Synthesis, spectral, and anti-microbial studies of thioiminium iodides and amine hydrochlorides

Article abstract of DOI:10.1016/j.saa.2013.09.108

To avoid the undesired deprotonation during the addition of organolithium and organomagnesium reagents to ketones, the thioiminium salts, easily prepared from lactams and amides are converted into 2,2-disubstituted and 2-monosubstituted amines by reaction with simple nucleophiles such as organocerium and organocopper reagents. The reaction of thioiminium iodides with organocerium reagents derived by transmetalation of corresponding lithium reagents with anhydrous cerium(III) chloride has been investigated. These thioiminium iodides act as good electrophiles and accept alkylceriums towards bisaddition. The newly synthesized amines have been characterized by ¹H and ¹³C NMR, IR and mass spectra. The amines have been converted into their hydrochlorides and characterized by COSY. These hydrochlorides have been subjected to antimicrobial screening with clinically isolated microorganisms, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi and Candida albicans. The hydrochlorides show quite good activity against these bacteria and fungus.

Full text of DOI:10.1016/j.saa.2013.09.108

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 120 (2014) 489–493
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Synthesis, spectral, and anti-microbial studies of thioiminium iodides
and amine hydrochlorides
b
b
Sebastian Britto a, , Philippe Renaud , Maruthai Nallu
⇑
a Department of Chemistry, St. Joseph’s College, Tiruchirappalli 620002, India
b Universität Bern, Departement für Chemie und Biochemie, Freiestrasse 3, 3012 Bern, Switzerland
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
A series of germinal bis-alkyl cyclic amines and their hydrochlorides have been prepared by simple nucle-
ophilic addition on appropriate thioiminium iodides using organocerium reagents. The amine hydrochlo-
rides thus prepared display considerable antimicrobial activity.
ꢀ
ꢀ
ꢀ
The use of simple nucleophiles results
in bis and mono addition.
The ultrasound sonication is used to
prepare the organocerium reagents.
The arrangement of protons in the
amine hydrochlorides is investigated
by COSY.
ꢀ
ꢀ
The amine hydrochlorides are found
to be active against some
microorganisms.
The functionalities in the molecules
that cause for such activity are
rationalized.
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 18 August 2013
Received in revised form 6 September 2013
Accepted 26 September 2013
Available online 23 October 2013
To avoid the undesired deprotonation during the addition of organolithium and organomagnesium
reagents to ketones, the thioiminium salts, easily prepared from lactams and amides are converted into
2,2-disubstituted and 2-monosubstituted amines by reaction with simple nucleophiles such as organoce-
rium and organocopper reagents. The reaction of thioiminium iodides with organocerium reagents
derived by transmetalation of corresponding lithium reagents with anhydrous cerium(III) chloride has
been investigated. These thioiminium iodides act as good electrophiles and accept alkylceriums towards
bisaddition. The newly synthesized amines have been characterized by 1H and 13C NMR, IR and mass
spectra. The amines have been converted into their hydrochlorides and characterized by COSY. These
hydrochlorides have been subjected to antimicrobial screening with clinically isolated microorganisms,
Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi and Candida albi-
cans. The hydrochlorides show quite good activity against these bacteria and fungus.
Keywords:
Deprotonation
Nucleophile
Transmetalation
Electrophile
Bisaddition
Antimicrobial screening
Ó 2013 Elsevier B.V. All rights reserved.
Introduction
and organocerium reagents [1]. Heterocycles having methylsulfo-
nyl group and particularly cyclic amines with N-benzyl substituent
Bis addition products of thioiminium ions have been exten-
sively studied and are reported to be done by organomagnesium
possess considerable biological activity [2,3]. Thioiminium ions are
prepared from lactams converted into thiolactams and reaction of
them with methyl iodide. Bis alkylation is mainly dependent on
nucleophilicity of organometallic reagents. For instance, we test
alkylmagnesium reagents in bis-alkylation and find they are
not quite nucleophilic enough to give addition products on
⇑
Corresponding author at: Department of Chemistry, St. Joseph’s College,
Tiruchirappalli 620002, India. Tel.: +91 9003640804.
E-mail address: brittoseba@yahoo.co.in (S. Britto).
1386-1425/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.saa.2013.09.108

490
S. Britto et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 120 (2014) 489–493
thioiminium ions. Now we report that organocerium reagents are
very effective for addition reactions of these salts. The preparation
of thioiminium ions are shown in the scheme 1.
was cooled down to À78 °C and the alkyllithium reagent solution
(1.2 mmol) was added dropwise. The solution became pale yellow
and stirring was continued for about 30 min. The thioiminium salt
was added as a solid (0.3 mmol), the cooling bath was removed and
the mixture was stirred for about 6 h. The dark brown suspension
was treated with saturated NH4Cl and the aqueous phases were ex-
tracted with dichloromethane (3Â). The collected organic phases
were dried over MgSO4, filtered and the solvent was evaporated
under reduced pressure. The crude product was purified by FC
(cyclohexane/tert-BuOMe) to afford the gem-dialkylated amine.
Experimental
All reactions were performed under nitrogen atmosphere in
oven-dried flasks (120 °C) unless otherwise stated. Dry solvents
for reactions were filtered through a column of dry alumina under
positive pressure of argon. Solvents for flash chromatography were
of technical grade and used without
purification. Other chemicals were obtained from commercial
sources and used without further purifications. The reactions were
monitored by TLC (analytical plates, Merck silica gel 60 F254) and
visualized under UV light and/or stained with a solution of KMnO4
or phosphomolibdic acid followed by heating. Flash chromatogra-
phy (FC) was performed using Baker silica gel (0.065–0.200 mm).
Melting points (m.p.) determined are not corrected. 1H and 13C
NMR spectra were recorded on Bruker Avance-300 (1H: 300 MHz,
13C: 75.5 MHz) or Bruker DRX-400 (1H: 400 MHz, 13C: 100 MHz)
or Bruker Avance-III (1H: 400 MHz, 13C: 100 MHz) spectrometers.
The 1H spectra were referred to an internal standard (TMS,
0 ppm) or to the residual 1H of CDCl3 (7.26 ppm). 13C spectra were
referred to residual signal of CDCl3 (77.0 ppm). IR spectra were re-
corded on Jasco FT-IR 460 plus. Mass spectroscopy (MS) and high
resolution mass spectroscopy (HRMS) analyses were performed
on Waters Micromass Autospec Q/Qstar Pulsar.
Five bacterial cultures one gram-positive Staphylococcus aureus,
three gram-negative namely, Klebsiella pneumoniae, Pseudomonas
aeruginosa and Salmonella typhi and one fungal strain namely Can-
dida albicans, were used for the bioassay. All the organisms were
isolated from clinical patients and obtained from K.A.P. Viswana-
tham Government Medical College, Tiruchirappalli, India.
The organisms were maintained on agar slopes at 4 °C and sub
cultured for 24 h before use. While the bacteria strains were incu-
bated into nutrient broth throughout 24 h, the fungal strains were
incubated into Saubouraud’s dextrose agar throughout 48 h.
General procedure C: preparation of amine hydrochlorides in Scheme 2
The free amine was treated with HCl (generated from the addi-
tion of acetyl chloride to MeOH at 0 °C) to give the amine
hydrochlorides.
Results and discussion
Synthesis of thioiminium iodides
The thioiminium iodides (7–9, 12 and 15) were prepared by the
action of methyl iodide on thiolactams. These thiolactams were ob-
tained from the commercially available and easily prepared lac-
tams (1–3, 10 and 13) (Scheme 1). The lactam 1 is commercially
available, whereas, 2 and 3 [4] are prepared by N-benzylation of
d-valerolactam and 6-caprolactam respectively. Conversion of lac-
tams (1–3) into thiolactams enables to prepare the thioiminium
ions (7–9) [5]. The reaction of thiolactams with methyl iodide took
about 8 h to give the salts with good yield. The reaction between
thiolactams and other alkyl halides like ethyl, propyl and butyl io-
dides was found to be slow. The lactams 1-(pyrrolidin-1-yl)etha-
none (13) and 1-(3,4-dihydroisoquinolin-2(1H)-yl)ethanone (10)
are prepared simply by acetylation of pyrrolidine and 1,2,3,4-tetra-
hydroisoquinoline respectively. They are converted into thioimini-
um ions (15 and 12). Biological activities of some of thioiminium
iodides were also screened (Table 1).
Among the above thioiminium iodides, 7, 8 and 12 are stable at
room temperature for a long time in a closed container. The salt 9
is unstable at room temperature and 15 is hygroscopic in nature.
FT-IR spectra of 7–9, 12 and 15 showed the characteristic C@N,
CAS stretching frequencies that could be seen in 1600–1495 and
700–693 cmÀ1 respectively. CAC stretching appeared between
1299–1243 cmÀ1. CAH (aromatic) stretch and C@C ring stretch
(aromatic) appeared at 3085–3000 and 1590–1466 cmÀ1
respectively.
General procedure A: synthesis of thioiminium ions in Scheme 1
Lawesson’s reagent (2.02 g, 5.0 mmol) was added to a solution
of the lactam (10 mmol) in dry CH2Cl2 (100 mL). The mixture
was stirred at room temperature for 1–4 h until the starting mate-
rial was consumed (TLC monitoring). The solvent was evaporated
and the crude mixture was filtered on short column of silica gel
(cyclohexane/EtOAc). The thiolactam (10 mmol) was suspended
in dry THF (100 mL) and MeI (1.0 mL, 16 mmol) was added. The
mixture was stirred at room temperature overnight. The thioimin-
ium ion was isolated by filtration and washed with cold THF to ob-
tain yellowish solid.
1H NMR spectra of 7–9 showed a sharp singlet that was ob-
served at the range of d 5.23–4.93 ppm. This is assigned to two
benzylic protons. The signal for CH2 protons adjacent to N atom
in 9 is shifted to the downfield at d 4.22 ppm. This is the typical
triplet with unexpected intensity ratio and this downfield shift is
because of the adjacent positively charged nitrogen atom, which
may deshield the methylene protons by the electron withdrawing
nature. The CH2 protons adjacent to positively charged nitrogen
atom showed a triplet around at d 4.17 ppm (7) and d 3.75 ppm
General procedure B: synthesis of gem-dialkylated amines in Scheme 2
A suspension of CeCl3 (0.296 g. 1.2 mmol) in dry THF (4 mL) was
soniccated at room temperature for about 30 min. The suspension
Table 1
Antimicrobial screening of some selected compounds.
Name of the organism
Standard
antibiotic
Standard zone of inhibition
for selectivity (mm)
Diameter of zone of inhibition obtained (mm)
+ve control*
7
8
12
30
31
32
34
35
36
40
46
48
Staphylococcus aureus
Salmonella typhi
Pseudomonas aeruginosa
Candida albicans
Ampicillin
Chloramphenicol
Gentamicin
Ketoconazole
Streptomycin
17
18
15
18
15
–
3
9
–
–
6
9
9
10
–
6
7
8
–
–
5
6
3
4
–
1
–
1
–
–
2
2
1
–
–
–
–
1
–
–
1
–
1
1
1
1
2
4
–
1
–
–
2
–
–
1
–
1
–
–
1
1
2
2
1
–
–
3
3
–
Klebsiella pneumoniae
*
zone of inhibition obtained (mm) for the standard antibiotics used.

S. Britto et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 120 (2014) 489–493
491
(J = 6 Hz) (8). The C3 protons in 7 and 8 were observed as a triplet
around d 3.79 and 3.23 ppm (J = 6 Hz) respectively. The C4 protons
of 7 showed a quintet in the upfield at d 2.41 ppm. The multiplets
appeared like singlets for C3, C4, C5 and C6 protons in 9 may be
due to the relaxation effect. The same kind of effect could be seen
for all the ring protons in 15. The merged multiplet appeared for C4
and C5 protons of 8. The aromatic protons of 7–9 also appeared as
merged multiplets. The salt 12 is obtained as a mixture of rota-
mers, therefore, all the eight aromatic protons appeared as a
merged mutiplet. Two singlets for C1 protons adjacent to the pos-
itively charged nitrogen atom and two triplets for C3 protons were
appeared. One triplet for C4 protons of two rotamers appeared, this
may be due to the same environment possessed by all the four pro-
tons. For the two methyl groups, four singlets appeared like two
tively. The amines 27–29 showed C„C stretch in the range of
1598–1597 cmÀ1
.
The merged multiplet was observed for aromatic protons of 16–
29 in the range of d 7.45–7.11 ppm. A sharp singlet appeared in the
range of d 3.73–3.42 ppm for benzylic protons of 16–26 and the
same was shifted to d 3.99 ppm for 27–29. This peak appeared as
broad singlet for 28. The ring protons of these amines appeared
in the range of d 1.69–1.23 ppm and the same was shifted to d
2.42–2.21 ppm for 25 and 27. This is due to the electron withdraw-
ing effect of phenyl rings as well as the triple bonds. The character-
istic triplet for CH2 protons adjacent to the ring nitrogen appeared
in the range of d 2.68–2.26 ppm for 16–20, 28 and 29. These
triplets are looking like singlets due to the relaxation effect in
21–23. In all the amines, methylene protons in the alkyl groups
showed merged peaks with ring protons.
The ipso carbon of the compounds 16–19 and 20–23 was
observed in the range d 141.72–141.55 ppm, for 27 and 28, in the
range d 140.02–138.62 ppm, and for 7 membered amines 24–26,
in the range d 143.25–143.08. This may be due to the substituent
effect. 13C NMR spectra of 16, 25–29 showed a signal for the qua-
ternary carbon in the region of d 60.26–60.02 ppm. The same was
observed in the region of d 64.82–64.51 ppm for 17–19 and d
57.65–57.25 ppm for 21, 22, and 27. The six membered amines
20 and 28 showed the quaternary carbon at d 53.24 ppm and d
58.23 ppm respectively. The seven membered amine 24 showed
the same carbon at d 55.98 ppm. The signal for alkyne carbons in
27 were showed at d 87.82 and 83.69 ppm. The same in 28 were
observed at d 88.31 and 84.40 ppm. These carbons in 29 presented
at d 90.72 and 82.05 ppm. The difference in the chemical shifts may
be due to the different ring size.
doublets. The appearance of
a signal around at d 193.69–
187.52 ppm in 13C NMR and mass peaks in HRMS confirmed the
presence of iminium moiety in all the thioiminium ions.
Synthesis of bis-alkylated and alkynylated amines
We report that thioiminium salts thus prepared from lactams
and amides, can be converted into 2,2-disubstitued amines by
reaction with simple nucleophile i.e. organocerium reagents. Treat-
ment of the thioiminium salt 7 with allylmagnesium bromide
afforded the desired gem-diallylated pyrrolidine [1]. The best re-
sults are obtained with 3 equiv of allylmagnesium bromide in
THF at room temperature.
In contrast to Klaver et al. [6] neither the solvent nor the tem-
perature influences the product distribution. For instance, when
the reaction of 7 was performed with only one equivalent of allyl-
magnesium bromide in dichloromethane at À78 °C, no monoallyla-
tion was observed. Instead, the bisallylated amine was obtained in
40% yield together with lactam 7 arising from aqueous workup.
Introduction of geminal dialkyl group proved not to be feasible
by using either alkylmagnesium halides or alkyllithium deriva-
tives, despite the isolated example reported by Klaver et al. [6].
These reagents are presumably too basic and deprotonate the
thioiminium salts rather than undergoing the desired addition.
Organocerium derivatives are often used to avoid undesired depro-
tonation during addition of organolithium and organomagnesium
reagents to ketones [7]. Alkylcerium dichlorides, easily prepared
from the commercially available organolithium derivatives are
tested with thioiminium iodides (7–9, 12 and 15). These reagents
reacted cleanly with the thioiminium iodides 7–9, 12 and afforded
the gem-dialkyl derivatives 16–19, 20–23, 24–26 and 41–44 and
gem-dialkynyl amines 27–29 (Scheme 2) in good yields over the
three steps from the parent lactams. The progress of the reaction
was followed by TLC analysis using cyclohexane : TBME as eluent.
Interestingly, the reaction in the presence of 1 equiv of n-butylce-
rium with 7 affords 18 as single isolated product in 20% yield.
According to the results of the organomagnesium allylation, no
product resulting from the monoaddition was detected [8].
The reaction was also tested with acetamide 15, but was not
successful. Then, we prepared N-tert-butyltetrahydroisoquinoline
41 from acetamide 10 via the thioiminium ion 12. The acetyla-
tion-gem-dimethylation process represents a useful method for
the conversion of secondary amines into tert-butyl tertiary amines.
Secondary and tertiary alkylcerium reagents do not add to the
thioiminium salts and after aqueous work up, the parent lactams
are recovered [1]. It is unclear whether this result is due to a lack
of reactivity or a competitive deprotonation. Amines in Schemes
2, 3 and 5 are not stable for a long time at room temperature.
Hence, they are immediately converted to their hydrochlorides.
The compounds 16–19 and 20–26 showed their characteristic
CAH (aromatic), C@C ring stretch (aromatic) and C-N stretch in
the range of 3000–2996, 1605–1466 and 1258–1026 cmÀ1 respec-
The multiplets for aromatic protons in the region of d 7.43–
7.03 ppm were observed for 41–44. The C2 protons of these amines
showed a sharp singlet in the region of d 3.80–3.69 ppm and C3
and C4 protons appeared as multiplets in the region of d 2.83–
2.70 ppm.
Synthesis of amine hydrochlorides
The preparation of hydrochloride salts of above amines is
shown in Scheme 4 and 6. The characteristic N-H stretch of 30–
32, 36 and 38–40 could be seen between 2597–2534 cmÀ1
,
whereas, 33 and 37 showed the same at 2857 cmÀ1
. The
compounds 34 and 35 showed the N-H stretch between 2489–
2477 cmÀ1. This variation may be due to the difference in ring size.
A broad singlet was observed in the range d 12.10–11.03 and
10.96–10.38 ppm for 30–40. This difference may due to the varia-
tion in ring size. The aromatic protons peaks are well separated.
They show the coupling of protons clearly and explain the split-
ting pattern of benzylic as well as ring protons satisfactorily. The
spin coupling of NAH protons and geminal coupling of benzylic
protons resulted in the doublet of doublets appeared for benzylic
protons. In Fig. 1, the splitting of all the signals in 1H NMR of the
free amine 16 by NAH proton in the corresponding amine hydro-
chloride 30 has been shown. The COSY of 30 proves this spatial
arrangement of NAH very well (Fig. 2). The interaction of NAH
protons with the ring protons made the peaks for the ring protons
to be multiplets. This interaction is found to be weak in the cases of
34, 35 and 38.
The spectra of 30 and 35 showed the quaternary carbon in the
range of d 69.03–69.02 ppm, whereas, 31–33 show in the range d
75.87–75.17 ppm. The hydrochloride 34 showed the same at d
62.74 ppm, whereas, 36 and 37 showed in the range of d 68.39–
68.31 ppm. The seven membered amine hydrochloride 38 showed
the quaternary carbon at d 67.31 ppm, whereas, others 39 and 40
show in the range of d 73.78–73.10 ppm. This variation may be
due to the increase in number of a, ß, c and d carbons.

492
S. Britto et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 120 (2014) 489–493
Fig. 1. Comparison of 1H NMR spectra of amine 16 and its hydrochloride 30.
Coupling of NAH protons with ring protons
at 37 °C, for a period of 18–24 h for bacteria and at 25 °C, for 24–
48 h for fungi. Discs treated with 10 l of DMSO was used as neg-
ative controls and commercial discs of gentamicin (10 g), chlor-
amphenicol (30 g), streptomycin (100 g), ampicillin (10 g)
and ketoconazole (10 g) which were purchased at Himedia lab.
l
The coupling pattern of protons especially the interaction of
NAH protons with the ring protons was very much clear by their
spectra. The hydrochlorides (96–99) of amines 92–95 were pre-
pared and characterized by their IR, 1H, 13C and mass spectral data.
They showed the characteristic quaternary carbon in the range
of d 70.55–69.48 ppm whereas 96 shows at d 63.55 ppm. This may
l
l
l
l
l
Pvt. Ltd. were used as positive control. All determinations were
done duplicate. The compounds produced distinct, clear, circular
zones of inhibition around the discs and the diameters of clear
zones were measured with calipers (Attaie et al., 1987) and used
as an indication of antibacterial and antifungal activity [10].
All the tested organisms (S. aureus, K. pneumoniae, P. aeruginosa,
S. typhi and C. albicans) were found to be multidrug resistance to
various commercial antibiotics available (results not shown).
The effect of bis-quaternary ammonium salts on the growth of
various bacteria and the yeast depends on substituents at the qua-
ternary nitrogen atom [3]. We prepared the thioiminium salts as
well as the hydrochlorides of cyclic amines with N-benzyl substitu-
ent. So this study will be useful to understand the efficiency of ben-
zyl group against the microorganisms tested.
be due to the increase in the number of a, ß, c and d carbons.
Antimicrobial screening
For the investigation of the antibacterial and antifungal activity,
filter paper disc- agar diffusion method (Kirby-Bauer method) was
employed [9]. Thioiminium iodides 7, 8 and 12 amine hydrochlo-
rides 30–32, 34–36, 40, 46, and 48 were weighed and dissolved
in DMSO to obtain 100 mg/ml concentration. These solutions were
impregnated with Whatman No. 3 filter paper discs, dried under
laminar air flow and placed on the Muller–Hinton agar plate for
bacteria and Saubouraud’s dextrose agar plate for fungi, which
had been inoculated with a lawn of 0.1 ml of a 24 h broth culture
of test bacteria and fungi. The inoculated plates were incubated
The compounds 7 and 8 were found to be moderately active
against Staphylococcus and highly active against Salmonello and
Pseudomonas. But the ion 57 showed poor response against

S. Britto et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 120 (2014) 489–493
493
Acknowledgements
We thank Dr. G. Muralitharan, Assistant Professor, Department
of Microbiology, and Mr. C. Sakthivel, Research Scholar, School of
Chemistry Bharathidasan University, India. S.B. is very grateful to
the Swiss Federal Commission for Scholarships for Foreign Stu-
dents (FCS) for a scholarship.
ppm
0
1
2
3
Appendix A. Supplementary material
4
Supplementary data associated with this article can be found,
in the online version, at http://dx.doi.org/10.1016/j.saa.2013.09.
108.
5
6
7
References
8
9
[1] A. Agosti, S. Britto, P. Renaud, Org. Lett. 10 (2008) 1417–1420.
[2] B. Ekstrom, M. Ovesson, B.G. Pring, J. Med. Chem. 18 (1975) 1166–1168.
[3] J. Chlebicki, J. Wegrzynska, I. Maliszewska, M. Oswiecimska, J. Surfactants
Detergents 8 (2005) 227–232.
[4] P. Desai, K. Schildknegt, K.A. Agrios, C. Mossman, G.L. Milligan, J. Aube, J. Am.
Chem. Soc. 122 (2000) 7226–7232.
[5] H. Takahata, K. Takahashi, E.C. Wang, T. Yamazaki, J. Chem. Soc., Perkin Trans. 1
(1989) 1211–1214.
[6] W. Klaver, H. Hiemstra, W.N. Speckamp, J. Am. Chem. Soc. 111 (1989) 2588–
2595.
[7] H. Liu, K. Shia, X. Shang, B. Zhu, Tetrahedron 55 (1999) 3803–3830.
[8] H.B. Kagan, J.L. Namy, Tetrahedron 42 (1986) 6573–6614.
[9] A.W. Bauer, W.M.M. Kirby, J.C. Sherris, M. Turck, Amer. J. Clin. Pathol. 45 (1966)
493–496.
[10] R. Attaie, J. Whalen, K.M. Shahani, M.A. Amer, J. Food Protec. 50 (1987) 224–
228.
10
11
12
ppm
0
12 11 10
9
8
7
6
5
4
3
2
1
Fig. 2. COSY of amine hydrochloride 30 showing the coupling of N–H proton with
other protons.
Candida. Both the salts showed the poor response to Klebsiella. The
compound 12 responded moderately against all the above organ-
isms except Klebsiella.