A combined experimental and theoretical study on the reaction mechanism and molecular structure of 4-(diphenylamino)-3-iodo-2(5H)-furanone

Article abstract of DOI:10.1071/CH16616

The simultaneous α-iodination and N^β-arylation mechanism of 5-alkyloxy-4-phenylamino-2(5H)-furanone by (diacetoxyiodo) benzene was investigated by means of density functional theory (DFT) with B3LYP/6-31G?//LANL2DZ, selecting 4-(diphenylamino)-5-methyloxy-3-iodo-2(5H)-furanone as the calculation model. In addition, the effect of solvent on the reaction pathway was investigated using the Polarisable Continuum Model (PCM). Good agreement was found between the computational and the experimental results. Furthermore, single crystals of 4-(diphenylamino)-5-ethoxy-3-iodo-2 (5H)-furanone were grown by slow evaporation technique. The molecular structure analysis was performed by single crystal X-ray analysis and theoretical calculations using a semi-empirical quantum chemical method and DFT/B3LYP methods with a LANL2DZ as basis set.

Full text of DOI:10.1071/CH16616

CSIRO PUBLISHING
Aust. J. Chem.
Full Paper
http://dx.doi.org/10.1071/CH16616
A Combined Experimental and Theoretical Study on
the Reaction Mechanism and Molecular Structure of
4-(Diphenylamino)-3-iodo-2(5H)-furanone
A C
,
B
A C
,
A C D
, ,
Xiumei Song,
Fuling Xue, Zongcai Feng,
Yun Wang,
B
A C
,
Zhaoyang Wang, and Yanli Xi
A
School of Chemistry and Chemical Engineering, Ling Nan Normal University,
Guangdong Province, Zhanjiang 524048, China.
B
School of Chemistry and Environment, South China Normal University,
Guangdong Province, Guangzhou 510006, China.
C
Development Center for New Materials Engineering and Technology in
Universities of Guangdong, Guangdong Province, Zhanjiang 524048, China.
D
Corresponding author. Email: wangyun203@hotmail.com
The simultaneous a-iodination and Nb-arylation mechanism of 5-alkyloxy-4-phenylamino-2(5H)-furanone by (diacetox-
yiodo)benzene was investigated by means of density functional theory (DFT) with B3LYP/6-31G*//LANL2DZ, selecting
4-(diphenylamino)-5-methyloxy-3-iodo-2(5H)-furanone as the calculation model. In addition, the effect of solvent on the
reaction pathway was investigated using the Polarisable Continuum Model (PCM). Good agreement was found between
the computational and the experimental results. Furthermore, single crystals of 4-(diphenylamino)-5-ethoxy-3-iodo-2
(5H)-furanone were grown by slow evaporation technique. The molecular structure analysis was performed by single
crystal X-ray analysis and theoretical calculations using a semi-empirical quantum chemical method and DFT/B3LYP
methods with a LANL2DZ as basis set.
Manuscript received: 30 October 2016.
Manuscript accepted: 25 January 2017.
Published online:
10 March 2017.
Introduction
chemical method (AM1) and DFT/B3LYP methods with a
LANL2DZ basis set.
2(5H)-Furanones have been widely explored since they are
frequently found in many natural products and have recently
emerged as significant synthetic intermediates.[1–7] Among
the studies on 2(5H)-furanone chemistry,[8–15] much attention
has also been focussed on the efficient synthesis of iodo-2
(5H)-furanones for their diverse value.[16–20] In our previous
work,[21] a series of novel 4-diarylamino-3-iodo-2(5H)-
furanones were synthesised accidentally via the simultaneous
a-iodination and Nb-arylation by an efficient difunctiona-
lizable transfer reagent PhI(OAc)2 ((diacetoxyiodo)benzene,
DIB), during our study on the intramolecular cyclization of
4-arylamino-2(5H)-furanones. A possible mechanism of the
simultaneous a-iodination and Nb-arylation was also pro-
posed. As part of the ongoing studies, further investigation on
the simultaneous a-iodination and Nb-arylation mechanism
was carried out by means of density functional theory (DFT)
calculations with B3LYP/6-31G*//LANL2DZ, and the effect
of solvent on the reaction pathway using the Polarisable
Continuum Model (PCM). In addition, the molecular
structure analysis of the product 4-(diphenylamino)-5-
ethoxy-3-iodo-2(5H)-furanone was performed by single
crystal X-ray and quantum chemical calculations. The geo-
metrical parameters (bond lengths, bond angles, and torsion
angles) were calculated by a semi-empirical quantum
Experimental
Synthesis of 4-Diarylamino-3-iodo-2(5H)-furanones
The 4-diarylamino-3-iodo-2(5H)-furanones were synthesized
in our previous study (Scheme 1).[21]
X-Ray Crystallographic Studies
The single crystals of 4-(diphenylamino)-5-ethoxy-3-iodo-2
(5H)-furanone used for data collection were obtained by slow
evaporation of a petroleum ether–dichloromethane solvent
mixture with a temperature variation of 258C. A yellow block
R2
R2
PhI(OAc)2/CH3CN
I
N
HN
60ꢁC
R1O
R1O
R1 ꢀ CH3,CH2Ph
O
O
O
O
R2 ꢀ H,CH3,OCH3,F,Cl,Br
Scheme 1. Synthesis of 4-(diphenylamino)-3-iodo-2(5H)-furanone.
Journal compilation ꢀ CSIRO 2017
www.publish.csiro.au/journals/ajc

B
X. Song et al.
single crystal of the compound with dimensions of 0.24 mm ꢀ
0.21 mm ꢀ 0.18 mm was chosen. The crystal data collections
were made using a Bruker SMART 1000 CCD area detector
equipped with graphite used for data collection, cell refinement,
and data reduction. The structure was solved by direct methods
using the SHELXS program of the SHELXL-97 package and
refined with the SHELXL program.[22,23] The final refinement
was performed by a full-matrix least-squares method with ani-
sotropic thermal parameters on F2 for the non-hydrogen atoms.
The hydrogen atoms were determined by theoretical calcula-
tions. The details of the X-ray data collection, structure solution,
and structure refinement are given in Table 1. Crystallographic
data has been deposited at the Cambridge Crystallographic Data
Centre. CCDC No: 1038867 contains the supplementary crys-
tallographic data for this paper. Copies of the data can be
obtained free of charge on application to the CCDC, 12 Union
Road, Cambridge CB2 IEZ, UK. Fax: þ44-(0)1223-336033 or
email: deposit@ccdc.cam.ac.uk.
Table 1. Crystal data and structure refinement for 4-(diphenylamino)-
5-ethoxy-3-iodo-2(5H)-furanone
Empirical formula
C18H16INO3
Formula weight
Temperature [K]
421.22
298(2)
˚
Wavelength [A]
0.71073
Crystal system
Space group
Monoclinic
P2(1)/c
˚
a [A]
10.7597(19)
˚
b [A]
9.8460(18)
˚
c [A]
18.725(3)
b [8]
114.829(8)
3
˚
Volume [A ]
1800.4(5)
Z
4
Dc [g m3]
1.554
m [mmꢁ1
F(000)
]
1.792
832
2y range for data collection
Index ranges
2.098 , y ,25.258
ꢁ12 # h # 12, ꢁ11 # k # 11,
ꢁ22 # l # 21
Computational Details
Reflections measured
9001
Quantum Chemical Calculations
Unique reflections
3260
All the calculations were performed by using the Gaussian 03
package and Gauss-View molecular visualization software on a
personal computer without restricting any symmetry for the title.
For modelling, the initial guess of the compound was first
obtained from the X-ray coordinates and the structure was
optimized by a semi-empirical quantum chemical method
(AM1) and density functional theory (DFT)/B3LYP methods
with LANL2DZ as the basis set. Geometric parameters
for optimized molecular structures and electric charge densi-
ties were calculated by the B3LYP method with LANL2DZ
basis sets.
Observed reflections (I . 2s(I))
Goodness-of-fit on F2
2554
1.040
Final R indexes [I . 2s(I)]
Final R indexes [all data]
˚
Largest diff. peak/hole [e A
R1 ¼ 0.0483, wR2 ¼ 0.1333
R1 ¼ 0.0609, wR2 ¼ 0.1453
1.075/ꢁ1.163
ꢁ3
]
with permittivities of 46.826, 35.688, 10.125, 8.930, and 2.374,
for DMSO, CH3CN, CH2ClCH2Cl, CH2Cl2, and toluene,
respectively.
Results and Discussion
Reaction Mechanism Study
In our previous work,[21] a possible simultaneous a-iodination
and Nb-arylation mechanism of 5-alkyoxy-4-phenylamino-2
(5H)-furanone in the presence of DIB was proposed (Scheme 2).
In the proposed mechanism, as the transition structures are
unstable and it is difficult to detect them experimentally,
theoretical studies seemed to be more appropriate. To determine
the conformational stability of the transition structures and
products, we carried out molecular geometry optimization
calculations for all conformations using the 6-31G* or
LANL2DZ basis set with the B3LYP method. Energy, frequency
calculations, and zero-point energy (ZPE) corrections were
performed at the same level of theory. As for the transition
structures calculation, the B3LYP method was applied with the
LANL2DZ basis set. In order to lower the computational cost,
4-(diphenylamino)-5-methoxy-3-iodo-2(5H)-furanone was sele-
cted as the calculation model. The computed stationary points
werecharacterized asminima or transitionstates bydiagonalizing
the Hessian matrix and analyzing the vibrational normal modes.
In this way, the stationary points can be classified as minima if no
imaginary frequencies are shown, or as transition structures if
only one imaginary frequency is obtained.[24] Furthermore, the
intrinsic reaction coordinate (IRC) calculations were performed
to confirm that the optimized transition states correctly connect
two relevant minima.[25] The particular nature of the transition
structures has beendeterminedby analyzing the motion described
by the eigenvector associated with the imaginary frequency.
The solvation energies for the reactants, transition structures,
and products were computed using the solvation model PCM
Reaction Mechanism
The DFT calculations suggest
a possible simultaneous
a-iodination and Nb-arylation mechanism of 5-alkyoxy-4-
phenylamino-2(5H)-furanone via DIB. The possible reaction
path is that of reaction via TS1, TS2, and TS3 leading to
the reaction product. The optimized stationary structures (the
reactant, the transition structures, and the product) on the
potential energy surfaces of the reactions are depicted
schematically in Figs 1–5. Geometry optimization of the tran-
sition structures involved was carried out at the B3LYP level of
theory with the LANL2DZ basis set. Normal mode analysis
clearly indicates the structures have only one imaginary fre-
quency of 17.725i, 174.7878i, and 28.1065i cmꢁ1, which were
confirmed to be the first-order saddle point connecting the
corresponding reactants and products by IRC calculations.
The transition structure TS1 was formed from substrate 1 and
PhI(OAc)2 in the first step. In the transition structure TS1, the
new bond produced between Ph-I7 and C1 has a bond distance of
˚
˚
2.10 A. The distance between O23 and I7 is 2.54 A, and the
˚
distance between O26 and I7 is 3.61 A (the atom numbering is
given in Fig. 2). The distances between the oxygen atom in
acetate and I7 are all longer than a normal bond distance. So A is
not actually produced in the reaction and the bond of O23 and I7
or the bond of O26 and I7 is automatically broken to give the
transition structure TS1. Furthermore, the distance between
˚
˚
N and H (1.01 A), before the reaction, increases to 1.07 A after
the reaction. Due to the increase of distance, the N–H bond
disconnects. TS1 in then converted into TS2 in the second step.

Study on 4-(Diphenylamino)-3-iodofuran-2(5H)-one
C
R2
R2
R2
OAc
fast
OAc
ꢃ Hꢂ
PhI(OAc)2
ꢃ AcOH
•
–
–
N
HN
I
H
N
H
I
ꢃ AcOꢃ
H
O
R1O
R1O
O
R1O
O
O
O
O
A
B
1
(unstable)
R2
R2
R2
R2
ꢃ
Iꢂ
ꢂ
N
N
I
N
I
N
I
ꢃ
R1O
R1O
O
O
R1O
R1O
O
O
O
O
O
O
C
D
2
Scheme 2. Plausible mechanism for DIB-promoted difunctionalization.
1.01
1.37
2.17
1.35
2.17
2.20
1.49
˚
Fig. 1. DFT-optimized structures of 1 and PhI(OAc)2, distances are in A.
2.19
2.54
4.75
2.10
3.61
1.07
1.46
1.39
1.34
˚
Fig. 2. DFT-optimized structures of TS1, distances are in A.

D
X. Song et al.
2.22
2.03
1.45
1.38
1.38
1.43
4.20
2.10
1.30
1.48
Fig. 5. DFT-optimized structures of product (R1 ¼ CH3, R2 ¼ H), distances
˚
are in A.
˚
Fig. 3. DFT-optimized structures of TS2, distances are in A.
reaction are depicted in Table 2. From Table 2, we can see that the
activation energy for the formation of TS2 is 400.766 kcalmolꢁ1
,
which is in good agreement with the experimental observations.
The DHgas of the reaction is 342.724kcal molꢁ1, so the reaction is
endothermic, which indicates a higher temperature can promote
the reaction, but the temperature should not exceed a certain
range. The calculated results were verified by experiments on
temperature (Table 2).[21]
The effect of solvent on the reaction pathway was investigated
using the PCM model. As shown in Table 3, the solvation energy
(negative value) decreases with the increasing polarity of the
solvent. This clearly indicates that reactants, transition structures,
and products become more stable when the polarity of the solvent
increases. Thus, the reactants, transition structures, and products
in CH3CN are more stable compared with those in other organic
solvents, even if CH3CN is not the most polar of the five solvents.
This can be rationalized in that solvents play a crucial role in the
reaction by stabilizing transition structures and providing an
alternative lower energy pathway by which the reaction may
proceed. Furthermore, the calculated results indicate CH3CN is
the best solvent for the reaction, which were verified by experi-
ments on the solvent effect (Table 4) in our previous study.[21]
1.42
1.35
2.08
1.50
Molecular Structure
˚
Fig. 4. DFT-optimized structures of TS3, distances are in A.
As one of the 4-diarylamino-3-iodo-2(5H)-furanone products,
the structure of 4-(diphenylamino)-5-ethoxy-3-iodo-2(5H)-
furanone was confirmed by the result of a single crystal X-ray
structure determination. The molecular structure with atom num-
bering of 4-(diphenylamino)-5-ethoxy-3-iodo-2(5H)-furanone is
shown in Fig. 6. Experimental details for data collection and
structure refinement are summarized in Table 1. The selected bond
lengths and angles are presented in Tables 5 and 6.
The compound 4-(diphenylamino)-5-ethoxy-3-iodo-2(5H)-
furanone is a 2(5H)-furanone derivative in which the structure
shows two phenyl rings and a butenolide ring linked by an N atom.
The two phenyl rings and butenolide ring are near to planarity, the
angles between each phenyl ring and the butenolide ring being
122.8(4)8 (C15–N1–C12) and 121.1(4)8 (C15–N1–C6), respec-
tively. The C14–C15–N1–C12 torsion angle is 16.6(10)8. The
five-membered butenolide ring containing the atoms O2, C13,
In the second step, the bond length between I7 and C17 (the atom
numbering is given in Fig. 2) which is I7 and C11 in Fig. 3,
˚
increased slowly from 2.19 to 2.22 A. The distance between N6
and C17 (the atom numbering is given in Fig. 2) which is N6 and
˚
C11 in Fig. 3, decreased slowly from 4.75 to 4.20 A. These
changes are beneficial for N6, C11, I7, C1, and C2 to form a five-
membered cycle (the atom numbering is given in Fig. 3). In the
third step, the TS2 is converted into TS3 (Fig. 4) through a five-
membered cycle. In the process, the phenyl bonded to I7
transfers to N6. Finally, the TS3 transforms into the product
(Fig. 5) by bond length changes of the compound.
By means of the interrelationship of reactants, products, and
transition states, as well as their relative energies, the potential
energy surface profiles of the pathways corresponding to the

Study on 4-(Diphenylamino)-3-iodofuran-2(5H)-one
E
Table 2. B3LYP/6–31G* //LANL2DZ calculated thermodynamic properties (total energy with zero-point
energy, free energy) of the reactants, transition states, and products
Species
DEgas [Hartree molꢁ1
]
DHgas [Hartree molꢁ1
]
DGgas [Hartree molꢁ1
]
1
ꢁ705.980148
ꢁ699.590636
ꢁ1176.496972
ꢁ947.471747
ꢁ947.557964
ꢁ947.565188
ꢁ229.015190
ꢁ228.445176
ꢁ705.979204
ꢁ699.589691
ꢁ1176.496028
ꢁ947.470803
ꢁ947.557019
ꢁ947.564244
ꢁ229.014246
ꢁ228.444231
ꢁ706.033555
ꢁ699.658400
ꢁ1176.580906
ꢁ947.544385
ꢁ947.626276
ꢁ947.636682
ꢁ229.047024
ꢁ228.477200
PhI(OAc)2
TS1
TS2
TS3
Product
Acetic acid
Acetate
Table 3. The solvation energies (kcal mol21) of the reactants,
transition structures, and products in seven distinct solvents
C9
C8
C10
Species
DMSO
CH3CN
CH2ClCH2Cl
CH2Cl2
Toluene
C7
1
ꢁ14.70
ꢁ19.69
ꢁ26.49
ꢁ32.92
ꢁ18.31
ꢁ20.64
ꢁ4.43
ꢁ15.38
ꢁ21.57
ꢁ28.06
ꢁ34.03
ꢁ19.11
ꢁ21.64
ꢁ5.29
ꢁ14.20
ꢁ20.48
ꢁ26.24
ꢁ31.22
ꢁ17.79
ꢁ20.09
ꢁ5.24
ꢁ13.92
ꢁ20.10
ꢁ25.75
ꢁ30.59
ꢁ17.46
ꢁ19.71
ꢁ5.15
ꢁ7.53
ꢁ10.50
ꢁ13.93
ꢁ16.63
ꢁ9.78
C2
C11
PhI(OAc)
TS1
C1
C3
C12
C15
C6
N1
TS2
TS3
C4
Product
Acetic acid
Acetate
ꢁ10.84
ꢁ3.15
I1
C5
O3
ꢁ57.00
ꢁ59.42
ꢁ56.19
ꢁ55.34
ꢁ34.31
C18
C14
C13
C16
C17
Table 4. Comparison of the 4-(diphenylamino)-5-methoxy-3-iodo-2
O2
O1
(5H)-furanone isolated yields in different solvents
Fig. 6. Molecular structure of 4-(diphenylamino)-5-ethoxy-3-iodo-2(5H)-
furanone, showing 30 % probability displacement ellipsoids and atom
labelling scheme.
EntryA
Solvent
YieldB [%]
1
2
3
4
5
CH3CN
86
73
ClCH2CH2Cl
Toluene
CH2Cl2
65
LANL2DZ methods are listed in Tables 5 and 6. These
selected parameters are compared with their experimental
values. It is well known that DFT-optimized bond lengths
are usually longer and more accurate than AM1, due to the
inclusion of electron correlation. Conversely, according to
correlations values, the AM1 method correlates well with
the bond lengths compared with the B3LYP method. While
the B3LYP method gave more accurate results for the
bond angles compared with the AM1 method, the AM1
method gave more accurate results for the torsion angles
compared with the B3LYP method. From Table 5 it is seen
that most bond lengths are found to be greater than
the experiment results. These differences are probably due
to the experimental results corresponding to the solid phase
while the theoretical calculations correspond to the gaseous
phase. In the solid state, the existence of the crystal field along
with the intermolecular interactions has connected the molecules
together, which results in the differences of bond parameters
between the calculated and experimental values.
45
DMSO
Trace
AReaction conditions: 5-methoxy-4-phenylamino-2(5H)-furanone 0.2 mmol,
DIB 0.3mmol, solvent 10mL, reaction temperature 608C, reaction time 40h.
BIsolated yield.
C14, C15, and C16 and is defined by a plane with the least square
plane equation: 0.6254x ꢁ 0.7387y þ 0.2513z ¼ ꢁ0.7004. Fur-
thermore, the atoms O1, N1, and I1 attached to the butenolide
ring are nearly coplanar with the butenolide ring, with deviations
˚
from the plane of 0.1220, 0.0347, and 0.0599 A, respectively. Both
˚
˚
the C14–C15 (1.348(7) A) and C13–O1 (1.207(7) A) bonds show
typical double bond characteristics. The C15–N1 bond length
˚
(1.358(6) A) is significantly shorter than for C6–N1 (1.449(7) A)
˚
and C12–N1 (1.433(7) A). The shortening of C15–N1, and atoms
˚
N1 and O1 being nearly coplanar with the butenolide ring,
indicates that extensive conjugation take places among lone pair
electrons of N1, the C14–15 double bond, and the C13–O1
carbonyl bond.
The structural parameters of 4-(diphenylamino)-5-ethoxy-
3-iodo-2(5H)-furanone were also calculated theoretically and
the optimized molecular structure is shown in Fig. 7. Some
selected optimized parameters (bond lengths, bond angles, and
torsion angles) theoretically calculated by AM1 and B3LYP/
The electric charge distribution for 4-(diphenylamino)-5-
ethoxy-3-iodo-2(5H)-furanone by B3LYP/LANL2DZ is
shown in Table 7. The electric charge densities for atoms
N1, C15, C14, C13, and O1 are ꢁ0.500, 0.201, ꢁ0.450, 0.785,
and ꢁ0.565 e, respectively, which supports the observation
that the essential part of the electron delocalization is concen-
trated in the N1, C15, C14, C13, and O1 region, forming the

F
X. Song et al.
˚
Table 5. Comparison of the selected bond lengths (A) of 4-(diphenylamino)-5-ethoxy-3-iodo-2(5H)-furanone by using AM1 and B3LYP/LANL2DZ
˚
Bond length [A]
˚
Bond length [A]
Bond
Bond
AM1
B3LYP
Experimental
AM1
B3LYP
Experimental
C(14)–C(15)
C(15)–C(16)
C(15)–N(1)
C(13)–C(14)
C(14)–I(1)
1.381
1.558
1.361
1.470
1.988
1.427
1.399
1.406
1.222
1.511
1.431
1.433
1.431
1.373
1.552
1.382
1.478
2.097
1.461
1.434
1.433
1.229
1.534
1.480
1.454
1.447
1.348(7)
1.511(8)
1.358(6)
1.434(8)
2.070(6)
1.411(8)
1.369(9)
1.375(8)
1.207(7)
1.497(2)
1.435(11)
1.449(7)
1.433(7)
C(5)–C(6)
C(6)–C(1)
C(4)–C(5)
C(3)–C(4)
C(2)–C(3)
C(1)–C(2)
C(11)–C(12)
C(12)–C(7)
C(10)–C(11)
C(9)–C(10)
C(8)–C(9)
C(7)–C(8)
1.408
1.411
1.393
1.393
1.394
1.392
1.409
1.409
1.393
1.394
1.394
1.393
1.408
1.409
1.405
1.410
1.408
1.407
1.410
1.410
1.405
1.408
1.409
1.405
1.374(9)
1.385(8)
1.395(9)
1.373(10)
1.378(11)
1.377(9)
1.369(8)
1.395(8)
1.384(9)
1.372(10)
1.359(11)
1.390(10)
C(16)–O(2)
C(16)–O(3)
C(13)–O(2)
C(13)–O(1)
C(17)–C(18)
O(3)–C(17)
N(1)–C(6)
N(1)–C(12)
Table 6. Comparison of the selected bond angles (8) of 4-(diphenylamino)-5-ethoxy-3-iodo-2(5H)-furanone by using AM1 and B3LYP/ LANL2DZ
Angle
Size of angle [deg.]
B3LYP
Angle
Size of angle [deg.]
B3LYP
AM1
Experimental
AM1
Experimental
C(14)–C(15)–C(16)
C(14)–C(15)–N(1)
C(16)–C(15)–N(1)
C(15)–C(14)–C(13)
C(15)–C(14)–I(1)
C(13)–C(14)–I(1)
C(15)–C(16)–O(2)
C(15)–C(16)–O(3)
O(2)–C(16)–O(3)
C(16)–O(2)–C(13)
C(14)–C(13)–O(2)
C(14)–C(13)–O(1)
O(2)–C(13)–O(1)
C(16)–O(3)–C(17)
O(3)–C(17)–C(18)
C(15)–N(1)–C(6)
C(15)–N(1)–C(12)
107.514
131.627
120.836
108.138
131.549
120.311
105.176
115.277
106.879
109.275
109.638
135.593
114.759
118.159
110.089
121.186
123.015
108.298
132.630
119.069
109.946
131.089
118.762
104.376
114.080
112.637
109.698
107.650
131.203
121.129
119.732
114.090
119.174
123.502
106.9(5)
133.8(5)
119.2(5)
109.6(5)
133.4(4)
116.9(4)
105.4(5)
108.5(5)
112.0(6)
109.3(5)
108.5(5)
131.3(7)
120.1(6)
106.4(7)
107.1(9)
121.1(4)
122.8(4)
C(4)–C(3)–C(2)
C(2)–C(1)–C(6)
C(6)–C(1)–C(2)
N(1)–C(12)–C(11)
N(1)–C(12)–C(7)
C(11)–C(12)–C(7)
C(12)–C(11)–C(10)
C(11)–C(10)–C(9)
C(10)–C(9)–C(8)
C(9)–C(8)–C(7)
C(12)–C(7)–C(8)
C(6)–N(1)–C(12)
N(1)–C(6)–C(5)
N(1)–C(6)–C(1)
C(5)–C(6)–C(1)
C(6)–C(5)–C(4)
C(5)–C(4)–C(3)
119.750
120.516
119.972
119.584
120.924
119.441
119.839
120.515
119.849
120.526
119.830
115.590
120.857
119.863
119.253
119.925
120.583
119.734
120.112
119.857
120.469
119.662
119.819
119.905
120.474
119.446
120.434
119.920
117.322
120.145
119.608
120.233
119.685
120.370
120.5(6)
119.5(6)
119.5(6)
120.8(5)
119.1(5)
120.0(5)
120.6(6)
119.4(7)
120.7(7)
120.7(6)
118.6(6)
116.1(4)
120.9(5)
118.5(5)
120.6(5)
119.6(6)
119.6(7)
Torsion angle
Size of torsion angle [deg.]
Torsion angle
Size of torsion angle [deg.]
AM1
B3LYP
Experimental
AM1
B3LYP
Experimental
C(14)–C(15)–N(1)–C(12)
C(14)–C(15)–N(1)–C(6)
C(14)–C(15)–C(16)–O(2)
N(1)–C(15)–C(16)–O(3)
C(12)–N(1)–C(6)–C(5)
N(1)–C(12)–C(11)–C(10)
N(1)–C(6)–C(5)–C(4)
7.818
28.466
ꢁ150.977
0.867
16.6(10)
ꢁ164.0(6)
4.5(7)
C(15)–C(14)–C(13)–O(1)
C(15)–C(16)–O(2)–C(13)
O(3)–C(16)–O(2)–C(13)
C(16)–O(2)–C(13)–O(1)
C(12)–N(1)–C(6)–C(1)
N(1)–C(12)–C(7)–C(8)
N(1)–C(6)–C(1)–C(2)
ꢁ178.969
ꢁ4.978
ꢁ179.716
ꢁ1.672
ꢁ172.3(7)
ꢁ2.0(8)
ꢁ166.701
4.879
118.022
177.473
84.568
122.609
179.524
41.901
115.8(6)
175.8(7)
56.6(7)
68.992
56.896
61.2(8)
ꢁ92.826
179.604
177.541
ꢁ135.525
178.903
178.094
ꢁ121.3(6)
177.5(5)
179.5(7)
ꢁ178.167
ꢁ177.384
ꢁ179.612
ꢁ177.761
ꢁ178.2(5)
ꢁ178.5(6)
conjugation system N1–C15–C14–C13–O1. Obviously, the
electric charge transfers from N1 to O1. It is interesting to
find that C6 and C12 are electropositive, accompanied by the
other carbon atoms being electronegative in the two phenyl
rings. The electric charge distribution result shows that excel-
lent electron delocalization among N1, C15, C14, C13, and
O1 takes place at the expense of the weakening degree of
conjugation of the phenyl rings.
The compound is stabilized by an intermolecular hydrogen
bond between C10–H10 as donor and the carbonyl oxygen atom
˚
O1 as acceptor, forming C10–H10?O1 (dH10?O1 2.5013 A,
˚
˚
dC10–H10 0.9300 A, dC10–H10?O1 3.1997 A, +C10–H1–O1
132.0768), as shown in Fig. 8. In addition, the extended crystal
of the title compound is further stabilized by aromatic paralled-
displaced p?p stacking interactions, and the centroid–
˚
centroid distance is 5.8634(8) A, as shown in Fig. 9.

Study on 4-(Diphenylamino)-3-iodofuran-2(5H)-one
G
(a)
(b)
Fig. 7. Theoretical geometric structure of 4-(diphenylamino)-5-ethoxy-3-iodo-2(5H)-furanone by (a) AM1 and (b) DFT/B3LYP methods.
Table 7. The nbo charge distribution (e) for the 4-(diphenylamino)-5-
ethoxy-3-iodo-2(5H)-furanone molecule by B3LYP
Atom
Charge
Atom
Charge
Atom
Charge
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
ꢁ0.222
ꢁ0.200
ꢁ0.217
ꢁ0.196
ꢁ0.229
0.165
C(9)
ꢁ0.210
ꢁ0.199
ꢁ0.201
0.156
C(17)
C(18)
N(1)
I(1)
ꢁ0.057
ꢁ0.664
ꢁ0.500
0.257
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
0.785
O(1)
O(2)
O(3)
ꢁ0.565
0.604
ꢁ0.450
0.201
ꢁ0.237
ꢁ0.202
ꢁ0.631
0.432
Fig. 9. p?p Stacking interaction of 4-(diphenylamino)-5-ethoxy-3-iodo-
2(5H)-furanones, H atoms not involved in the motif shown have been
omitted.
Conclusion
In summary, on the basis of the synthesis of 4-diarylamino-3-
iodo-2(5H)-furanones via the simultaneous a-iodination
and Nb-arylation by an efficient difunctionalizable transfer
reagent PhI(OAc)2, 4-(diphenylamino)-5-methoxy-3-iodo-2(5H)-
furanone was selected as the calculation model to further study
the proposed reaction mechanism by DFT calculations. The
calculations data show a good agreement with the experimental
results. The effect of solvent on the reaction pathway was carried
out by the PCM model, indicating that CH3CN is the best solvent
for the reaction. In addition, the molecular structure analysis
of 4-(diphenylamino)-5-ethoxy-3-iodo-2(5H)-furanone was
studied experimentally (single crystal X-ray) and theoretically
(AM1 and DFT/B3LYP method). The theoretical optimized
geometric parameters (bond lengths, bond angles, and torsion
angles)werecomparedwiththe experimental data.The calculated
Fig. 8. Packing crystal structure of 4-(diphenylamino)-5-ethoxy-3-iodo-
2(5H)-furanone, the hydrogen bonds are shown as dashed lines.

H
X. Song et al.
data are only slightly different from the experimental ones. An
extensive conjugation takes places among N1, C14, C15, C13,
and O1 at the expense of a weakened degree of conjugation of
the phenyl rings. The crystal molecules are stabilized by an
intermolecular hydrogen bond and aromatic paralled-displaced
p?p stacking interactions.
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[13] X. S. Xue, X. Li, A. Yu, C. Yang, C. Song, J. P. Cheng, J. Am. Chem.
This research was financed by Guangdong Natural Science Foundation
(project no. 2014A030313429), National Spark Program Office of the
People’s Republic of China (project no. 2014GA780082), and Zhanjiang
Science and Technology Bureau (project nos. 2014B01031 and
2015A02008). The authors also thank the South China Normal University,
Faculty of Chemistry and Environment Central Laboratories for allocation
of time for the single crystal X-ray measurements.
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