Direct synthesis of ethers from aldehydes and ketones. One-pot reductive etherification of benzaldehydes, alkyl aryl ketones, and benzophenones

Article abstract of DOI:10.1134/S1070428016040047

Benzyl alcohols formed by the reduction of benzaldehydes, alkyl aryl ketones, and benzophenones with sodium tetrahydridoborate in alcohols undergo in situ etherification with the solvent in the presence of a catalytic amount of HCl. Thus the process may be regarded as one-pot transformation of carbonyl compounds into the corresponding benzyl ethers. The yields of ethers depend on the substituent nature in the aromatic fragment of the initial carbonyl compound and on the alcohol used as reduction medium.

Full text of DOI:10.1134/S1070428016040047

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2016, Vol. 52, No. 4, pp. 503–512. © Pleiades Publishing, Ltd., 2016.
Original Russian Text © S.S. Mochalov, A.N. Fedotov, E.V. Trofimova, N.S. Zefirov, 2016, published in Zhurnal Organicheskoi Khimii, 2016, Vol. 52, No. 4,
pp. 515–525.
Direct Synthesis of Ethers from Aldehydes and Ketones.
One-Pot Reductive Etherification of Benzaldehydes,
Alkyl Aryl Ketones, and Benzophenones
S. S. Mochalov, A. N. Fedotov, E. V. Trofimova, and N. S. Zefirov
Faculty of Chemistry, Moscow State University, Leninskie gory 1, Moscow, 119991 Russia
e-mail: fed@org.chem.msu.ru
Received January 11, 2016
Abstract—Benzyl alcohols formed by the reduction of benzaldehydes, alkyl aryl ketones, and benzophenones
with sodium tetrahydridoborate in alcohols undergo in situ etherification with the solvent in the presence of
a catalytic amount of HCl. Thus the process may be regarded as one-pot transformation of carbonyl compounds
into the corresponding benzyl ethers. The yields of ethers depend on the substituent nature in the aromatic
fragment of the initial carbonyl compound and on the alcohol used as reduction medium.
DOI: 10.1134/S1070428016040047
Benzyl ethers are widely used in various trans-
formations in organic synthesis [1]. They are generally
prepared from benzyl alcohols [2–5] which are ob-
tained in turn by reduction of the corresponding car-
bonyl compounds. However, development of modern
low-cost technologies for the synthesis of ethers
requires new protocols ensuring direct transformation
of carbonyl compounds into ethers.
benzyl ethers. The procedure includes NaBH4 reduc-
tion of carbonyl compound to the corresponding ben-
zyl alcohol and subsequent acid-catalyzed etherifica-
tion with the alcohol solvent in a one-pot process
(Scheme 1).
We initially studied reductive etherification of
4-methoxyacetophenone (1a) in various alcohols in
order to estimate the range of alcohols as possible co-
reactants and compare the results with those obtained
in the transformation of the same ketone according to
the procedure described in [7]. The reductive etheri-
fication of 1a with a large series of primary and secon-
dary aliphatic alcohols under the proposed conditions
was as efficient as that reported in [7] (Table 1,
Scheme 2) with the difference that the use of NaBH4 as
reducing agent considerably simplifies the experi-
mental procedure.
Attempts have already been made to obtain benzyl
ethers directly from carbonyl compounds. Benzyl
ethers can be synthesized from benzaldehydes via
successive reactions first with benzyloxy(trimethyl)-
silane and then with triethylsilane in the presence of
a catalytic amount of FeCl3 [6]. Another way is cata-
lytic hydrogenation of acetyl-substituted arenes with
gaseous hydrogen, followed by copper-catalyzed ether-
ification with alcohol as coreactant [7]. It is seen that
these procedures require specific reagents [6] or ex-
plosive gaseous reducing agent [7].
As follows from the data in Table 1, the yields of
the corresponding benzyl ethers with secondary alco-
hols were lower than with primary alcohols provided
that the reaction time was fixed at 5 h. The lower
yields were due to incomplete etherification of
1-(4-methoxyphenyl)ethanol formed as a result of
reduction of 1a; prolonged heating increased the yield
of 2c and 2g to quantitative.
Herein we describe a simple and efficient method
of direct transformation of benzaldehydes, alkyl aryl
ketones, and benzophenones into the corresponding
Scheme 1.
O
OR3
R2
(1) NaBH4, R3OH, 20°C
(2) HCl, ∆
According to [7], the opposite relation was ob-
served: benzyl ethers with branched alkoxy groups
were formed in a shorter time than those with un-
R2
R1
R1
503

MOCHALOV et al.
504
Scheme 2.
O
OR
(1) NaBH4, ROH, 20°C
(2) 10% aq. HCl, 60°C, 5 h
Me
Me
MeO
MeO
1a
2a–2i
R = Et (a), Pr (b), i-Pr (c), Bu (d), i-Bu (e), C8H17 (f), Cy (g), Me (h), PhCH2 (i).
branched alkyl radicals. The authors [7] presumed that
secondary (more nucleophilic) aliphatic alcohols re-
acted with benzyl alcohols at a higher rate. The dif-
ference between the dependences of the etherification
rate on the alcohol coreactant structure reported in [7]
and observed by us may be indicative of different
etherification mechanisms. It was also quite surprising
that the reductive etherification of 1a in methanol at
60°C was much slower (24 h) than, e.g., the reaction in
ethanol (5 h) [7]. In our case, the reactions in both
methanol and ethanol, as well as in propan-1-ol, at
60°C were equally efficient, and the yields of the
corresponding ethers were equally high (Table 1). It
should be noted that in our case the reduction of 1a in
methanol, as well as in benzyl alcohol, was carried out
by adding NaBH4 to a solution of 1a in methanol (or
benzyl alcohol); otherwise, i.e., when a solution of
NaBH4 in these alcohols was prepared preliminarily,
a large part of the reducing agent decomposed, and the
yield of 1-(4-methoxyphenyl)ethanol was reduced. In
the reactions with other aliphatic alcohols, the order of
addition of the reactants was the same as reported in
the literature.
yield of target benzyl ethers (Table 2, Scheme 3). It is
seen that the presence of such a weak electron-with-
drawing substituent as bromine atom in acetophenone
1i prevents formation of the corresponding benzyl
ether, though the reduction of 1i to 1-(3-bromophenyl)-
ethanol (3i) in both ethanol and propan-2-ol was
quantitative (run nos. 21, 22). Unlike 1i, unsubstituted
acetophenone (1b) and 4-tert-butylacetophenone (1c)
were converted into the corresponding benzyl ethers;
however, the latter were obtained in modest yields
even at elevated temperature and prolonged reaction
time (Table 2, run nos. 1–6). High yields of benzyl
ethers were achieved in the reductive etherification of
acetophenones 1e–1h containing strong electron-
donating groups in the para position of the benzene
ring. Alkoxy-substituted acetophenones 1f–1h gave
benzyl ethers with higher yields in shorter time
(run nos. 12–20).
Scheme 3.
(1) NaBH4, ROH, 20°C
(2) 10% aq. HCl
O
OH
OR
+
Ar
Me
1b–1k
Ar
Me
3b–3k
Ar
Me
4a–4w
We then proceeded to study the behavior of various
substituted acetophenones with the goal of elucidating
the effect of substituent in the aromatic ring on the
1, 3, Ar = Ph (b), 4-t-BuC6H4 (c), 4-cyclopropylphenyl (d),
4-(1-methylcyclopropyl)phenyl (e), 4-EtOC6H4 (f), 2,3-dihy-
dro-1,4-benzodioxin-6-yl (g), 3,4-(MeO)2C6H3 (h), 3-BrC6H4
(i), 5-methylfuran-2-yl (j), 5-ethylthiophen-2-yl (k); 4, Ar =
Ph, R = i-Pr (a); Ar = 4-t-BuC6H4, R = i-Pr (b), Pr (c),
i-Bu (d); Ar = 4-cyclopropylphenyl, R = Me (e), Et (f),
i-Pr (g); Ar = 4-(1-methylcyclopropyl)phenyl, R = Et (h),
i-Pr (i); Ar = 4-EtOC6H4, R = Pr (j), i-Pr (k); Ar = 2,3-dihy-
dro-1,4-benzodioxin-6-yl, R = Me (l), Pr (m), C8H17 (n),
Cy (o); Ar = 3,4-(MeO)2C6H3, R = Et (p), Pr (q), i-Pr (r);
Ar = 5-methylfuran-2-yl, R = Et (s), i-Pr (t); Ar =
5-ethylthiophen-2-yl, R = Me (u), i-Pr (w).
Table 1. Reductive etherification of 4-methoxyaceto-
phenone (1a) in different alcohols
Alcohol solvent
Benzyl ether
Yield, %
EtOH
2a
2b
2c
2d
2e
2f
100
100
068
100
100
098
090
089
0a91a
PrOH
i-PrOH
BuOH
Acetylhetarenes 1j and 1k were converted into the
corresponding ethers even at 20°C, though in a longer
time (Table 2, run nos. 23–27). In this case, time
expenditure is justified since attempts to accelerate
etherification of alcohols 3j and 3k formed in the
reduction step by raising the temperature to 60°C led
to formation of complex product mixtures. Unlike thio-
i-BuOH
Octan-1-ol
Cyclohexanol
MeOH
2g
2h
2i
Benzyl alcohol
a
Calculated on the reduced ketone 1a.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 4 2016

DIRECT SYNTHESIS OF ETHERS FROM ALDEHYDES AND KETONES.
Table 2. Reductive etherification of acetophenones 1b–1k
505
Run
no.
Temperature,
°C
Reduction
product
Acetophenone Alcohol solvent
Time, h Benzyl ether Yield, %
Yield, %
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
1b
1b
1c
1c
1c
1c
1d
1d
1d
1e
1e
1f
i-PrOH
i-PrOH
i-PrOH
i-PrOH
PrOH
75
75
75
75
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
78
20
20
20
20
20
15
50
07
20
15
15
08
10
15
10
10
05
05
04
05
05
05
03
03
05
10
10
06
18
12
12
20
4a
4a
4b
4b
4c
4d
4e
4f
022
040
035
050
041
025
095
092
075
085
040
098
095
100
100
088
085
100
100
092
–
3b
3b
3c
3c
3c
3c
78
60
64
50
58
75
–
i-BuOH
MeOH
EtOH
a
a
–
3d
3d
3e
3e
3f
3f
–
05
25
14
58
03
04
–
i-PrOH
EtOH
4g
4h
4i
i-PrOH
PrOH
4j
1f
i-PrOH
MeOH
PrOH
4k
4l
1g
1g
1g
1g
1h
1h
1h
1i
4m
4n
4o
4p
4q
4r
–
–
–
Octan-1-ol
Cyclohexanol
EtOH
3g
3g
–
07
12
–
PrOH
–
–
i-PrOH
EtOH
3h
3i
3i
3j
3j
–
05
1000
1000
03
12
–
1i
i-PrOH
EtOH
–
–
1j
4s
4t
095
086
100
095
092
1j
i-PrOH
MeOH
EtOH
1k
1k
1k
4u
4v
4w
3k
3k
02
07
i-PrOH
a
The reaction mixture before etherification contained alcohol 3d and initial acetophenone 1d.
phene analogs, ethers derived from 2-acetyl-5-methyl-
furan (1j) were unstable on storage, and they gave rise
to multicomponent mixtures in 48–60 h at 20°C. One
of the transformation products of ethers 4s and 4t was
identified as 2,2′-(ethane-1,1-diyl)bis(5-methylfuran).
The second step of the one-pot process under
consideration is in fact acid-catalyzed intermolecular
etherification of benzyl alcohols with alcohols coreac-
tants [3, 4]. Therefore, the formation of ethers from
benzyl alcohols quantitatively* generated by reduction
of acetophenones 1a–1k with NaBH4, as well as
etherification of preliminarily isolated alcohols [3, 4],
should be considered to follow a common mechanism
mediated by benzyl type carbenium ions.
We also found that structural analogs of aceto-
phenones, alkoxy-substituted alkyl aryl ketones 5a–5c,
are very readily converted into benzyl ethers 7a–7j
under the proposed reductive etherification conditions
(Table 3, Scheme 4). Quantitative etherification of
alcohols derived from aryl cyclopropyl ketones 5a and
5c was observed even at 20°C (Table 3; run nos. 1, 2,
5–7). The complete reduction of 5a and 5c with
NaBH4 requires a longer time than the reduction of 5b,
5d, and 5e. On the other hand, etherification of benzyl
cyclopropyl alcohols is considerably faster than the
etherification of alcohols derived from 5b, 5d, and 5e,
1
* According to the H NMR spectra of the reaction mixtures
before etherification step.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 4 2016

MOCHALOV et al.
506
Scheme 4.
(1) NaBH4, R'OH, 20°C
(2) 10% aq. HCl
O
OH
OR'
10% aq. HCl
Ar
5a–5e
R
Ar
6a–6e
R
Ar
7a–7j
R
5, 6, Ar = 4-MeOC6H4, R = cyclopropyl (a); Ar = 2,3-dihydro-1,4-benzodioxin-6-yl, R = Et (b), cyclopropyl (c), PhCH2 (d);
Ar = 3,4-dihydro-2H-1,5-benzodiazepin-7-yl, R = PhCH2 (e); 7, Ar = 4-MeOC6H4, R = cyclopropyl, R′ = Et (a), i-Pr (b); Ar = 2,3-di-
hydro-1,4-benzodioxin-6-yl, R = Et, R′ = Pr (c), i-Bu (d); 2,3-dihydro-1,4-benzodioxin-6-yl, R = cyclopropyl, R′ = Et (e), Pr (f),
i-Pr (g); Ar = 2,3-dihydro-1,4-benzodioxin-6-yl, R = PhCH2, R′ = Pr (h), i-Bu (i); Ar = 3,4-dihydro-2H-1,5-benzodiazepin-7-yl,
R = PhCH2, R′ = Pr (j).
Scheme 5.
O
OH
(1) NaBH4, ROH, 20°C
(2) 10% aq. HCl
OEt
HCl, 50–60°C
MeO
MeO
MeO
5a
6a
8
though in all cases the corresponding benzyl ethers are
formed in quantitative yield (Table 3). These findings
indicate that benzyl type carbocations generated from
cyclopropyl carbinols 6a and 6c are more stable than
those generated from ethyl- and benzyl-substituted
analogs 6b, 6d, and 6e. Etherification of 6a and 6c
should not be conducted at elevated temperature.
When the second step in the reductive etherification of
5a was carried out at 50–60°C, after 0.5 h in the
into benzhydrol ethers 11a–11i under the proposed
conditions (Table 4, Scheme 6). Weak electron-with-
drawing substituents such as halogen atoms present in
one benzene ring of 9c and 9d almost did not affect
acid-catalyzed etherification. Like aryl cyclopropyl
ketones 5a and 5c, the reduction of 9a–9d to benz-
hydrols 10a–10d with NaBH4 required a longer time or
elevated temperature (compared to 1a–1k or 5b, 5d,
and 5e). On the other hand, the etherification of 10a–
10d was as fast as with alcohols derived from alkoxy-
aryl alkyl ketones (Tables 3, 4).
1
reaction mixture we detected by H NMR unsaturated
ether 8 resulting from opening of the cyclopropane
ring (Scheme 5). Facile acid-catalyzed modification of
cyclopropane ring in compounds analogous to 6a has
been reported previously [8]; in our case (20°C) no
such process was observed, at least during the given
reaction time (Table 3; run nos. 1, 2, 5–7).
It is known [3, 4] that benzyl alcohols containing
no electron-donating groups in the benzene ring are
very difficult to involve in acid-catalyzed intermolec-
ular condensations. It is believed that such substrates
are incapable of generating the corresponding benzyl
type cations at a sufficient rate. Therefore, the nature
of substituent in the benzene ring of benzaldehydes
Diaryl ketones 9a–9d containing alkoxy substit-
uents in one benzene ring were also readily converted
Table 3. Reductive etherification of alkoxyaryl alkyl ketones 5a–5e
Run no.
Initial ketone
Alcohol solvent
Temperature, °C
Reaction time, h Benzyl ether
Yield, %
01
02
03
04
05
06
07
08
09
10
5a
5a
5b
5b
5c
5c
5c
5d
5d
5e
EtOH
20
20
60
60
20
20
20
60
60
60
2
3
4
4
6
6
6
5
5
5
7a
7b
7c
7d
7e
7f
100
100
100
100
100
100
100
100
100
098
i-PrOH
PrOH
i-BuOH
EtOH
PrOH
i-PrOH
PrOH
7g
7h
7i
i-BuOH
PrOH
7j
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 4 2016

DIRECT SYNTHESIS OF ETHERS FROM ALDEHYDES AND KETONES.
507
Scheme 6.
(1) NaBH4, ROH, 20°C
(2) 10% aq. HCl
O
OH
OR
10% aq. HCl
Ar
Ar'
9a–9d
Ar
Ar'
Ar
Ar'
10a–10d
11a–11i
9, 10, Ar = 3,4-(MeO)2C6H3, Ar′ = Ph (a); Ar = 2,3-dihydro-1,4-benzodioxin-6-yl, Ar′ = 4-MeC6H4 (b), 4-FC6H4 (c); Ar = 7-bromo-
2,3-dihydro-1,4-benzodioxin-6-yl, Ar′ = 2-Th (d); 11, Ar = 3,4-(MeO)2C6H3, Ar′ = Ph, R = Et (a), i-Pr (b); Ar = 2,3-dihydro-1,4-
benzodioxin-6-yl, Ar′ = 4-MeC6H4, R = Me (c), Et (d), i-Pr (e), C5H11 (f); Ar′ = 4-FC6H4, R = Et (g), Pr (h); Ar = 7-bromo-2,3-
dihydro-1,4-benzodioxin-6-yl, Ar′ = thiophen-2-yl, R = i-Pr (i).
was expected to affect their reductive etherification to
a stronger extent than in the case of acetophenones. In
fact, neither benzaldehyde (12a) nor 3-methoxybenz-
aldehyde (12b) nor furan-2-carbaldehyde (12c) was
converted into the corresponding ethers under standard
conditions, though respective alcohols 13a–13c were
formed in high yields (Table 5, Scheme 7). Unlike
12a–12c, 4-alkoxybenzaldehydes 12d–12f afforded
high yields of benzyl ethers 14a–14f. The observed
difference in the behaviors of benzaldehydes 12b and
12d differing only by the position of methoxy group
(Table 5, run nos. 2, 3, 7–9) convincingly shows
efficient stabilization of benzyl type carbenium ion
derived from 12d by the p-methoxy group and the lack
of such stabilization in m-methoxy analog.
Thus, the proposed procedure for the synthesis of
unsymmetrical ethers via reductive etherification of
carbonyl compounds can be successfully applied to
Table 4. Reductive etherification of benzophenones 9a–9d
Run no. Benzophenone
Alcohol solvent
Temperature, °C Reaction time, h
Benzyl ether
Yield, %
1
2
3
4
5
6
7
8
9
9a
9a
9b
9b
9b
9b
9c
9c
9d
EtOH
60
60
60
60
60
60
60
60
60
5
5
11a
11b
11c
11d
11e
11f
100
0a81a
096
100
100
095
100
100
100
i-PrOH
MeOH
EtOH
.03.5
.03.5
6
i-PrOH
C5H11OH
EtOH
5
4
11g
11h
11i
PrOH
4
i-PrOH
.03.5
a
The mixture contained ~15% of 10a (1H NMR).
Table 5. Reductive etherification of benzaldehydes 12a–12f
Run no. Benzaldehyde
Alcohol solvent
Temperature, °C Reaction time, h
Product
Yield, %
01
02
03
04
05
06
07
08
09
10
11
12a
12b
12b
12c
12c
12d
12d
12d
12e
12e
12f
EtOH
60
60
60
20
20
60
60
60
60
60
60
25
20
30
12
12
05
05
15
05
15
08
13a
13b
13b
13c
13c
14a
14b
14c
14d
14e
14f
96
a92a
a88a
91
MeOH
PrOH
EtOH
i-PrOH
MeOH
EtOH
95
95
96
i-PrOH
MeOH
i-PrOH
EtOH
75
85
81
88
a
The reaction mixture before etherification contained initial aldehyde 12b (1H NMR).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 4 2016

MOCHALOV et al.
(2H, CH2CH3, J = 7.0 Hz), 3.22 t (2H, OCH2, J =
508
Scheme 7.
(1) NaBH4, ROH, 20°C
(2) 10% aq. HCl
6.9 Hz), 3.80 s (3H, OCH3), 4.31 q (1H, CHCH3, J =
6.3 Hz), 6.84 d (2H, Harom, J = 9.4 Hz), 7.19 d (2H,
ArCHO
12a–12f
ArCH2OH
+
ArCH2OR
H
arom, J = 9.4 Hz). Found, %: C 73.88, 73.98; H 9.14,
13a–13f
14a–14f
9.21. C12H18O2. Calculated, %: C 74.19; H 9.34.
12, 13, Ar = Ph (a), 3-MeOC6H4 (b), furan-2-yl (c), 4-MeO-
C6H4 (d), 4-EtOC6H4 (e), 4-PhCH2OC6H4 (f); 14, Ar =
4-MeOC6H4, R = Me (a), Et (b), i-Pr (c); Ar = 4-EtOC6H4,
R = Me (d), i-Pr (e); Ar = 4-PhCH2OC6H4, R = Et (f).
1-(1-Butoxyethyl)-4-methoxybenzene (2d).
1H NMR spectrum, δ, ppm: 0.93 t (3H, CH2CH3, J =
7.5 Hz), 1.39 m (2H, CH2CH3), 1.41 d (3H, CHCH3,
J = 6.4 Hz), 1.54 m (2H, OCH2CH2), 3.26 t (2H,
OCH2, J = 6.8 Hz), 3.80 s (3H, OCH3), 4.29 q (1H,
CHCH3, J = 6.4 Hz), 6.83 d (2H, Harom, J = 9.4 Hz),
7.19 d (2H, Harom, J = 9.4 Hz). Found, %: C 74.68,
74.74; H 9.35, 9.46. C13H20O2. Calculated, %: C 74.96;
H 9.68.
benzaldehydes, alkyl aryl ketones, and benzophenones
containing electron-donating substituents in the para
positions of the benzene rings.
EXPERIMENTAL
1-Methoxy-4-[1-(2-methylpropan-1-yloxy)ethyl]-
benzene (2e). H NMR spectrum, δ, ppm: 0.92 d [6H,
1
1
The H NMR spectra were recorded on a Varian
VXR-400 spectrometer (400 MHz) from solutions in
CDCl3; the chemical shifts were measured relative to
the residual proton signal of the solvent. The elemental
analyses were obtained on a Varian-11 CHN analyzer.
The products were isolated by chromatography on
alumina (Brockmann activity grade II) using diethyl
ether–hexane (1:3 or 1:4) as eluent.
CH(CH3)2, J = 6.6 Hz], 1.41 d (3H, CHCH3, J =
6.4 Hz), 1.85 sept [1H, CH(CH3)2], 3.03 d (2H, OCH2,
J = 6.6 Hz), 3.82 s (3H, OCH3), 4.29 q (1H, CHCH3,
J = 6.4 Hz), 6.84 d (2H, Harom, J = 9.4 Hz), 7.19 d (2H,
Harom, J = 9.4 Hz). Found, %: C 74.59, 74.72; H 9.42,
9.51. C13H20O2. Calculated, %: C 74.96; H 9.68.
1-Methoxy-4-[1-(octyloxy)ethyl]benzene (2f).
1H NMR spectrum, δ, ppm: 0.91 t (3H, CH2CH3, J =
6.7 Hz), 1.21–1.33 m (10H, (CH2)5CH3], 1.43 d (3H,
CHCH3, J = 6.4 Hz), 1.56 m (2H, OCH2CH2), 3.27 t
(2H, OCH2, J = 7.1 Hz), 3.81 s (3H, OCH3), 4.32 q
(1H, CHCH3, J = 6.4 Hz), 6.86 d (2H, Harom, J =
9.1 Hz), 7.23 d (2H, Harom, J = 9.1 Hz). Found, %:
C 76.88, 77.01; H 10.42, 10.51. C17H28O2. Calculated,
%: C 77.22; H 10.67.
General procedure for the reductive etherifica-
tion of carbonyl compounds 1a–1k, 5a–5e, 9a–9d,
and 12a–12f. Carbonyl substrate, 0.02 mol, was added
in portions to a suspension of 0.01 mol NaBH4 in
0.3 mol of the corresponding alcohol solvent, and the
mixture was stirred for 2–2.5 h at 20°C. The resulting
boron derivatives of benzyl alcohols were decomposed
with 10% aqueous HCl (3.7 mL), and the mixture was
stirred for a required time at a required temperature
(see Tables 1–5), cooled, and poured into 200 mL of
cold water. The products were extracted with diethyl
ether (2×40 mL), the combined extracts were washed
with water and dried over anhydrous sodium sulfate,
the solvent was distilled off on a rotary evaporator, and
1-[1-(Cyclohexyloxy)ethyl]-4-methoxybenzene
1
(2g). H NMR spectrum, δ, ppm: 1.19 m (3H), 1.29 m
(2H), 1.50 m (1H), 1.71 m (3H), 1.93 m (1H), 3.13 m
(1H) (C6H11); 1.38 d (3H, CHCH3, J = 6.4 Hz), 3.79 s
(3H, OCH3), 4.52 q (1H, CHCH3, J = 6.4 Hz), 6.83 d
(2H, Harom, J = 9.3 Hz), 7.21 d (2H, Harom, J = 9.3 Hz).
Found, %: C 76.41, 76.56; H 9.18, 9.27. C15H22O2.
Calculated, %: C 76.88; H 9.46.
1
the residue was analyzed by H NMR. If necessary,
benzyl ethers were isolated by chromatography. Alco-
hol coreactants poorly soluble in water were removed
from the diethyl ether extracts by vacuum distillation,
and the target ethers ware isolated from the still
residue. Ethers 2a [9], 2c [3], 2h, 4a [10], 4b [11], 4i,
4l, 7e, 10c, 10d, 10e [4], and 13a [12] were described
previously. Ethers 2b, 2d–2g, 2i, 4c–4h, 4j, 4k, 4m–
4w, 7a–7d, 7f, 7g, and 13b–13f are mobile liquids, and
7h–7j, 10a, 10b, and 10f–10i are viscous liquids.
1-[1-(Benzyloxy)ethyl]-4-methoxybenzene (2i).
1H NMR spectrum, δ, ppm: 1.53 d (3H, CHCH3, J =
6.6 Hz), 3.86 s (3H, OCH3), 4.32 d and 4.48 d (1H
each, CH2Ph, J = 11.7 Hz), 4.51 q (1H, CHCH3, J =
6.6 Hz), 6.96 d (2H, Harom, J = 8.5 Hz), 7.32–7.42 m
(7H, Harom). Found, %: C 78.92, 79.03; H 7.11, 7.23.
C16H18O2. Calculated, %: C 79.31; H 7.49.
1-Methoxy-4-(1-propoxyethyl)benzene (2b).
1H NMR spectrum, δ, ppm: 0.94 t (3H, CH2CH3, J =
7.0 Hz), 1.42 d (3H, CHCH3, J = 6.3 Hz), 1.58 sext
1-tert-Butyl-4-[1-(propoxy)ethyl]benzene (4c).
1H NMR spectrum, δ, ppm: 0.95 t (3H, CH2CH3, J =
7.2 Hz), 1.36 s (9H, t-Bu), 1.42 d (3H, CHCH3, J =
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509
6.2 Hz), 1.59 sext (2H, CH2CH3), 3.25 m (2H, OCH2),
4.33 q (1H, CHCH3, J = 6.2 Hz), 7.19 d (2H, Harom, J =
8.3 Hz), 7.32 d (2H, Harom, J = 8.3 Hz). Found, %:
C 81.33, 81.52; H 10.72, 10.79. C15H24O. Calculated,
%: C 81.76; H 10.98.
OCH2CH2CH3), 3.24 t (2H, OCH2CH2CH3, J =
6.4 Hz), 4.02 q (2H, OCH2CH3, J = 6.6 Hz), 4.32 q
(1H, CHCH3, J = 6.2 Hz), 6.83 d (2H, Harom, J =
8.0 Hz), 7.19 d (2H, Harom, J = 8.0 Hz). Found, %:
C 74.51, 74.64; H 9.32, 9.46. C13H20O2. Calculated, %:
C 74.96; H 9.68.
1-tert-Butyl-4-[1-(2-methylpropan-1-yloxy)-
ethyl]benzene (4d). 1H NMR spectrum, δ, ppm: 0.89 t
[6H, CH(CH3)2, J = 6.8 Hz], 1.32 s (9H, t-Bu), 1.37 d
(3H, CHCH3, J = 6.3 Hz), 1.82 sept [1H, CH(CH3)2],
3.01 m (2H, OCH2), 4.25 q (1H, CHCH3, J = 6.3 Hz),
7.12 d (2H, Harom, J = 8.1 Hz), 7.26 d (2H, Harom, J =
8.1 Hz). Found, %: C 81.38, 81.56; H 10.92, 11.01.
C16H26O. Calculated, %: C 81.99; H 11.18.
1-Ethoxy-4-[1-(propan-2-yloxy)ethyl]benzene
1
(4k). H NMR spectrum, δ, ppm: 1.09 d and 1.15 d
[3H each, CH(CH3)2, J = 6.0 Hz], 1.38 d (3H, CHCH3,
J = 6.3 Hz), 1.44 t (3H, OCH2CH3, J = 6.8 Hz),
3.48 sept [1H, CH(CH3)2], 4.01 q (2H, OCH2CH3, J =
6.8 Hz), 4.45 q (1H, CHCH3, J = 6.3 Hz), 6.81 d (2H,
Harom, J = 9.2 Hz), 7.19 d (2H, Harom, J = 9.2 Hz).
Found, %: C 74.62, 74.81; H 9.33, 9.52. C13H20O2.
Calculated, %: C 74.96; H 9.68.
1-Cyclopropyl-4-(1-methoxyethyl)benzene (4e).
1H NMR spectrum, δ, ppm: 0.72 m (2H), 0.97 m (2H),
1.92 m (1H) (C3H5); 1.45 d (3H, CHCH3, J = 6.6 Hz),
3.23 s (3H, OCH3), 4.28 q (1H, CHCH3, J = 6.6 Hz),
7.07 d (2H, Harom, J = 8.0 Hz), 7.21 d (2H, Harom, J =
8.0 Hz). Found, %: C 81.22, 81.37; H 8.87, 8.94.
C12H16O. Calculated, %: C 81.77; H 9.15.
6-(1-Propoxyethyl)-2,3-dihydro-1,4-benzodioxine
(4m). 1H NMR spectrum, δ, ppm: 0.92 t (3H, CH2CH3,
J = 7.5 Hz), 1.36 d (3H, CHCH3, J = 6.4 Hz), 1.55 sext
(2H, CH2CH3, J = 7.5 Hz), 3.20 m (2H, CH2CH2CH3),
4.21 m (5H, OCH2CH2O, CHCH3), 6.69–6.76 m
(3H, Harom). Found, %: C 69.78, 69.92; H 7.91, 8.02.
C13H18O3. Calculated, %: C 70.24; H 8.16.
1-Cyclopropyl-4-(1-ethoxyethyl)benzene (4f).
1H NMR spectrum, δ, ppm: 0.71 m (2H), 0.96 m (2H),
1.91 m (1H) (C3H5); 1.21 t (3H, OCH2CH3, J =
7.6 Hz), 1.44 d (3H, CHCH3, J = 6.6 Hz), 3.35 q (2H,
OCH2, J = 7.6 Hz), 4.37 q (1H, CHCH3, J = 6.6 Hz),
7.06 d (2H, Harom, J = 8.2 Hz), 7.21 d (2H, Harom, J =
8.2 Hz). Found, %: C 81.63, 81.77; H 9.21, 9.31.
C13H18O. Calculated, %: C 82.06; H 9.53.
6-[(1-Octyloxy)ethyl]-2,3-dihydro-1,4-benzo-
1
dioxine (4n). H NMR spectrum, δ, ppm: 0.88 t (3H,
CH2CH3, J = 6.8 Hz), 1.21–1.33 m [10H, (CH2)5CH3],
1.39 d (3H, CHCH3, J = 6.4 Hz), 1.55 m (2H,
OCH2CH2CH2), 3.27 m (2H, CHOCH2), 4.25 s (4H,
OCH2CH2O), 4.27 q (1H, CHCH3, J = 6.4 Hz),
6.78 d.d (1H, Harom, J = 1.9, 8.4 Hz), 6.83 d (1H,
1-Cyclopropyl-4-[1-(propan-2-yloxy)ethyl]ben-
1
H
arom, J = 8.4 Hz), 6.84 d (1H, Harom, J = 1.9 Hz).
zene (4g). H NMR spectrum, δ, ppm: 0.73 m (2H),
Found, %: C 73.33, 73.56; H 9.32, 9.44. C18H28O3.
Calculated, %: C 73.93; H 9.65.
0.98 m (2H), 1.93 m (1H) (C3H5); 1.14 d and 1.19 d
[3H each, CH(CH3)2, J = 6.0 Hz], 1.43 d (3H, CHCH3,
J = 6.4 Hz), 3.53 sept [1H, OCH(CH3)2], 4.52 q (1H,
CHCH3, J = 6.4 Hz), 7.06 d (2H, Harom, J = 8.2 Hz),
7.24 d (2H, Harom, J = 8.2 Hz). Found, %: C 81.81,
82.03; H 9.41, 9.56. C14H20O. Calculated, %: C 82.30;
H 9.87.
6-[1-(Cyclohexyloxy)ethyl]-2,3-dihydro-1,4-
1
benzodioxine (4o). H NMR spectrum, δ, ppm: 1.15–
1.33 m (6H), 1.42 m (1H), 1.69 m (2H), 1.87 m (1H),
3.14 m (1H) (C6H11); 1.33 d (3H, CHCH3, J = 6.4 Hz),
4.20 s (4H, OCH2CH2O), 4.42 q (1H, CHCH3, J =
6.4 Hz), 6.71–6.77 m (3H, Harom). Found, %: C 72.81,
72.94; H 8.14, 8.26. C16H22O3. Calculated, %: C 73.25;
H 8.45.
1-(1-Ethoxyethyl)-4-(1-methylcyclopropyl)ben-
1
zene (4h). H NMR spectrum, δ, ppm: 0.75 m (2H),
0.90 m (2H) (C3H5); 1.22 t (3H, OCH2CH3, J =
7.2 Hz), 1.45 s (3H, CH3), 1.46 d (3H, CHCH3, J =
6.1 Hz), 3.38 q (2H, OCH2CH3, J = 7.2 Hz), 4.39 q
(1H, CHCH3, J = 6.1 Hz), 7.24 s (4H, Harom). Found,
%: C 81.73, 81.98; H 9.47, 9.63. C14H20O. Calculated,
%: C 82.30; H 9.87.
4-(1-Ethoxyethyl)-1,2-dimethoxybenzene (4p).
1H NMR spectrum, δ, ppm: 1.09 t (3H, OCH2CH3, J =
7.0 Hz), 1.31 d (3H, CHCH3, J = 6.4 Hz), 3.23 m (2H,
OCH2CH3), 3.76 s (3H, OCH3), 3.79 s (3H, OCH3),
4.21 q (1H, CHCH3, J = 6.4 Hz), 6.68 s (2H, Harom),
6.75 s (1H, Harom). Found, %: C 68.11, 68.23; H 8.31,
8.42. C12H18O3. Calculated, %: C 68.55; H 8.63.
1-Ethoxy-4-(1-propoxyethyl)benzene (4j).
1H NMR spectrum, δ, ppm: 0.93 t (3H, CH2CH2CH3,
J = 7.2 Hz), 1.42 d (3H, CHCH3, J = 6.2 Hz), 1.43 t
(3H, OCH2CH3, J = 6. 6 Hz), 1. 58 m (2H,
1,2-Dimethoxy-4-(1-propoxyethyl)benzene (4q).
1H NMR spectrum, δ, ppm: 0.81 t (3H, CH2CH3, J =
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MOCHALOV et al.
510
(2H, CH2CH3, J = 7.5 Hz), 3.65 sept [1H, CH(CH3)2],
4.71 q (1H, CHCH3, J = 6.0 Hz), 6.60 d and 6.72 d
(1H each, 3-H, 4-H, J = 4.4 Hz). Found, %: C 66.19,
66.32; H 8.89, 9.01. C11H18OS. Calculated, %:
C 66.62; H 9.15.
7.0 Hz), 1.27 d (3H, CHCH3, J = 6.2 Hz), 1.43 sext
(2H, CH2CH3, J = 7.0 Hz), 3.09 t (2H, OCH2, J =
6.9 Hz), 3.72 s (3H, OCH3), 3.75 s (3H, OCH3), 4.16 q
(1H, CHCH3, J = 6.2 Hz), 6.64 s (2H, Harom), 6.72 s
(1H, Harom). Found, %: C 69.16, 69.31; H 8.76, 8.81.
C13H20O3. Calculated, %: C 69.61; H 8.99.
1-[Cyclopropyl(ethoxy)methyl]-4-methoxyben-
1
zene (7a). H NMR spectrum, δ, ppm: 0.24 m (1H),
1,2-Dimethoxy-4-[1-(propan-2-yloxy)ethyl]ben-
1
0.44 m (2H), 0.62 m (1H), 1.15 m (1H) (C3H5); 1.21 t
(3H, OCH2CH3, J = 7.0 Hz), 3.38 m (2H, OCH2CH3),
3.62 d (1H, CHOCH2, J = 7.7 Hz), 3.81 s (3H, OCH3),
6.87 d (2H, Harom, J = 8.6 Hz), 7.24 d (2H, Harom, J =
8.6 Hz). Found, %: C 75.12, 75.38; H 8.48, 8.61.
C13H18O2. Calculated, %: C 75.69; H 8.79.
zene (4r). H NMR spectrum, δ, ppm: 0.97 d and
1.03 d [3H each, CH(CH3)2, J = 7.4 Hz), 1.26 d (3H,
CHCH3, J = 6.2 Hz), 3.36 sept [1H, OCH(CH3)2],
3.73 s (3H, OCH3), 3.77 s (3H, OCH3), 4.31 q (1H,
CHCH3, J = 6.2 Hz), 6.66 s (2H, Harom), 6.75 s (1H,
Harom). Found, %: C 69.07, 69.33; H 8.69, 8.79.
C13H20O3. Calculated, %: C 69.61; H 8.99.
1-[Cyclopropyl(propan-2-yloxy)methyl]-
1
1
2-(1-Ethoxyethyl)-5-methylfuran (4s). H NMR
4-methoxybenzene (7b). H NMR spectrum, δ, ppm:
spectrum, δ, ppm: 1.17 t (3H, OCH2CH3, J = 7.2 Hz),
1.47 d (3H, CHCH3, J = 6.6 Hz), 2.27 s (3H, CH3),
3.39 m and 3.45 m (1H each, OCH2CH3), 4.35 q (1H,
CHCH3, J = 6.6 Hz), 5.86 m (1H, 4-H), 6.06 d (1H,
3-H, J = 3.9 Hz). Found, %: C 69.83, 69.92; H 8.86,
8.95. C9H14O2. Calculated, %: C 70.10; H 9.15.
0.25 m (1H), 0.42 m (2H), 0.61 m (1H), 1.14 m (1H)
(C3H5); 1.11 d and 1.13 d [3H each, OCH(CH3)2, J =
7.6 Hz], 3.51 sept [1H, CH(CH3)2], 3.71 d [1H,
CHOCH(CH3)2, J = 7.7 Hz], 3.82 s (3H, OCH3),
6.87 d (2H, Harom, J = 8.8 Hz), 7.25 d (2H, Harom, J =
8.8 Hz). Found, %: C 75.91, 76.02; H 8.88, 8.97.
C14H20O2. Calculated, %: C 76.32; H 9.15.
5-Methyl-2-[1-(propan-2-yloxy)ethyl]furan (4t).
1H NMR spectrum, δ, ppm: 1.08 d and 1.14 d [3H
each, CH(CH3)2, J = 6.2 Hz], 1.44 d (3H, CHCH3,
J = 6.3 Hz), 2.26 s (3H, 5-CH3), 3.62 sept [1H,
CH(CH3)2], 4.45 q (1H, CHCH3, J = 6.3 Hz), 5.85 m
(1H, 4-H), 6.05 d (1H, 3-H, J = 3.9 Hz). Found, %:
C 71.09, 71.17; H 9.35, 9.47. C10H16O2. Calculated, %:
C 71.39; H 9.59.
6-(1-Propoxypropyl)-2,3-dihydro-1,4-benzodi-
1
oxine (7c). H NMR spectrum, δ, ppm: 0.88 t (3H,
CH2CH2CH3, J = 7.2 Hz), 0.92 t (3H, CH2CH3, J =
7.2 Hz), 1.56 q (2H, CH2CH3, J = 7.2 Hz), 1.58 m and
1.73 m (1H each, OCH2CH2CH3), 3.14 m and 3.25 m
(1H each, OCH2CH2CH3), 3.93 t (1H, CHOCH2, J =
6.0 Hz), 4.21 s (4H, OCH2CH2O), 6.68 d (1H, J =
9.1 Hz), 6.73 s (1H, Harom), 6.75 d (1H, Harom, J =
9.1 Hz). Found, %: C 70.78, 70.91; H 8.22, 8.36.
C14H20O3. Calculated, %: C 71.16; H 8.53.
2-Ethyl-5-(1-methoxyethyl)thiophene (4u).
1H NMR spectrum, δ, ppm: 1.31 t (3H, CH2CH3, J =
7.6 Hz), 1.51 d (3H, CHCH3, J = 6.6 Hz), 2.82 d.q
(2H, CH2CH3), 3.24 s (3H, OCH3), 4.45 q (1H,
CHCH3, J = 6.6 Hz), 6.59 d and 6.72 d (1H each, 3-H,
4-H, J = 4.3 Hz). Found, %: C 63.11, 63.31; H 7.98,
8.14. C9H14OS. Calculated, %: C 63.48; H 8.29.
6-[1-(2-Methylpropan-1-yloxy)propyl]-2,3-dihy-
1
dro-1,4-benzodioxine (7d). H NMR spectrum, δ,
ppm: 0.89 t (3H, CH2CH3, J = 7.1 Hz), 0.90 d and
0.92 d [3H, CH(CH3)2, J = 6.3 Hz], 1.61 m [1H,
CH(CH3)3], 1.74 m and 1.82 m (1H each, CH2CH3),
2.95 m and 3.08 m (1H each, OCH2), 3.93 t (1H,
CHCH2CH3, J = 6.8 Hz), 4.22 s (4H, OCH2CH2O),
2-(1-Ethoxyethyl)-5-ethylthiophene (4v).
1H NMR spectrum, δ, ppm: 1.20 t (3H, OCH2CH3, J =
7.0 Hz), 1.32 t (3H, CH2CH3, J = 7.6 Hz), 1.53 d
(3H, CHCH3, J = 6.3 Hz), 2.82 q (2H, CH2CH3, J =
7.6 Hz), 3.38 m and 3.47 m (1H each, OCH2CH3),
4.58 q (1H, CHCH3, J = 6.3 Hz), 6.61 d and 6.72 d
(1H each, 3-H, 4-H, J = 4.3 Hz). Found, % C 64.78,
64.92; H 8.56, 8.61. C10H16OS. Calculated, %:
C 65.17; H 8.75.
6.69 d.d (1H, Harom, J = 1.8, 8.2 Hz), 6.73 d (1H, Harom
,
J = 1.8 Hz), 6.76 d (1H, Harom, J = 8.2 Hz). Found, %:
C 71.56, 71.71; H 8.58, 8.69. C15H22O3. Calculated, %:
C 71.97; H 8.86.
6-[Cyclopropyl(propoxy)methyl]-2,3-dihydro-
1
1,4-benzodioxine (7f). H NMR spectrum, δ, ppm:
2-Ethyl-5-[1-(propan-2-yloxy)ethyl]thiophene
(4w). H NMR spectrum, δ, ppm: 1.14 d and 1.17 d
[3H each, CH(CH3)2, J = 6.0 Hz], 1.33 t (3H, CH2CH3,
J = 7.5 Hz), 1.51 d (3H, CHCH3, J = 6.4 Hz), 2.82 q
0.25 m (1H), 0.42 m (2H), 0.56 m (1H), 1.08 m (1H)
(C3H5); 0.92 t (3H, CH2CH3, J = 7.5 Hz), 1.57 sext
(2H, CH2CH3, J = 7.5 Hz), 3.22 m and 3.26 m (1H
each, CHOCH2), 3.56 d (1H, CHOCH2, J = 6.4 Hz),
1
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DIRECT SYNTHESIS OF ETHERS FROM ALDEHYDES AND KETONES.
511
4.23 s (4H, OCH2CH2O), 6.73–6.78 m (3H, Harom).
Found, %: C 72.03, 72.21; H 7.89, 7.96. C15H20O3.
Calculated, %: C 72.55; H 8.12.
OCH2CH3, J = 7.1 Hz), 3.48 q (2H, OCH2CH3, J =
7.1 Hz), 3.78 s (3H, OCH3), 3.79 s (3H, OCH3), 5.24 s
(1H, CHOCH2), 6.73 d (1H, Harom, J = 8.2 Hz),
6.80 d.d (1H, Harom, J = 8.2, 1.6 Hz), 6.83 d (1H, Harom
,
6-[Cyclopropyl(propan-2-yloxy)methyl]-2,3-di-
hydro-1,4-benzodioxine (7g). H NMR spectrum, δ,
1
J = 1.6 Hz), 7.17 m (1H, Harom), 7.23–7.33 m (4H,
Harom). Found, %: C 74.58, 74.71; H 7.02, 7.14.
C17H20O3. Calculated, %: C 74.97; H 7.40.
ppm: 0.25 m (1H), 0.36 m (2H), 0.49 m (1H), 1.01 m
(1H) (C3H5); 1.04 d and 1.06 d [3H each, CH(CH3)2,
J = 6.0 Hz]; 3.43 sept [1H, OCH(CH3)2], 3.63 d [1H,
CHOCH(CH3)2, J = 6.7 Hz], 4.20 s (4H, OCH2CH2O),
6.70–6.74 m (3H, Harom). Found, %: C 72.11, 72.33;
H 7.85, 8.01. C15H20O3. Calculated, %: C 72.55;
H 8.12.
1,2-Dimethoxy-4-[phenyl(propan-2-yloxy)-
1
methyl]benzene (11b). H NMR spectrum, δ, ppm:
1.21 d and 1.23 d [3H each, CH(CH3)2, J = 6.8 Hz],
3.65 sept [1H, OCH(CH3)2], 3.83 s (3H, OCH3), 3.84 s
(3H, OCH3), 5.37 s [1H, CHOCH(CH3)2], 6.75 d
(1H, Harom, J = 8.2 Hz), 6.81 d.d (1H, Harom, J = 8.2,
1.6 Hz), 6.83 d (1H, Harom, J = 1.6 Hz), 7.18 m
(1H, Harom), 7.24–7.30 m (4H, Harom). Found, %:
C 74.96, 75.12; H 7.48, 7.62. C18H22O3. Calculated, %:
C 75.50; H 7.74.
6-(2-Phenyl-1-propoxyethyl)-2,3-dihydro-1,4-
1
benzodioxine (7h). H NMR spectrum, δ, ppm: 0.84 t
(3H, CH2CH3, J = 7.5 Hz), 1.51 sext (2H, CH2CH3,
J = 7.5 Hz), 2.79 d.d (1H, J = 13.9, 5.2 Hz) and
2.98 d.d (1H, J = 13.9, 7.0 Hz) (CH2Ph), 3.06 m and
3.25 m (1H each, CHOCH2), 4.20 s (4H, OCH2CH2O),
6-[(4-Methylphenyl)(pentyloxy)methyl]-2,3-dihy-
1
4.21 t (1H, CHOCH2, J = 6.6 Hz), 6.63 d.d (1H, Harom
,
dro-1,4-benzodioxine (11f). H NMR spectrum, δ,
J = 8.0, 1.8 Hz), 6.77 d (1H, Harom, J = 1.8 Hz), 6.78 d
(1H, Harom, J = 8.0 Hz), 7.17 m (3H, Harom), 7.22 m
(2H, Harom). Found, %: C 76.01, 76.16; H 7.08, 7.16.
C19H22O3. Calculated, %: C 76.48; H 7.43.
ppm: 1.03 t (3H, CH2CH3, J = 7.2 Hz), 1.38–1.55 m
(4H, CH2CH2CH3), 1.72 m (2H, CH2CH2CH2CH3),
2.42 s (3H, CH3), 3.49 m (2H, CHOCH2), 4.23 s
(4H, OCH2CH2O), 5.24 s (1H, CHOCH2), 6.84 s (2H,
H
arom), 6.90 s (1H, Harom), 7.17 d (2H, Harom, J =
6-[1-(2-Methylpropan-1-yloxy)-2-phenylethyl]-
2,3-dihydro-1,4-benzodioxine (7i). H NMR spec-
1
8.0 Hz), 7.28 d (2H, Harom, J = 8.0 Hz). Found, %:
C 76.87, 77.01; H 7.72, 7.84. C21H26O3. Calculated, %:
C 77.27; H 8.03.
trum, δ, ppm: 0.88 d [6H, CH(CH3)2, J = 6.4 Hz],
1.82 sept [1H, CH(CH3)2], 2.87 d.d (1H, J = 14.0,
5.2 Hz) and 2.92 d.d (1H, J = 14.0, 7.1 Hz) (CH2Ph),
3.05 m and 3.11 m (1H each, CHOCH2), 4.26 s (4H,
OCH2CH2O), 4.27 t (1H, CHOCH2, J = 7.6 Hz),
6-[Ethoxy(4-fluorophenyl)methyl]-2,3-dihydro-
1
1,4-benzodioxine (11g). H NMR spectrum, δ, ppm:
1.32 t (3H, OCH2CH3, J = 7.2 Hz), 3.54 m (2H,
OCH2CH3), 4.22 s (4H, OCH2CH2O), 5.24 s (1H,
CHOCH2), 6.81 d.d (1H, Harom, J = 8.0, 1.6 Hz), 6.83 d
(1H, Harom, J = 8.0 Hz), 6.87 d (1H, Harom, J = 1.6 Hz),
7.02 t (2H, Harom, J = 8.4, JFH = 8.4 Hz), 7.34 d.d
(2H, Harom, J = 8.4, JFH = 5.3 Hz). Found, %: C 70.36,
70.58; H 5.67, 5.78. C17H17FO3. Calculated, %:
C 70.82; H 5.94.
6.69 d.d (1H, Harom, J = 8.1, 1.8 Hz), 6.77 d (1H, Harom
,
J = 1.8 Hz), 6.78 d (1H, Harom, J = 8.1 Hz), 7.17 m
(3H, Harom), 7.24 m (2H, Harom). Found, %: C 76.41,
76.62; H 7.52, 7.61. C20H24O3. Calculated, %: C 76.89;
H 7.74.
7-(2-Phenyl-1-propoxyethyl)-3,4-dihydro-2H-
1
1,5-benzodioxepine (7j). H NMR spectrum, δ, ppm:
0.85 t (3H, CH2CH3, J = 7.5 Hz), 1.53 sext (2H,
CH2CH3, J = 7.5 Hz), 2.21 quint (2H, 3-H, J = 5.6 Hz),
2.85 d.d (1H, J = 14.9, 6.0 Hz) and 3.09 d.d (1H, J =
14.9, 8.4 Hz) (CH2Ph), 3.15 m (1H) and 3.31 m (1H
each, CHOCH2), 4.23 t (4H, 2-H, 4-H, J = 6.0 Hz),
4.33 t (1H, CHOCH2, J = 6.4 Hz), 6.82 d.d (1H,
6-[(4-Fluorophenyl)(propoxy)methyl]-2,3-dihy-
dro-1,4-benzodioxine (11h). H NMR spectrum, δ,
1
ppm: 1.04 t (3H, CH2CH3, J = 7.3 Hz), 1.71 sext (2H,
CH2CH3, J = 7.3 Hz), 3.42 m (2H, CHOCH2), 4.23 s
(4H, OCH2CH2O), 5.22 s (1H, CHOCH2), 6.78 d.d
(1H, Harom, J = 8.1, 1.6 Hz), 6.81 d (1H, Harom, J =
8.1 Hz), 6.85 d (1H, Harom, J = 1.6 Hz), 7.02 t (2H,
Harom, J = 8.4, JFH = 8.4 Hz), 7.33 d.d (2H, Harom, J =
8.4, JFH = 5.4 Hz). Found, %: C 70.92, 71.18; H 6.04,
6.17. C18H19FO3. Calculated, %: C 71.51; H 6.33.
Harom, J = 8.2, 2.2 Hz), 6.90 d (1H, Harom, J = 2.2 Hz),
6.94 d (1H, Harom, J = 8.2 Hz), 7.16 m (2H, Harom),
7.21 m (1H, Harom), 7.26 m (2H, Harom). Found, %:
C 76.33, 76.71; H 7.43, 7.57. C20H24O3. Calculated, %:
C 76.89; H 7.74.
6-Bromo-7-[(propan-2-yloxy)(thiophen-2-yl)-
methyl]-2,3-dihydro-1,4-benzodioxine (11i).
1H NMR spectrum, δ, ppm: 1.25 d and 1.29 d [3H
4-[Ethoxy(phenyl)methyl]-1,2-dimethoxyben-
1
zene (11a). H NMR spectrum, δ, ppm: 1.26 t (3H,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 4 2016

MOCHALOV et al.
512
each, CH(CH3)2, J = 6.4 Hz], 3.72 sept [1H,
OCH(CH3)2], 4.24 s (4H, OCH2CH2O), 5.99 s [1H,
CHOCH(CH3)2], 6.85 d.d (1H, 3′-H, J = 3.8, 1.2 Hz),
6.90 d.d (1H, 4′-H, J = 5.1, J = 3.8 Hz), 7.05 s (1H,
CH2OCH2CH3), 5.12 s (2H, PhCH2), 7.02 d (2H,
arom, J = 8.5 Hz), 7.34 d (2H, Harom, J = 8.5 Hz),
7.38 t (1H, Harom, J = 7.6 Hz), 7.44 t (2H, Harom, J =
7.6 Hz), 7.50 d (2H, Harom, J = 7.6 Hz). Found, %:
C 78.95, 79.11; H 7.21, 7.32. C16H18O2. Calculated, %:
C 79.31; H 7.49.
H
H
arom), 7.17 s (1H, Harom), 7.22 d.d (5′-H, J = 5.1,
1.2 Hz). Found, %: C 51.55, 51.71; H 4.31, 4.47.
C16H17BrO3S. Calculated, %: C 52.04; H 4.64.
This study was performed under financial support
by the Council for Grants at the President of the
Russian Federation (project no. NSh 5130.2014.3/2015).
1-(Ethoxymethyl)-4-methoxybenzene (14b).
1H NMR spectrum, δ, ppm: 1.25 t (3H, OCH2CH3, J =
7.0 Hz), 3.50 q (2H, OCH2CH3, J = 7.0 Hz), 3.79 s
(3H, OCH3), 4.42 s (2H, CH2OEt), 6.84 d (2H, Harom
,
REFERENCES
J = 8.4 Hz), 7.24 d (2H, Harom, J = 8.4 Hz). Found, %:
C 71.88, 72.02; H 8.21, 8.32. C10H14O2. Calculated, %:
C 72.26; H 8.49.
1. Greene, T.W. and Wuts, P.G.M., Protective Groups in
Organic Synthesis, New York: Wiley, 1999, 3rd ed.,
p. 76.
1-Methoxy-4-[(propan-2-yloxy)methyl]benzene
2. Boyer, B., Keramane, E-M., Roque, J-P., and
1
(14c). H NMR spectrum, δ, ppm: 1.24 d [6H,
Pavia, A.A., Tetrahedron Lett., 2000, vol. 41, p. 2891.
OCH(CH3)2, J = 7.4 Hz], 3.70 sept [1H, OCH(CH3)2],
3.82 s (3H, OCH3), 4.48 s (2H, CH2OCH), 6.91 d (2H,
3. Yu, J.-L., Wang, H., Zou, K.-F., Zhang, J.-R., Gao, X.,
Zang, D.-W., and Li, Z.-T., Tetrahedron, 2013, vol. 69,
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Jesse, K.A., Hamilton, R.E., Shattuck, M.A., Hu, A.C.,
Lafe, R.G., and Wenzel, A.G., Synlett, 2015, vol. 26,
p. 765.
H
arom, J = 8.5 Hz), 7.31 d (2H, Harom, J = 8.5 Hz).
Found, %: C 72.93, 73.06; H 8.71, 8.79. C11H16O2.
Calculated, %: C 73.30; H 8.95.
1-Ethoxy-4-(methoxymethyl)benzene (14d).
1H NMR spectrum, δ, ppm: 1.44 t (3H, OCH2CH3, J =
6.7 Hz), 3.34 s (3H, OCH3), 4.01 q (2H, OCH2CH3,
J = 6.7 Hz), 4.37 s (2H, CH2OCH3), 6.82 d (2H, Harom
,
J = 8.5 Hz), 7.21 d (2H, Harom, J = 8.5 Hz). Found, %:
C 71.93, 72.11; H 8.19, 8.33. C10H14O2. Calculated, %:
C 72.26; H 8.49.
6. Iwanami, K., Seo, H., Tobita, Y., and Oriyama, T.,
Synthesis, 2005, no. 2, p. 183.
7. Zaccheria, F., Psaro, R., and Ravasio, N., Tetrahedron
Lett., 2009, vol. 50, p. 5221.
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Thomson, J.E., Org. Lett., 2012, vol. 14, p. 4278.
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Mamedov, F.N., Prisadki Smaz. Maslam, 1969, no. 2,
p. 108.
1-Ethoxy-4-[(propan-2-yloxy)methyl]benzene
1
(14e). H NMR spectrum, δ, ppm: 1.24 d [6H,
OCH(CH3)2, J = 6.6 Hz], 1.44 t (3H, OCH2CH3, J =
7.0 Hz), 3.71 sept [1H, OCH(CH3)2], 4.05 q (2H,
OCH2CH3, J = 7.0 Hz), 4.47 s (2H, CH2OCH), 6.89 d
(2H, Harom, J = 8.5 Hz), 7.28 d (2H, Harom, J = 8.5 Hz).
Found, %: C 73.81, 73.96; H 9.03, 9.11. C12H18O2.
Calculated, %: C 74.19; H 9.34.
1
1-(Benzyloxy)-4-ethoxybenzene (14f). H NMR
spectrum, δ, ppm: 1.31 t (3H, OCH2CH3, J = 7.4 Hz),
3.58 q (2H, OCH2CH3, J = 7.4 Hz), 4.51 s (2H,
12. Bettoni, M., J. Phys. Org. Chem., 2005, vol. 19, p. 18.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 4 2016