh),
144.0 (Cpheno), 154.5 (C¼N), 165.8 (C¼O). IR (KBr) ꢁ (cmÀ1) 1647. Anal.
calcd for C32H29N3O2S: C, 73.96; H, 5.62; N, 8.09. Found: C, 74.13; H, 5.42;
N, 8.40.
1-{3-[2-(10H-Phenothiazin-10-yl)ethyl]-4-oxa-1,2-diazaspiro[4.5]dec-2-
1
en-1-yl}ethanone 3d: White crystals. H NMR ꢀ (ppm) 0.98–1.22 (4H, m,
2 Â CH2), 1.30–1.47 (4H, m, 2 Â CH2), 1.92 (3H, s, CH3C¼O), 2.14–2.29
(2H, m, CH2), 2.72 (2H, t, J ¼ 6.0 Hz, CH2C¼N), 4.24 (2H, t, J ¼ 6.0 Hz,
CH2N), 6.94 (2H, dt, J ¼ 7.4, 1.1 Hz, Harom), 7.02–7.22 (6H, m, Harom);
13C NMR ꢀ (ppm) 22.0 (CH2), 22.3 (CH2), 22.3 (CH3), 23.8 (CH2), 31.7
(CH2), 42.5 (CH2), 100.4 (O–C–N), 115.9 (CHpheno), 122.7 (CHpheno),
124.2 (Cpheno), 127.1 (CHpheno), 127.6 (CHpheno), 144.2 (Cpheno), 154.4
(C¼N), 165.4 (C¼O). IR (KBr) ꢁ (cmÀ1) 1664. Anal. calcd for
C23H25N3O2S: C, 67.79; H, 6.18; N, 10.31. Found: C, 68.00; H, 6.45; N,
10.20.
1-{2-Methyl-5-[2-(10H-phenothiazin-10-yl)ethyl}-2-phenyl-1,3,4-oxa-
1
diazol-3-yl]ethanone 3e: White crystals. H NMR ꢀ (ppm) 1.90 (3H, s,
CH3), 1.94 (3H, s, CH3CO), 2.81 (2H, t, J ¼ 5.6, CH2C¼N), 4.23 (2H,
t, J ¼ 5.6, CH2N), 6.97 (2H, t, J ¼ 7.4, CHarom), 7.08 (2H, d, J ¼ 7.9,
H
arom), 7.17–7.40 (9H, m, Harom); 13C NMR ꢀ (ppm) 21.7 (CH3), 22.0
(CH3), 23.6 (CH2), 42.4 (CH2), 99.1 (O–C–N), 116.0 (CHpheno), 122.8
(CHpheno), 124.4 (Cpheno), 125.7 (CHPh), 127.2 (CHpheno), 127.7
(CHpheno), 128.0 (CHPh), 128.8 (CHPh), 139.0 (CPh), 144.3 (Cpheno),
154.3 (C¼N), 165.1 (C¼O). IR (KBr) ꢁ (cmÀ1) 1639. Anal. calcd
for C25H23N3O2S: C, 69.91; H, 5.40; N, 9.78. Found: C, 70.05; H, 5.37;
N, 10.01.
Acetic acid N-[3-(10H-phenothiazin-10-yl)propionyl]-N 0-(1-phenylethyl-
idene)hydrazide 4e: White crystals. 1H NMR
ꢀ (ppm) 2.05 (3H, s,
CH3C¼), 2.32 (3H, s, CH3CO), 3.15 (2H, t, J ¼ 6.7 Hz, CH2CO), 4.21
(2H, t, J ¼ 6.7 Hz, CH2N), 6.92 (2H, dt, J ¼ 7.6, 1.0, Harom), 7.05 (2H, d,
J ¼ 7.6, Harom), 4.10–7.18 (4H, m, Harom), 7.43–7.54 (3H, m, Harom),
7.83–7.86 (2H, m, Harom); 13C NMR ꢀ (ppm) 16.7 (CH3), 25.8 (CH3),
34.8 (CH2), 48.5 (CH2), 115.6 (CHpheno), 122.6 (CHpheno), 123.5 (Cpheno),
127.1 (CHPh), 127.2 (CHpheno), 127.6 (CHpheno), 128.6 (CHPh),
131.4 (CHPh), 136.1 (CPh), 144.4 (Cpheno), 168.9 (C¼N), 170.0 (C¼O),

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150
Bacu, Couture, and Grandclaudon
175.1 (C¼O). IR (KBr) ꢁ (cmÀ1) 1699. Anal. calcd for C25H23N3O2S: C,
69.91; H, 5.40; N, 9.78. Found: C, 70.11; H, 5.63; N, 9.69.
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Received in the UK November 26, 2001

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