One-pot ester synthesis from allyl and benzyl halides and alcohols by palladium-catalyzed carbonylation

Article abstract of DOI:10.1055/s-0031-1289659

A mild and efficient one-pot synthesis of esters based on the Pd-catalyzed alkoxy- and aryloxycarbonylation of allylic and benzylic halides is described. The methodology has been applied to primary, secondary, and tertiary alcohols as well as to phenol derivatives. The O-protection of some biologically relevant molecules is also reported. Georg Thieme Verlag Stuttgart New York.

Full text of DOI:10.1055/s-0031-1289659

PAPER
423
One-Pot Ester Synthesis from Allyl and Benzyl Halides and Alcohols by
Palladium-Catalyzed Carbonylation
Sara Tommasi, Serena Perrone, Francesca Rosato, Antonio Salomone, Luiginio Troisi*
Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, University of Salento, via Prov. le Lecce-Monteroni, 73100 Lecce, Italy
Fax +39(0832)298732; E-mail: luigino.troisi@unisalento.it
Received 13 October 2011; revised 23 November 2011
Palladium(0)-catalyzed carbonylation using carbon mon-
Abstract: A mild and efficient one-pot synthesis of esters based on
oxide and various aryl iodides with polymer-supported
the Pd-catalyzed alkoxy- and aryloxycarbonylation of allylic and
benzylic halides is described. The methodology has been applied to
primary, secondary, and tertiary alcohols as well as to phenol deriv-
atives. The O-protection of some biologically relevant molecules is
also reported.
primary and secondary alcohols is also known9
(Scheme 3).
O
O
R2
I
Key words: alcohols, allyl halides, benzyl halides, esterification,
Pd-catalysis
R3
R2
R3
CO, Pd(PPh3)4
base, DMF
+
HO
R1
R1
Esters are widely found among all naturally occurring
compounds, and they are also significantly important in-
termediates in organic synthesis.1 The ester bond is one of
the most common linkages in organic chemistry and could
be formed by different strategies using acids,2 anhydrides,3
or acyl chlorides4 with alcohols as starting substrates. The
reactions proceed with or without the help of a base or an
acid and also with5 or without6 a metallic catalysis. Palla-
dium is one of the most common metals used as a catalyst
in these reactions. A rapid palladium-catalyzed synthesis
of esters from aryl halides utilizing Mo(CO)6 as a solid
carbon monoxide source has been reported (Scheme 1).7
Scheme 3
As reported in our previous work,10 an allyl or a benzyl
halide, in THF, under the pressure of CO and in the pres-
ence of Pd(0), produces an acylpalladium halide, which
can be deprotonated in the a-position by a tertiary amine,
and in the presence of imines incurs a [2+2] cycloaddition
(Scheme 4).
O
X
N
O
OR2
Ar1
Ar2
X
Mo(CO)6, [Pd]
Pd(0)
R2OH
Ar2
+
150–190 °C
15–20 min
microwaves
N
R1
R1
Ar1
Scheme 1
PdX
PdX
According to Zim et al., a regioselective synthesis of 2-
arylpropionic esters can be achieved by palladium-cata-
lyzed hydroesterification of styrene derivatives in ionic
liquid (MBI·BF4)8 (Scheme 2).
O
PdX
Et3N
O
CO
PdCl2(PhCN)2
(+)-NMDPP
X = Cl, Br
Ar
Ar
Oi-Pr
Ar
CO2i-Pr
+
MBI⋅BF4, TsOH
CO (10 atm), 70 °C
cyclohexane, 20 h
+
89%
1%
CO2i-Pr
Scheme 4
i-PrOH
+
Ar
<1%
The reaction occurs with a variety of different allyl and
benzyl halides, and gives the possibility to produce many
differently substituted and functionalized b-lactams.10
The production of the acylpalladium halide in this catalyt-
ic system prompted us to investigate about the possibility
of using it in the acylation of functions such as NH, OH,
Scheme 2
SYNTHESIS 2012, 44, 423–430
Advanced online publication: 29.12.2011
DOI: 10.1055/s-0031-1289659; Art ID: Z97311SS
x
x
.x
x
.2
0
1
1
© Georg Thieme Verlag Stuttgart · New York

424
S. Tommasi et al.
PAPER
SH, and ≡CH. Surely protection of one of this group is of- attention was directed toward the synthesis of cholesteryl
ten relevant in the success of a more complex synthesis of esters as interesting targets for their structural and bio-
an organic compound. Thus, it became possible to trans- chemical connection with membrane phospholipids and
form aliphatic or aromatic, primary or secondary amines their potential roles in cardiovascular health.12 Significant
into amides of different structure using appropriate allyl results were obtained in the acylation of cholesterol that,
or benzyl halides (Scheme 5).11
in the same reaction conditions, was transformed into es-
ters trans-4a, cis-4a and 4b, with a consequent increase in
lipophilicity; the isomeric distribution, after 15 hours, was
found to be slightly in favor of the g,d-unsaturated ester
4b (Table 1, entry 7).
R1
H
N
R2
Et3N
R1, R2 = H, alkyl, aryl
O
O
R1
PdX
N
R2
When the reaction was carried out on 1,2:5,6-di-O-isopro-
pylidene-a-D-glucofuranose in the same time (15 h) and
reaction conditions mentioned above, only the isomers
with the conjugate C=C bond trans- and cis-5a (ratio
55:45) were formed (Table 1, entry 8). After examining
the reactivity of aliphatic alcohols, we next turned our at-
tention to the reactions of phenols and polyhydroxylated
aromatic compounds. By performing the reaction under
the already mentioned conditions, phenol too was smooth-
ly acylated; interestingly, only the isomerized products,
trans-6a and cis-6a were formed in 12 hours and in high
yields (99%) (trans/cis ratio: 75:25, Table 1, entry 9).
Phenoxy function favors the migration of the C=C bond to
the a-position, even more than alkoxy group, probably be-
cause of the favorable formation of highly conjugated
products.
Scheme 5
We envisaged that the same methodology of reaction
could be applied to other compounds such as alcohols and
the results of this investigation are reported in this article.
In order to investigate such a hypothesis, the following ex-
periment was carried out: n-butanol (1.0 mmol), allyl
chloride (1.2 mmol), Pd(OAc)2 (0.02 mmol), Ph3P (0.08
mmol), and Et3N (2.0 mmol) were dissolved in THF (15
mL); the mixture was placed in an autoclave, pressurized
with CO (400 psi), and heated to 100 °C under magnetic
stirring for about 10 hours. After this time, more than 90%
of the alcohol had reacted and then the solvent was evap-
orated under reduced pressure. Products were isolated by
column chromatography on silica gel and fully character-
ized by 1H NMR, 13C NMR, FT-IR, and GC-MS analysis
(Scheme 6).
Therefore, the methodology was applied to phenolic sub-
strates of biological interest. 4-Methylcatechol, in the
same reaction conditions underwent acylation at both oxy-
gens producing compounds trans- and cis-7a, and regio-
isomeric compounds trans- and cis-8a to a similar extent.
For all isomers, the double bonds are located in conjugat-
ed position and the ratio trans/cis was found to be about
70:30 in both cases (Table 1, entry 10). Traces of doubly
acylated product were also observed by GC-MS analysis.
However, when an excess of allyl chloride was used (3.0
mmol) the double acylation was complete and a mixture
of trans,trans-9a, trans,cis-9a, cis,trans-9a, and cis,cis-
9a, resolved by column chromatography on silica gel, was
obtained (Table 1, entry 11).
n-BuOOC
n-BuOH
1a
Et3N, THF, 100 °C
+
+
Ph3P, Pd(OAc)2
CO (400 psi)
Cl
n-BuOOC
1b
Scheme 6
It was found that n-butanol had been transformed to the
expected ester 1b beside two other isomeric esters trans-
1a and cis-1a. The origin of such products could be attrib-
uted to the migration of C=C bond to the position conju-
gated with the carbonyl group. The undesired
isomerization could be due to the increased stability of
conjugated alkenes cis- and trans-1a with respect to the
terminal alkene 1b (Table 1, entry 1). The isomer distribu-
tion is influenced by the heating time; in fact, if the reac-
tion mixture was heated for 20 hours a major percentage
of the conjugated esters trans-1a and cis-1a was obtained
(Table 1, entry 2). The same trend was observed for sec-
butyl alcohol and tert-butyl alcohol in forming trans-2a,
cis-2a, 2b and trans-3a, cis-3a, 3b, respectively (Table 1,
entries 3–6), with the trans/cis ratio being nearly to 7:1 at
longer reaction times.
Phenolic group seems to be more reactive than alcoholic
one; thus, when tyrosol was treated with allyl chloride
(1.2 mmol) for 12 hours acylation occurred only at the
phenolic oxygen and the ratio 10a/10b was near to 95:5,
while the ratio trans-10a/cis-10a was 82:13 (Table 1, en-
try 12). Even in this case, traces of double acylation were
visible by GC-MS. A very similar behavior occurred with
4-hydroxybenzyl alcohol: when allyl chloride was used in
slight excess (1.2 mmol) mainly the isomers trans-11a
and cis-11a were obtained, 78% and 19%, respectively,
and 11b only in 3% (Table 1, entry 13). In contrast, when
allyl chloride was used in large quantities (3.0 mmol),
only the isomers trans-12a and cis-12a, with both hy-
droxy groups functionalized, were formed (Table 1, entry
14). It is worth mentioning that the double bond shift has
been noticed only for the acylic moiety bonded to the phe-
nolic oxygen and never on the other unsaturated chain
bonded to the aliphatic hydroxy group. The ratio trans-
The applicability of this method has been verified on more
complex alcoholic substrates of biological interest. Our
Synthesis 2012, 44, 423–430
© Thieme Stuttgart · New York

PAPER
One-Pot Conversion of Allyl and Benzyl Halides into Esters
425
12a/cis-12a (doubly acetylated product) is slightly influ- lated and GC-MS analysis showed the presence of 12 iso-
enced by the excess of allyl chloride. Finally, hydroxyty- meric products, all having the same molecular weight
rosol was subjected to acylation using an excess of allyl (Table 1, entry 15). Unfortunately, the mixture was very
chloride (5.0 mmol): the three OH functions were all acy- difficult to separate by column chromatography on silica
Table 1 Ester Synthesis by Pd-Catalyzed Alkoxy- and Aryloxycarbonylation of Allyl Chloride
Et3N, THF, 100 °C
Cl
+
+
RO2C
RO2C
RO2C
1b–13b
ROH
+
Ph3P, Pd(OAc)2
CO (400 psi)
trans-1a–13a
cis-1a–13a
Entry
ROH
Allyl chloride Time
Total yield Conjugated alkene
Non-conjugated
(equiv)
(h)
(%)a
1a-13a (%)b
alkene 1b-13b (%)b
1
2
3
4
5
6
n-BuOH
n-BuOH
s-BuOH
s-BuOH
t-BuOH
t-BuOH
1.2
1.2
1.2
1.2
1.2
1.2
10
20
10
20
10
20
75
77
68
68
60
58
trans-1a (10)/cis-1a (2)
trans-1a (70)/cis-1a (10)
trans-2a (12)/cis-2a (4)
trans-2a (75)/cis-2a (8)
trans-3a (8)/cis-3a (4)
trans-3a (65)/cis-3a (8)
1b (88)
1b (20)
2b (84)
2b (17)
3b (88)
3b (27)
R1
7c
15
15
56
58
trans-4a (33)/cis-4a (12)
4b (55)
1.2
1.2
HO
O
O
O
8
trans-5a (55)/cis-5a (45)
trans-6a (75)/cis-6a (25)
–
O
O
HO
OH
9
12
15
99
99
–
–
1.2
1.2
OH
trans-7a (36)/cis-7a (14)
trans-8a (34)/cis-8a (16)
10
OH
trans,trans-9a (45)
trans,cis-9a (21)
cis,trans-9a (24)
cis,cis-9a (10)
OH
11
3.0
17
99d
–
OH
OH
12
13
14
1.2
1.2
3.0
12
12
15
99
99
99
trans-10a (82)/cis-10a (13)e
trans-11a (78)/cis-11a (19)e
trans-12a (88)/cis-12a (12)d
10b (5)f
11b (3)f
–
HO
HO
OH
OH
HO
HO
HO
15
OH
5.0
17
99g
13a
13b (10)
a Isolated yields after column chromatography.
b Calculated by GC-MS analysis of the crude reaction mixture.
c R1 = isohexyl.
d Mixture of doubly acylated isomeric products.
e cis/trans stereochemistry refers to the but-2-enoyl moiety bonded to phenolic oxygen.
f Not isolated.
g Mixture of 12 isomeric products.
© Thieme Stuttgart · New York
Synthesis 2012, 44, 423–430

426
S. Tommasi et al.
PAPER
Table 2 Esters Synthesis by Pd-Catalyzed Alkoxy- and Aryloxycarbonylation of Benzylic and Allylic Chlorides
O
O
R2
CO (400 psi), Pd(OAc)2
Et3N, Ph3P, THF, 100 °C
R1O
16a, 17a
R3
+
R1O
14–17b
R2
Cl
R1OH
+
Entry
R1
R2
Time
(h)
Yield
(%)a
Conjugated alkenes
Nonconjugated alkenes
16a, 17a (%)b
14–17b (%)b
Ph
COOn-Bu
COOt-Bu
1
2
n-Bu
t-Bu
Ph
Ph
20
68
55
–
14
Ph
20
10
–
15
COOPh
COOPh
3
4
Ph
Ph
95
90
16a (trans/cis = 25:12)
16b (63)
17b (45)
COOPh
COOPh
10
17a (55)
a Isolated yields after column chromatography.
b Calculated by GC analysis of the crude reaction mixture.
gel and only the triester 13b, with all the C=C double its use in substitution of other less advantageous reactions,
bonds not conjugated with the carbonyl moiety, was iso- especially on substrates particularly sensible to more dras-
lated. This result is very important because the polyester tic conditions.
13b, easily obtained with the described methodology, is a
rather stable molecule in contrast to the parent substrate
Et3N, Pd(OAc)2, Ph3P, and all other chemicals used are commer-
that, according to Gambacorta et al., is very susceptible to
degradation, because of an intrinsic instability to air and
silica.13 In contrast, the ester 13b can be stored, unaffect-
ed, at room temperature for months.
cially available and were used without further purification. THF
was purified by distillation from sodium/benzophenone, under N2
atmosphere, before use. Petroleum ether (PE) refers to the fraction
boiling at 40–60 °C. The 1H and the 13C NMR spectra were record-
ed with a Bruker Avance 400 spectrometer (400.13 and 100.62
MHz, for 1H and 13C, respectively) with CDCl3 as the solvent and
TMS as an internal standard (d = 7.26 ppm for 1H spectra; d = 77.0
On the basis of the data reported here and by considering
our previous knowledge, the probable reaction mecha-
nism for the palladium-catalyzed alkoxycarboylation of ppm for 13C spectra). The IR spectra were recorded with an FT-IR
spectrophotometer Digilab Scimitar Series FTS 2000. GC-MS anal-
alcohols and phenols could be similar to that one reported
yses were performed with an Agilent Technologies 6850 series II
for amines (Scheme 4).
gas chromatograph (5% phenylpolymethylsiloxane capillary col-
Various allylic and benzylic chlorides have been also used
for the acylation reaction (Table 2). In particular, benzyl
chloride reacting with n-butanol and tert-butyl alcohol
produced esters 14 and 15, respectively (Table 2, entries
1, 2); while phenol, reacting with 1-chloro-3-methylbut-
2-ene and 3-chloro-2-methylpropene gave, in good yields,
compounds trans-16a, cis-16a, 16b and 17a, 17b, respec-
tively (Table 2, entries 3, 4).
umn, 30 m, 0.25 mm i.d.), equipped with a 5973 Network mass-se-
lective detector operating at 70 eV. Melting points were determined
with an Electrothermal melting point apparatus and are uncorrected.
TLC was performed on Merck silica gel plates with F-254 indicator;
viewing was by UV light (254 nm). Column chromatography was
performed on silica gel (63–200 mm) using PE–Et2O mixture as
eluent. All reactions involving air-sensitive reagents were per-
formed under an atmosphere of N2 in oven-dried glassware by using
syringe/septum cap techniques. Spectroscopic data of compounds
trans- and cis-1a,14 1b,15 trans- and cis-2a,16 2b,17 trans-3a,18 cis-
3a,19 3b,15 trans-6a,20 cis-6a,21 14,22 15,23 17a,20 and 17b24 have
been reported.
Moreover, we verified that all reactions reported here pro-
ceed in a very similar manner by starting from allyl and
benzyl bromide; because of negligible differences it was
considered unnecessary to report these data. Instead, we
proved that the methodology is not effective when alkyl or
aryl halides are used in the reaction with alcohols or phe-
nols.
Palladium-Catalyzed Synthesis of Esters; General Procedure
A solution of alcohol (1.0 mmol), allylic or benzylic halide (1.2
mmol or an excess when required, see Table 1), Pd(AcO)2 (4 mg,
2% mmol), Ph3P (21 mg, 0.08 mmol), and Et3N (202 mg, 2.0 mmol)
in THF (10 mL) was placed in a 45 mL autoclave. The autoclave
was purged, pressurized with CO (400 psi), and then heated at
100 °C, under magnetic stirring, for 10–20 h. After this time, the so-
lution was cooled to r.t. and the solvent was removed under reduced
pressure to give the crude material. The crude mixture was then pu-
rified by chromatography on silica gel (PE–Et2O, 90:10–97:3) to af-
ford the corresponding ester (Tables 1 and 2).
In conclusion, our methodology represents a useful way
of protection of alcoholic and phenolic functions by using
several allyl and benzyl halides (bromides and chlorides).
The simple method of operation and good yields of this
new strategy for the Pd-catalyzed acylation, could lead to
Synthesis 2012, 44, 423–430
© Thieme Stuttgart · New York

PAPER
One-Pot Conversion of Allyl and Benzyl Halides into Esters
427
trans-3b-Cholest-5-en-3-yl But-3-enoate (trans-4a)
Yield: 79 mg (18%); white solid; mp 108–111 °C (hexane).
GC-MS (EI, 70 eV): m/z (%) = 328 ([M+], 1), 313 (40), 255 (8), 195
(10), 169 (20), 101 (80), 69 (100).
IR (CHCl3): 3030, 2949, 2867, 1707 (C=O), 1457, 1378, 1276,
1190, 1103, 1014 cm–1.
HRMS (ESI): m/z [M + H]+ calcd for C17H25O7: 329.1590; found:
329.1591.
1H NMR (400 MHz, CDCl3): d = 6.96 (dq, J = 6.9, 15.5 Hz, 1 H,
CH3CH=CH), 5.82 (dd, J = 15.5, 1.7 Hz, 1 H, CH3CH=CH), 5.37
(dd, J = 4.4, 2.0 Hz, 1 H, C=CHCH2), 4.63–4.68 (m, 1 H, OCH),
2.34 (d, J = 7.2 Hz, 2 H, OCHCH2), 2.02–0.85 (m, 41 H, aliphatic
CH, CH2, CH3), 0.68 (s, 3 H, CHCH3).
13C NMR (100 MHz, CDCl3): d = 11.9, 17.9, 18.7, 19.3, 21.1, 22.6,
22.8, 23.8, 24.3, 27.9, 28.0, 28.3, 31.9, 35.8, 36.2, 36.6, 37.0, 38.2,
39.5, 39.8, 42.3, 50.1, 56.2, 56.7, 73.7 (C–O), 122.6, 123.3, 139.8,
144.1, 166.0 (C=O).
cis-1,2:5,6-Di-O-isopropylidene-a-D-glucofuranos-3-yl But-2-
enoate (cis-5a)
Yield: 90 mg (26%); colorless oil.
IR (CHCl3): 3030, 2990, 2870, 1723 (C=O), 1646, 1377, 1224,
1162, 1076, 1022 cm–1.
1H NMR (400 MHz, CDCl3): d = 6.42 (dq, J = 11.7, 7.2 Hz, 1 H,
CH3CH=CH), 5.88 (d, J = 3.7 Hz, 1 H, OCHO), 5.80 (dq, J = 11.7,
1.7 Hz, 1 H, CH3CH=CH), 5.29 (d, J = 2.5 Hz, 1 H, OCH), 4.52 (d,
J = 3.7 Hz, 1 H, OCH), 4.27–4.21 (m, 2 H, 2 × OCH), 4.09–4.01 (m,
2 H, OCH2), 2.17 (dd, J = 7.2, 1.7 Hz, 3 H, CH3CH=CH), 1.53 (s, 3
H, CH3), 1.41 (s, 3 H, CH3), 1.31 (s, 3 H, CH3), 1.30 (s, 3 H, CH3).
HRMS (ESI): m/z [M + H]+ calcd for C30H49O2: 441.3732; found:
441.3733.
cis-3b-Cholest-5-en-3-yl But-3-enoate (cis-4a)
13C NMR (100 MHz, CDCl3): d = 15.5, 17.9, 25.2, 26.2, 26.8, 67.0,
72.5, 75.6, 79.7, 83.4, 105.0, 109.3, 112.2, 119.7, 147.0, 164.8
(C=O).
Yield: 30 mg (7%); white solid; mp 98–100 °C (hexane).
IR (CHCl3): 3030, 2940, 2867, 1710 (C=O), 1466, 1378, 1260,
1190, 1006 cm–1.
GC-MS (EI, 70 eV): m/z (%) = 328 ([M+], 1), 313 (45), 255 (10),
195 (11), 169 (18), 101 (82), 69 (100).
HRMS (ESI): m/z [M + H]+ calcd for C17H25O7: 329.1590; found:
329.1590.
1H NMR (400 MHz, CDCl3): d = 6.27–6.31 (m, 1 H, CH3CH=CH),
5.77 (dd, J = 11.5, 1.7 Hz, 1 H, CH3CH=CH), 5.37 (br s, 1 H,
C=CHCH2), 4.63–4.67 (m, 1 H, OCH), 2.36–0.85 (m, 43 H, aliphat-
ic CH, CH2, CH3), 0.68 (s, 3 H, CHCH3).
trans-2-Hydroxy-5-methylphenyl But-2-enoate (trans-7a) and
trans-2-Hydroxy-4-methylphenyl But-2-enoate (trans-8a)
Inseparable mixture of regioisomers; yield: 135 mg (70%); color-
less oil.
13C NMR (100 MHz, CDCl3): d = 11.9, 18.7, 19.3, 21.1, 22.6, 22.8,
23.8, 24.3, 28.0, 28.2, 29.7, 31.9, 35.8, 36.2, 36.6, 37.1, 38.1, 38.3,
39.5, 39.8, 42.3, 50.1, 56.2, 56.7, 73.4 (C–O), 121.2, 122.6, 139.8,
144.6, 166.0 (C=O).
IR (CHCl3): 3576 (OH, free), 3374 (OH, br), 3026, 2923, 2850,
1736 (C=O), 1655, 1506, 1442, 1296, 1178, 1149, 1110, 969 cm–1.
HRMS (ESI): m/z [M + H]+ calcd for C30H49O2: 441.3732; found:
441.3734.
1H NMR (400 MHz, CDCl3): d = 8.55 (br s, 2 H, OH), 7.25–7.18
(m, 2 H, CH3CH=CH), 6.94 (d, J = 8.1 Hz, 2 Harom), 6.76 (br s, 2
Harom), 6.71–6.68 (m, 2 Harom), 6.06 (dq, J = 1.4, 15.5 Hz, 2 H,
CH3CH=CH), 2.25 (br s, 6 H, ArCH3), 1.97–1.94 (2 m, 6 H,
CH3CH=CH).
13C NMR (100 MHz, CDCl3): d = 17.8, 18.2, 20.4, 20.9, 117.6,
118.3, 121.4, 122.0, 122.7, 127.4, 130.5, 136.3, 136.9, 138.2, 144.8,
146.8, 148.1, 165.0 (C=O), 165.1 (C=O).
3b-Cholest-5-en-3-yl But-3-enoate (4b)
Yield:137 mg (31%); white solid; mp 81–83 °C (hexane).
IR (CHCl3): 3030, 2949, 2878, 1724 (C=O), 1642, 1467, 1379,
1329, 1260, 1182, 1000 cm–1.
1H NMR (400 MHz, CDC13): d = 6.00–5.85 (m, 1 H, CH2=CH),
5.37 (dd, J = 4.4, 2.0 Hz, 1 H, C=CHCH2), 5.18–5.14 (m, 2 H,
CH2=C), 4.60–4.64 (m, 1 H, OCH), 3.06 (d, J = 6.9 Hz, 2 H,
CH2CO), 2.32 (d, J = 7.7 Hz, 2 H, C=CHCH2), 1.99–0.85 (m, 38 H,
aliphatic CH, CH2, CH3), 0.67 (s, 3 H, CHCH3).
GC-MS (EI, 70 eV): m/z (%) = 192 ([M+], 10), 124 (12), 69 (100).
cis-2-Hydroxy-5-methylphenyl But-2-enoate (cis-7a) and cis-2-
Hydroxy-4-methylphenyl But-2-enoate (cis-8a)
Inseparable mixture of regioisomers; yield: 58 mg (30%); colorless
oil.
13C NMR (100 MHz, CDCl3): d = 11.9, 18.7, 19.3, 21.0, 22.6, 22.8,
24.3, 27.7, 28.0, 28.2, 31.9, 35.8, 36.2, 36.6, 37.0, 38.1, 39.5, 39.7,
42.3, 50.0, 56.2, 56.7, 118.3, 122.7, 130.6, 139.6, 170.9 (C=O).
HRMS (ESI): m/z [M + H]+ calcd for C30H49O2 [M + H]+: 441.3732;
found: 441.3732.
IR (CHCl3): 3574 (OH, free), 3339 (OH, br), 3033, 2925, 2855,
1738 (C=O), 1643, 1507, 1439, 1296, 1178, 1147 cm–1.
trans-1,2:5,6-Di-O-isopropylidene-a-D-glucofuranos-3-yl But-2-
enoate (trans-5a)
Yield: 110 mg (32%); colorless oil.
1H NMR (400 MHz, CDCl3): d = 8.60 (br s, 2 H, OH), 6.98 (d, J =
8.1 Hz, 2 Harom), 6.83 (d, J = 1.4 Hz, 2 Harom), 6.72 (dd, J = 1.4, 8.1
Hz, 2 Harom), 6.62–6.55 (m, 2 H, CH3CH=CH), 6.09–6.05 (m, 2 H,
CH3CH=CH), 2.28 (s, 3 H, ArCH3), 2.40 (s, 3 H, ArCH3), 2.23–2.21
(2 m, 6 H, CH3CH=CH).
13C NMR (100 MHz, CDCl3): d = 17.9, 20.5, 20.9, 22.7, 117.6,
118.3, 119.1, 121.6, 122.0, 122.8, 127.4, 130.7, 136.1, 137.0, 138.1,
144.7, 146.7, 149.1, 164.5 (C=O), 164.6 (C=O).
IR (CHCl3): 3030, 2987, 2870, 1723 (C=O), 1655, 1377, 1213,
1165, 1076, 1023 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.03 (dq, J = 17.0, 6.9 Hz, 1 H,
CH3CH=CH), 5.89–5.83 (m, 2 H, CH3CH=CH, OCHO), 5.30 (d,
J = 2.2 Hz, 1 H, OCH), 4.52 (d, J = 3.7 Hz, 1 H, OCH), 4.26–4.22
(m, 2 H, 2 × OCH), 4.09–4.01 (m, 2 H, OCH2), 1.90 (dd, J = 1.7, 6.9
Hz, 3 H, CH3CH=C), 1.53 (s, 3 H, CH3), 1.41 (s, 3 H, CH3), 1.31 (s,
3 H, CH3), 1.30 (s, 3 H, CH3).
13C NMR (100 MHz, CDCl3): d = 15.2, 18.1, 25.3, 26.2, 26.8, 67.0,
72.5, 75.9, 79.8, 83.4, 105.0, 109.3, 112.3, 121.9, 146.2, 165.0
(C=O).
GC-MS (EI, 70 eV): m/z (%) = 192 ([M+], 9), 124 (14), 69 (100).
trans,trans-4-Methyl-1,2-phenylene Dibut-2-enoate
(trans,trans-9a)
Yield: 117 mg (45%); colorless oil.
IR (CHCl3): 3022, 2924, 2854, 1743 (C=O), 1656, 1505, 1442,
1256, 1212, 1155, 1110, 970 cm–1.
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1H NMR (400 MHz, CDCl3): d = 7.17–7.01 (m, 5 H, 3 Harom
,
1 H, CH3CH=CH), 6.03 (dd, J = 1.7, 11.5 Hz, 1 H, CH3CH=CH),
4.30 (t, J = 7.0 Hz, 2 H, CH2CH2O), 2.94 (t, J = 7.0 Hz, 2 H,
CH2CH2O), 2.21 (dd, J = 1.7, 7.4 Hz, 3 H, CH3CH=CH).
2 × CH3CH=CH), 6.00 (d, J = 15.7 Hz, 2 H, 2 × CH3CH=CH), 2.34
(s, 3 H, ArCH3), 1.93 (d, J = 6.9 Hz, 6 H, 2 × CH3CH=CH).
13C NMR (100 MHz, CDCl3): d = 17.8, 18.1 (2 C), 20.9, 121.4,
122.9, 123.8, 127.0, 136.5, 139.9, 141.9, 147.2, 147.3, 163.9 (C=O),
164.0 (C=O).
13C NMR (100 MHz, CDCl3): d = 18.2, 39.1, 65.0, 121.6, 122.0,
129.8, 135.1, 146.9, 149.4, 164.9 (C=O).
GC-MS (EI, 70 eV): m/z (%) = 206 ([M+], 1), 188 (12), 120 (100),
91 (15).
GC-MS (EI, 70 eV): m/z (%) = 260 ([M+], 11), 129 (26), 124 (10),
69 (100).
HRMS (ESI): m/z [M + H]+ calcd for C12H15O3: 207.1021; found:
207.1023.
cis,trans-4-Methyl-1,2-phenylene Dibut-2-enoate (cis,trans-9a)
and trans,cis-4-Methyl-1,2-phenylene Dibut-2-enoate (trans,cis-
9a)
Inseparable mixture of stereoisomers (1:1 ratio); yield: 117 mg
(45%); colorless oil.
trans-4-(Hydroxymethyl)phenyl But-2-enoate (trans-11a)
Yield: 150 mg (78%); colorless oil.
IR (CHCl3): 3604 (OH, free), 3431 (OH, br), 3011, 2930, 2855,
1735 (C=O), 1654, 1507, 1442 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.34 (d, J = 8.4 Hz, 2 Harom), 7.18
(dq, J = 15.6, 6.9 Hz, 1 H, CH3CH=CH), 7.06 (d, J = 8.4 Hz, 2
Harom), 6.03 (dq, J = 1.7, 15.6 Hz, 1 H, CH3CH=CH), 4.62 (s, 2 H,
CH2O), 1.96 (dd, J = 1.7, 6.9 Hz, 3 H, CH3CH=CH).
13C NMR (100 MHz, CDCl3): d = 18.0, 64.2, 121.4, 121.7, 127.9,
138.2, 147.2, 149.8, 165.1 (C=O).
GC-MS (EI, 70 eV): m/z (%) = 192 ([M+], 10), 174 (2), 124 (8), 107
(13), 69 (100).
IR (CHCl3): 3026, 2926, 2854, 1743 (C=O), 1654, 1504, 1442,
1259, 1133, 969 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.17–6.97 (m, 4 H, 3 Harom
,
CH3CH=CH), 6.52–6.46 (m, 1 H, CH3CH=CH), 6.01–5.96 (m, 2 H,
CH3CH=CH), 2.31 (s, 3 H, ArCH3), 2.18–2.15 (m, 3 H,
CH3CH=CH), 1.95–1.91 (m, 3 H, CH3CH=CH).
13C NMR (100 MHz, CDCl3): d = 15.5, 18.1, 20.9, 119.2, 121.4,
123.0, 123.9, 125.5, 127.0, 136.5, 139.7, 139.9, 141.7, 141.9, 147.1,
147.9, 148.0, 163.8 (C=O), 163.9 (C=O).
GC-MS (EI, 70 eV): m/z (%) = 260 ([M+], 13), 129 (24), 124 (9), 69
(100).
HRMS (ESI): m/z [M + H]+ calcd for C11H13O3: 193.0865; found:
193.0864.
cis-4-(Hydroxymethyl)phenyl But-2-enoate (cis-11a)
Yield: 35 mg (18%); colorless oil.
cis,cis-4-Methyl-1,2-phenylene Dibut-2-enoate (cis,cis-9a)
Yield: 23 mg (9% mg); colorless oil.
IR (CHCl3): 3604 (OH, free), 3431 (OH, br), 3017, 2927, 2854,
1735 (C=O), 1644, 1509, 1142, 1013, 954 cm–1.
IR (CHCl3): 3022, 2926, 2855, 1743 (C=O), 1645, 1504, 1413,
1261, 1214, 1128 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.37 (d, J = 8.5 Hz, 2 Harom), 7.09
(d, J = 8.5, 2 Harom), 6.57–6.50 (m, 1 H, CH3CH=CH), 6.03 (dd, J =
1.8, 11.2 Hz, 1 H, CH3CH=CH), 4.67 (s, 2 H, CH2O), 2.20 (dd, J =
1.8 Hz, J = 7.2 Hz, 3 H, CH3CH=CH).
13C NMR (100 MHz, CDCl3): d = 18.0, 64.7, 119.7, 121.8, 128.1,
138.3, 148.0, 149.9, 164.8 (C=O).
GC-MS (EI, 70 eV): m/z (%) = 192 ([M+], 12), 174 (5), 124 (13),
107 (58), 69 (100).
HRMS (ESI): m/z [M + H]+ calcd for C11H13O3: 193.0865; found:
193.0864.
1H NMR (400 MHz, CDCl3): d = 7.11–7.03 (m, 3 Harom), 6.53–6.46
(m, 2 H, CH3CH=CH), 6.00–5.97 (m, 2 H, CH3CH=CH), 2.35 (s, 3
H, ArCH3), 2.20–2.15 (m, 6 H, 2 × CH3CH=CH).
13C NMR (100 MHz, CDCl3): d = 18.0, 20.9, 25.6, 119.3, 123.1,
123.9, 127.0, 129.4, 136.6, 139.8, 141.7, 147.9, 148.0, 163.7 (C=O),
163.8 (C=O).
GC-MS (EI, 70 eV): m/z (%) = 260 ([M+], 12), 129 (24), 124 (8), 69
(100).
trans-4-(2-Hydroxyethyl)phenyl But-2-enoate (trans-10a)
Yield: 169 mg (82% mg); colorless oil.
trans-4-[(But-3-enoyloxy)methyl]phenyl But-2-enoate (trans-
12a)
Yield: 221 mg (85%); colorless oil.
IR (CHCl3): 3580 (OH, free), 3430 (OH, br), 3010, 2930, 2850,
1730 (C=O), 1655, 1502, 1440 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.40 (d, J = 8.3 Hz, 2 Harom), 7.15
(dq, J = 15.6, 6.9 Hz, 1 H, CH3CH=CH), 6.98 (d, J = 8.3 Hz, 2
IR (CHCl3): 3025, 2950, 2855, 1735 (C=O), 1655, 1510, 1443,
1163, 1010, 979 cm–1.
Harom), 6.00 (dq, J = 1.7, 15.6 Hz, 1 H, CH3CH=CH), 4.26 (t, J = 7.1
1H NMR (400 MHz, CDCl3): d = 7.37 (d, J = 8.5 Hz, 2 Harom), 7.23–
7.14 (m, 1 H, CH3CH=CH), 7.10 (d, J = 8.5 Hz, 2 Harom), 6.04 (dd,
J = 1.7, 15.6 Hz, 1 H, CH3CH=CH), 5.97–5.86 (m, 1 H,
CH2=CHCH2), 5.19–5.15 (m, 2 H, CH2=CHCH2), 5.12 (s, 2 H,
CH2O), 3.15–3.12 (m, 2 H, CH2=CHCH2), 1.97 (dd, J = 1.6, 6.9 Hz,
3 H, CH3CH=CH).
13C NMR (100 MHz, CDCl3): d = 18.1, 39.0, 65.8, 118.7, 121.7,
121.9, 129.4, 130.0, 133.2, 147.1, 150.6, 164.7 (C=O), 171.3
(C=O).
Hz, 2 H, CH2CH2O), 2.86 (t, J = 7.1 Hz, 2 H, PhCH2CH2O), 1.93
(dd, J = 1.7, 6.9 Hz, 3 H, CH3CH=CH).
13C NMR (100 MHz, CDCl3): d = 16.6, 38.5, 65.1, 120.8, 121.5,
128.1, 137.0, 144.1, 150.3, 163.1 (C=O).
GC-MS (70 eV): m/z (%) = 206 ([M+], <1), 188 (10), 120 (100), 107
(19), 91 (16), 69 (10).
HRMS (ESI): m/z [M + H]+ calcd for C12H15O3: 207.1021; found:
207.1022.
GC-MS (EI, 70 eV): m/z (%) = 260 ([M+], 4), 192 (4), 69 (100).
HRMS (ESI): m/z [M + H]+ calcd for C15H17O4: 261.1127; found:
cis-4-(2-Hydroxyethyl)phenyl But-2-enoate (cis-10a)
Yield: 27 mg (13%); colorless oil.
261.1126.
IR (CHCl3): 3580 (OH, free), 3435 (OH, br), 3015, 2930, 2850,
1727 (C=O), 1650, 1500, 1440 cm–1.
cis-4-[(But-3-enoyloxy)methyl]phenyl But-2-enoate (cis-12a)
Yield: 36 mg (14%); colorless oil.
1H NMR (400 MHz, CDCl3): d = 8.53 (br s, OH), 7.23 (d, J = 8.4
Hz, 2 Harom), 7.05 (d, J = 8.4 Hz, 2 Harom), 6.53 (dq, J = 7.4, 11.5 Hz,
Synthesis 2012, 44, 423–430
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PAPER
One-Pot Conversion of Allyl and Benzyl Halides into Esters
429
IR (CHCl3): 3025, 2956, 2861, 1734 (C=O), 1644, 1509, 1415,
1218, 1142, 1014 cm–1.
IR (CHCl3): 3032, 2950, 2878, 1724 (C=O), 1640, 1450, 1260 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.23 (t, J = 8.3 Hz, 2 H, Harom),
7.13 (t, J = 8.3 Hz, 1 H, Harom), 7.07 (d, J = 8.3 Hz, 2 H, Harom), 5.50
(t, J = 7.5 Hz, 1 H, C=CHCH2), 2.95 (d, J = 7.5 Hz, 2 H,
C=CHCH2), 1.91 (s, 3 H, CH3), 1.75 (s, 3 H, CH3).
13C NMR (100 MHz, CDCl3): d = 19.1, 24.5, 30.1, 116.8, 122.0,
125.6, 128.7, 133.1, 152.0, 168,1 (C=O).
1H NMR (400 MHz, CDCl3): d = 7.38 (d, J = 8.5 Hz, 2 Harom), 7.11
(d, J = 8.5 Hz, 2 Harom), 6.56–6.50 (m, 1 H, CH3CH=CH), 6.03 (d,
J = 11.5 Hz, 1 H, CH3CH=CH), 5.98–5.92 (m, 1 H, CH2=CHCH2),
5.19–5.15 (m, 2 H, CH2=CHCH2), 5.12 (s, 2 H, CH2O), 3.14 (d, J =
7.0 Hz, 2 H, CH2=CHCH2), 2.20 (dd, J = 1.7, 7.3 Hz, 3 H,
CH3CH=CH2).
13C NMR (100 MHz, CDCl3): d = 17.9, 39.0, 65.8, 118.7, 119.6,
121.8, 129.4, 130.0, 133.2, 148.0, 150.4, 164.5 (C=O), 171.3
(C=O).
HRMS (ESI): m/z [M + H]+ calcd for C12H15O2: 191.1072; found:
191.1072.
GC-MS (EI, 70 eV): m/z (%) = 260 ([M+], 5), 192 (5), 69 (100).
Acknowledgment
HRMS (ESI): m/z [M + H]+ calcd for C15H17O4: 261.1127; found:
261.1128.
Thanks are due to the University of Salento and C.I.N.M.P.I.S.
(Consorzio Interuniversitario Nazionale Metodologie e Processi
Innovativi di Sintesi) for financial support.
4-[2-(But-3-enoyloxy)ethyl]-1,2-phenylene Dibut-3-enoate
(13b)
References
Yield: 36 mg (10%); colorless oil.
IR (CHCl3): 3025, 2927, 2850, 1762 (C=O), 1733 (C=O), 1643,
1505, 1142, 1023 cm–1.
(1) (a) Greene, T. W.; Wuts, P. G. M. Protective Groups in
Organic Synthesis; Wiley: New York, 1999. (b) Larock, R.
C. Comprehensive Organic Transformations; VCH:
Weinheim, 1989, 966.
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(b) Pittelkow, M.; Kamounah, F. S.; Boas, U.; Pedersen, B.;
Christensen, J. B. Synthesis 2004, 2485.
1H NMR (400 MHz, CDCl3): d = 7.14–7.00 (m, 3 Harom), 6.00–5.80
(m, 3 H, CH2=CHCH2), 5.29–5.13 (m, 6 H, CH2=CHCH2), 4.30 (t,
J = 6.8 Hz, 2 H, CH2O), 3.62–3.55 (m, 2 H, CH2=CHCH2), 3.31–
3.27 (m, 2 H, CH2=CHCH2), 3.08 (d, J = 6.9 Hz, 2 H,
CH2=CHCH2), 2.93 (t, J = 6.8 Hz, 2 H, ArCH2).
(3) (a) Sakakura, A.; Kawajiri, K.; Ohkubo, T.; Kosugi, Y.;
Ishihara, K. J. Am. Chem. Soc. 2007, 129, 14775.
(b) Kadam, S. T.; Kim, S. S. Synthesis 2008, 267.
(c) Chandra, K. L.; Saravan, P.; Singh, R. K.; Singh, V. K.
Tetrahedron 2002, 58, 1369. (d) Chakraborti, A. K.;
Gulhane, R.; Shivani Synthesis 2004, 111. (e) Khan, A. T.;
Choudry, L. H.; Ghosh, S. Eur. J. Org. Chem. 2005, 2782.
(f) Procopio, A.; Dalpozzo, R.; De Nino, A.; Maiuolo, L.;
Nardi, M.; Romeo, G. Org. Biomol. Chem. 2005, 3, 4129.
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D’Annibale, A.; Fanfoni, A.; Minissi, F. Org. Lett. 2005, 7,
1805.
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Kaneda, K. Tetrahedron Lett. 2003, 44, 9205.
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Technol. 2010, 112, 593. (b) Liu, K. J.; Huang, Y. R.
J. Biotechnol. 2010, 146, 215.
13C NMR (100 MHz, CDCl3): d = 29.5, 34.4, 38.8, 39.1, 64.5, 118.6,
119.1, 119.3, 123.2, 123.8, 127.0, 129.4, 130.1, 136.7, 140.6, 141.8,
148.5, 168.8 (C=O), 168.9 (C=O), 171.4 (C=O).
GC-MS (EI, 70 eV): m/z (%) = 358 ([M+], 1), 272 (3), 204 (21), 136
(100), 69 (23).
HRMS (ESI): m/z [M + H]+ calcd for C20H22O6: 358.1416; found:
358.1417.
trans-Phenyl 4-Methylpent-2-enoate (trans-16a)
Yield: 44 mg (24%); colorless oil.
IR (CHCl3): 3030, 2949, 2875, 1702 (C=O), 1650, 1450, 1265 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.36 (t, J = 8.1 Hz, 2 H, Harom),
7.15 (t, J = 8.1 Hz, 1 H, Harom), 7.07 (d, J = 8.1 Hz, 2 H, Harom), 6.84
(dd, J = 16.0, 7.0 Hz, 1 H, CHCH=CH), 5.81 (d, J = 16.0 Hz, 1 H,
CHCH=CH), 2.50–2.53 (m, 1 H, CHCH=CH), 1.10 (d, J = 6.5 Hz,
6 H, 2 × CH3).
13C NMR (100 MHz, CDCl3): d = 21.9, 30.7, 116.1, 121.3, 125.3,
128.7, 150.1, 153.2, 161.9 (C=O).
(7) Georgsson, J.; Hallberg, A.; Larhed, M. J. Comb. Chem.
2003, 5, 350.
(8) Zim, D.; de Souza, R. F.; Dupont, J.; Monteiro, A. L.
Tetrahedron Lett. 1998, 39, 7071.
HRMS (ESI): m/z [M + H]+ calcd for C12H15O2: 191.1072; found:
(9) Takahashi, T.; Inoue, H.; Tomida, S.; Doi, T.; Bray, A. M.
Tetrahedron Lett. 1999, 40, 7843.
191.1073.
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Org. Chem. 2004, 1357. (b) Troisi, L.; Pindinelli, E.;
De Vitis, L.; Granito, C.; Ronzini, L. Tetrahedron 2006, 62,
1564. (c) Troisi, L.; Granito, C.; Pindinelli, E. Tetrahedron
2008, 64, 11632.
(11) (a) Troisi, L.; Granito, C.; Rosato, F.; Videtta, V.
Tetrahedron Lett. 2010, 51, 371. (b) Cacchi, S.; Fabrizi, G.;
Filisti, E. Synlett 2009, 1817.
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C. J. Am. Chem. Soc. 2011, 133, 1584.
(13) Gambacorta, A.; Tofani, D.; Migliorini, A. Molecules 2007,
12, 1762.
cis-Phenyl 4-Methylpent-2-enoate (cis-16a)
Yield: 21 mg (11%); colorless oil.
IR (CHCl3): 3031, 2953, 2880, 1700 (C=O), 1650, 1450, 1265 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.27 (t, J = 8.2 Hz, 2 H, Harom),
7.16 (t, J = 8.2 Hz, 1 H, Harom), 7.07 (d, J = 8.2 Hz, 2 H, Harom), 6.12
(dd, J = 11.1, 7.1 Hz, 1 H, CHCH=CH), 5.74 (d, J = 11.1 Hz, 1 H,
CHCH=CH), 2.49 (m, 1 H, CHCH=CH), 1.12 (d, J = 6.5 Hz, 6 H,
2 × CH3).
13C NMR (100 MHz, CDCl3): d = 21.6, 30.1, 115.9, 121.6, 124.9,
128.6, 151.1, 152.8, 161.9 (C=O).
HRMS (ESI): m/z [M + H]+ calcd for C12H15O2: 191.1072; found:
191.1073.
(14) Campos, J. L.; De Giovani, W. F.; Romero, J. R. Synthesis
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4765.
Phenyl 4-Methylpent-3-enoate (16b)
Yield: 114 mg (60%); colorless oil.
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Synthesis 2012, 44, 423–430
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