Photoinduced one-pot synthesis of hydroxamic acids from aldehydes through in-situ generated silver nanoclusters

Article abstract of DOI:10.1007/s11164-018-3549-z

Hydroxamic acids have attracted significant attention due to their widespread use in applied chemistry. In this report, a modified Angeli–Rimini method has been achieved via the visible light-mediated catalytic transformation of a variety of heterocyclic, aromatic and aliphatic aldehydes 1a–j to their corresponding hydroxamic acids 2a–j in 81–93% yield. The unique ability of vitamin K₃ as a photoredox catalyst to expedite the development of completely new reaction mechanisms and to enable the construction of challenging carbon–nitrogen bonds has been investigated. It is shown for the first time that the vitamin K₃ and aldehyde are largely responsible for rapid in situ reduction of Ag⁺ ions to catalytic photoluminescent Ag nanoclusters that possess a bandgap energy of 2.87?eV and are less than 2 nm in size. A mechanism for this reaction has been proposed and is supported by UV–Vis, TEM, ESI/MS, FT-IR, ¹H NMR and ¹³C NMR analyses. The investigated method utilizes readily available reagents and produces the hydroxamic acids in high yields without the formation of side products, making it simple, practical and cost-effective.

Full text of DOI:10.1007/s11164-018-3549-z

Research on Chemical Intermediates
https://doi.org/10.1007/s11164-018-3549-z(0123456789(). -, vo
(
V
l
)
0
1
2
3
4
5
6
7
8
9
(
)
.
-
,
v
o
l
V
)
Photoinduced one-pot synthesis of hydroxamic acids
from aldehydes through in-situ generated silver
nanoclusters
1
Yasser A. Attia2 • Eirik Johansson Solum3
Yasser M. A. Mohamed
•
Received: 27 May 2018 / Accepted: 28 July 2018
Ó Springer Nature B.V. 2018
Abstract
Hydroxamic acids have attracted significant attention due to their widespread use in
applied chemistry. In this report, a modified Angeli–Rimini method has been
achieved via the visible light-mediated catalytic transformation of a variety of
heterocyclic, aromatic and aliphatic aldehydes 1a–j to their corresponding
hydroxamic acids 2a–j in 81–93% yield. The unique ability of vitamin K as a
3
photoredox catalyst to expedite the development of completely new reaction
mechanisms and to enable the construction of challenging carbon–nitrogen bonds
has been investigated. It is shown for the first time that the vitamin K and aldehyde
3
?
are largely responsible for rapid in situ reduction of Ag ions to catalytic photo-
luminescent Ag nanoclusters that possess a bandgap energy of 2.87 eV and are less
than 2 nm in size. A mechanism for this reaction has been proposed and is supported
1
13
by UV–Vis, TEM, ESI/MS, FT-IR, H NMR and C NMR analyses. The inves-
tigated method utilizes readily available reagents and produces the hydroxamic
acids in high yields without the formation of side products, making it simple,
practical and cost-effective.
Keywords Ag nanoclusters Á Angeli–Rimini reaction Á Hydroxamic
acids Á Vitamin K Á Photocatalysis
3
&
&
Yasser M. A. Mohamed
y.m.a.mohamed@outlook.com
Yasser A. Attia
yasserniles@niles.edu.eg
1
2
3
Photochemistry Department, National Research Center, Dokki, Giza 12622, Egypt
National Institute of Laser Enhanced Sciences, Cairo University, Giza 12613, Egypt
Faculty of Health Sciences, NORD University, 7800 Namsos, Norway
123

Y. M. A. Mohamed et al.
Introduction
Over the past few decades, the Angeli–Rimini reaction has enabled the synthesis of
hydroxamic acids from aldehydes and N-hydroxybenzene sulfonamide in the
presence of strong base [1]. However, this method has several drawbacks, including
the formation of a by-product which is difficult to remove from the desired product,
and low yields. To date, various methods for the preparation of hydroxamic acids
have been developed, including the reaction of nitroarenes with aldehydes in the
presence of Mn-oxide as a catalyst [2], the reaction of nitrosoarenes with aldehydes
catalysed by N-heterocyclic carbenes [3], the oxidative amidation of alcohols [4],
hydroacylation of aldehydes using dialkyl azodicarboxylates in the presence of
phenylglyoxylic acid [5], and the reaction of activated carboxylic acids, acyl halides
or esters with O-protected, N,O-protected [6–9] and unprotected hydroxylamines
[
10]. However, these synthetic approaches often require drastic conditions, long
reaction times and the use of expensive reagents. Hence, due to the importance of
hydroxamic acids as therapeutic agents [11, 12] and strong metal ion-chelators
[
13, 14], the development of new procedures for the synthesis of hydroxamic acids
is imperative. Specifically, reaction efficiency and product isolation can be
facilitated by the minimization of stoichiometric chemical waste. The exploration
of new concepts in the area of nanocluster photocatalysis provides opportunities to
develop novel green syntheses of valuable fine chemicals [15–19]. Recently,
nanoclusters have been extensively examined as active catalysts for several
reactions [20–22], including the oxidation of CO to CO [23], the NO–CO reaction
2
[
of formaldehyde (HCHO) and methanol (CH OH) from CO and H [26]. Silver
24], H production by way of photocatalytic water splitting [25], and the formation
2
3
2
nanoclusters have evolved to be used in sophisticated strategies in catalysis due to
their interesting luminescence properties [27, 28]. To date, many synthetic methods
have been developed to obtain colloidal silver nanoclusters such as direct chemical
reduction and photo- or thermally-induced transformations [25, 29]. The preparation
of water-soluble Ag clusters has also been demonstrated [30, 31]. Additionally, the
synthesis of Ag clusters using templated assemblies such as DNA [32–34],
polypeptides [35, 36], and proteins [37, 38] has been reported. Herein, the Ag
?
nanoclusters have generally been produced from the reduction of Ag ions under
photoredox catalysis conditions. One attractive aspect of this protocol is the
utilization of Ag nanoclusters as intermediates in the visible light-driven catalytic
conversion of a set of aldehydes to their corresponding hydroxamic acids through a
nucleophilic addition reaction.
Experimental
Materials and methods
All chemicals were obtained from Sigma-Aldrich and used without further
purification. All melting points (mp) are uncorrected. Thin-layer chromatography
(
TLC) was performed using silica gel plates 60 GF254, cellulose plates
1
23

Photoinduced one-pot synthesis of hydroxamic acids from…
(20 9 20 cm). The infrared spectra were recorded as a thin film on a PerkinElmer
FT-IR spectrometer. The nuclear magnetic resonance (NMR) spectra were obtained
1
13
on a Bruker Avance DPX (300 MHz for H and 75 MHz for and C, respectively).
The chemical shift data are reported in parts per million (ppm) downfield from
tetramethylsilane. DMSO-d6 was as partial deuterated-NMR solvent. UV–Vis
spectra were recorded on a Hewlett-Packard 8452A diode-array spectrophotometer.
Photoluminescence spectra were measured on a FP-8200 spectrofluorometer
(
PW1710 X-ray diffractometer using Cu Ka radiation (k = 1.54186 A). The XRD
Jasco). X-ray diffraction (XRD) measurements were performed using a Philips
˚
2
2
patterns were recorded from 20° to 70° H, with a step size of 0.020° H and
collecting 10 s per step. Transmission electron microscopy (TEM) micrographs of
the colloidal particles were measured using a JEOL JEM-2100 of 200 kV with a
magnification range of 10009 to 50,0009. The TEM samples were prepared and
placed on a copper grid by mixing one dilute drop of prepared aqueous particles
dispersed in 5 mL acetone to produce a slightly turbid solution that was allowed to
dry thoroughly. High-resolution mass (ESI/MS) spectra were recorded on an
Agilent 6230 Series accurate-mass time-of-flight (TOF) LC/MS.
General procedure for nicotine hydroxamic acid (2a) using the classical
Angeli–Rimini reaction
To a solution of N-hydroxybenzene sulfonamide (0.17 g, 1 mmol) in MeOH
(2 mL), MeONa (0.11 g, 2 mmol) was added. Pyridine-3-carboxaldehyde (1a)
(0.11 g, 1 mmol) was subsequently added and the reaction mixture was stirred at
room temperature for 24 h. The reaction was monitored by TLC. After completion
of the reaction, the mixture was concentrated and EtOAc (30 mL) was added. The
organic layer was collected, dried over anhydrous MgSO and then the solvent was
4
evaporated under reduced pressure using a rotatory evaporator. The obtained residue
was purified by a short plug of silica gel using (hexane:EtOAc, 1:1) to afford N-
hydroxynicotinamide (2a) in 55% yield.
General procedure for the photosynthesis of hydroxamic acids 2a–j
To an aqueous solution of AgNO (1.7 mg, 0.01 mmol, 1 mol%) in water (6 mL),
3
vitamin K (2.6 mg, 0.015 mmol, 1.5 mol%) dissolved in ethanol (2 mL) was
3
added, and then an appropriate aldehyde (1 mmol) dissolved in THF (2 mL) was
added to the reaction mixture followed by the addition of NH OHÁHCl (69 mg,
2
1
mmol) and Et N (0.14 mL, 1 mmol). The final solvent ratio (H O:EtOH:THF)
3 2
was (3:1:1). The mixture was stirred at room temperature for 30 min under visible
light irradiation using a halogen lamp (HALOPAR 20 75 W 230 V 30-GU10;
Osram, Italy). The reaction was monitored by TLC. After completion of the
reaction, EtOAc (30 mL) was added. The aqueous layer was collected and
concentrated under reduced pressure at 25 °C to obtain pure sample containing Ag
nanoparticles that was characterized by UV–Vis and TEM analyses. The organic
phase was collected, dried over anhydrous MgSO and filtered. The solvent was
4
evaporated under vacuum using a rotatory evaporator and then the residue was
123

Y. M. A. Mohamed et al.
purified by a short plug of silica gel using (Hexane:EtOAc, 1:1) to obtain
hydroxamic acids 2a–j in 81–92% yield.
Characterization data for compounds 2a–j
N-hydroxynicotinamide (2a)
1
White solid (93%); mp 136–137 °C [Literature [39] mp 135 °C]; H NMR
(
J = 4.2 Hz, 1H), 8.09 (d, J = 7.8 Hz, 1H), 7.76–7.74 (m, 1H), 7.36–7.32 (m, 1H);
300 MHz, DMSO-d ): d (ppm) 10.16 (br, s, 1H), 9.44 (br, s, 1H), 8.62 (d,
6
1
3
C NMR (75 MHz, DMSO-d ): d (ppm) 168.2, 152.5, 147.6, 136.8, 129.3, 126.0;
6
?
HRMS (ESI) m/z [M ? H] calcd for C H N O 139.0508, found 139.0572.
6
7 2 2
N-hydroxypicolinamide (2b)
Yellow solid (91%); mp 154–155 °C; H NMR (300 MHz, DMSO-d ): d (ppm)
1
6
1
0.32 (br, s, 1H), 9.36 (br, s, 1H), 8.78 (d, J = 8.4 Hz, 2H), 7.64 (d, J = 8.4 Hz,
1
3
2
H); C NMR (75 MHz, DMSO-d ): d (ppm) 167.2, 152.5, 143.4, 122.5; HRMS
6
?
ESI) m/z [M ? H] calcd for C H N O 139.0508, found 139.0556.
(
6 7 2 2
N-hydroxyfuran-2-carboxamide (2c)
White solid (87%); mp 126–127 °C; H NMR (300 MHz, DMSO-d ): d (ppm)
1
6
1
0.35 (br, s, 1H), 8.72 (br, s, 1H), 6.95-7.16 (m, 2H), 7.79 (d, J = 6.5 Hz, 1H), 8.80
1
3
(
br, s, 1H); C NMR (75 MHz, DMSO-d ): d (ppm) 164.5, 147.9, 144.7, 119.7,
6
?
1
12.3; HRMS (ESI) m/z [M ? H] calcd for C H NO : 128.0348, found 128.0352.
5 5 3
N-hydroxythiophene-2-carboxamide (2d)
1
Off-white solid (89%); mp 123–124 °C [Literature [1] mp 122–123 °C]; H NMR
(
300 MHz, DMSO-d ): d (ppm) 6.92–7.04 (m, 2H), 7.16 (d, J = 6.2 Hz, 1H), 9.42
6
13
(
br, s, 1H), 10.81 (br, s, 1H); C NMR (75 MHz, DMSO-d ): d (ppm) 160.8, 136.7,
6
?
1
found 144.0213.
32.0, 127.6, 127.2; HRMS (ESI) m/z [M ? H] calcd for C H NO S: 144.0119,
5 5 2
N-hydroxybenzamide (2e)
1
Off-white solid (85%); mp 125–126 °C [Literature [40] mp 127 °C]; H NMR
(
300 MHz, DMSO-d ): d (ppm) 10.97 (br, s, 1H), 0.8.75 (br, s, 1H), 7.69–7.62 (m,
6
1
3
2
H), 7.51-7.48 (m, 3H); C NMR (75 MHz, DMSO-d ): d (ppm) 165.3, 132.9,
6
?
32.1, 129.4, 127.1; HRMS (ESI) m/z [M ? H] calcd for C H NO : 138.0555,
1
found 138.0527.
7
8
2
1
23

Photoinduced one-pot synthesis of hydroxamic acids from…
N,2-dihydroxybenzamide (2f)
1
Brown solid (83%); mp 176–177 °C; H NMR (300 MHz, DMSO-d ): d (ppm)
6
1
2.15 (br, s, 1H), 11.76 (br, s, 1H), 9.81 (br, s, 1H), 7.64 (d, J = 7.8 Hz, 1H), 7.51 (t,
1
3
J = 7.8 Hz, 1H), 6.99-6.94 (m, 2H); C NMR (75 MHz, DMSO-d ): d (ppm)
6
?
68.5, 160.6, 136.3, 129.4, 122.1, 119.4, 117.1; HRMS (ESI) m/z [M ? H] calcd
1
for C H NO : 154.0504, found 154.0516.
7
8
3
N-hydroxy-3-phenylpropanamide (2g)
1
White solid (86%); mp 71–72 °C [Literature [41] mp 69–72 °C]; H NMR
(
300 MHz, DMSO-d ): d (ppm) 9.11 (br, s, 1H), 8.76 (br, s, 1H), 7.28–7.16 (m, 5H),
6
13
2
.82 (t, J = 7.5, 2H), 2.39 (t, J = 7.5, 2H); C NMR (75 MHz, DMSO-d ): d (ppm)
6
?
69.8, 140.9, 128.8, 128.5, 126.6, 35.3, 31.6; HRMS (ESI) m/z [M ? H] calcd for
1
C H NO : 166.0868, found 166.0862.
9
13
2
N-hydroxypentanamide (2h)
1
White solid (92%); mp 54–55 °C [Literature [42] mp 53–54 °C]; H NMR
300 MHz, DMSO-d ): d (ppm) 10.02 (br, s, 1H), 9.36 (br, s, 1H), 2.11 (t,
J = 7.1 Hz, 2H), 1.57 (m, 2H), 1.30 (m, 2H), 0.88 (t, J = 7.1 Hz, 3H); C NMR
(
6
1
3
(
m/z [M ? H] calcd for C H NO : 118.0868, found 118.0853.
75 MHz, DMSO-d ): d (ppm): d (ppm) 171.2, 32.6, 28.0, 22.6, 14.1. HRMS (ESI)
6
?
5
12
2
N-hydroxy-2-methylpentanamide (2i)
1
White solid (81%); mp 80–81 °C, H NMR (300 MHz, DMSO-d ): d (ppm) 10.41
6
(
br, s, 1H), 8.65 (br, s, 1H), 2.11–1.84 (m, 1H), 1.53–1.29 (m, 2H), 1.22–1.06 (m,
1
H), 0.88 (d, J = 6.9 Hz, 3H), 0.77 (t, J = 7.1 Hz, 3H); C NMR (75 MHz,
3
2
DMSO-d ): d (ppm) 172.2, 36.8, 35.2, 20.1, 18.4, 14.0; The NMR data are in
6
?
agreement with the literature [23]; HRMS (ESI) m/z [M ? H] calcd for
C H NO : 132.1052, found 132.01057.
6
14
2
N-hydroxyicosanamide (2j)
White solid (90%); mp 102–103 °C; H NMR (300 MHz, DMSO-d ): d 10.23 (br, s,
1
6
1
H), 9.74 (br, s, 1H), 2.39 (td, J = 7.4, 1.9 Hz, 2H), 1.64–1.56 (m, 2H), 1.34–1.22
1
3
(
m, 32H), 0.82 (t, J = 6.9 Hz, 3H); C NMR (75 MHz, DMSO-d ): d 172.3, 44.3,
6
3
for C H NO [M ? 1] 328.3216, found 328.3214.
2.3, 30.2 (8CH ), 30.1, 30.0, 29.9, 29.8, 29.7, 29.6, 23.1, 22.5, 14.5; HRMS Calcd
2
?
2
0 42
123

Y. M. A. Mohamed et al.
Results and discussion
In this protocol, it was demonstrated that vitamin K was a potential photoredox
3
catalyst which played an important role as an effective electron carrier and electron
?
transfer agent [43–45] in the reduction of Ag ions to Ag nanoclusters due to the
reactivity of the quinone moiety upon excitation under visible light. In an initial
series of experiments, it was observed that the reaction between vitamin K and
3
pyridine-3-carboxaldehyde (1a) and hydroxylamine under visible light irradiation
resulted in the production of pyridine-3-hydroxamic acid (2a) through the in situ
formation of Ag nanoclusters as active catalysts (Scheme 1).
The UV–Vis analysis of an aqueous solution provided evidence for the formation
of Ag nanoclusters, which showed no absorption peaks in the UV–visible region
[
25], while the photoluminescence measurement showed a peak with maximum
intensity at k = 432 nm at an excitation wavelength of 310 nm, constituting the first
indication of the formation of Ag clusters [25, 27] (Fig. 1a). The value of the
bandgap can be estimated using the emission peak energy (432 nm, i.e. 2.87 eV).
Although the TEM technique is not the best method for characterizing the size of
the metal clusters because of cluster fusion [25], the HRTEM image in Fig. 1b
showed fine distribution of Ag clusters with sizes below 2 nm.
A possible reaction mechanism for the synthesis of hydroxamic acids is
illustrated in Scheme 2.
In Scheme 2, pyridine-3-carboxaldehyde (1a) was converted into nicotine
hydroxamic acid (2a) via the formation of an acyl cation, an intermediate which
is known to be reactive towards nucleophiles. Thus, when the Ag -NOH group
n
attacked this cation, hydroxamic acid 2a was obtained. This proposed mechanism is
supported by FT-IR data. After 5 min of reaction progress, the IR spectrum
provided evidence for the formation of Ag nanoclusters via ionic interaction and
complexation with the present scaffolds which have multiple functional groups
(
?
OH, CHO and NOH) that allow strong interaction with Ag ions (Fig. 2).
-
1
As shown in the FT-IR spectrum, the appearance of a broad band at 4218 cm is
due to the presence of (NOH) groups attached to Ag clusters in the form Ag (NOH).
n
-
1
The OH groups of vitamin K H (see Scheme 2) appeared at 3688 and 3620 cm
3
2
which confirmed the conversion of vitamin K to its isomeric form; vitamin K H
3
3
2
1
-
under the action of light. The C=O of aldehyde 1a appeared at 1717 cm
-
.
Characteristics band for the N–O stretch appeared at 1586, 1478 cm and the C–O
1
-
1
stretch band appeared at 1220 cm . In addition, the reaction was monitored by an
off-line ESI/MS spectrometer. Characteristic peaks were observed for nicotine
Scheme 1 A model reaction: in-situ formation of Ag nanoclusters and their catalytic activity towards the
synthesis of hydroxamic acid 2a from aldehyde 1a
1
23

Photoinduced one-pot synthesis of hydroxamic acids from…
Fig. 1 a Photoluminescence spectrum of the formed Ag nanoclusters from the aqueous solution of the
reaction after 5 min; b TEM image of Ag nanoclusters
Scheme 2 Proposed reaction mechanism for the modified Angeli–Rimini procedure
?
hydroxamic acid (2a) (m/z [M ? 1] = 139.0572), unreacted pyridine-3-carbox-
?
aldehyde (1a) (m/z [M ? 1] = 108.0446), and vitamin K3 (m/z
?
M ? 1] = 173.0979) in addition to other characteristic peaks at m/z = 525.9054,
[
555.7309 and 663.8046, respectively, indicating the formation of Ag and Ag3
2
nanoclusters with mixed ligands (Table 1).
Complete conversion of pyridine-3-carboxaldehyde to nicotine hydroxamic acid
1
was observed after 30 min which was confirmed by H and C NMR spectral
13
1
measurements of the isolated organic substrate. The H NMR spectrum showed two
peaks at d = 10.16 and 9.44 ppm, respectively characteristic for NH and OH groups
present in hydroxamic acid. In addition, C NMR showed the characteristic peak of
1
3
(
(
CONHOH) at d = 168.2 ppm without the appearance of a significant peak for the
CHO) group (see Fig. 3a–d).
123

Y. M. A. Mohamed et al.
Fig. 2 FT-IR spectrum of the supernatant of the reaction mixture
Table 1 Molecular formula of
identified peaks
m/z
Expected molecular formula
525.9054
555.7309
663.8046
(C11
(C11
H
8
8
O
O
2
)(C
6
6
H
H
5
ON)Ag
2
2
-(HNO)
-(HNO)
H
2
)(C
5
ON)Ag
2
11 8 2 6 5 3
C H O )(C H ON)Ag -(HNO)
1
1
Fig. 3 a H NMR spectrum of pyridine-3-carboxaldehyde; b H NMR spectrum of the isolated organic
substrate indicating the formation of nicotine hydroxamic acid; c C NMR spectrum of pyridine-3-
1
3
1
carboxaldehyde; d C NMR spectrum of hydroxamic acid
3
1
23

Photoinduced one-pot synthesis of hydroxamic acids from…
Scheme 3 Pyridine-3-carboxaldehyde as model substrate for the Angeli–Rimini reaction
For completeness, we examined the reaction (Scheme 3) under various
conditions (Table 2).
It was observed that the reaction between the aldehyde and hydroxylamine in the
absence of catalyst did not proceed (Table 2, entry 1). In addition, in the presence of
AgNO (Table 2, entry 2), in the dark or under visible light, respectively, the
3
aldehyde was recovered. Also, when we employed the catalytic system (AgNO3/
vitamin K ) in the dark, the aldehyde was recovered (Table 2, entry 3). However,
3
interestingly, the use of AgNO /vitamin K under visible light (Table 2, entry 4)
3
3
delivered the hydroxamic acid 2a in excellent yield (93%), which indicates that light
is necessary for the reaction. Finally, a classical Angeli–Rimini reaction was
performed and gave nicotine hydroxamic acid in 55% yield after 24 h (Table 2,
entry 5). From the above results, a modified methodology for the Angeli–Rimini
protocol was designed by the reaction of AgNO , aldehyde and hydroxylamine in
3
the presence of vitamin K as a photoredox catalyst due to its ability to transfer
3
Table 2 Screening of different reaction conditions used in the synthesis of nicotine hydroxamic acid
from pyridine-3-carboxaldehyde
Entry
Additives
Reaction conditions
Yield %
a
1
2
3
4
5
Without catalyst
In dark or under visible light
In dark or under visible light
In dark
n.d.
n.d.
n.d.
93%
55%
b
AgNO
AgNO
AgNO
3
3
3
c
3
/vitamin K
/vitamin K
d
3
Under visible light
Room temperature
e
N-hydroxybenzene sulfonamide/MeONa
n.d. not detected
a
Reaction conditions: pyridine-3-carboxaldehyde (1a) (1 equivalent), NH
1 equivalent) in H O:EtOH:THF (3:1:1) stirred at room temperature under visible light for 24 h
Reaction conditions: pyridine-3-carboxaldehyde 3a (1 equivalent), NH
OHÁHCl (1 equivalent), Et
equivalent), AgNO (1 mol%) in H O:EtOH:THF (3:3:1) stirred in the dark or under visible light for 24 h
Reaction conditions: pyridine-3-carboxaldehyde (1a) (1 equivalent), NH OH/HCl (1 equivalent), Et
1 equivalent), AgNO (1 mol%), vitamin K (1.5 mol%) in H O:EtOH:THF (3:1:1) stirred in the dark
for 48 h
2
OHÁHCl (1 equivalent), Et
3
N
(
b
2
2
3
N (1
3
2
c
2
3
N
(
3
3
2
d
Reaction conditions: pyridine-3-carboxaldehyde (1a) (1 equivalent), NH
1 equivalent), AgNO (1 mol%), vitamin K (1.5 mol%) in H O:EtOH:THF (3:1:1) stirred under visible
light for 30 min
2
OHÁHCl (1 equivalent), Et
3
N
(
3
3
2
e
Conditions for the classical Angeli–Rimini reaction: pyridine-3-carboxaldehyde (1a) (1 equivalent),
MeONa (2 equivalent), N-hydroxybenzene sulfonamide (1 equivalent) in MeOH. The reaction was stirred
under ambient conditions at room temperature for 24 h
123

Y. M. A. Mohamed et al.
electrons via excitation under visible light [43–45]. Herein, it was demonstrated that
vitamin K induced electron transfer through oxidative-reductive modes in aqueous
3
solution upon excitation by using visible light. Silver ions were then reduced to
form silver nanoparticles as shown below in Eqs. 1 and 2.
À
Vitamin K3 þ hm þ C2H5OH=H2O þ 2e $ Vitamin K3H2
ð1Þ
ð2Þ
À
0
À
AgNO þ e ! Ag þ NO
3
3
The Ag cluster was formed via the reaction of Ag nanoparticles with aldehyde,
hydroxylamine and vitamin K (Eq. 3), as evidenced by ESI/MS and IR data.
3
0
Ag þ NH2OH þ R-CHO þ Vitamin K3 þ hm
!
ðR-CHOÞðVitamin K3H2ÞAg À NOH
ð3Þ
n
By way of a sequential pathway, the Ag -NOH adduct reacted with the aldehyde
n
to afford hydroxamic acid and Ag nanoparticles (Eq. 4).
0
ðR-CHOÞðVitamin K3H2ÞAg - NOH þ R-CHO þ hm ! R-CONHOH þ Ag ð4Þ
n
It was shown that this transformation was facilitated by the powerful catalytic
activity of in situ formed Ag nanoclusters that possess powerful semiconducting
properties with a bandgap of * 3 eV [27, 46]. At the end of the reaction, the
presence of a surface plasmon resonance absorption peak at 403 nm revealed the
formation of Ag NPs (Fig. 4a). In addition, a representative TEM image showed
that the solution consists of Ag NPs with an average size of about 4.6 ± 1.81 nm
due to aggregation of clusters to larger nanoparticles (Fig. 4b) which was
considered as new evidence for the proposed mechanism. Also, XRD patterns
corresponding to the (111), (200) and (220) planes of the formed Ag NPs (Fig. 4c)
were observed at 2h angles of 38.25°, 44.32° and 64.51°, respectively [47].
Finally, the methodology was successfully applied to the synthesis of a series of
hydroxamic acid derivatives. A set of photocatalytic reactions were performed
between an array of aldehydes, including pyridine-4-carboxaldehyde 1b, furan-2-
carboxaldehyde 1c, thiophene-2-carboxaldehyde 1d, benzaldehyde 1e, salicylalde-
hyde 1f, 3-phenylpropanal 1g, hexanal 1h, 2-methylpentanal 1i, and eicosanal 1j,
respectively, with hydroxylamine in the presence of AgNO3 and vitamin K3,
affording adducts 2b–j (Scheme 4).
In all cases, the products were obtained in excellent yields ranging from 81 to
2% (Table 3).
As observed from the aforementioned results, this procedure provides an
9
interesting solution for the synthesis of hydroxamic acids from aldehydes.
Advantages of this method include the preparation of hydroxamic acids in one
step, the low-cost reaction setup, short reaction times, tolerance to ambient
conditions, use of a clean photocatalytic reaction under visible light irradiation, and
the obtainment of products in excellent yields without recourse to protection/
deprotection strategies.
1
23

Photoinduced one-pot synthesis of hydroxamic acids from…
Fig. 4 a Absorption spectrum of the supernatant solution after completion of the reaction that indicates
the formation of Ag NPs, b TEM image of the formed Ag NPs and c XRD pattern of the formed Ag NPs
Scheme 4 The synthesis of a series of hydroxamic acids from aldehydes
Conclusions
In summary, we have investigated a simple, efficient and green modified Angeli–
Rimini procedure for the synthesis of heterocyclic, aromatic and aliphatic
hydroxamic acids from aldehyde derivatives. The successful use of Ag nanoclusters
in an unconventional reaction has been demonstrated. The mild reaction conditions
employed, high product yields, short reaction times, and the absence of undesirable
side products make this procedure more practical than previously reported methods.
This approach should inspire novel applications of Ag nanocluster photocatalysts in
organic synthesis.
123

Y. M. A. Mohamed et al.
Table 3 Visible light-induced transformation of aldehydes 1b–j to 2b–j
Substrate
Product
Yield %
9
1
8
7
8
8
9
5
8
3
8
9
6
2
8
9
1
0
Acknowledgements This research did not receive any specific grant from funding agencies in the public,
commercial, or not-for-profit sectors. The authors are grateful to the National Research Center (Egypt),
National Institute of Laser Enhanced Sciences, Cairo University (Egypt) and NORD University (Norway)
for providing the facilities.
Compliance with ethical standards
Conflict of interest The authors have declared no conflict of interest.
1
23

Photoinduced one-pot synthesis of hydroxamic acids from…
References
1
2
3
4
5
6
7
8
9
. A. Porcheddu, G. Giacomelli, J. Org. Chem. 71, 7057 (2006)
. K.S. Jain, K.A.A. Kumar, S.B. Bharate, R.A. Vishwakarm, Org. Biomol. Chem. 12, 6465 (2014)
. F.T. Wong, P.K. Patra, J. Seayad, Y. Zhang, J.Y. Ying, Org. Lett. 10, 2333 (2008)
. S.L. Yedage, B.M. Bhanage, Synthesis 47, 526 (2015)
. G.N. Papadopoulos, C.G. Kokotos, Chem. Eur. J. 22, 6964 (2016)
. J.C.S. Woo, E. Fenster, G.R. Dake, J. Org. Chem. 69, 8984 (2004)
. A. Gissot, A. Volonterio, M. Zanda, J. Org. Chem. 70, 6925 (2005)
. J.R. Martinelli, D.M.M. Freckmann, S.L. Buchwald, Org. Lett. 8, 4843 (2006)
. K. Thalluri, S.R. Manne, D. Dev, B. Mandal, J. Org. Chem. 79, 3765 (2014)
10. B. Vasantha, H.P. Hemantha, V.V. Sureshbabu, Synthesis 2010, 2990 (2010)
11. E.M. Muri, M.J. Nieto, R.D. Sindelar, J.S. Williamson, Curr. Med. Chem. 9, 1631 (2002)
12. A. Yekkour, A. Meklat, C. Bijani, O. Toumatia, R. Errakhi, A. Lebrihi, F. Mathieu, A. Zitouni, N.
Sabaou, Lett. Appl Microbiol. 60, 589 (2015)
1
1
1
3. N. T u¨ rkel, J. Chem. Eng. Data 56, 2337 (2011)
4. M. Harty, S.L. Bearne, J. Therm. Anal. Calorim. 123, 2573 (2016)
5. H. Chen, C. Liu, M. Wang, C. Zhang, N. Luo, Y. Wang, H. Abroshan, G. Li, F. Wang, ACS Catal. 7,
3
632 (2017)
6. M. Miyauchi, H. Irie, M. Liu, X. Qiu, H. Yu, K. Sunada, K. Hashimoto, J. Phys. Chem. Lett. 7, 75
2016)
7. M.A. Koklioti, T. Skaltsas, Y. Sato, K. Suenaga, A. Stergiou, N. Tagmatarchis, Nanoscale 9, 9685
2017)
1
1
(
(
18. J.C. Ahern, S. Kanan, H.H. Patterson, Comments Inorg. Chem. 35, 59 (2015)
19. H. Zhu, N. Goswami, Q. Yao, T. Chen, Y. Liu, Q. Xu, D. Chen, J. Lu, J. Xie, J. Mater. Chem. A 6,
1102 (2018)
2
0. S. Abbet, A. Sanchez, U. Heiz, W.D. Schneider, A.M. Ferrari, G. Pacchioni, N. R o¨ sch, J. Am. Chem.
Soc. 122, 3453 (2000)
2
1. Y. Liu, H. Tsunoyama, T.C. Akita, S. Xie, T.C. Tsukuda, ACS Catal. 1, 2 (2011)
2. F.F. Schweinberger, M.J. Berr, M. D o¨ blinger, C. Wolff, K.E. Sanwald, A.S. Crampton, C.J. Ridge, F.
J a¨ cke, J. Feldmann, M. Tschurl, U. Heiz, J. Am. Chem. Soc. 135, 13262 (2013)
3. U. Heiz, A. Sanchez, S. Abbet, W.D. Schneider, Chem. Phys. 262, 189 (2000)
4. A.S. W o¨ rz, K. Judai, S. Abbet, U. Heiz, J. Am. Chem. Soc. 125, 7964 (2003)
5. Y. Attia, M. Samer, Renew. Sustain. Energy Rev. 79, 878 (2017)
6. S. Yin, Z. Wang, E.R. Bernstein, Phys. Chem. Chem. Phys. 15, 4699 (2013)
7. Y. Attia, D. Buceta, C. Blanco-Varela, M. Mohamed, G. Barone, M.A. L o´ pez-Quintela, J. Am.
Chem. Soc. 136, 1182 (2014)
2
2
2
2
2
2
2
2
3
3
8. Y. Attia, D. Buceta, F. Requejo, L. Giovanetti, M.A. L o´ pez-Quintela, Nanoscale 7, 11273 (2015)
9. Y. Lu, W. Chen, Chem. Soc. Rev. 41, 3594 (2012)
0. B. Adhikari, A. Banerjee, Chem. Mater. 22, 4364 (2010)
1. N. Cathcart, P. Mistry, C. Makra, B. Pietrobon, N. Coombs, M. Jelokhani-Niaraki, V. Kitaev,
Langmuir 25, 5840 (2009)
32. S. Dai, X. Zhang, T. Li, Z. Du, H. Dang, Appl. Surf. Sci. 249, 346 (2005)
33. W. Guo, J. Yuan, Q. Dong, E. Wang, J. Am. Chem. Soc. 132, 932 (2010)
34. H.C. Yeh, J. Sharma, J.J. Han, J.S. Martinez, J.H. Werner, Nano Lett. 10, 3106 (2010)
35. C.I. Richards, S. Choi, J.C. Hsiang, Y. Antoku, T. Vosch, A. Bongiorno, Y.L. Tzeng, R.M. Dickson,
J. Am. Chem. Soc. 130, 5038 (2008)
3
6. X.L. Guevel, B. H o¨ tzer, G. Jung, K. Hollemeyer, V. Trouillet, M. Schneider, J. Phys. Chem. C 115,
10955 (2011)
37. J. Xie, Y. Zheng, J.Y. Ying, J. Am. Chem. Soc. 131, 888 (2009)
38. A. Mathew, P.R. Sajanlal, T. Pradeep, J. Mater. Chem. 21, 11205 (2011)
39. N.K. Makhmudova, ZCh. Kadyrova, E.A. Del’yaridi, KhT Sharipov, Russ. J. Org. Chem. 37, 866
(2001)
4
4
4
4
0. O. Kreye, S. Wald, M.A.R. Meier, Adv. Synth. Catal. 355, 81 (2013)
1. G. Dettori, S. Gaspa, A. Porcheddu, L. De Luca, Adv. Synth. Catal. 356, 2709 (2014)
2. A.R. Katritzky, N. Kirichenko, B.V. Rogovoy, Synthesis 2003, 2777 (2003)
3. J. Schlupmann, F. Lendzian, M. Plato, K. Mobius, J. Chem. Soc. Faraday Trans. 89, 2853 (1993)
123

Y. M. A. Mohamed et al.
4. N. Dur a´ n, P.D. Marcato, O.L. Alves, G.D. Souza, E. Esposito, J. Nanobiotech. 3, 8 (2005)
5. A. Kr o´ l-Gracz, P. Nowak, E. Michalak, A. Dyonizy, Acta Phys. Pol. A 121, 196 (2012)
6. S.E. Selva, D. Martinez, M.J. Buceta, M.C. Rodriguez-Vazquez, M.A. Blanco, G.Egea Lopez-
Quintela, J. Am. Chem. Soc. 132, 6947 (2010)
4
4
4
47. K. Jyoti, M. Baunthiyal, A. Singh, J. Radiat. Res. Appl. Sci. 9, 217 (2016)
1
23