Ultrasound-assisted synthesis of RO- and RS-substituted (hetero)acenes via oxo- and thio-Friedel-Crafts/Bradsher reactions

Article abstract of DOI:10.1016/j.ultsonch.2019.104640

Two heteroatom-variants of the Friedel-Crafts/Bradsher cyclization of o-acetalaryl(aryl)methyl ethers and o-dithioacetalaryl(aryl)methyl thioethers, have been realized with the ultrasound assistance. The environmentally friendly “oxo-variant” (Oxo-F-C/B),

Full text of DOI:10.1016/j.ultsonch.2019.104640

Ultrasonics-Sonochemistry58(2019)104640
Contents lists available at ScienceDirect
Ultrasonics - Sonochemistry
journal homepage: www.elsevier.com/locate/ultson
Ultrasound-assisted synthesis of RO- and RS-substituted (hetero)acenes via
oxo- and thio-Friedel-Crafts/Bradsher reactions
⁎
Piotr Bałczewskia,b, , Emilia Kowalskaa, Joanna Skalika, Marek Koprowskia,b
,
Krzysztof Owsianika, Ewa Różycka-Sokołowskab
a Division of Organic Chemistry, Group of Functional Materials Synthesis, Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112,
90-363 Łódź, Poland
b Faculty of Mathematics and Natural Sciences, Institute of Chemistry, Health and Food Sciences, Department of Material & Structural Chemistry, Jan Długosz University in
Częstochowa, Armii Krajowej 13/15, 42-201 Częstochowa, Poland
A R T I C L E I N F O
A B S T R A C T
Keywords:
Two heteroatom-variants of the Friedel-Crafts/Bradsher cyclization of o-acetalaryl(aryl)methyl ethers and o-
dithioacetalaryl(aryl)methyl thioethers, have been realized with the ultrasound assistance. The environmentally
friendly “oxo-variant” (Oxo-F-C/B), proceeding in a medium containing mineral acid and a large amount of
water (HClaq/CH3CN) led to a very efficient formation of RO-substituted (hetero)acenes in less than 5 min. In the
“thio-variant” (Thio-F-C/B), o-dithioacetalaryl(aryl)methyl thioethers underwent ultrasound-assisted cyclization
in nonaqueous medium (FeCl3/KI/EtOH) in less than 25 min., in lower yields than in the “oxygen variant” to
give RS-substituted (hetero)acenes. The RO-(hetero)acenes cyclized at 25–60 °C in aqueous media but did not
cyclize in organic solvents while the RS-(hetero)acenes required higher temperatures 55–60 °C and cyclized in
organic solvents but did not react in aqueous media. The acceleration of the ultrasound-assisted reactions
compared to the reactions carried out under silent conditions exceeded 7500 times in the most effective example
of the oxo-variant and on average 2 times for the thio-variant. The plausible reaction mechanisms under ul-
trasound and silent conditions have been proposed. The ultrasonic mechanism involves disturbing of solvation
layers and formation of the reactive (“naked”) carbocations upon operation of the shock wave produced by the
bubble collapse. The o-acetalaryl(aryl)methyl ethers underwent a selective ultrasound-assisted deacetalization to
give o-formylaryl(aryl)methyl ethers, without subsequent cyclization under the acidic reaction conditions.
Oxo- and thio-Friedel-Crafts/Bradsher
reactions
Electrophilic aromatic substitution
Cyclization
Ultrasounds
Acenes
Deacetalization
1. Introduction
intramolecular modification of the Friedel-Crafts reaction [13], for the
first time reported by Bradsher in 1940 [8,9], is based on the acid-
Unflagging interest in the field of π-extended organic materials is
connected with their application as active elements in new generations
of optoelectronic devices. Among the wide range of polycyclic, fused
aromatic hydrocarbons, linear (hetero)acenes draw special attention.
They have been successfully used as semiconducting materials in or-
ganic field effect transistors (OFETs) [1], organic light-emitting diodes
(OLEDs) [2–5] and organic photovoltaic cells (OPVs) [6]. Therefore,
during the last few decades a variety of (hetero)acene derivatives have
been designed and synthesized in order to improve properties of these
materials and the devices performance. One of the synthetic methods
toward linearly fused aromatic hydrocarbons is the Bradsher cyclization
of o-formyl [7], o-acyl [8,9] and o-carboxy [10] diarylmethanes and o-
carboxy [11,12] diarylketones. The Bradsher reaction, being an
catalyzed cyclodehydration of o-formyl or o-acyl substituted dia-
rylmethanes I leading to acenes II (Scheme 1). These cyclizations, ex-
cept the o-formyl variant, have never been carried out under ultra-
sounds irradiation. This o-formyl variant has recently been realized in
our lab starting from o-formylaryl(aryl)methanes I which were sono-
chemically cyclized to (hetero)acenes II under aqueous or non-aqueous
media [14]. Ultrasound-assisted syntheses of heterocyclic systems other
than (hetero)acenes, proceeding via the SEAr mechanism, such as oxi-
ndoles [15] and chromeno[4,3- b]quinolin-6-ones [16], have been
realized, as well.
In this work, we report further progress in this area, including the
ultrasound-assisted cyclizations proceeding according to the hetero-
variants of the Friedel-Crafts/Bradsher reactions of o-acetalaryl(aryl)
⁎ Corresponding author at: Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Łódź, Poland.
E-mail addresses: pbalczew@cbmm.lodz.pl (P. Bałczewski), kowalska@cbmm.lodz.pl (E. Kowalska), jskalik@cbmm.lodz.pl (J. Skalik),
mkopr@cbmm.lodz (M. Koprowski), owsianik@cbmm.lodz.pl (K. Owsianik), e.sokolowska@ajd.czest.pl (E. Różycka-Sokołowska).
https://doi.org/10.1016/j.ultsonch.2019.104640
Received 3 January 2019; Received in revised form 29 May 2019; Accepted 13 June 2019
Availableonline14June2019
1350-4177/©2019ElsevierB.V.Allrightsreserved.

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
Scheme 1. Ultrasound assisted cyclization of o-acetalaryl(aryl)methyl ethers (M = Z = O atoms) and o-dithioacetalaryl(aryl)methyl thioethers (M = Z = S atom) IV
to R1O-(hetero)acenes Va (Z = O) and R1S-(hetero)acenes Vb (Z = S). Selective, sonochemical deprotection of IV (Z = O) to o-formylaryl(aryl)methyl ethers III
under HClaq/CH3CN aqueous conditions.
methyl ethers (M = Z = O) IV in aqueous medium (Oxygen variant,
Oxo-F-C/B, Scheme 1) and o-dithioacealaryl(aryl)methyl thioethers
(M = Z = S) IV in non-aqueous media (Thio-variant,Thio-F-C/B,
Scheme 1). These transformations lead to formation of R1O- and R1S-
substituted acenes and heteroacenes Va and Vb, respectively, under
very mild reaction conditions and with significant acceleration, despite
their ionic and homogenous character. Moreover, the R1Z-(hetero)
acenes V has never been obtained under harsh conditions of the original
Bradsher reaction requiring very high temperatures. The aqueous re-
action medium has also been used in a selective deacetalization of o-
acetalaryl(aryl)methyl ethers IV under sonochemical conditions to give
o-formyl diarylmethyl ethers III without further cyclization to acenes.
The effect of various acidic catalysts, their concentrations, physical
state and stoichiometry, kind of organic solvent and temperature has
also been investigated in these reactions. Plausible reaction mechan-
isms under ultrasound and silent conditions, and reasons of the un-
expected acceleration of these reactions have been proposed.
a resolving power of 10.000 (10% valley definition). Melting points
were measured using Boetius apparatus. Thin layer chromatography
(TLC) was performed on precoated Merck 60 (F254 60) silica gel plates
with fluorescent indicator, and monitored with the UV detector at 254
and 360 nm. Column chromatography was done on a Merck silica gel
(Kieselgel 60, 230–400 mesh). Elemental analysis was determined by
using a EuroVector analizator model 301. Ultrasonication was per-
formed by an Ultrasonic processor model GEX 600 with the resonance
frequency of 20 kHz and power 600 W, equipped with a coupler and a
stepped titanium alloy microtip Ti-6Al-4 V (diameter 6 mm, length
113 mm, amplitude 75 μm, volume 10–50 mL). The cyclisation reac-
tions were carried out in open vessels (thick-walled glass tube).
2.2. Experimental procedures
2.2.1. General procedure for synthesis of o-acetalaryl(aryl)methanols 3
Aromatic o-bromoacetal 1 (1.0 mmol) was placed in the round-
bottom flask (50 mL) and dissolved in dry THF (8 mL) at −78 °C under
argon atmosphere. Next, n-BuLi (1.1 mmol, 2.5 M in hexanes) was
added. The resulting mixture was stirred for 15 min. under argon and
then aromatic aldehyde 2 (1.2 mmol) was added in dry THF. Stirring
was continued for 2 h at −78 °C and the reaction mixture was warmed
to room temperature. Saturated aqueous NH4Cl solution was added and
the solvent was evaporated. The residue was diluted with ethyl acetate
(3x10 mL), washed with water (15 mL) and dried over anhydrous
MgSO4. After filtration, ethyl acetate was removed in vacuum and the
crude product 3 was purified by column chromatography over silica gel
with a mixture of petroleum ether/acetone (4:1 v/v).
2. Experimental
2.1. Materials and apparatus
All organic solvents were purchased from commercial sources and
used as received or dried by MB SPS-800 (MBRAUN Solvent
Purification System). All chemicals used in this work, were purchased
from Aldrich and were used without further purification. The 1H NMR
and 13C NMR spectra were recorded on a Bruker AV 200 and AV 500
spectrometers in C6D6 with chemical shift (δ) given in ppm, relative to
TMS as an internal standard. Mass spectra of pure compounds were
recorded on a Finnigan MAT 95 double focusing (BE geometry) mass
spectrometer (Finnigan MAT, Bremen, Germany). Standard, low-re-
solution EI mass spectra were obtained using electron energy of 70 eV,
accelerating voltage of 4.6 kV, and ion source temperature of 250 °C.
Samples were introduced via a direct insertion probe, heated from 30 to
2.2.2. General procedure for the synthesis of o-acetalaryl(aryl)methyl
ethers 4
A solution of the corresponding diarylmethanol 3 (1.0 mmol) in dry
THF (5 mL) was added to a suspension of NaH (1.1 mmol, 60% in mi-
neral oil) in dry THF (3 mL) at RT. The resulting mixture was stirred for
30 min., then the corresponding alkyl or arylalkyl halide (1.5 mmol)
was added and stirring was continued for 18 h at the same temperature.
300 °C. Accurate mass measurements were measured by
a peak
matching technique using perfluorokerosene as an internal standard at
2

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
After evaporation of the solvent, the residue was diluted with ethyl
acetate and washed with water (3x20 mL). The organic layer was dried
(MgSO4) and then filtered. After filtration, ethyl acetate was removed in
vacuum and the crude product 4 was purified by column chromato-
graphy over silica gel with a mixture of petroleum ether/acetone (4:1
v/v).
the solvent was removed. To the crude product, ethyl acetate (10 mL)
was added and the resulting mixture was poured to the saturated so-
lution of Na2S2O3aq (10 mL). The organic layer was dried over anhy-
drous MgSO4. After filtration, the solvent was evaporated to give pro-
ducts 10, which were purified using a gradient column chromatography
(petroleum ether:acetone, 10:1 v/v).
2.2.3. General procedure for the synthesis of R1O-substituted (hetero)
acenes 5 using ultrasounds (HClaq/CH3CN).
2.3. Representative spectral data
A solution of o-acetalaryl(aryl)methyl ethers 4 (0.2 mmol) in acet-
onitrile (8 mL) was placed in the thick-walled glass tube (25 mL). The
titanium alloy microtip was immersed in the reaction mixture to the
height of 2.0 cm. Then, the aqueous solution of HClaq (6.8 N, 4 mL) (v/
v = 1/1) was added and the resulting mixture was sonicated (ampli-
tude 26.3 μm (35%), pulse on/off 2 s, 55 °C). The temperature 55 °C was
set on the processor automatically and was maintained using water
bath. The reaction mixture was sonicated until disappearance of the
starting material (monitoring by TLC). After the reaction was com-
pleted, the reaction mixture was poured into NaHCO3aq (20 mL) and
extracted with ethyl acetate (3x10 mL). The organic layer was washed
with water and then dried over anhydrous MgSO4. After filtration, ethyl
acetate was removed in vacuum and the crude product was purified by
column chromatography over silica gel with a mixture of petroleum
ether/acetone (10:1 v/v) to afford the corresponding anthracenes 5.
The same procedure was used for the synthesis of o-formylaryl(aryl)
methyl ethers 6 from 4 (Table 6).
2.3.1. (2-(1,3-Dioxan-2-yl)phenyl)(3,4,5-trimethoxyphenyl)methanol
(3aa)
Yield: 67%; colorless oil; 1H NMR (C6D6, 500 MHz): δ = 0.51–0.56
(m, 1H, OCH2CHeqH), 1.69–1.80 (m, 1H, OCH2CHHax), 3.27–3.36 (m,
2H, 2xOCHaxH), 3.35 (s, 6H, 2xOCH3), 3.65–3.75 (m, 2H, 2x OCHHeq),
3.84 (s, 3H, 3xOCH3), 5.50 (s, 1H, OCHO), 6.49–6.52 (m, 1H, CHOH),
6.91 (s, 2H, 2xHAr), 7.03–7.07 (m, 2H, 2xHAr), 7.30–7.35 (m 1H, HAr),
7.67–7.70 (m, 1H, HAr) ppm; 13C NMR (C6D6, 125 MHz): δ = 26.3, 56.4
(2C), 61.2, 68.0, 68.06, 72.8, 102.6, 105.32 (2C), 128.30, 128.4, 130.2,
130.2, 137.5, 138.9, 139.8, 144.3, 154.78 (2C) ppm; Anal. Calcd for
C
20H24O6: C, 66.65; H, 5.71; Found: C, 66.82; H, 6.83; HRMS (EI,
70 eV): m/z [M]+ Calcd for C20H24O6: 360.1573; Found: 360.1555; MS
(EI, 70 eV): m/z (%) 360 [M+, 10], 284 [M+, eC6H4, 100], 269 [M+
eC6H4, eCH3, 40].
,
2.3.2. (2-(1,3-Dioxan-2-yl)phenyl)(3,5-dimethoxyphenyl)methanol (3ab)
Yield: 65%; light yellow oil; 1H NMR (C6D6, 500 MHz):
δ = 0.54–0.60 (m, 1H, OCH2CHeqH), 1.67–1.79 (m, 1H, OCH2CHHax),
3.29 (s, 6H, 2xOCH3), 3.31–3.40 (m, 2H, 2 × OCHaxH), 3.67–3.75 (m,
2H, 2xOCHHeq), 3.94 (d, 1H, 3JH-H = 5.0 Hz, OH), 5.51 (s, 1H, OCHO),
2.2.4. General procedure for the synthesis of R1O-substituted (hetero)
acenes 5 under silent conditions (HClaq/CH3CN).
3
3
To a solution of the corresponding o-acetalaryl(aryl)methyl ethers 4
(0.2 mmol), dissolved in CH3CN (20 mL), the aqueous solution of 6.8 N
HCl (4 mL) was added and the resulting mixture was stirred at the re-
levant temperature (Table 5) until disappearance of the starting mate-
rial (monitoring by TLC). The reaction mixture was extracted with ethyl
acetate (50 mL), and the organic layer was washed with water (30 mL),
NaHCO3aq. (30 mL) and again with water (30 mL), then dried over
anhydrous MgSO4. After filtration, the solvent was removed in vacuum
and the crude products were purified by using column chromatography
(petroleum ether:acetone 4:1 v/v) to afford corresponding anthracenes
5.
6.42 (d, 1H, JH-H = 5.0 Hz, CHOH), 6.49 (t, 1H, JH-H = 5.0 Hz, HAr),
6.92 (d, 2H, 3JH-H = 5.0 Hz, 2xHAr), 6.98–7.05 (m, 2H, 2xHAr), 7.33 (d,
1H, 3JH-H = 10.0 Hz, HAr), 7.68 (d, 1H, 3JH-H = 10.0 Hz, HAr); 13C NMR
(C6D6, 125 MHz): δ = 26.0, 55.2 (2C), 67.6, 67.7, 72.5, 100.1, 101.7,
105.50 (2C), 127.7, 128.0, 129.8, 129.8, 137.1, 143.7, 147.0, 161.8
(2C) ppm; Anal. Calcd for C19H22O5: C, 69.07; H, 6.71; Found: C, 68.89;
H, 6.82; HRMS (EI, 70 eV): m/z [M]+ Calcd for C19H22O5: 330.1467;
Found: 330.1465; MS (EI, 70 eV) m/z (%): 330 [M+, 8], 254 [M+
eHOCH2CH2CH2OH, 100].
,
2.3.3. (2-(1,3-Dioxan-2-yl)phenyl)(benzo[b]thien-2-yl)methanol (3ac)
Yield: 87%; colorless crystals; m.p. 80–82 °C; 1H NMR (C6D6,
2.2.5. General procedure for the synthesis of R1S-substituted (hetero)acenes
10 using ultrasounds (FeCl3/KI in EtOH).
500 MHz): δ = 0.46–0.50 (m, 1H, OCH2CHeqH), 1.60–1.73 (m, 1H,
3
3
OCH2CHHax), 3.25 (2xdt, 2H, JH-H = 15.0 Hz, JH-H = 5.0 Hz,
2xOCHaxH), 3.65 (dd, 2H, 3JH-H = 15.0 Hz, 3JH-H = 5.0 Hz, 2xOCHHeq),
4.36 (d, 1H, 3JH-H = 5.0 Hz, OH), 5.46 (s, 1H, OCHO), 6.56 (d, 1H, 3JH-
A solution of diarylmethyl thioether 8 (1.1 mmol) in dry EtOH
(10 mL) was placed in the thick-walled glass tube (25 mL). The titanium
alloy microtip was immersed in the reaction mixture to the height of
2.0 cm. Then, the FeCl3 (1.21 mmol) and KI (1.21 mmol) was added and
the resulting mixture was sonicated (amplitude 26.3 μm (35%), pulse
on/off 2 s, 50–60 °C). The temperature 50–60 °C was set on the pro-
cessor automatically and was maintained using oil bath. The reaction
mixture was sonicated until disappearance of the starting material
(monitoring by TLC). After the reaction was completed, the solvent was
removed. To the crude product, ethyl acetate (10 mL) was added and
the resulting mixture was poured to saturated solution of Na2S2O3aq
(10 mL). The organic layer was dried over anhydrous MgSO4. After
filtration, ethyl acetate was removed in vacuum and the crude product
was purified by column chromatography over silica gel with a mixture
of petroleum ether/acetone (10:1 v/v) to afford the corresponding
anthracenes 10.
3
3
H = 5.0 Hz, CHOH), 6.98 (dt, 1H, JH-H = 5.0 Hz, JH-H = 5.0 Hz, HAr),
3
7.02–7.09 (m, 4H, 4xHAr), 7.40 (d, 1H, JH-H = 5.0 Hz, HAr), 7.44 (dd,
3
3
3
1H, JH-H = 5.0 Hz, JH-H = 5.0 Hz, HAr), 7.49 (d, 1H, JH-H = 10.0 Hz,
3
3
H
Ar), 7.70 (dd, 1H, JH-H = 5.0 Hz, JH-H = 10.0 Hz, HAr) ppm; 13C
NMR (C6D6, 125 MHz): δ = 25.2, 66.9, 68.0, 70.1, 1007, 121.0, 122.3,
123.5, 123.9, 124.1, 127.1, 127.9, 128.8, 129.3, 136.2, 140.0, 140.1,
141.6, 149.5 ppm; Anal. Calcd for C19H18O3S: C, 69.91; H, 5.56; S, 9.82;
Found: C, 70.02; H, 5.49; S, 9.74; HRMS (EI, 70 eV): m/z [M]+ Calcd
for C19H18O3S: 326.0977; Found: 326.0978; MS (EI, 70 eV): m/z (%)
326 [M+
,
5], 250 [M+
,
eHOCH2CH2CH2OH, 100], 221 [M+
,
eCHOCH2CH2CH2OH, eOH, 23].
2.3.4. (2-(1,3-Dioxan-2-yl)phenyl)(1-methyl-1H-indol-2-yl)methanol
(3ad)
Yield: 74%; colorless crystals, m.p. 178–180 °C; 1H NMR (C6D6,
500 MHz): δ = 0.46–0.51 (m, 1H, OCH2CHeqH), 1.65–1.76 (m, 1H,
OCH2CHHax), 3.10 (s, 3H, NCH3), 3.20–3.30 (m, 3H, OH and
2xOCHaxH), 3.59–3.70 (m, 2H, 2xOCHHeq), 5.45 (s, 1H, OCHO), 6.54
2.2.6. General procedure for the synthesis of R1S-substituted (hetero)acenes
10 under silent conditions (FeCl3/KI in EtOH).
To
a solution of o-dithioacetalaryl(aryl)methyl thioether 8
3
(1.1 mmol) in dry EtOH (10 mL), FeCl3 (1.21 mmol) and KI (1.21 mmol)
were added. The mixture was refluxed until disappearance of the
starting material (monitoring by TLC). After completion of the reaction,
(d, 1H, JH-H = 4.0 Hz, CHOH), 6.82 (s, 1H, HAr), 6.92–6.97 (m, 1H,
H
Ar), 7.00–7.06 (m, 2H, 2x HAr), 7.15–7.23 (m, 3H, 3xHAr), 7.60–7.69
(m, 2H, 2xHAr) ppm; 13C NMR (C6D6, 125 MHz): δ = 26.3, 30.7, 67.9,
3

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
68.0, 68.2, 102.3, 102.7, 109.9, 120.6, 121.8, 122.3, 128.4, 128.6,
129.0, 129.4, 130.3, 137.3, 139.3, 141.8, 142.8 ppm; Anal. Calcd for
134.6, 138.3, 142.2, 148.1, 149.2 ppm; Anal. Calcd for C22H20O5: C,
72.51; H, 5.53; Found C, 72.27; H, 5.48; HRMS (EI, 70 eV): m/z [M]+
Calcd for C22H20O5: 364.1311; Found: 364.1318; MS (CI, isobutane):
m/z (%) 347 [M+, eOH, 40], 289 [M+, eHOCH2CH2CH2O, 100].
C
20H21NO3: C, 74.28; H, 6.55; N, 4.33; Found C, 74.11; H, 6.62; N,
4.40; HRMS (EI, 70 eV): m/z [M]+ Calcd for C20H21NO3: 323.1521;
Found: 323.1527; MS (EI, 70 eV): m/z (%) 323 [M+, 68], 247 [ M+
,
-C6H4, 95], 218 [M+, eCHO(CH2)3O, eOH, 42]; MS (CI, izobutane): m/
z (%) 323 [M+, 100], 306 [M+, eOH, 55].
2.3.9. (6-(1,3-Dioxan-2-yl)benzo[d][1,3]dioxol-5-yl)(phenyl)methanol
(3ci)
Yield: 62%; colorless oil; 1H NMR (C6D6, 500 MHz): δ = 0.60–0.65
(m, 1H, OCH2CHeqH), 1.74–1.85 (m, 1H, OCH2CHHax), 3.35–3.42 (m,
2H, 2xOCHaxH), 3.62 (s, 1H, OH), 3.74–3.81 (m, 2H, 2xOCHHeq),
5.24–5.30 (m, 2H, OCH2O), 5.51 (s, 1H, OCHO), 6.37 (s, 1H, CHO),
2.3.5. (2-(1,3-Dioxan-2-yl)phenyl)(thianthrene-1-yl)methanol (3ae)
Yield: 62%; white powder, m.p. 162–164 °C; 1H NMR (C6D6,
500 MHz): δ = 0.59–0.68 (m, 1H, OCH2CHeqH), 1.76–1.97 (m, 1H,
OCH2CHHax), 3.41–3.60 (m, 2H, 2xOCHaxH), 3.71–4.95 (m, 2H,
3
6.90 (s, 1H, HAr), 7.14 (t, 1H, JH-H = 5.0 Hz, HAr), 7.21 (s, 1H, HAr),
3
3
3
2xOCHHeq), 4.04 (d, 1H, JH-H = 4.0 Hz), 5,99 (s, 1H, OCHO), 6.79 (s,
7.25 (t, 1H, JH-H = 5.0 Hz, HAr), 7.44 (s, 1H, HAr), 7.65 (d, 2H, JH-
H = 10.0 Hz, 2xHAr) ppm; 13C NMR (C6D6, 125 MHz): δ = 26.2, 67.8,
67.9, 72.2, 101.1, 101.9, 108.1, 110.0, 127.61 (2C), 127.0, 129.08
(2C), 131.7, 138.5, 144.7, 148.0, 149.1 ppm; Anal. Calcd for C18H18O5:
C, 68.78; H, 5.77; Found C, 68.58; H, 5.96; HRMS (EI, 70 eV): m/z [M]+
Calcd for C18H18O5: 314.1154; Found: 314.1152; MS (EI, 70 eV): m/z
(%) 314 [M+, 8], 255 [M+, eOCH2CH2CH2, eH, 30], 238 [M+, C6H5,
100].
1H, CH-OH), 6.76–6.83 (m, 1H,
HAr), 6.87–6.88 (m, 1H, HAr),
6.92–7.32 (m, 6H, 6xHAr), 7.41 (dd, 1H, 4JH-H = 2.0 Hz, 3JH-H = 8.0 Hz,
3
3
H
H
Ar), 7.99 (d, 1H, JH-H = 8.0 Hz, HAr), 8.13 (d, 1H, JH-H = 8.0 Hz,
Ar) ppm; 13C NMR (C6D6, 125 MHz): δ = 25.3, 66.9, 67.0, 69.6, 100.7,
126.8, 126.8, 127.2, 127.8, 127.8, 128.0, 128.5, 128.8, 129.3, 135.6,
136.0, 136.4, 136.8, 141.60 (2C) ppm; Anal. Calcd for C23H20O3S2: C,
67.62; H, 4.93; S, 15.70; Found: C, 67.81; H, 5.04; S, 15.74; HRMS (EI,
70 eV): m/z [M]+ Calcd for C23H20O3S2: 408.0854; Found: 408.0861;
MS (EI, 70 eV): m/z (%) 408 [M+, 30], 332 [M+, eHOCH2CH2CH2OH,
100], 299 [M+, 38], 271 [M+, 35].
2.3.10. (6-(1,3-Dioxan-2-yl)benzo[d][1,3]dioxol-5-yl)(1-methyl-1H-
indol-2-yl)methanol (3 cd)
Yield: 90%; white solid, m.p. 161–162 °C; 1H NMR (C6D6, 600 MHz):
δ = 0.48–0.52 (m, 1H, OCH2CHeqH), 1.64–1.74 (m, 1H, OCH2CHHax),
2.3.6. (4-Bromophenyl)(6-(5,5-dimethyl-1,3-dioxan-2-yl)benzo[d][1,3]
dioxol-5-yl)methanol (3bf)
3
3.13 (d, 1H, JH-H = 2.0 Hz, OH), 3.15 (s, 3H, NCH3), 3.20–3.31 (m,
Yield: 72%; white powder, m.p. 89–90 °C; 1H NMR (C6D6,
500 MHz): δ = 0.22 (s, 3H, CH3), 1.03 (s, 3H, CH3), 3.03–3.33 (m, 5H,
2xOCH2 and OH), 5.14–15.19 (m, 2H, OCH2O), 5.28 (s, 1H, CHOH),
6.08 (s, 1H, OCHO), 6.65 (s, 1H, HAr), 7.22–7.28 (m, 4H, 4xHAr), 7.37
(s, 1H, HAr) ppm; 13C NMR (C6D6, 125 MHz): δ = 22.1, 23.7, 30.4, 71.5,
71.5, 78.1, 101.3, 102.0, 108.2, 109.5, 121.9, 129.42 (2C), 131.5,
132.2, 132.2, 137.8, 143.5, 148.3, 149.2 ppm; Anal. Calcd for
2H, 2xOCHaxH), 3.60–3.70 (m, 2H, 2xOCHHeq), 5.15–5.18 (m, 2H,
OCH2O), 5.43 (s, 1H, OCHO), 6.39 (d, 1H, 3JH-H = 2.0 Hz, CHOH), 6.80
3
(s, 1H, HAr), 6.90 (s, 1H, HAr), 7.02 (d, 1H, JH-H = 6.0 Hz, HAr),
3
7.16–7.24 (m, 2H, 2xHAr), 7.33 (s, 1H, HAr), 7.68 (d, 1H, JH-
H = 6.0 Hz, HAr), ppm; 13C NMR (C6D6, 150 MHz): δ = 26.2, 30.6, 67.8,
67.9, 67.9, 101.6, 102.0, 102.3, 108.7, 109.5, 110.0, 120.6, 121.9,
122.4, 129.0, 131.7, 136.1, 139.3, 142.2, 148.3, 149.3 ppm; Anal.
Calcd for C21H21NO5: C, 68.65; H, 5.76; N, 3.81; Found: C, 68.58; H,
5.86; N, 3.78; HRMS (EI, 70 eV): m/z [M]+ Calcd for C21H21NO5:
367.1420; Found: 367.1418; MS (EI, 70 eV): m/z (%) 367 [M+, 56],
291 [M+, eHOCH2CH2CH2OH, 100]; MS (CI, izobutane): m/z (%) 367
[M+, 100], 350 [M+, eOH, 23], 292 [M+, eHOCH2CH2CH2O, 54].
C
20H21BrO5: C, 57.02; H, 5.02; Found C, 57.12; H 4.98; HRMS (EI,
70 eV): m/z [M]+ Calcd for C20H21BrO5: 420.0572; Found: 420.0568;
MS (EI, 70 eV): m/z (%) 420 [M+, 2], 333 [M+, eHOCH2C(CH3)2CH2,
33], 318 [M+, eHOCH2C(CH3)2CH2OH, 100], 255 [M+, 28], 238 [M+
,
24].
2.3.7. (6-(5,5-Dimethyl-1,3-dioxan-2-yl)benzo[d][1,3]dioxol-5-yl)(3-
2.3.11. (6-(1,3-Dioxan-2-yl)benzo[d][1,3]dioxol-5-yl)(4-methoxyphenyl)
methanol (3cj)
methoxyphenyl)methanol (3bg)
Yield: 75%; light yellow oil; 1H NMR (C6D6, 200 MHz): 1H NMR
(C6D6, 500 MHz): δ = 0.22 (s, 3H, CH3), 1.05 (s, 3H, CH3), 3.06–3.12
(m, 2H, OCH2), 3.28 (s, 3H, OCH3), 3.27–3.36 (m, 2H, OCH2),
Yield: 67%; colorless oil; 1H NMR (C6D6, 500 MHz): δ = 0.50–0.55
(m, 1H, OCH2CHeqH), 1.65–1.75 (m, 1H, OCH2CHHax), 3.27 (s, 3H,
OCH3), 3.28–3.33 (m, 2H, 2xOCHaxH), 3.41 (s, 1H, OH), 3.65–3.71 (m,
2H, 2xOCHHeq), 5.15–5.21 (m, 2H, OCH2O), 5.45 (s, 1H, OCHO), 6.26
(s, 1H, CHOH), 6.78 (d, 2H, 3JH-H = 10.0 Hz, 2xHAr), 6.88 (s, 1H, HAr),
3
5.12–5.17 (m, 2H, OCH2O), 5.40 (s, 1H, CHOH), 6.26 (d, 1H, JH-
H = 2.0 Hz, OH), 6.69–6.71 (m, 1H, HAr), 6.86 (s, 1H, HAr), 7.09–7.17
(m, 2H, 2xHAr), 7.36 (s, 1H, HAr), 7.42 (s, 1H, HAr) ppm; 13C NMR
(C6D6, 125 MHz): δ = 22.1, 23.7, 30.5, 55.4, 72.1, 78.1, 78.2, 100.9,
101.9, 108.1, 110.0, 113.1, 113.8, 120.0, 130.2, 131.5, 138.5, 146.2,
148.1, 149.2, 161.0 ppm; Anal. Calcd for C21H24O6: C, 67.89; H, 6.64;
Found C, 67.73; H 6.50; HRMS (EI, 70 eV): m/z [M]+ Calcd for
3
7.38 (s, 1H, HAr), 7.47 (d, 2H, JH-H = 10.0 Hz, 2xHAr) ppm; 13C NMR
(C6D6, 125 MHz): δ = 25.9, 55.1, 67.5, 67.6, 71.6, 100.7, 101.5, 107.8,
109.6, 114.29 (2C), 128.50 (2C), 131.4, 136.4, 138.5, 147.6, 148.8,
159.57 ppm; Anal. Calcd for C19H20O6: C, 66.27; H, 5.85; found C,
66.26; H, 5.91; HRMS (EI, 70 eV): m/z [M]+ calcd for C19H20O6:
344.1260; found: 344.1264; MS (EI, 70 eV): m/z (%): 344 [M+, 6], 285
[M+, eHOCH2CH2CH3, 30], 268 [M+, eHOCH2CH2CH2OH, 88], 177
[M+, 100].
C
21H24O6: 372.1573; Found: 372.1558; MS (EI, 70 eV): m/z (%) 372
[M+, 36], 357 [M+, eCH3, 38], 268 [M+, eOHCH2C(CH3)2CH2OH,
24], 217 [M+
,
eOHCH2OH, eC6H4OCH3, 100], 149 [M+
,
eOHCH2C(CH3)2CH2O, eC6H4OCH3, 40].
2.3.12. (2-(1,3-Dioxan-2-yl)benzo[b]thien-3-yl)(thien-2-yl)methanol
(3fk)
2.3.8. (6-(1,3-Dioxan-2-yl)benzo[d][1,3]dioxol-5-yl)(naphth-1-yl)
methanol (3ch)
Yield: 65%; light yellow oil; 1H NMR (C6D6, 500 MHz):
δ = 0.49–0.55 (m, 1H, OCH2CHeqH), 1.70–1.82 (m, 1H, OCH2CHHax),
3.22–3.36 (m, 2H, 2xOCHaxH), 3.68–3.75 (m, 2H, 2xOCHHeq), 3.87 (d,
Yield: 63%; white needles, m.p. 124–125 °C; 1H NMR (C6D6,
500 MHz): δ = 0.46–0.51 (m, 1H, OCH2CHeqH), 1.60–1.74 (m, 1H,
OCH2CHHax), 3.21–3.31 (m, 2H, 2xOCHaxH), 3.62–3.70 (m, 3H,
2xOCHHeq and OH), 5.11–5.17 (m, 2H, OCH2O), 5.46 (s, 1H, CHOH),
6.46 (s, 1H, OCHO), 6.83 (s, 1H, HAr), 7.18–7.22 (m, 2H, HAr), 7.36 (s,
1H, HAr), 7.51–7.65 (m, 4H, 4xHAr), 8.24 (s, 1H, HAr) ppm; 13C NMR
(C6D6, 125 MHz): δ = 26.2, 67.8, 67.9, 72.3, 101.2, 101.9, 108.2,
110.2, 126.0, 126.4, 126.6, 127.0, 128.8, 129.0, 129.2, 131.9, 133.9,
3
3
1H, JH-H = 5.0 Hz, OH), 5.79 (s, 1H, OCHO), 6.59 (d, 1H, JH-
H = 5.0 Hz, CHOH), 6.68–6.70 (m, 1H, HAr), 6.79–6.81 (m, 1H, HAr),
3
6.92–6.94 (m, 1H, HAr), 7.01–7.10 (m, 2H, 2xHAr), 7.50 (d, 1H, JH-
H = 10.0 Hz, HAr), 7.88 (d, 1H, JH-H = 10.0 Hz, HAr) ppm; 13C NMR
3
(C6D6, 125 MHz): δ = 26.0, 67.8, 67.9, 68.0, 98.6, 123.4, 124.9, 125.1,
125.4, 125.7, 125.8, 127.9, 136.3, 139.6, 140.5, 145.9, 148.7 ppm;
4

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
4
Anal. Calcd for C17H16O3S2: C, 61.42; H, 4.85; S, 19.29; Found: C,
3JH-H = 10.0 Hz, 3xHAr), 7.51 (d, 1H, JH-H = 5.0 Hz, HAr), 7.73–7.78
61.65; H, 4.81; S, 19.07; HRMS (EI, 70 eV): m/z [M]+ Calcd for
(m, 2H, 2xHAr) ppm; 13C NMR (C6D6, 125 MHz): δ = 26.4, 67.8, 71.4,
76.1, 101.6, 122.8, 123.2, 124.5, 124.9, 125.0, 128.0, 128.4, 128.65
(2C), 129.0, 129.3 (2C), 129.5, 130.3, 138.4, 139.8, 140.2, 140.9,
141.2 ppm; Anal. Calcd for C26H24O3S: C, 74.97; H, 5.81; S, 7.70;
Found: C, 75.11; H, 6.04; S, 7.52; HRMS (EI, 70 eV): m/z [M]+ Calcd
for C26H24O3S: 416.1446; Found: 416.1439; MS (EI, 70 eV): m/z (%):
C
17H16O3S2: 332.0541; Found: 332.0542; MS (EI, 70 eV): m/z (%) 332
[M+
,
22], 273 [M+
,
eHOCH2CH2CH2, 10], 256 [M+
,
HOCH2CH2CH2OH, 41], 189 [M+, eC4H4S, eHOCH2CH2CH2, 100].
2.3.13. 2-(2-(Benzyloxy(3,4,5-trimethoxyphenyl)methyl)phenyl)-1,3-
dioxane (4aa(Bn))
416 [M+
,
2], 340 [M+
,
eHOCH2CH2CH2OH, 13], 325 [M+
,
,
Yield: 83%; Colorless oil; 1H NMR (C6D6, 500 MHz): δ = 0.67–0.72
(m, 1H, OCH2CHeqH), 1.80–1.93 (m, 1H, OCH2CHHax), 3.35–3.54 (m,
2H, 2xOCHaxH), 3.48 (s, 6H, 2 × OCH3), 3.76–3.95 (m, 2H,
2xOCHHeq), 3.90 (s, 3H, OCH3), 4.62–4.76 (m, 2H, OCH2O), 5.70 (s,
eCH2C6H5, 38], 267 [M+, eCH2C6H5, eOCH2CH2CH2, 77], 133 [M+
100].
2.3.17. 2-((2-(1,3-Dioxan-2-yl)phenyl)(methoxy)methyl)-1-methyl-1H-
1H, OCHO), 6.28 (s, 1H, CHO), 7.04 (s, 2H, 2xHAr), 7.13–7.20 (m, 1H,
indole (4ad(Me))
3
H
Ar), 7.21–7.26 (m, 4H, 4xHAr), 7.43 (d, 2H, JH-H = 10,0 Hz, 2xHAr),
Yield: 95%; light yellow powder, m.p. 126–128 °C; 1H NMR (C6D6,
500 MHz): δ = 0.53–0.57 (m, 1H, OCH2CHeqH), 1.73–1.84 (m, 1H,
OCH2CHHax), 3.23 (s, 3H, NCH3), 2.22–3.37 (m, 2H, 2xOCHaxH), 3.34
(s, 3H, OCH3), 3.69–3.79 (m, 2H, 2xOCHHeq), 5.64 (s, 1H, CHOCH3),
3
3
7.73 (d, 1H, JH-H = 5,0 Hz, HAr), 7.94 (d, 1H, JH-H = 5,0 Hz, HAr
)
ppm; 13C NMR (C6D6, 125 MHz): δ = 25.7, 55.53 (2C), 60.3, 67.0, 67.1,
70.5, 77.8, 100.6, 105.0 (2C), 127.1, 127.4, 127.8 (2C), 127.8, 128.4
(2C), 128.6, 129.2, 137.5, 138.2, 138.3, 139.3, 140.3, 153.9 (2C) ppm;
Anal. Calcd for C27H30O6: C, 71.98; H, 6.71; Found: C, 71.85; H, 6.89;
HRMS (EI, 70 eV): m/z [M]+ Calcd for C27H30O6: 450.2042; Found:
450.2015; MS (EI, 70 eV): m/z (%) 450 [M+, 8], 359 [M+, eCH2C6H5,
50], 283 [M+, eC6H2(OCH3)3, 64].
3
5.93 (s, 1H, OCHO), 6.27 (s, 1H, HAr), 7.06 (d, 1H, JH-H = 10.0 Hz,
H
Ar), 7.08–7.14 (m, 3H, 3xHAr), 7.15–7.21 (m, 2H, 2xHAr), 7.51–7.57
3 3
(m, 2H, 2xHAr), 7.97 (dd, 1H, JH-H = 10.0 Hz, JH-H = 10.0 Hz, HAr
)
ppm; 13C NMR (C6D6, 125 MHz): δ = 25.6, 29.6, 56.5, 66.8 (2C), 75.9,
99.8, 103.2, 109.1, 119.6, 121.0, 121.7, 127.0, 127.8, 128.0, 128.7
(2C), 137.0, 137.7, 138.5, 139.4 ppm; Anal. Calcd for C21H23NO3: C,
74.75; H, 6.87; N, 4.15; Found C, 74.71; H, 6.90; N, 4.18; HRMS (EI,
70 eV): m/z [M]+ Calcd for C21H23NO3: 337.1678; Found: 337.1686;
MS (EI, 70 eV): m/z (%) 337 [M+, 48], 305 [M+, eOCH3, eH, 57]; MS
(CI, izobutane): m/z (%) 337 [M+, 53], 306 [M+, eOCH3, 100], 262
[M+, eO(CH2)3O, -H, 93].
2.3.14. 2-(2-(4-Trifluoromethylbenzyloxy(3,4,5-trimethoxyphenyl)
methyl)phenyl)-1,3-dioxane (4aa(Bnp-CF3)
Yield: 68%; white powder, m.p. 107–108 °C; 1H NMR (CDCl3,
500 MHz): δ = 0.65–0.70 (m, 1H, OCH2CHeqH), 1.71–1.84 (m, 1H,
OCH2CHHax), 3.33–3.48 (m, 2H, 2xOCHaxH), 3.50 (s, 6H, 2xOCH3),
3.71–3.90 (m, 2H, 2xOCHHeq), 3.90 (s, 3H, OCH3), 4.51–4.60 (m, 2H,
OCH2O), 5.60 (s, 1H, OCHO), 6.26 (s, 1H, CHOCH2), 7.03 (s, 2H,
2xHAr), 7.17–7.26 (m, 2H, 2xHAr), 7.24 (d, 2H, 3JH-H = 5.0 Hz, 2xHAr),
2.3.18. 2-((2-(1,3-Dioxan-2-yl)phenyl)(naphth-2-ylmethoxy)methyl)-1-
methyl-1H-indole (4ad(Naphth))
3
3
7.40 (d, 2H, JH-H = 5.0 Hz, 2xHAr), 7.72 (d, 2H, JH-H = 5.0 Hz, HAr),
Yield: 67%; light yellow powder, m.p. 115–116 °C; 1H NMR (C6D6,
200 MHz): δ = 0.50–0.59 (m, 1H, OCH2CHeqH), 1.73–1.97 (m, 1H,
OCH2CHHax), 3.12–3.41 (m, 2H, 2xOCHaxH), 3.41 (s, 3H, NCH3),
3.71–3.90 (m, 2H, 2xOCHHeq), 4.65–4.86 (m, 2H, OCH2), 5.76 (s, 1H,
OCHO), 6.32 (s, 1H, CHOCH2), 6.51 (s, 1H, HAr), 7.14–7.36 (m, 9H,
9xHAr), 7.49–7.55 (m, 1H, HAr), 7.65–7.83 (m, 5H, 5xHAr), 8.13–8.20
(m, 1H, HAr) ppm; 1H NMR (C6D6, 500 MHz): δ = 0.47–0.51 (m, 1H,
OCH2CHeqH), 1.74–1.85 (m, 1H, OCH2CHHax), 3.09–3.30 (m, 2H,
2 × OCHaxH), 3.35 (s, 3H, NCH3), 3.65–3.80 (m, 2H, 2xOCHHeq),
4.61–4.77 (m, 2H, OCH2), 5.68 (s, 1H, OCHO), 6.26 (s, 1H, CHOCH2),
6.44 (s, 1H, HAr), 7.10 (d, 1H, 3JH-H = 10.0 Hz, HAr), 7.16–7.28 (m, 6H,
3
7.84 (d, 2H, JH-H = 5.0 Hz, HAr) ppm; 13C NMR (CDCl3, 125 MHz):
δ = 26.5, 56.5 (2C), 61.2, 68.0, 68.0, 70.4, 78.8, 102.0, 105.9 (2C),
2
1
126.1, 126.1 (q, JC-F = 3.3 Hz), 127.5 (q, JC-F = 270.0 Hz), 128.3,
128.6 (2C), 129.5, 130.2, 130.2, 138.3, 138.8, 139.4, 141.0, 144.4,
154.9 (2C) ppm; Anal. Calcd for C27H26F3O5: C, 66.52; H, 5.38; Found:
C, 64.73; H, 5.60; HRMS (EI, 70 eV): m/z [M]+ Calcd for C27H26F3O5:
518.1916; Found: 518.1913; MS (EI, 70 eV): m/z (%) 518 [M+, 10],
359 [M+
,
eCH2C6H4CF3, 47], 301 [M+
,
72], 283 [M+
, eCF3,
eC6H2(OCH3)3, 64], 133 [M+, 100].
3
3
2.3.15. 2-(2-(Benzyloxy(3,5-dimethoxyphenyl)methyl)phenyl)-1,3-
6xHAr), 7.45 (dd, 1H, JH-H = 10.0 Hz, JH-H = 10.0 Hz, HAr), 7.60 (d,
3 3
dioxane (4ab(Bn))
1H, JH-H = 5.0 Hz, HAr), 7.63–7.67 (m, 3H, 3xHAr), 7.71 (d, 1H, JH-
Yield: 67%; Colorless oil; 1H NMR (C6D6, 600 MHz): δ = 0.58–0.62
(m, 1H, OCH2CHeqH), 1.71–1.81 (m, 1H, OCH2CHHax), 3.31 (s, 6H,
2xOCH3), 3.34–3.40 (m, 2H, 2xOCHaxH), 3.70–3.84 (m, 2H,
2xOCHHeq), 4.54–4.62 (m, 2H, OCH2), 5.58 (s, 1H, OCHO), 6.20 (s, 1H,
CHOCH2), 6.47 (s, 1H, HAr), 7.01 (s, 2H, 2xHAr), 7.05–7.14 (m, 5H,
H = 10.0 Hz, HAr), 7.75 (s, 1H, HAr), 8.08 (d, 1H, JH-H = 5.0 Hz, HAr
)
3
ppm; 13C NMR (C6D6, 125 MHz): δ = 26.5, 30.7, 67.7, 67.8, 72.0, 74.6,
100.6, 104.4, 110.1, 120.6, 122.1, 122.8, 126.9, 127.1 (2C), 127.5,
128.2, 128.2, 128.6, 129.0, 129.0, 129.0, 129.3, 129.9, 134.2, 134.5,
136.9, 138.0, 138.9, 139.5, 140.4 ppm; Anal. Calcd for C31H29NO3: C,
80.32; H, 6.31; N, 3.02; Found C, 80.45; H, 6.49; N, 2.98; HRMS (EI,
70 eV): m/z [M]+ Calcd for C31H29NO3: 463.2147; Found: 463.2154;
MS (EI, 70 eV): m/z (%) 463 [M+, 5], 305 [M+, eOCH2C10H7, 9] 245
[M+, eCHO(CH2)3O, eOCH2C10H7, 21].
3
5xHAr), 7.31 (d, 2H, JH-H = 6.0 Hz, 2xHAr), 7.64–7.68 (m, 1H, HAr),
7.80–7.84 (m, 1H, HAr) ppm; 13C NMR (C6D6, 151 MHz): δ = 25.4, 54.4
(2C), 66.8, 66.9, 70.2, 77.5, 99.1, 100.3, 105.3 (2C), 126.8, 127.1,
127.3, 127.6 (2C), 128.1 (2C), 128.4, 128.9, 137.2, 139.1, 140.0,
145.2, 161.06 (2C) ppm; Anal. Calcd for C26H28O5: C, 74.26; H, 6.71;
Found: C, 74.23; H, 6.52; HRMS (EI, 70 eV): m/z [M]+ Calcd. for
2.3.19. 2-(3-(Benzyloxy(thianthren-1-yl)methyl)phenyl)-1,3-dioxane
(4ae(Bn))
C
26H28O5: 420.1937; Found: 330.1942; MS (EI, 70 eV) m/z (%): 420
[M+, 1], 329 [M+, eCH2C6H5, 10], 312 [M+, HOCH2C6H5], 253 [M+
eCH2C6H5, eHOCH2CH2CH2OH, 100], 133 [M+, 32].
,
Yield: 73%; white solid; m.p. 56 °C; 1H NMR (C6D6, 200 MHz):
δ = 0.53–0.62 (m, 1H, OCH2CHeqH), 1.82–2.02 (m, 1H, OCH2CHHax),
3.10–3.52 (m, 2H, 2 × OCHaxH), 3.67–4.91 (m, 2H, 2xOCHHeq),
4.68–5.05 (m, 2H, OCH2), 5,66 (s, 1H, OCHO), 6.70–6.95 (m, 4H, CHO,
2.3.16. 2-(2-(Benzo[b]thien-2-yl(bezyloxy)methyl)phenyl-1,3-dioxane
(4ac(Bn))
3x HAr), 7.04–7.36 (m, 8H, 8xHAr), 7.42–7.55 (m, 3H, 3xHAr),
Yield: 79%; yellow oil; 1H NMR (C6D6, 500 MHz): δ = 0.49–0.53
(m, 1H, OCH2CHeqH), 1.62–1.73 (m, 1H, OCH2CHHax), 3.20–3.28 (m,
2H, 2xOCHaxH), 3.64–3.73 (m, 2H, 2xOCHHeq), 4.50–4.64 (m, 2H,
OCH2), 5.51 (s, 1H, CHOCH2), 6.43 (s, 1H, OCHO), 6.96–6.99 (m, 1H,
7.71–7.76 (m, 1H, HAr), 8.05–8.11(m, 1H, HAr); 13C NMR (C6D6,
125 MHz): δ = 25.5, 66.7, 66.9, 71.3, 78.5, 99.7, 126.9, 127.2, 127.3,
127.33, 127.6 (2C), 128.0 (2C), 128.0, 128.1, 128.1, 128.4, 128.8,
128.7, 128.9, 135.8, 136.2, 137.1 (2C), 137.2, 137.4, 138.1, 138.6,
141.7; Anal. Calcd for C30H26O3S2: C, 72.26; H, 5.26; S, 12.86; Found:
H
Ar), 7.01–7.09 (m, 3H, 3xHAr), 7.10–7.17 (m, 4H, 4xHAr), 7.37 (t, 3H,
5

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
C, 72.17; H, 5.21; S, 12.81; HRMS (EI, 70 eV): m/z [M]+ Calcd for
OCH2Naphth), 5.10–5.20 (m, 2H, OCH2O), 5.45 (s, 1H, OCHO), 6.25 (s,
1H, CHOCH2), 7.18–7.22 (m, 4H, 4xHAr), 7.23 (s, 1H, HAr), 7.50–7.54
(m, 2H, 2xHAr), 7.55–7.64 (m, 6H, 6xHAr), 7.72–7.77 (m, 2H, 2xHAr),
8.21 (s, 1H, HAr) ppm; 13C NMR (C6D6, 125 MHz): δ = 26.3, 67.7, 67.9,
71.3, 78.1, 100.6, 101.9, 108.1, 109.5, 126.5, 126.7, 126.8, 127.0,
127.0, 127.1, 127.7, 128.7, 128.7, 129.0 (2C), 129.0, 129.2, 129.3,
133.0, 134.0, 134.2, 134.6, 134.6, 135.0, 137.6, 141.5, 148.5,
149.5 ppm; Anal. Calcd for C33H28O5: C, 78.55; H, 5.59; Found: C,
78.31; H, 5.65; HRMS (EI, 70 eV): m/z [M]+ Calcd for C33H28O5:
504.1937; Found: 504.1930; MS (EI, 70 eV): m/z (%) 504 [M+, 1], 363
[M+, eCH2C10H7, 100], 305 [M+, 88], 215 [M+, eOCH2CH2CH2O,
eCH2C10H7, 18].
C
30H26O3S2: 498.1323; Found: 498.1326; MS (EI, 70 eV): m/z (%) 498
[M+
,
73], 407 [M+
,
eCH2C6H5, 8], 349 [M+
,
eCH2C6H5,
eOCH2CH2CH2, 100].
2.3.20. 5-((4-Bromophenyl)(butoxy)methyl)-6-(5,5-dimethyl-1,3-dioxan-
2-yl)benzo[d][1,3]dioxole (4bf(Bu))
Yield: 51%; white solid, m.p. 70–72 °C; 1H NMR (C6D6, 200 MHz):
δ = 0.39 (s, 3H, CH3), 0.93 (t, 3H, 3JH-H = 8.0, CH3), 1.20 (s, 3H, CH3),
1,35–1.73 (m, 4H, CH2CH2), 3.21–3.32 (m, 2H, OCH2), 3.45–3.59 (m,
4H, 2xOCH2), 5.27–5.33 (m, 2H, OCH2O), 5.57 (s, 1H, CHO), 5.87 (s,
1H, OCHO), 7.09 (s, 1H, HAr), 7.40 (s, 4H, 4xHAr), 7.56 (s, 1H, HAr
)
ppm; 13C NMR (C6D6, 50 MHz): δ = 12.6, 18.3, 20.0, 21.7, 28.3, 30.9,
67.2, 76.0, 76.2, 76.5, 98.5, 99.7, 105.8, 106.7, 119.7, 127.6 (2C),
130.0, 130.0, 133.0, 141.2, 146.1, 147.3 (one signal of quaternary
carbon is hidden by C6D6 signals) ppm; Anal. Calcd for C24H29BrO5: C,
60.38; H, 6.12; Found C, 60.47; H, 6.19; HRMS (EI, 70 eV): m/z [M]+
Calcd for C24H29BrO5: 476.1198; Found: 476.1186; MS (EI, 70 eV): m/z
(%) 478 [M+, 12], 421 [M+, eC4H9, 11], 374 [M+, eHOC4H9, eCH3,
eCH3, 8], 333 M+, eCH2CH3, eHOCH2C(CH3)2CH2OH, 100].
2.3.24. 5-(1,3-dioxan-2-yl)-6-(methoxy(phenyl)methyl)benzo[d][1,3]
dioxole (4ci(Me))
Yield: 90%; white powder, m.p. 111–113 °C; 1H NMR (C6D6,
200 MHz): δ = 0.64–0.73 (m, 1H, OCH2CHeqH), 1.74–1.98 (m, 1H,
OCH2CHHax), 3.33–3.53 (m, 2H, 2xOCHaxH), 3.37 (s, 3H, OCH3),
3.80–3.94 (m, 2H, 2xOCHHeq), 5.22–5.30 (m, 2H, OCH2O), 5.67 (s, 1H,
OCHO), 5.92 (s, 1H, CHO), 7.06–7.31 (m, 4H, 4xHAr), 7.57 (s, 1H, HAr),
3
2.3.21. 5-(5,5-Dimethyl-1,3-dioxan-2-yl)-6-(methoxy(3-methoxyphenyl)
methyl)benzo[d][1,3]dioxole (4bg(Me))
7.68 (d, 2H, JH-H = 8.0 Hz, 2xHAr); 13C NMR (C6D6, 50 MHz):
δ = 25.4, 56.2, 66.8, 66.9, 79.9, 99.7, 100.8, 106.9, 108.0, 126.9,
Yield: 92%; white powder, m.p. 94–95 °C; 1H NMR (C6D6,
500 MHz): δ = 0.25 (s, 3H, CH3), 0.35 (s, 3H, CH3), 1.10 (s, 3H, OCH3),
3.13–3.19 (m, 2H, OCH2), 3.27 (s, 3H, OCH3), 3.36–3.44 (m, 2H,
OCH2), 5.10–5.17 (m, 2H, OCH2O), 5.56 (s, 1H, OCHO), 5.81 (s, 1H,
127.0, 128.0, 128.1, 128.3, 131.6, 134.3, 143.0; Anal. Calcd for
C
19H20O5: C, 69.50; H, 6.14; Found C, 69.39; H, 6.25; HRMS (EI,
70 eV): m/z [M]+ Calcd for C19H20O5: 328.1311; Found: 328.1308; MS
(EI, 70 eV): m/z (%) 328 [M+, 58], 313 [M+, eCH3, 30], 296 [ M+
,
3
3
CHO), 6.68 (dd, 1H, JH-H = 10.0 Hz, JH-H = 6.0 Hz, HAr), 7.09–7.13
eOCH3, 22], 252 [M+
,
eC6H5, 92], 149 [M+
,
eC6H5,
3
(m, 2H, 2xHAr), 7.20 (d, 1H, JH-H = 10.0 Hz, HAr), 7.35 (s, 1H, HAr),
eCHOCH2CH2CH2O, eCH3, 65].
7.51 (s, 1H, HAr) ppm; 13C NMR (C6D6, 125 MHz): δ = 22.2, 23.9, 30.5,
55.3, 57.2, 78.2, 78.3, 80.8, 100.6, 101.8, 107.9, 108.8, 113.6, 113.7,
120.3, 130.2, 132.3, 135.3, 148.3, 149.5, 155.0, 161.0 ppm; Anal.
Calcd for C22H26O6: C, 68.38; H, 6.78; Found: C, 68.08; H, 68.11; HRMS
(EI, 70 eV): m/z [M]+ Calcd for C22H26O6: 386.1729; Found: 386.1719;
MS (EI, 70 eV): m/z (%) 386 [M+, 5], 354 [M+, eCH3OH, 10], 299
[M+, eHOCH2C(CH3)2CH2, 26], 282 [M+, eHOCH2C(CH3)2CH2OH,
100], 267 [M+, eHOCH2C(CH3)2CH2OH, eCH3, 43].
2.3.25. 2-((6-(1,3-Dioxan-2-yl)benzo[d][1,3]dioxol-5-yl)(methoxy)
methyl)-1-methyl-1H-indole (4 cd(Me))
Yield: 88%; white solid, m.p. 128–129 °C; 1H NMR (C6D6, 600 MHz):
δ = 0.51–0.55 (m, 1H, OCH2CHeqH), 1.70–1.80 (m, 1H, OCH2CHHax),
3.19–3.37 (m, 2H, 2xOCHaxH), 3.24 (s, 3H, NCH3), 3.36 (s, 3H, OCH3),
3.65–3.78 (m, 2H, 2xOCHHeq), 5.23–5.26 (m, 2H, OCH2O), 5.58 (s, 1H,
OCHO), 5.79 (s, 1H, CHOCH3), 6.36 (s, 1H, HAr), 7.06–7.16 (m, 2H,
3
2.3.22. 5-(1,3-Dioxan-2-yl)-6-(methoxy(naphth-2-yl)methyl)benzo[d]
[1,3]dioxole (4ch(Me))
2xHAr), 7.19–7.24 (m, 2H, 2xHAr), 7.58 (d, 1H, JH-H = 6.0 Hz, HAr),
7.62 (s, 1H, HAr) ppm; 13C NMR (C6D6, 150 MHz): δ = 26.5, 30.6, 57.3,
67.7, 67.8, 76.6, 100.2, 101.9, 104.0, 108.4, 109.1, 110.0, 120.6,
122.1, 122.8. 129.0, 132.1, 133.1, 139.5, 140.4, 148.6, 149.1 ppm;
Anal. Calcd for C22H23NO5: C, 69.28; H, 6.08; N, 3.67; Found: C, 69.27;
H, 6.15; N, 3.72; HRMS (EI, 70 eV): m/z (%) Calcd for C22H23NO5:
381.1576; Found: 381.1587; MS (EI, 70 eV): m/z (%) 381 [M+, 78],
Yield: 94%; Colorless oil; 1H NMR (C6D6, 200 MHz): δ = 0.63–0.71
(m, 1H, OCH2CHeqH), 1.76–2.03 (m, 1H, OCH2CHHax), 3.36–3.54 (m,
2H, 2xOCHaxH), 3.43 (s, 3H, OCH3), 3.80–3.95 (m, 2H, 2xOCHHeq),
5.21–5.29 (m, 2H, OCH2O), 5.73 (s, 1H, OCHO), 6.08 (s, 1H, CHO),
7.25 (s, 1H, HAr), 7.27–7.33 (m, 2H, 2xHAr), 7.61 (s, 1H, HAr),
7.63–7.81 (m, 4H, 4xHAr), 8.23 (s, 1H, HAr) ppm; 13C NMR (C6D6,
125 MHz): δ = 26.4, 57.3, 67.8, 68.0, 81.0, 100.8 (2C), 108.0, 109.2,
126.5, 126.6, 126.9, 128.7 (2C), 129.0, 129.2, 132.8, 134.0, 134.6,
135.1, 141.5, 148.3, 149.4 ppm; Anal. Calcd for C23H22O5: C, 73.00; H,
5.86; Found C, 73.05; H, 5.77; HRMS (EI, 70 eV): m/z [M]+ Calcd for
C23H22O5: 378.1467; Found: 378.1462; MS (EI, 70 eV): m/z (%) 378
349 [M+, eCH3OH, 43], 322 [M+, eHOCH2CH2CH2, 48], 290 [M+
,
eHOCH2CH2CH2OH, eCH3, 100], 276 [M+, eOCH2CH2CH2O, eOCH3,
26]; MS (CI, izobutane): m/z (%) 381 [M+, 100], 350 [M+, eCH3O,
80], 306 [M+, HOCH2CH2CH2O, 46].
[M+
,
10], 319 [M+
,
eHOCH2CH2CH2, 68], 302 [M+
,
2.3.26. 5-(1,3-Dioxan-2-yl)-6-(methoxy(4-methoxyphenyl)methyl)benzo
[d][1,3]dioxole (4cj(Me))
eHOCH2CH2CH2OH, 100], 287 [M+, eHOCH2CH2CH2OH, eCH3, 45],
202 [M+, 45], 177 [M+, 45].
Yield: 89%; white powder, m.p. 100–102 °C; 1H NMR (C6D6,
200 MHz): δ = 0.63–0.72 (m, 1H, OCH2CHeqH), 1.75–1.99 (m, 1H,
OCH2CHHax), 3.35 (s, 3H, OMe), 3.39 (s, 3H, OMe), 3.39–3.56 (m, 2H,
2xOCHaxH), 3.82–3.96 (m, 2H, 2xOCHHeq), 5.24–5.30 (m, 2H,
OCH2O), 5.69 (s, 1H, OCHO), 5.89 (s, 1H, CHO), 6.86 (s, 1H, HAr), 6.91
(s, 1H, HAr), 7.26 (s, 1H, HAr), 7.57–7.62 (m, 2H, 2xHAr), 7.63 (s, 1H,
2.3.23. 5-(1,3-Dioxan-2-yl)-6-(naphth-2-yl)(naphth-2-ylmethoxy)methyl)
benzo[d][1,3]dioxole (4ch(Naphth))
Yield: 66%; white powder, m.p. 54–55 °C; 1H NMR (C6D6,
200 MHz): δ = 0.51–0.55 (m, 1H, OCH2CHeqH), 1.63–1.88 (m, 1H,
OCH2CHHax), 3.13–3.30 (m, 2H, 2xOCHaxH), 3.68–3.85 (m, 2H,
2xOCHHeq), 4.78–4.97 (m, 2H, OCH2Naphth), 5.21–5.31 (m, 2H,
OCH2O), 5.56 (s, 1H, OCHO), 6.38 (s, 1H, CHOCH2), 7.25–7.36 (m, 5H,
5xHAr), 7.61–7.77 (m, 8H, 8xHAr), 7.84–7.90 (m, 2H, 2xHAr), 8.34 (s,
1H, HAr) ppm; 1H NMR (C6D6, 500 MHz): δ = 0.37–0.42 (m, 1H,
OCH2CHeqH), 1.59–1.70 (m, 1H, OCH2CHHax), 3.05–3.14 (m, 2H,
2xOCHaxH), 3.58–3.71 (m, 2H, 2xOCHHeq), 4.68–4.83 (m, 2H,
H
Ar) ppm; 13C NMR (C6D6, 125 MHz): δ = 26.6, 55.5, 57.3, 67.9, 68.0,
80.9, 100.7, 101.9, 108.0, 108.9, 114.7, 129.1, 129.4 (2C), 132.6,
135.7, 136.0, 148.2, 149.5, 160.1 ppm; Anal. Calcd for C20H22O6: C,
67.03; H, 6.19; Found: C, 67.02; H, 6.14; HRMS (EI, 70 eV): m/z [M]+
Calcd for C20H22O6: 358.1416; Found: 358.1419; MS (EI, 70 eV): m/z
(%): 358 [M+, 41], 299 [M+, eOCH2CH2CH2O, 100], 177 [M+
eC6H4OMe, eOCH2CH2CH2O, 36].
,
6

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
2.3.27. 3-(Benzyloxy(thianthren-1-yl)methyl)-2-(1,3-dioxan)-2-yl)-1-
methylindole (4ee(Bn))
2.3.31. 1,2,3-Trimethoxy-10-(4-trifluoromethyl)benzyloxy)anthracene
(5aa(Bnp-CF3))
Yield: 33%, white solid, m.p. 92–93 °C; 1H NMR (C6D6, 200 MHz):
δ = 0.50–0.55 (m, 1H, OCH2CHeqH), 1.70–1.81 (m, 1H, OCH2CHHax),
3.18–3.25 (m, 2H, 2xOCHaxH), 3.70–3.78 (m, 2H, 2xOCHHeq), 3.88 (s,
3H, NCH3), 4.72–4.94 (m, 2H, OCH2), 6.18 (s, 1H, OCHO), 6.68 (s, 1H,
Yield: 68%; orange oil; 1H NMR (C6D6, 500 MHz): δ = 3.42 (s, 3H,
OCH3), 3.89 (s, 3H, OCH3), 4.01 (s, 3H, OCH3), 4.92 (s, 2H, OCH2),
7.23 (s, 1H, HAr), 7.29–7.31 (m, 3H, 3xHAr), 7.35–7.41 (m, 1H, HAr),
7.45 (d, 2H, 3JH-H = 5.0 Hz, 2xHAr), 7.98 (d, 1H, 3JH-H = 10.0 Hz, HAr),
3
3
CHO), 6.71 (t, 1H, JH-H = 10.0 Hz, HAr), 6.78–6.88 (m, 2H, 2xHAr),
8.34 (d, 1H, JH-H = 10.0 Hz, HAr), 8.80 (s, 1H, HAr) ppm; 13C NMR
3
7.06–7.27 (m, 9H, 9xHAr), 7.40–7.44 (m, 2H, 2xHAr), 7.55 (d, 1H, JH-
(C6D6, 125 MHz): δ = 55.8, 61.7, 61.9, 76.4, 96.3, 118.2, 122.8, 123.8,
3
2
H = 10.0 Hz, HAr), 7.72 (d, 1H, JH-H = 10.0 Hz, HAr) ppm; 13C NMR
125.9, 126.0, 126.5, 126.5 (q, JC-F = 3.7 Hz), 126.6, 126.9, 127.7 (q,
(C6D6, 50 MHz): δ = 26.7, 32.5, 68.2, 68.2, 71.7, 76.4, 97.7, 110.6,
111,4, 121.0, 121.3, 123.8, 127.8, 128.2, 128.3, 128.5, 128.6, 128.8,
129.1 (2C), 129.5, 129.5, 129.6, 129.8, 135.5, 136.5, 137.3, 138.1,
138.8, 138.9, 139.7, 142.7 ppm; Anal. Calcd for C33H29NO3S2: C, 71.84;
H, 5.30; N, 2.54; S, 11.62; Found: C, 71.33; H, 5.57; N, 2.49; S, 11.35;
HRMS (EI, 70 eV): m/z [M]+ Calcd for C33H29NO3S2: 551.1589; Found:
1JC-F = 270.0 Hz), 128.5 (2C), 130.2, 131.1, 132.5, 142.3, 143.2, 149.0,
150.9, 155.0; Anal. Calcd for C25H21F3O4: C, 67.87; H, 4.78; Found: C,
67.68; H, 4.85; HRMS (EI, 70 eV): m/z [M]+ Calcd for C25H21F3O4:
442.1392; Found: 442.1393; MS (EI, 70 eV): m/z (%) 442 [M+, 100],
411 [M+, eOMe, 39], 283 [M+, eOCH2C6H4CF3, 74].
551.1593; MS (EI, 70 eV): m/z (%): 551 [M+, 100], 460 [M+
,
,
2.3.32. 10-(Benzyloxy)-1,3-dimethoxyanthracene (5ab(Bn))
eCH2C5H6, 41], 445 [M+
,
eCH3, eCH2C5H6, 83], 386 [M+
Yield: 67%, yellow oil; 1H NMR (C6D6, 500 MHz): δ = 3.38 (s, 3H,
OCH3), 3.42 (s, 3H, OCH3), 5.00 (s, 2H, OCH2), 6.41 (s, 1H, HAr),
7.08–7.13 (m, 2H, 2xHAr), 7.17–7.21 (m, 3H, 3xHAr), 7.25–7.30 (m, 1H,
eOCH2CH2CH2O, eCH2C5H6, 42].
3
3
HAr), 7.45 (d, 2H, JH-H = 10,0 Hz, 2xHAr), 7.89 (d, 1H, JH-H = 10,0
2.3.28. 3-(Benzyloxy(3,4,5-trimethoxyphenyl)methyl)-2-(1,3-dioxan-2-
Hz, HAr), 8.37 (d, 1H, 3JH-H = 10,0 Hz, HAr), 8.83 (s, 1H, HAr) ppm; 13
C
yl)-1-methyl-1H-indole (4ea(Bn))
Yield: 41%; yellow solid, m.p. 53–54 °C; 1H NMR (C6D6, 200 MHz):
δ = 0.64–0.73 (m, 1H, OCH2CHeqH), 1.70–1.97 (m, 1H, OCH2CHHax),
3.32–3.52 (m, 2H, 2xOCHaxH), 3.50 (s, 6H, 2xOCH3), 3.80–3.92 88 (m,
2H, 2xOCHHeq), 3.86 (s, 3H, CH3), 3.90 (s, 3H, OCH3), 4.57–4.87 (m,
2H, OCH2), 6.07 (s, 1H, OCHO), 6.26 (s, 1H, CHO), 7.14 (s, 2H, 2xHAr),
7.05–7.22 (m, 6H, 6xHAr), 7.39 (d, 2H, 3JH-H = 2.0 Hz, 2xHAr), 8.06 (d,
3JH-H = 8.0 Hz, HAr) ppm; 13C NMR (C6D6, 50 MHz): δ = 24.5, 30.0,
54.2 (2C), 59.0, 66.0, 66.1, 68.9, 74.0, 95.6, 103.7 (2C), 108.4, 112.0,
118.7, 119.6, 121.6, 125.0, 126.1, 126.9 (2C), 127.1 (2C), 132.6 (2C),
136.8, 137.1, 138.0, 152.5 (2C) ppm; Anal. Calcd for C30H33NO6: C,
71.55; H, 6.61; N, 2.78; Found: C, 71.63; H, 6.59; N, 2.84; HRMS (EI,
70 eV): m/z [M]+ calcd for C30H33NO6: 503.2308; found: 503.1203; MS
(EI, 70 eV): m/z (%) 503 [M+, 78], 396 [M+, OCH2C6H5, 100], 336 [M
+, eCH2C6H5, eHOCH2CH2CH2OH, 98].
NMR (C6D6, 125 MHz): δ = 55.5, 55.8, 77.3, 92.1, 98.9, 118.7, 123.0,
124.4, 125.4, 126.8, 127.1, 127.6, 128.6 (2C), 128.8, 129.5 (2C),
130.3, 131.8, 139.3, 150.7, 158.1, 159.2 ppm; Anal. Calcd for
C
23H20O3: C, 80.21; H, 5.85; Found: C, 80.15; H, 6.02; HRMS (EI,
70 eV): m/z [M]+ Calcd for C23H20O3: 344.1412; Found: 344.1405; MS
(EI, 70 eV): m/z (%) 344 [M+, 5], 253 [M+, eCH2C6H5, 100].
2.3.33. 6-(Benzyloxy)benzo[d]naphtho[2,3-b]thiophene (5ac(Bn))
Yield: 9%; orange powder, m.p. 109–110 °C, 1H NMR (C6D6,
500 MHz): δ = 5.09 (s, 2H, OCH2), 7.06–7.18 (m, 5H, 5xHAr),
3
7.26–7.30 (m, 2H, 2xHAr), 7.40 (d, 1H, JH-H = 5.0 Hz, HAr), 7.44 (d,
3
2H, 2xHAr), 7.79–7.82 (m, 1H, HAr), 7.86 (d, 1H, JH-H = 5.0 Hz, HAr),
8.13 (s, 1H, HAr), 8.27–8.31 (m, 1H, HAr) ppm; 13C NMR (C6D6,
125 MHz): δ = 75.8, 117.2, 122.5, 123.2, 123.8, 125.4, 126.4, 126.7,
127.9, 128.6, 129.0, 129.0 (2C), 129.1, 129.5, 129.5, 129.8, 134.0,
136.8, 137.5, 138.5, 141.2, 150.3 ppm; HRMS (EI, 70 eV): m/z [M]+
Calcd for C23H16OS: 340.0922; Found: 340.0913; MS (EI, 70 eV): m/z
(%): 340 [M+, 62], 250 [M+, 100], 221 [M+, 90].
2.3.29. 2-(3-(Methoxy(thien-2-yl)methyl)benzo[b]thien-2-yl)-1,3-dioxan
(4fk(Me))
Yield: 93%; light yellow oil; 1H NMR (C6D6, 500 MHz):
δ = 0.52–0.57 (m, 1H, OCH2CHeqH), 1.74–1.86 (m, 1H, OCH2CHHax),
3.25 (s, 3H, OCH3), 3.28–3.38 (m, 2H, 2xOCHaxH), 3.74–3.79 (m, 2H,
2xOCHHeq), 5.85 (s, 1H, OCHO), 6.20 (s, 1H, CHO), 6.60–6.63 (m, 1H,
2.3.34. 11-Methoxy-5-methyl-5H-benzo[b]carbazole (5ad(Me))
Yield: 69%; yellow crystals, m.p. 116–117 °C; 1H NMR (C6D6,
500 MHz): δ = 3.47 (s, 3H, OCH3), 3.48 (s, 3H, NCH3), 6.88 (d, 1H, 3JH-
H = 10.0 Hz, HAr), 7.14 (t, 1H, 3JH-H = 10.0 Hz, HAr), 7.28 (dt, 1H, 3JH-
3
HAr), 6.77–6.80 (m, 1H, HAr), 6.88 (d, 1H, JH-H = 5.0 Hz, HAr),
3
H = 10.0 Hz, JH-H = 10.0 Hz, HAr), 7.34 (dd, 1H, 3JH-H = 10.0 Hz, 3JH-
6.95–7.06 (m, 2H, 2xHAr), 7.47 (d, 1H, JH-H = 10.0 Hz, HAr), 8.17 (d,
3
3
1H, JH-H = 10.0 Hz, HAr), 13C NMR (C6D6, 125 MHz): δ = 26.1, 57.4,
H = 10.0 Hz, HAr), 7.40 (dt, 1H, 3JH-H = 10.0 Hz, 3JH-H = 10.0 Hz, HAr),
67.8, 67.8, 77.1, 98.3, 123.4, 125.0, 125.7, 125.8, 125.9, 127.6, 129.0,
133.0, 139.2, 140.6, 142.0, 146.3 ppm; Anal. Calcd for C18H18O3S2: C,
62.40; H, 5.24; S, 18.51; Found: C, 62.51; H, 5.22; S, 18.30; HRMS (EI,
70 eV): m/z [M]+ Calcd for C18H18O3S2: 346.0697; Found: 346.0706;
3
3
7.87 (d, 1H, JH-H = 10.0 Hz, HAr), 7.97 (d, 1H, JH-H = 10.0 Hz, HAr),
8.10 (s, 1H, HAr), 8.29 (d, 1H, JH-H = 10.0 Hz, HAr) ppm; 13C NMR
3
(CDCl3, 125 MHz): δ = 31.1, 63.1, 108.2, 114.6, 119.0, 120.5, 120.7,
122.8, 123.0, 124.8, 126.7, 127.1, 127.4, 128.5, 128.9, 131.5, 138.5,
144.1 ppm; Anal. Calcd for C18H25NO: C, 82.73; H, 5.79; N, 5.36; Found
C, 80.81; H, 5.86; N, 5.39; HRMS (EI, 70 eV): m/z [M]+ Calcd for
C18H25NO: 261.1154; Found: 261.1159; MS (EI, 70 eV): m/z (%) 261
[M+, 100], 246 [M+, eCH3, 100].
MS (EI, 70 eV): m/z (%) 346 [M+, 70], 331 [M+, eCH3, 13], 287 [M+
eHOCH2CH2CH2, 100], 270 [M+, eHOCH2CH2CH2OH, 50], 227 [M+
eCHOCH2CH2CH2OH, 60], 189 [M+, 51].
,
,
2.3.30. 10-(Benzyloxy)-1,2,3-trimethoxyanthracene (5aa(Bn))
Yield: 67%; orange oil; 1H NMR (CDCl3, 500 MHz): δ = 3.98 (s, 3H,
OCH3), 4.11 (s, 3H, OCH3), 4.23 (s, 3H, OCH3), 5.29 (s, 2H, OCH2),
7.33 (s, 1H, HAr), 7.45–7.52 (m, 2H, 2xHAr), 7.50–7.57 (m, 3H, 3xHAr),
2.3.35. 5-Methyl-11-(naphth-2-ylmethoxy)-5H-benzo[b]carbazole (5ad
(Naphth))
Yield: 38%; Red oil; 1H NMR (C6D6, 200 MHz): δ = 3.50 (s, 3H,
3
3
3
7.70 (d, 2H, JH-H = 10.0 Hz, 2xHAr), 8.10 (d, 1H, JH-H = 10.0 Hz,
CH3), 4.92 (s, 2H, OCH2), 6.89 (d, 1H, JH-H = 10.0 Hz, HAr), 7.20 (t,
3
3
3
H
Ar), 8.36 (d, 1H, JH-H = 10.0 Hz, HAr), 8.53 (s, 1H, HAr) ppm; 13C
1H, JH-H = 10.0 Hz, HAr), 7.22–7.29 (m, 2H, 2xHAr), 7.32 (t, 1H, JH-
NMR (CDCl3, 125 MHz): δ = 55.8, 61.3, 61.5, 77.4, 95.6, 116.5, 122.0,
122.6, 124.8, 124.8, 125.3, 125.4, 128.1 (2C), 128.3 (2C), 128.8,
128.9, 131.2, 137.8, 140.9, 147.4, 149.7, 153.1 ppm; Anal. Calcd for
H = 10.0 Hz, HAr), 7.35–7.44 (m, 3H, 3xHAr), 7.60–7.67 (m, 3H,
3
3xHAr), 7.89 (s, 1H, HAr), 7.95 (d, 1H, JH-H = 10.0 Hz, HAr), 8.05 (d,
3
3
1H, JH-H = 10.0 Hz, HAr), 8.21 (s, 1H, HAr), 8.45 (d, 1H, JH-
H = 10.0 Hz, HAr) ppm; 13C NMR (C6D6, 125 MHz): δ = 32.5, 78.6,
110.1, 116.9, 121.0, 122.7, 124.8, 125.0, 126.9, 127.0, 127.8 (2C),
127.8, 128.1, 129.0, 129.1, 129.2, 129.6, 129.9, 130.2, 130.7, 131.2,
C
24H22O4: C, 76.99; H, 5.92; Found: C, 76.78; H, 5.95; HRMS (EI,
70 eV): m/z [M]+ calcd for C24H22O4: 374.1518; Found: 374.1516; MS
(EI, 70 eV): m/z (%) 374 [M+, 6], 283 [M+, eC7H7, 100].
7

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
133.9, 135.1, 135.5, 137.0, 139.2, 146.2 ppm; Anal. Calcd for
2.3.40. 6-(Methoxy(naphth-2-yl)methyl)benzo[d][1,3]dioxole-5-
C
28H21NO: C, 85.43; H, 5.68; N, 4.15; Found: C, 85.48; H, 5.72; N, 3.95;
carbaldehyde (6ch(Me))
HRMS (EI, 70 eV): m/z [M]+ Calcd for C28H21NO: 387.1523; Found:
387.1626; MS (EI, 70 eV): m/z (%) 387 [M+, 25], 246 [M+,
eCH2C10H7, 100].
Yield: 61%, colorless oil; 1H NMR (C6D6, 200 MHz): δ = 3.17 (s, 3H,
OMe), 5.12–5.18 (m, 2H, OCH2O), 6.29 (s, 1H, CHOMe), 7.20 (s, 1H,
H
Ar), 7.24–7.28 (m, 2H, 2xHAr), 7.30 (s, 1H, HAr), 7.52–7.55 (m, 1H,
HAr), 7.59–7.68 (m, 3H, 3xHAr), 8.01 (s, 1H, HAr), 10.09 (s, 1H, CHO)
ppm; 13C NMR (C6D6, 125 MHz): δ = 57.3, 80.9, 102.6, 109.0, 111.1,
126.0, 126.9, 127.1, 127.2, 128.7, 129.2, 129.3, 129.7, 134.1, 134.5,
140.0, 142.4, 148.5, 153.2, 190.0 ppm; Anal. Calcd for C20H16O4: C,
74.99; H, 5.03; Found C, 74.81; H, 4.97; HRMS (EI, 70 eV): m/z [M]+
Calcd for C20H16O4: 320.1049; Found: 320.1051; MS (EI, 70 eV): m/z
(%) 320 [M+, 100], 305 [M+, eCH3, 38], 289 [M+, eOCH3, 56], 177
[M+, eC10H8, eCH3, 88].
2.3.36. 5,8-Dimethoxyanthra[2,3-d][1,3]dioxole (5bg(Me))
Yield: 72%, yellow crystals, m.p. 124–123 °C; 1H NMR (C6D6,
500 MHz): δ = 3.43 (s, 3H, OCH3), 3.67 (s, 3H, OCH3), 5.22 (s, 2H,
3
3
OCH2O), 7.02 (s, 1H, HAr), 7.16 (dd, 1H, JH-H = 5,00 Hz, JH-
3
H = 10,00 Hz, HAr), 7.42 (d, 1H, JH-H = 10,00 Hz, HAr), 7.56 (d, 1H,
3JH-H = 5,00 Hz, HAr), 7.62 (s, 2H, 2xHAr) ppm; 13C NMR (C6D6,
125 MHz): δ = 55.4, 62.0, 98.1, 99.1, 101,7, 104.1, 120.8, 122.2,
123.9, 126.0, 129.5, 129.9, 130.9, 148.5, 149.4, 151.2, 158.3 ppm;
Anal. Calcd for C17H14O4: C, 72.33; H, 5.00; Found: C, 72.08; H, 5.09;
HRMS (EI, 70 eV): m/z [M]+ Calcd for C17H14O4: 282.0892; Found:
282.0899; MS (EI, 70 eV): m/z (%) 282 [M+, 40], 267 [M+, eCH3,
100].
2.3.41. 6-(Naphth-2-yl)(naphth-2-ylmethoxy)methyl)benzo[d][1,3]
dioxole-5-carbaldehyde (6hd(Naphth))
Yield: 42%, yellow oil; 1H NMR (C6D6, 200 MHz): δ = 4.55–4.71
(m, 2H, OCH2), 5.17–5.24 (m, 2H, OCH2O), 6.88 (s, 1H, HC-O),
7.25–7.34 (m, 5H, 5xHAr), 7.44 (s, 1H, HAr), 7.45–7.52 (m, 1H, HAr),
7.60–7.75 (m, 8H, 8xHAr), 8.13 (s, 1H, HAr), 10.15 (s, 1H, CHO) ppm;
1H NMR (C6D6, 500 MHz): δ = 4.46–4.56 (m, 2H, OCH2), 5.05–5.12
(m, 2H, OCH2O), 6.56 (s, 1H, HC-O), 7.10 (s, 1H, HAr), 7.13–7.22 (m,
2.3.37. 5-Methoxy-6-methyl-6H-[1,3]benzodioxolo[3,2-b]carbazole (5 cd
(Me))
3
4
4H, 4xHAr), 7.31 (s, 1H, HAr), 7.36 (dd, 1H, JH-H = 10,0 Hz, JH-
H = 5,0 Hz, HAr), 7.50–7.59 (m, 7H, 7xHAr), 7.62 (s, 1H, HAr), 8.00 (s,
1H, HAr), 10.02 (s, 1H, HAr) ppm; 13C NMR (C6D6, 50 MHz): δ = 72.0,
78.8, 102.7, 109.3, 111.1, 126.1, 126.9 (2C), 127.0, 127.0, 127.2,
127.3, 127.6 (2C), 128.7, 129.0, 129.2, 129.4 (2C), 129.7, 134.1,
134.2, 134.5, 134.5, 136.7, 140.2, 142.4, 148.6, 153.3, 190.2 ppm;
Anal. Calcd for C30H22O4: C, 80.70; H, 4.97; Found C, 80.49; H, 5.06;
HRMS (EI, 70 eV): m/z [M]+ calcd for C30H22O4: 446.1518; found:
446.1499; MS (EI, 70 eV): m/z (%) 305 [M+, eCH2C10H7, 100], 177
[M+, eCH2C10H7, eC10H7, eH, 100].
Yield: 53%, orange solid; mp 183–184 °C (from MeOH); 1H NMR
(C6D6, 500 MHz): δ = 3.51 (s, 3H, OMe), 3.60 (s, 3H, NMe), 5.38 (s, 2H,
3
OCH2O), 7.03 (d, 1H, JH-H = 8.1 Hz, HAr), 7.23–26 (m, 1H, HAr), 7.22
(s, 1H, HAr), 7.42–7.45 (m, 1H, HAr), 7.75 (s, 1H, HAr), 8.03 (s, 1H, HAr),
3
8.07 (d, 1H, JH-H = 7.7 Hz, HAr); 1H, HAr), 7.21–7.25 (m, 2H, 2xHAr),
7.36 (s, 1H, HAr), 7.71 (d, 1H, J = 7.1 Hz, HAr) ppm; 13C NMR (C6D6,
125 MHz): δ = 31.4, 62.8, 98.1, 101.6, 105.2, 109.2, 114.9, 119.9,
121.5, 124.3, 125.3, 126.8, 127.1, 127.6, 132.1, 140.0, 144.7, 147.1,
148.9 ppm; Anal. Calcd for C19H15NO3: C, 74.74; H, 4.95; N, 4.59;
Found: C, 74.61; H, 5.08; N, 4.72; HRMS (EI, 70 eV): m/z (%) Calcd for:
C
19H15NO3 305.1052; Found: 305.1051; MS (EI) m/z (%): 305 [M+1
,
2.3.42. 6-(Methoxy(phenyl)methyl)benzo[d][1,3]dioxole-5-carbaldehyde
(6ci(Me))
57], 290 [M+1, eMe, 100].
Yield: 64%; light yellow oil; 1H NMR (C6D6, 500 MHz): δ = 3.01 (s,
3H, OCH3), 5.02–5.08 (m, 2H, OCH2O), 6.00 (s, 1H, CHOCH3), 6.97 (t,
1H, 3JH-H = 5.0 Hz, HAr), 7.03–7.08 (t, 2H, 3JH-H = 5.0 Hz, 2xHAr), 7.08
2.3.38. 2-(Benzyloxy(thianthren-2-yl)methyl)benzaldehyde (6ae(Bn))
Yield: 65%; colorless oil; 1H NMR (C6D6, 500 MHz): δ = 4.43–4.61
(m, 2H, OCH2), 6.68–6.75 (m, 3H, 3xHAr), 6.88–6.97 (m, 2H, 2xHAr),
6.98 (s, 1H, HAr), 7.02 (d, 1H, 3JH-H = 10.0 Hz, HAr), 7.05–7.10 (m, 2H,
2xHAr), 7.14–7.18 (m, 1H, HAr), 7.18–7.23 (m, 1H, HAr), 7.25 (d, 2H,
3
(s, 1H, HAr), 7.12 (s, 1H, HAr), 7.33 (d, 2H, JH-H = 10.0 Hz, 2xHAr),
9.94 (s, 1H, CHO); 13C NMR (C6D6, 125 MHz): δ = 56.9, 80.5, 102.2,
108.5, 110.7, 127.8 (2C), 128.7, 129.0 (2C), 129.3, 142.3, 142.4,
148.1, 152.9, 189.6 ppm; Anal. Calcd for C16H14O4: C, 71.10; H, 5.22;
Found: C, 71.08; H, 5.19; HRMS (EI, 70 eV): m/z [M]+ Calcd for
3
3JH-H = 10.0 Hz, 2xHAr), 7.31 (d, 1H, JH-H = 10.0 Hz, HAr), 7.55 (dd,
1H, 3JH-H = 10.0 Hz, 4JH-H = 5.0 Hz, HAr), 10.13 (s, 1H, CHO) ppm; 13
C
C
16H14O4: 270.0892; Found: 270.0890; MS (EI, 70 eV): m/z (%) 270
NMR (C6D6, 125 MHz): δ = 71.5, 77.0, 126.7, 127.1, 127.6 (2C), 127.8
(2C), 128.1, 128.3 (2C), 128.5, 128.5, 128.7, 129.0, 131.9, 133.3 (2C),
134.7, 135.3, 136.6, 136.7, 136.8, 138.0, 140.8, 141.6, 191.2 ppm;
Anal. Calcd for C27H20O2S2: C, 73.61; H, 4.58; S, 14.56; Found: C,
73.35; H, 4.52; S, 14.31; HRMS (EI, 70 eV): m/z [M]+ Calcd for
[M+, 83], 255 [M+, eCH3, 100], 238 [M+, eCH3OH, 60], 177 [M+
eC6H6, eCH3, 62].
,
2.3.43. 3-(Methoxy(thien-2-yl)methyl)benzo[b]thiophene-2-carbaldehyde
(6fk(Me))
C
27H20O2S2: 440.0905; Found: 440.0897; MS (EI, 70 eV): m/z (%) 440
Yield: 56%;white solid, 95–96 °C; 1H NMR (C6D6, 500 MHz):
δ = 2.89 (s, 3H, OCH3), 5.93 (s, 1H, CHOCH3), 6.45–6.47 (m, 2H,
2xHAr), 6.71–6.74 (m, 1H, HAr), 6.87–6.90 (m, 2H, 2xHAr), 7.20–7.24
(m, 1H, HAr), 7.81–7.85 (m, 1H, HAr), 10.41 (s, 1H, CHO) ppm; 13C
NMR (C6D6, 125 MHz): δ = 56.4, 75.9, 123.0, 124.7, 125.4, 125.6,
125.7, 126.6, 128.0, 138.0, 140.7, 142.1, 143.0, 144.0, 184.0 ppm;
Anal. Calcd for C15H12O2S2: C, 62.47; H, 4.19; S, 22.24; Found: C,
62.19; H, 4.05; S, 22.17; HRMS (EI, 70 eV): m/z [M]+ Calcd for
[M+, 66], 349 [M+, CH2C6H5, 74].
2.3.39. 6-((4-Bromophenyl)(butoxy)methyl)benzo[d][1,3]dioxole-5-
carbaldehyde (6bf(Bu))
Yield: 75%; yellow oil; 1H NMR (C6D6, 500 MHz): δ = 0.75 (t, 3H,
3
3JH-H = 7.5 Hz, CH3), 1.17–1.26 (sextet, 2H, JH-H = 7.0 Hz, CH2CH3),
3
1.35–1.42 (q, 2H, JH-H = 6.3 Hz, CH2CH2CH3), 3.10–3.21 (m, 2H,
CH2CH2CH2CH3), 5.04–5.08 (m, 2H, OCH2O), 6.07 (s, 1H, CHOCH2),
C15H12O2S2: 288.0279; Found: 288.0281; MS (EI, 70 eV): m/z (%) 288
3
7.00 (s, 1H, HAr), 7.07 (d, 2H, JH-H = 10.0 Hz, 2xHAr), 7.08 (s, 1H,
[M+, 82], 256 [M+, eHOCH3, 23], 227 [M+, eOCH3, eH2CO, 36],
189 [M+, eC4H4S, 100].
H
Ar), 7.19 (d, 2H, 3JH-H = 10.0 Hz, 2xHAr), 9.83 (s, 1H, CHO) ppm; 13
C
NMR (C6D6, 50 MHz): δ = 14.7, 20.4, 32.9, 69.7, 78.5, 102.6, 108.8,
111.6, 122.4, 129.4, 129.8 (2C), 132.4 (2C), 142.2, 142.4, 148.4,
153.2, 190.1 ppm; Anal. Calcd for C19H19BrO4: C, 58.33; H, 4.89;
Found: C, 58.41; H, 4.98; HRMS (EI, 70 eV): m/z [M]+ Calcd for
3. Results and discussion
o-Acetalaryl(aryl)methyl ethers 4, the key intermediates in the oxo-
variant of the Friedel-Crafts/Bradsher reaction leading to RO-sub-
stituted (hetero)acenes 5, were obtained, in good to excellent yields,
C
19H19BrO4: 390.0467; Found: 390.0462; MS (EI, 70 eV): m/z (%) 390
[M+, 10], 332 [M+, -C4H10, 100], 176 [M+, eC4H10, eC5H5Br, 50].
8

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
Table 1
Synthesis of o-acetalaryl(aryl)methanols 3 and the corresponding ethers 4.
Entry Aromatic o-bromo acetal 1 Aromatic aldehyde 2 o-Acetal aryl(aryl)methanol 3 Yield (%)a Alkyl, aryl halide (R1X) o-Acetalaryl(aryl)methyl ether 4 Yield (%)a
1
67
83
68
2
65
67
3
4
87
74
92
95
MeI
67
73
5
62
6
7
72
75
51
92
MeI
(continued on next page)
9

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
Table 1 (continued)
Entry Aromatic o-bromo acetal 1 Aromatic aldehyde 2 o-Acetal aryl(aryl)methanol 3 Yield (%)a Alkyl, aryl halide (R1X) o-Acetalaryl(aryl)methyl ether 4 Yield (%)a
8
63
MeI
94
66
90
9
62
MeI
10
98 [26,28] MeI
99 [26,28]
11
12
13
90
MeI
MeI
88
67
89
63 [28]
69 [28]
14
15
—
—
33b
41b
16
65
MeI
93
a
b
Yields of isolated products.
Yields of isolated products after two steps.
10

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
Table 2
Optimization
of
ultrasound-assisted
cyclization
of
4 cd(Me)
in
various
solvents
at
different
HClaq
concentrations.
)))
O
Me O
O
1 N, 3.4 N or 6.8 N HClaq
Me
N
25oC
t = 30s
solvent
N
Me
O
Me
4cd(Me)
5cd(Me)
Entry Solvent
Concentration/equiv. of
HClaq
Yield (%)a Entry Concentration/ equiv. of
HClaq
Yield (%)a Entry Concentration/ equiv. of
HClaq
Yield (%)a
1
2
3
4
5
6
Methanol
1.0 N/25 equiv. of HClaq
21
23
0
7
3.4 N/85 equiv. of HClaq
67
95
5
13
14
15
16
17
18
6.8 N/145 equiv. of HClaq
49
95
58
33
37
95
Acetone
8
Benzene
9
Dichloromethane
0
10
11
12
0
1,2-dichloro-ethane
Acetonitrile
0
0
45
95
a
Based on the 1H NMR spectra.
according to the procedure elaborated earlier in our lab [17–25]. The
procedure included: i) Br/Li exchange with n-BuLi in aromatic acetals 1
followed by condensation of the resulting aryllithiums with aromatic
aldehydes 2, and ii) protection of hydroxyl group in the resulting o-
acetalaryl(aryl)methanols 3 with alkyl or benzyl halides in order to
prevent formation of reactive izobenzofurans. Thus, ethers 4 containing
o-acetalaryl Ar(I) and aryl Ar(II) moieties were obtained as a simple
combination of two aromatic aldehydes units (Table1). The inter-
mediates 3 were obtained in 62–90% yields. The derivatives 3ee and
3ea, due to their high instability during purification, were immediately
converted to 4ee(Bn) and 4ea(Bn) in 33% and 41% yields, respec-
tively, upon two steps from 1.
Table 3
Optimization of ultrasound-assisted cyclization of 4bg(Me) in the presence of
various acidic reagents.
Entry Acidic
reagent
Temperature [°C] Time [min] Yield (%)a Equivalents
of acid
Having o-acetalaryl(aryl)methyl ethers 4 in hand, we carried out
optimization of the Friedel-Crafts/Bradsher reaction conditions. First,
optimization of solvent was made using 4 cd(Me) as a substrate
(Table 2). The ultrasound-assisted cyclization (25 °C, 30 s) performed In
aqueous solution of 1 N HCl in MeOH or acetone, gave the desired
product 5 cd(Me) in only 21 and 23% yield, respectively (Table 2, entry
1 and 2 for 1 N HCl). The best, 45% yield of 5 cd(Me) was achieved
using 1 N HClaq in acetonitrile (Table 2, entry 6 for 1 N HCl). Appli-
cation of higher concentrations of HCl, i.e. 3.4 and 6.8 N, was more
effective for all the solvents used. Even for water-immiscible solvents:
benzene, dichloromethane and 1,2-dichloroethane, the yields of 5 cd
(Me) increased up to 58%, at the highest concentration of HCl
(Table 2). However, the highest yields of 5 cd(Me) (95%), were gained
in water miscible solvents: acetone and acetonitrile (Table 2, entry 12,
14 and 18 for 3.4 N and 6.8 N HCl). In all experiments presented in
Table 2, ultrasounds pulses were generated every 2 s at room tem-
perature, at the amplitude of 26.3 μm (35%), within 30 s.
1
2
3.4 N HClaq
25
60 min
20 min
60 min
60 min
60 min
2 min
10
83
21
31
74
99
95
68
99
44
65
3.4 N HClaq
6.8 N HClaq
6.8 N HClaq
6.8 N HClaq
6.8 N HClaq
6.8 N HClaq
6.8 N HBraq
6.8 N HBraq
3.4 N
50–55
25
65
3
145
220
290
290
145
145
145
65
4
25
5
25
6
50–55
50–55
25
7
10 min
60 min
2 min
8
9
50–55
50–55
10
60 min
H2SO4aq
11
12
6.8 N
25
45 min
2 min
82
99
145
145
H2SO4aq
6.8 N
50–55
H2SO4aq
14
15
CH3COOH
50–55
50–55
60 min
60 min
0
0
375
–
Amberlite®
IR120
16
Amberlyst®
15
50–55
60 min
0
–
Next, optimization of acidic reagent was carried out, using o-acet-
alaryl(aryl)methyl ether 4bg(Me) as a substrate. Aqueous solutions of
strong mineral acids (preferably HCl, HBr or H2SO4) were most effec-
tive among various acidic reagents, including Lewis acids, organic
carboxylic acids and acidic ion-exchange resins. The use of aqueous
solutions of hydrochloric acid in acetonitrile (290 equivalents of 6.8 N
HCl) at 50–55 °C, gave the best results and the desired acene 5bg(Me)
was obtained in 99% yield after 2 min. (Table 3, entry 6). Other strong
mineral acids, HBr and H2SO4, gave similar results as HCl using even
smaller amounts of the acid (Table 3, entry 9 and 12). Weaker acidic
reagents, such as CH3COOH, Cu(OTf)2 and Zn(OTf)2, gave the un-
reacted substrate only. Application of other Lewis acids or acidic ion-
exchange resins afforded mixtures of unidentified products (Table 3,
entries 15, 16, 18–20). In all experiments (Table 3) ultrasounds pulses
were generated every 2 s at room temperature, at the amplitude of
26.3 μm (35%).
17
18
19
20
p-TsOH
50–55
5 min
0
0
0
0
1
1
1
1
FeCl3
25
5 min
SnCl2·2H2O
50–55
10 min
BiBr3
50–55
10 min
21
Cu(OTf)2
Zn(OTf)2
50–55
50–55
10 min
10 min
0
1
22
0
1
a
Based on the 1H NMR spectra.
and the room temperature or 50–60 °C were applied as the general ones
for the ultrasounds assisted oxo-Friedel-Crafts/Bradsher cyclisation of
o-acetalaryl(aryl)methyl ethers 4 to (hetero)acene systems 5. The yields
of the obtained crude 5 ranged from 94% to quantitative (Table 4).
Only in case of less stable substrates under acidic conditions, 4ad
(Naphth) and 4ac(Bn), the yields of the corresponding products 5ad
Then, the optimized reaction conditions (6.8 N HClaq in acetonitrile)
11

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
Table 4
Ultrasound-assisted cyclization of ethers 4 to (hetero)acenes 5 using the optimized reaction conditions.
Entry
1
o-Acetalaryl(aryl)methyl ether 4
Time [min]
5 min
Temperature[°C]
50–60
Equiv. of 6.8 N HCl
145
(Hetero)acene 5
Yield of 5 (%)a/(%)b
96/67
OMe
OMe
OMe
O
5aa(Bn)
Ph
2
5 min
50–60
25
145
145
290
290
quant./68
93/62
10 min
< 1 min
5 min
50–60
25
quant./70
91/66
3
4
< 1 min
< 1 min
1 min
25
25
25
25
290
145
40
quant./72
quant./67
quant./65
quant./65
2 min
20
2 min
50–60
145
—/9
5
6
< 1 min
< 1 min
5 min
25
145
85
95/63
25
95/71
25
20
quant./69
quant./65
1 min
50–60
20
3 min
50–60
20
—/38
Naphth
O
O
O
Me
N
Me
N
O
5ad(Naphth)
Naphth
4ad(Naphth)
7
8
9
2 min
50–60
25
290
290
145
145
quant./72
81/58
15 min
10 min
40 min
O
Me O
50–60
25
95/61
O
OMe
75/51
O
O
4bg(Me)
2 min
50–60
25
145
290
290
quant./73
81/58
< 1 min
< 1 min
50–60
quant./90
< 1 min
25
290
95/53
(continued on next page)
12

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
Table 4 (continued)
Entry
10
o-Acetalaryl(aryl)methyl ether 4
Time [min]
Temperature[°C]
Equiv. of 6.8 N HCl
(Hetero)acene 5
Yield of 5 (%)a/(%)b
30 min
5 min
25
290
145
145
87/62
94/71
79/52
50–60
25
60 min
a
b
Based on the 1H NMR spectra.
Isolated yields.
Table 5
A comparison of the results of cyclizations of 4 under silent and ultrasound conditions.
Entry
o-Acetal aryl(aryl)methyl ether 4
Equiv. of HCl
Temperature [°C]
(Hetero)acene 5
Ultrasonic irradiation)))
Silent conditions
Time [s, min, h]
Yield (%)a
Time [s, min, h]
Yield (%)a
1
2
4ad(Me)
4ad(Me)
85
20
25
25
5ad(Me)
5ad(Me)
< 1min
5 min
95
1 min
1.5 h
95
89
quant.
3
4
5
6
4bg(Me)
4bg(Me)
4bg(Me)
4bg(Me)
290
290
145
145
25
5bg(Me)
5bg(Me)
5bg(Me)
5bg(Me)
15 min
81
6 h
85
50–60
25
2 min
quant.
75
10 min
10 h
1 h
quant.
76
40 min
10 min
50–60
quant
81
7
8
9
4db(Bn)
4db(Bn)
4db(Bn)
290
145
145
25
5db(Bn)
5db(Bn)
5db(Bn)
30 min
87
94
79
6.5 h
76
91
85
50–60
5 min
1 h
25
60 min
8 h
10
11
12
13
4aa(BnpCF3)
4aa(BnpCF3)
4aa(BnpCF3)
4aa(BnpCF3)
290
290
145
145
25
5aa(BnpCF3)
5aa(BnpCF3)
5aa(BnpCF3)
5aa(BnpCF3)
5 min
91
15 min
5 min
1.5 h
84
95
82
95
50–60
25
< 1 min
10 min
5 min
quant.
93
50–60
quant.
45 min
14
15
16
17
4ab(Bn)
4ab(Bn)
4ab(Bn)
4ab(Bn)
290
145
40
25
25
25
25
5ab(Bn)
5ab(Bn)
5ab(Bn)
5ab(Bn)
< 1 min
< 1 min
1 min
quant.
quant.
quant.
quant.
< 1 min
< 1 min
3 min
quant.
quant.
quant.
quant.
20
2 min
5 min
18
19
4ca(Me)
4 cd(Me)
290
290
50–60
25
5ca(Me)
5 cd(Me)
< 1 min
< 1 min
quant.
95%
5 days
2 h
56%
98%
a
Based on the 1H NMR spectra.
(Naphth), 5ac(Bn) after isolation, were lower, namely 38 and 9%,
respectively (Table 4, entry 4, 6). o-Acetalaryl(aryl)methyl ethers 4aa
(Bn), 4aa(Bnp-CF3), 4ca(Me) and 4bg(Me) required higher tempera-
ture 50–60 °C and 145 equiv. or even 290 equiv. of 6.8 N HClaq to give
acenes 5aa(Bn), 5aa(Bnp-CF3), 5ca(Me) and 5bg(Me), respectively in
excellent yields and in short reaction times from 30 s to 10 min.
(Table 4, entry 1, 2, 7, 8). These reaction times may further be reduced
to a few seconds by using more equiv. of HCl and higher temperature.
Finally, we compared effectiveness of the oxo-Friedel-Crafts/
Bradsher cyclization carried out under silent (6.8 N HClaq/CH3CN,
25–60 °C) and sonochemical conditions (6.8 N HClaq/CH3CN,))),
25–60 °C) (Table 5). In general, application of ultrasounds significantly
accelerated reactions up to more than 7500 times (Table 5, entry 18).
Usually, reduction in time and increase of yield occurred at higher
temperature or by application of greater amounts of HCl. In case of 4ab
(Bn), the cyclization process was quantitative and very fast both with
and without ultrasounds, and the ultrasounds contribution in this case
was negligible (Table 5, entries 14–17).
Interestingly, some o-acetalaryl(aryl)methyl ethers 4, underwent
deacetalization process only, without further cyclization to 5 under the
reaction conditions (ultrasounds, 6.8 N HClaq/CH3CN, room tempera-
ture, or 50–60 °C) to give o-formylaryl(aryl)methyl ethers 6 in 42–75%
yields (Table 6). Thus, this selective, ultrasonically assisted deacetali-
zation might be a useful reaction for further utilization and functiona-
lizations of the aldehyde group in compounds 6. Pal et al. described a
three component synthesis of quinolines under sonochemical
13

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
Table 6
Ultrasound-assisted deacetalization of o-acetalaryl(aryl)methyl ethers 4 to o-formylaryl(aryl)methyl ethers 6 under acidic conditions.
Entry
1
o-Acetalary(aryl)lmethyl ether 4
Time [s, min, h]
2 min.
Temperature [°C]
50–60
Equiv. of 6.8 N HCl
145
o-Formylaryl(aryl)methyl ether 6
Yield (%)a
65
2
2 min.
50–60
145
75
3
4
5 min.
2 min.
25
25
85
54
42
145
Naphth
Naphth
O
O
O
O
O
O
O
6hd(Naphth)
O
4hd(Naphth)
O
5
6
5 min.
5 min.
25
25
85
85
64
56
a
Isolated yields.
conditions, however the deacetalization did not stop at the stage of free
aldehyde, as in our case [26,27].
of alcohols 3 with PhSH under acidic conditions led neither to o-acet-
alaryl(aryl)methyl thioethers 7 (M = O atom) nor to o-dithioacetal aryl
(aryl)methyl thioethers 8 (M = S atom), as a result of conversion of the
acetal to the dithioacetal group with excess of PhS. Therefore, we em-
ployed the reaction of o-dithioacetalaryl(aryl)methanols 9 with thiols
R1SH (R1 = C6H5, 4-MeOC6H4) in the presence of p-TsOH·2H2O [30] to
obtain the desired products 8 (M = S atom) in 28–54% yields via the
OH/SR exchange. (Scheme 2). Methanols 9 were obtained in 52–72%
yields from o-bromopiperonal dithioacetal 11 via the Br/Li exchange
and subsequent condensation of the resulting aryllithium with aromatic
aldehydes 2 followed by the Takano’s protocol [28]. Unlike the “oxygen
variant”, the “thio-variant” of the Friedel-Crafts/Bradsher cyclization of
8 required non-aqueous reaction conditions (FeCl3/KI/EtOH) and gave
(hetero)acenes 10 in 15–46% yields (Table 7). As a heterogeneous re-
action, it is particularly predisposed to the beneficial use of ultrasounds.
Compounds 4cj(Me), 4ee(Bn) and 4ea(Bn) (Table 1, entries 12, 15,
14) were not stable under acidic conditions and underwent decom-
position. It was also observed that compounds 4ch(Me), 4ci(Me) and
4fk(Me) were deacetalized with 85 equiv. of HClaq, however they de-
composed when more HClaq was used. Other o-acetalaryl(aryl)methyl
ethers, were stable under 6.8 N HClaq/CH3CN/ultrasounds conditions
and were deacetalized cleanly to give o-formylaryl(aryl)methyl ethers
6, respectively.
In the last part of our work, we tried to carry out the ultrasound-
assisted “thio-variant” of the Friedel-Crafts/Bradsher cyclization of o-
acetalaryl(aryl)methyl thioethers 7 (M = O) and o-dithioacetalaryl
(aryl)methyl thioethers 8 (M = S) to RS-substituted (hetero)acenes 10
(Scheme 2, Table 7) [30]. At the beginning, we found that the reaction
14

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
Scheme 2. Ultrasound-assisted synthesis of R1S-substituted (hetero)acenes 10 from 9 and their attempted synthesis from 3.
However, the “thio-variant” required higher reaction temperatures
(50–60 °C under ultrasound conditions or reflux in ethanol under silent
conditions) than the “oxygen variant” (r.t. or max. 50–60 °C) at which
the effectiveness of the ultrasound-assisted reaction was lower due to
instability of 8 which decomposed before cyclization, lowering the final
yield. Despite this unfavorable process which did not lead to significant
increase in yields of 10, the reduction of reaction times in the ultra-
sound assisted reactions, was on average two fold (1.5–2.5) and the
Table 7
Synthesis of RS-substituted (hetero)acenes 10 via the thio- Friedel-Crafts/Bradsher cyclization of o-dithioacetalaryl(aryl)methyl thioethers 8 under ultrasound ir-
radiation and silent conditions.
S
O
S
))) or silent conditions
FeCl3/KI
O
O
S R1
O
Ar II
Y
EtOH
50-60oC or reflux
Ar II
S
R1
Y
8
10
R1 = C6H5, C6H4p-OMe
Entry
1
o-Dithioacetal aryl(aryl)methyl thioether 8
Silent conditions time [min]
30
Ultrasound irradiation)))time [min]
20
(Hetero)acenes 10
Yield [%]a/[%]b
46/38
OMe
S
OMe
OMe
O
O
O
S
S
O
S
10a
8a
MeO
OMe
OMe
2
3
60
60
25
25
32/29
15/18
S
O
O
O
O
S
S
S
S
10b
8b
OMe
S
OMe
O
O
O
O
S
O
O
S
S
S
10c
OMe
8c
OMe
O
O
a
b
Yields after purification with column chromatography (silent conditions).
Yields after purification with column chromatography (ultrasounds irradiation).
15

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
Scheme 3. Plausible reaction mechanisms for the oxo-F-C/B cylization under silent conditions.
yields of 10 remained at the same level (18–38%) (Table 7).
Plausible reaction mechanism for the oxo-F-C/B reaction under silent
conditions: Under silent conditions, the reaction proceeds by protona-
tion of the acetal oxygen atom in VI, which leads to the cleavage of the
carbon–oxygen bond and formation of the benzyl carbocation VII sta-
bilized by electron pairs of the second acetal oxygen atom. Cyclization
of VII gives the intermediate carbocation VIII which undergoes de-
protonation followed by the diol elimination from IX and final ar-
omatization of X to give the acene XI (Pathway A, Scheme 3). The
second pathway B leading to the acene XI involves hydrolysis of the
acetal VI to the aldehyde XIV through the intermediate, protonated
hemiacetals XII and XIII obtained by addition of water to the carbo-
cation VII. Then, the resulting aldehyde XIV is protonated to give the
carbocation XV which undergoes cyclization, protonation, water elim-
ination and final aromatization via deprotonation of the benzyl carbo-
cation X to obtain the final acene XI (Scheme 3).
of this acceleration. According to current tenets of sonochemistry, there
are two main reaction sites where sonochemical effects occur: 1) inside
the collapsing cavitation bubble, where extreme conditions are pro-
duced (5000 K, 1000 atm., sonolysis of solvent or volatile compounds to
give radicals and activated molecules followed by radical reactions), or
2) at the interface between the cavity and the bulk liquid (around the
bubble) where the conditions are far less extreme (2000 K, 300 atm.,
sonolysis of non-volatile compounds due to pressure/temperature gra-
dients, radical reactions caused by radicals expelled from the bubble
interior). The bubble contains vapours from the solvent and from any
other volatile reagent [32].
In the bulk liquid surrounding the cavitation bubble, no primary,
sonochemical activity takes place (300 K, 1 atm.) and dominant me-
chanical effects on solids, metals and polymers, consecutive radical
reactions, disturbing of solvent layers, acceleration of mass/heat
transfer and fluid flow can be expected [33].
Plausible reaction mechanism for the oxo-F-C/B reaction under ultra-
sound conditions:
Cavity: On collapse, high temperatures and pressures generated
within the center of the bubble provide the activation energy required
to homolytically fragment the solvent and/or reagents which leads to
the generation of radicals and other reactive species (e.g. carbenes).
The radicals generated in the cavitation bubbles may react with other
radicals or with the substrate in secondary reactions to give new pro-
ducts [33–35].
The oxo-Friedel-Crafts/Bradsher reaction is a homogenous reaction
carried out in acetonitrile/HCl/H2O. It is also an ionic reaction pro-
ceeding with participation of non-volatile carbocations VII
- X
(pathway A) and VII, XII, XIII, XV, XVI, X (pathway B, Scheme 3) as
reactive species. Generally, the effects of ultrasonic irradiation on
chemical reactions in homogeneous systems are small [29].
The investigated oxo-F-C/B reaction results in very high or even in
quantitative yields and no secondary products involving substrates ra-
dicals could be detected (e.g. due to the acetal C(OR)2 or dibenzyl C-OR
radical cleavages). It is also relevant to consider the sonolysis of the
solvent molecules (CH3CN and H2O) and their reactions. For the case of
water, hydroxyl radicals, hydrogen radicals, hydrogen peroxide, and
molecular hydrogen are generated on the sonolysis [29]. For acetoni-
trile, the radical cleavage with formation of methyl and nitrile radicals
in the presence of air is also possible [36]. Analysis of the reaction
Reactions with ionic mechanisms also ought to be rather insensitive
to sonication [30]. Examples of ultrasonic acceleration of homogeneous
and ionic reactions have been scarse. Nevertheless, several examples of
such reactions accelerated by ultrasounds have been reported, mostly
hydrolysis and solvolysis [31]. We found that the investigated oxo-F-C/
B cyclization which joins this group of reactions, was accelerated by
ultrasounds up to at least 7500 times in the most effective example 5ca
(Me) (1 min. versus 5 days) and we proposed the plausible mechanism
16

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
Scheme 4. Proposed explanation of high acceleration in the F-C/B reactions: formation of the reactive (“naked”) carbocations at the interfacial region and in the bulk
liquid, as a result of disturbing their solvation layers during sonication.
products, also in this case, showed no side - products corresponding to
operation of OH, H, CH3 and CN radicals or oxidation products due to
H2O2. However, the radical mechanism of the Friedel-Crafts/Bradsher
reaction proceeding analogously to the ionic mechanism with the
homolytic cleavage of the acetal carbon-oxygen bond in VI and leading
to primary products XI cannot be completely discarded. Detection of
electron paramagnetic resonance (EPR) absorption in liquids under-
going the Friedel-Crafts alkylation reactions, catalyzed by aluminum
chloride under silent conditions, may suggest more complicated sce-
nario of the Friedel-Crafts cyclization under sonochemical conditions in
general, involving mixed ionic and radical pathways or “sonochemical
switching” [32], which requires further detailed investigations [37].
To exclude radical pathways in the oxo-Friedel-Crafts/Bradsher
cyclization, we performed ultrasound assisted reactions without acidic
components in order to enable the homolytic, acetal C(OR)2 cleavage as
the first step in the radical pathway (vide ionic pathway A). However,
only substrates could be detected. To test another radical pathway,
analogous to the ionic pathway B, involving a homolytic cleavage of the
aldehyde C]O bond, as the first step, we attempted the Bradsher cy-
clization of 2-(3,4,5-trimethoxybenzyl)benzaldehyde in acetone (8 min.
at r.t., then 20 min.at 30–35 °C, 10 min. 50–55 °C and 5 min. 70–75 °C,
ampl. 32%, pulse on 2 s, pulse off 2 s) and in the mixture of acetone/
water = 1/1 (10 min. at 60–65 °C, cond. as above) but in all the ex-
periments, the substrate benzaldehyde could only be detected. In order
for a chemical reagent to experience the extreme conditions generated
inside the cavitation bubble during collapse, it must enter the bubble
and so should be volatile.
oxygen atoms followed by the carbon - oxygen bond cleavage (Scheme
3). Ultrasounds have no effect on non-volatile materials in solution
since they have a negligible vapour pressure and so cannot enter the
bubble during sonication. Hence, sources of the sonochemical effects
the oxo-F-C/B cyclization should be sought at the interface between the
cavity and the bulk liquid and in the bulk liquid [32].
Interface and bulk medium: In the process of solvation, the carboca-
tions are surrounded by a concentric shell of water, acetonitrile and
chloride counterion (HClaq). The shock wave, produced by the bubble
collapse or even by the propagating ultrasonic wave itself, causes the
increased molecular motion induced by the pressure gradients asso-
ciated with the collapse. Thus, this process is able to disrupt the solvent
structure and to cause changes in the solvation of carbocations [38].
The disruption increases reactivity of these carbocations by altering
their solvation. The deformation of the solvation shell leads to the ex-
posure of a positive charge and thereby formation of the very reactive
(“naked”) carbocations, especially VII and XV, partially devoid of sta-
bilizing solvating molecules of water and acetonitrile. Next, the car-
bocations spontaneously cyclize to give the corresponding intermediate
products VIII and XVI and then final acenes XI with the observed large
ultrasonic acceleration (Scheme 4).
Plausible reaction mechanism for the thio-F-C/B reaction under silent
conditions:
In the first stage, FeCl3 catalyzes the process of oxidation of the
iodide anion I-, first to iodine and then to the electrophilic cation I+
[39]. The latter reacts with the dithioacetal sulfur atom of XVII to give
iodosulfonium salt XVIII, which usually is the first step in deprotection
of 1,3-dithianes to aldehydes under aqueous conditions [39–41]. In the
absence of water, XVIII undergoes the dithioacetal ring opening with
formation of the benzyl cation XIX stabilized by sulfur electron pairs
followed by electrophilic six-membered ring closure (pathway C,
Scheme 5). Final aromatization through the intermediates XX – XXIII,
On the ground of the accepted ionic mechanisms of the SEAr reac-
tions, the oxo-Friedel-Crafts/Bradsher cyclization proceeds with parti-
cipation of several carbocations, formed both in pathways A and B. The
stabilized carbocations are non-volatile and are produced mostly from
the corresponding oxonium ions, obtained as a result of protonation of
17

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
Scheme 5. Plausible reaction mechanism for the thio-F-C/B cyclization under silent conditions.
delivers the acene XXIV (Scheme 5). In this case, the pathway via free
aldehyde, analogous to the pathway B, will not be considered because
of the anhydrous reaction conditions which has been applied in the
thio-F-C/B variant (FeCl3/KI, EtOH). Interestingly, this reaction under
aqueous conditions, which have been used in the oxo-F-C/B variant,
does not proceed [39].
reactive (naked”) carbocations at the interface around the cavitation
bubble and in the bulk liquid surrounding the bubble.
In this work, we have also elaborated a selective ultrasound-assisted
deacetalization of several o-acetalaryl(aryl)methyl ethers, proceeding
without cyclization to acenes, which may be utilized in further func-
tionalizations of the aldehyde group.
We believe that the findings herein will spur interest and develop-
ment in the underexplored area of ultrasound-assisted cyclizations
based on the mechanism of the aromatic electrophilic substitution.
2Fe3+ + 2 e 2Fe2+
I
2e
I+
Sonochemical conditions: As mentioned earlier, the substrates 8 for
Acknowledgements
the thio-variant, turned out to be compounds of moderate stability and
they decomposed under extreme sonochemical conditions, thereby
lowering the final yields of acenes 10. However, the two fold shortening
of the reaction time brought some benefits from the use of ultrasounds.
The scientific work was financed from the Science Resources
(National Science Centre-Poland) 2014-2017 as research grant UMO-
2013/11/B/ST5/01610 and 2012-2016 as research grant UMO-2012/
07/M/ST5/01985. The authors thank prof. P.Kiełbasiński for reading
the manuscript and for his valuable comments.
4. Conclusion
This work shows acceleration exceeding 7500 times in the ultra-
sound-assisted oxygen-variant and two times in thio-variant of the
Friedel-Crafts/Bradsher cyclizations and presents mechanistic aspects
of these reactions under silent and ultrasonic conditions. The two, new
heteroatom modifications, involving two close elements of the group
XVI of the periodic table (oxygen and sulfur), together with the sono-
chemical variant of the original Bradsher reaction that has recently
been elaborated in our lab [14], are the first examples of ultrasound-
assisted SEAr cyclizations leading to RO-, RS-substituted (Friedel-Crafts)
and unsubstituted (hetero)acenes (Bradsher), respectively.
Appendix A. Supplementary data
Supplementary data to this article can be found online at https://
doi.org/10.1016/j.ultsonch.2019.104640.
References
[1] A.N. Lakshminarayana, A. Ong, Ch. Chi, Modification of acenes for n-channel OFET
materials, J. Mater. Chem. C 6 (2018) 3551–3563.
[2] H.D. Pham, H. Hu, F.-L. Wong, Ch.-S. Lee, W.-Ch. Chen, K. Feron, S. Manzhos,
H. Wang, N. Motta, Y.M. Lam, P. Sonar, Acene-based organic semiconductors for
organic light-emitting diodes and perovskite solar cells, J. Mater. Chem. C 6 (2018)
9017–9029.
A plausible reaction mechanism under ultrasound conditions in the
oxo-variant excluded radical mechanisms and included formation of
18

P. Bałczewski, et al.
Ultrasonics-Sonochemistry58(2019)104640
[3] K.H. Lee, J.N. You, S. Kang, J.Y. Lee, H.J. Kwon, Y.K. Kim, S.S. Yoon, Synthesis and
electroluminescent properties of blue-emitting t-butylated bis(diarylaminoaryl)an-
thracenes for OLEDs, Thin Solid Films 518 (2010) 6253–6258.
[4] Y.-Y. Lyu, J. Kwak, O. Kwon, S.-H. Lee, D. Kim, C. Lee, K. Char, Silicon-cored an-
thracene derivatives as host materials for highly efficient blue organic light-emit-
ting devices, Adv. Mater. 20 (2008) 2720–2729.
friedel-crafts reaction using O-protected ortho-acetal diarylmethanols, Chem. Eur.
J. 18 (2012) 4866–4876.
[23] A. Bodzioch, B. Marciniak, E. Różycka-Sokolowska, J.K. Jeszka, P. Uznanski,
S. Kania, J. Kuliński, P. Bałczewski, Milder bradsher conditions for blue light
emitting anthracenes, Synfacts and Highlights in Current Synthetic Organic
Chemistry 8 (2012) 619–625.
[5] J.K. Park, K.H. Lee, S. Kang, J.Y. Lee, J.S. Park, J.H. Seo, Y.K. Kim, S.S. Yoon, Highly
efficient blue-emitting materials based on 10-naphthylanthracene derivatives for
OLEDs, Org. Electron. 11 (2010) 905–915.
[24] P. Bałczewski, J. Skalik, P. Uznański, D. Guziejewski, D.W. Ciesielski, Use of iso-
meric, aromatic dialdehydes in the synthesis of photoactive, positional isomers of
higher analogs of o-bromo(hetero)acenaldehydes, RSC Adv. 5 (2015)
24700–24704.
[6] P. Gao, H.N. Tsao, J. Teuscher, M. Grätzel, Organic dyes containing fused acenes as
building blocks: Optical, electrochemical and photovoltaic properties, Chin. Chem.
Lett. 29 (2018) 289–292.
[25] P. Bałczewski, E. Kowalska, J. Skalik, 10-Thiosubstituted pentahydroxyanthracene
derivatives, a method of their preparation and intermediate compounds, (06.02.
2014) EP Appl. No EP 14460003.8, (PL 28896539, 01.02.2017).
[26] T. Ram Reddy, L.S. Reddy, G.R. Reddy, K. Yarbagi, Y. Lingappa, D. Rambabu,
G.R. Krishna, C.M. Reddy, K.S. Kumard, M. Pal, Construction of a quinoline ring via
a 3-component reaction in water: crystal structure analysis and H-bonding patterns
of a 2-aryl quinolone, Green Chem. 14 (2012) 1870–1872.
[7] M.S. Newman, N.S. Hussain, Synthesis of nuclear monobromobenz[a]anthracenes,
J. Org. Chem. 47 (1982) 2837–2840.
[8] C.K. Bradsher, A new route to 9-alkyl-and 9-arylanthracenes, J. Am. Chem. Soc. 62
(1940) 486–488.
[9] C.K. Bradsher, Formation of six-membered aromatic rings by cyclialkylation of
some aldehydes and ketones, Chem. Rev. 87 (1987) 1277–1297.
[10] R.G. Harvey, C. Cortez, T. Sugiyama, J.Y. Ito, T.W. Sawyer, J. DiGiovanni,
Biologically active dihydrodiol metabolites of polycyclic aromatic hydrocarbons
structurally related to the potent carcinogenic hydrocarbon 7,12-dimethylbenz[a]
anthracene, J. Med. Chem. 31 (1988) 154–159.
[27] A.S.G. Prasad, T.B. Rao, D. Rambabu, M.V.B. Rao, M. Pal, Ultrasound assisted
synthesis of quinoline derivatives in the presence of SnCl2•2H2O as a precatalyst in
water: evaluation of their antibacterial activities, Mini-Rev. Med. Chem. 17
(2017) 1–7.
[28] S. Takano, S. Otaki, K. Ogasawa, A new route to 1-phenylnaphthalenes by cy-
cloaddition: a simple and selective synthesis of some naphthalene lignan lactones,
Tetrahedron Lett. 26 (1985) 1659–1660.
[11] J.L. Hallman, R.A. Bartach, Synthesis of naphtho[f]ninhydrin, J. Org. Chem. 56
(1991) 6243–6245.
[12] K.L. Platt, F. Oesch, Reductive cyclization of keto acids to polycyclic aromatic hy-
drocarbons by hydroiodic acid-red phosphorus, J. Org. Chem. 46 (1981)
2601–2603.
[29] T. Kimura, Application of ultrasound to organic synthesis, in: F. Grieser, P.-K. Choi,
N. Enomoto, H. Harada, K. Okitsu, K. Yasui (Eds.), Sonochemistry and the Acoustic
Bubble, 1st ed., Elsevier, Amsterdam, Netherlands, 2015, pp. 171–186.
[30] R. Miethchen, Selected applications of sonochemistry in organic chemistry,
Ultrasonics 30 (1992) 173–179.
[13] C. Friedel, J.-M. Crafts, Sur une nouvelle méthode générale de synthése d'hy-
drocarbures, d'acétones, Compt. Rend. 84 (1877) 1392–1395.
[14] E. Kowalska, P. Bałczewski, Ultrasound assisted Bradsher reaction in aqueous and
non-aqueous media: First use of ultrasounds in electrophilic aromatic cyclisation
leading to polyacenes, Ultrason. Sonochem. 34 (2017) 743–753.
[15] A. Dandia, D.S. Bhati, A.K. Jain, G.N. Sharma, Ultrasound promoted clay catalyzed
efficient and one pot synthesis of substituted oxindoles, Ultrason. Sonochem. 18
(2011) 1143–1147.
[31] A. Tuulmets, G. Cravotto, S. Salmar, J. Järv, Sonochemistry of homogeneous ionic
reactions, Mini Rev. Org. Chem. 7 (2010) 204–211.
[32] J.M. Pestman, J.B.F.N. Engberts, F. de Jong, Sonochemistry: Theory and applica-
tions, Rec. Trav. Chim. Pays-Bas 113 (1994) 533–542.
[33] T.J. Mason, Ultrasound in synthetic organic chemistry, Chem. Soc. Rev. 26 (1997)
443–451.
[16] J.V. Prasad, J.S. Reddy, N.R. Kumar, K.A. Solomon, G. Gopikrishna, An efficient
ultrasound promoted catalyst-free protocol for the synthesis of chromeno[4,3-b]
quinolin-6-ones, J. Chem. Sci. 123 (2011) 673–679.
[34] F.P. Capote, M.D.L. de Castro, Analytical Applications of Ultrasounds in Techniques
and Instrumentation in Analytical Chemistry Vol. 26, Elsevier Science, Amsterdam,
Netherlands, 2007.
[17] P. Bałczewski, M. Koprowski, A. Bodzioch, B. Marciniak, E. Różycka-Sokołowska,
Unusual transformation of the diarylmethanol derivative into an unknown
1,2,3,6,7,10-hexahydroxylated anthracene system, J. Org. Chem. 71 (2006)
2899–2902.
[35] M. Sillanpää, T.-D. Pham, R.A. Shrestha, Ultrasound Technology in Green
Chemistry, SpringerBriefs in Green Chemistry for Sustainability, Springer,
Netherlands, 2011.
[36] W. Hu, F. Teng, H. Peng, J. Yu, S. Sun, J. Cheng, S. Ying, Radical N-cyanation of
sulfoximine through acetonitrile C-CN cleavage, Tetrahedron Lett. 56 (2015)
7056–7058.
[18] P. Bałczewski, A. Bodzioch, M. Koprowski, J. Skalik Preparation of new condensed
polyaromatic and polyheteroaromatic hydrocarbons and their intermediates, (24.
07.2014) PL 219155.
[37] J.Q. Adams, S.W. Nicksic, Free radicals in friedel-crafts reactions, J. Am. Chem. Soc.
84 (1962) 4355-4355.
[19] P. Bałczewski, A. Bodzioch, M. Koprowski, Preparation of new condensed poly-
aromatic and polyheteroaromatic hydrocarbons and intermediate compounds
thereof (25.08.2014) PL 219334.
[38] J. Lindley, T.J. Mason, Sonochemistry. Part 24-synthetic applications, Chem. Soc.
Rev. 16 (1987) 275–311.
[20] P. Bałczewski, A. Bodzioch, J. Skalik A method of preparation of polycyclic, fused
aromatic and heteroaromatic hydrocarbons and intermediates (11.09.2012) EP
12187708.8.
[39] M. Kirihara, S. Suzuki, Y. Ishizuka, K. Yamazaki, R. Matsushima, T. Suzuki, T. Iwai,
Environmentally benign deprotection of dithioacetals using 30% hydrogen peroxide
catalyzed by Fe(acac)3 and sodium iodide, Tetrahedron Lett. 54 (2013) 5477–5480.
[40] K. Nishide, K. Yokota, D. Nakamura, T. Sumiya, M. Node, M. Ueda, K. Fuji, A new
entry for the deprotection of monothioacetals and dithioacetals: silver nitrite - io-
dine system, Tetrahedron Lett. 34 (1993) 3425–3428.
[21] P. Bałczewski, A. Bodzioch, E. Różycka-Sokołowska, B. Marciniak, P. Uznański, First
approach to nitrogen-containing fused aromatic hydrocarbons as targets for orga-
noelectronics utilizing a new transformation of O-protected diaryl methanols,
Chem. Eur. J. 16 (2010) 2392–2400.
[41] N.G. Ganguly, S.K. Barik, A facile mild deprotection protocol for 1,3-dithianes and
1,3-dithiolanes with 30% hydrogen peroxide and iodine catalyst in aqueous mi-
cellar system, Synthesis 8 (2009) 1393–1399.
[22] A. Bodzioch, B. Marciniak, E. Różycka-Sokołowska, J.K. Jeszka, P. Uznański,
S. Kania, J. Kuliński, P. Bałczewski, Synthesis and optoelectronic properties of
hexahydroxylated 10-O-R-substituted anthracenes via a new modification of the
19