Synthesis and esterification reactions of aryl diazomethanes derived from hydrazone oxidations catalyzed by TEMPO

Article abstract of DOI:10.1016/j.tetlet.2013.04.079

Diverse hydrazones were oxidized to the corresponding diazoalkanes using sodium hypochlorite in the presence of catalytic amounts of TEMPO (2,2,6,6-tetramethylpiperidinyloxy). A library of diverse benzhydryl esters and analogues was prepared from diazoalkanes obtained by this procedure.

Full text of DOI:10.1016/j.tetlet.2013.04.079

Tetrahedron Letters 54 (2013) 3302–3305
Contents lists available at SciVerse ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Synthesis and esterification reactions of aryl diazomethanes derived from
hydrazone oxidations catalyzed by TEMPO
⇑
Carolina Perusquía-Hernández, Gonzalo R. Lara-Issasi, Bernardo A. Frontana-Uribe, Erick Cuevas-Yañez
Centro Conjunto de Investigación en Química Sustentable UAEM–UNAM, Carretera Toluca-Atlacomulco Km. 14.5, Toluca, Estado de México 50200, Mexico
a r t i c l e i n f o
a b s t r a c t
Article history:
Diverse hydrazones were oxidized to the corresponding diazoalkanes using sodium hypochlorite in the
presence of catalytic amounts of TEMPO (2,2,6,6-tetramethylpiperidinyloxy). A library of diverse benzhy-
dryl esters and analogues was prepared from diazoalkanes obtained by this procedure.
Ó 2013 Published by Elsevier Ltd.
Received 14 February 2013
Revised 16 April 2013
Accepted 19 April 2013
Available online 27 April 2013
Keywords:
Hydrazone
Diazo compound
Oxidation
TEMPO
Ester
Diazoalkanes are valuable and interesting synthetic materials
which represent an important source of carbene/carbenoid inter-
mediates as well as other precursors.1 One of the well-known
methods to prepare diazoalkanes involves the oxidation of diverse
the successful adaptation of this methodology to the synthesis of
aryldiazomethanes and their corresponding arylmethyl esters.
In a model study, benzophenone hydrazone 1 was treated with
an excess of 13% sodium hypochlorite solution in the presence of
catalytic amounts TEMPO (Scheme 1). After 5 min at 0 °C, the char-
acteristic reddish color associated with the diazo group appeared.
Purification of the reaction mixture afforded a violet oil which
was identified as diphenyldiazomethane 2 that shows the diazo
2
hydrazones. However, most of the oxidation protocols for hydra-
3
4
zones use transition metal based oxidizers, such as HgO, Ag
2
O,
5
6
7
8
9
CrO , Ni O , KMnO -Al O , MnO , Pb(AcO) , and triphenylbis-
2 2 3 4 2 3 2 4
1
0
muth carbonate. Due to the inherent toxicity of transition metals,
many research groups have developed environmentally friendly
procedures based on the use of less toxic oxidizing agents such
as OXONE™, calcium hypochlorite (only for synthesis of diazok-
2
etones from hydrazono carbonyl compounds), DMSO–(COCl) ,
À1
13
group band C@N@N in 2050 cm and a signal in the C NMR
spectrum in 54 ppm corresponding to the diazo group carbon. As
diazoalkanes are unstable to air and ambient conditions, diphenyl-
diazomethane 2 was reacted with acetic acid in order to determine
1
1
12
13
14–17
13
as well as hypervalent iodine reagents.
the reaction yield. Preliminary experiments demonstrated that
In connection with a current synthetic study, we required an ar-
ray of aryldiazoalkanes in which the aryl portion of the molecule
was widely varied through a nonexpensive method from readily
accessible reagents avoiding transition metals. Searching the avail-
able oxidation procedures, we were attracted by the oxoammoni-
um ion mediated oxidations derived from nitroxyl radicals; an
important kind of intermediates with applications as mild oxi-
benzhydryl ester 3 was obtained as major product in this step.
The success of the process motivated us to optimize some reac-
tion conditions. The experiments in Table 1 showed that tempera-
ture and reaction time play an important role in the reaction; the
best yield was obtained when the reaction was carried out at
À5 °C for 1 h (Table 1, entry 8). On the other hand, both calcium
and sodium hypochlorite were tested as oxidizing agents in this
1
8
dants. The most notable example of nitroxyl radical is TEMPO
2,2,6,6-tetramethylpiperidinyloxy), used mainly as catalyst in
(
19
selective oxidation of primary alcohols to aldehydes. Inspired
by these previous reports, we initiated an investigation about the
TEMPO catalyzed oxidations on hydrazones. This Letter describes
NaOCl
TEMPO cat.
NNH2
N2
OAc
Ph
AcOH
Ph
Ph
Ph
Ph
Ph
KBr, NaHCO3
Temp.
3
1
2
Scheme 1. Synthesis of benzhydryl ester 3 from diphenyldiazomethane 2 and
benzophenone hydrazone 1.
⇑
Corresponding author. Tel.: +52 722 276 66 10x7734; fax: +52 722 217 5109.
E-mail address: ecuevasy@uaemex.mx (E. Cuevas-Yañez).
0
040-4039/$ - see front matter Ó 2013 Published by Elsevier Ltd.
http://dx.doi.org/10.1016/j.tetlet.2013.04.079

C. Perusquía-Hernández et al. / Tetrahedron Letters 54 (2013) 3302–3305
3303
Table 1
NaOCl
TEMPO cat.
Effect of temperature and reaction time
AcOH
Entry Catalyst ratio
% mol)
Temperature
(°C)
Reaction time
(min)
Yield
(%)
OAc
KBr, NaHCO3
Temp.
(
NNH2
N2
1
4
1
2
3
4
5
6
7
8
9
3.8
3.8
3.8
3.8
3.8
3.8
3.8
3.8
3.8
0
0
0
0
0
15
30
45
60
90
60
60
60
60
32
53
60
83
10
22
83
92
86
12
13
Scheme 2. Synthesis of bornyl acetate 14 from diazoalkane 13 and camphor
hydrazone 12.
5
0
NaOCl
TEMPO cat.
À5
NNH2
N2
pyrazole
N
À10
N
Ph
Ph
Ph
Ph
KBr, NaHCO3
Temp.
Fe-Cu nano
1
2
Ph
Ph
1
5
Table 2
Effect of the oxidizing agent
Scheme 3. Synthesis of pyrazole 15 from diphenyldiazomethane 2 and benzophe-
none hydrazone 1.
Entry Catalyst ratio
Oxidizing
Agent
Oxidizing agent/
hydrazone (mmol)
Yield
(%)
(% mol)
NaOCl
TEMPO cat.
OCOR3
R2
1
2
3
4
5
6
7
8
3.8
3.8
3.8
3.8
3.8
3.8
3.8
3.8
Ca(ClO)
Ca(ClO)
Ca(ClO)
Ca(ClO)
NaClO
NaClO
NaClO
NaClO
2
2
2
2
1.0
2.0
3.0
4.0
1.0
2.0
3.0
4.0
52
57
65
58
80
70
92
85
NNH2
R2
N2
3
R CO H
2
R1
R1
R2
R1
KBr, NaHCO3
-5°C
Scheme 4. Synthesis of benzhydryl esters.
3
In addition, other additives (TEMPO, NaHCO , KBr) were evalu-
ated. Thus, the yield of ester 3 was improved to 95% (Table 3).
Using these optimized conditions, a series of benzhydryl esters
were prepared from diazoalkanes which in turn were synthesized
from diverse hydrazones (Scheme 4 and Table 4). All the com-
pounds were fully characterized by the conventional spectroscopic
Table 3
Effect of catalyst, co-oxidizing agent, base, and KBr
Entry Catalyst
ratio
NaOCl/
hydrazone
(mmol)
NaHCO
hydrazone
(mmol)
3
/
KBr/
hydrazone
(mmol)
Yield
(%)
20
techniques. Not only was this process readily applicable to the
(
% mol)
synthesis of benzhydryl esters from aryl diazomethanes. For exam-
ple, isopropyl ester derived from diazopropane was successfully
prepared by this procedure (Table 4, compound 9). Moreover, ste-
rically hindered esters such as bornyl acetate 14 were prepared
from diazolakane 13 which in turn was obtained from (±)-camphor
1
2
3
4
5
6
7
8
9
1
1
1
3.8
3.8
3.8
3.8
3.8
3.8
1
2
4
2
2
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
1
0.3
0.6
1.0
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.2
0.2
0.2
0.1
0.2
0.4
0.2
0.2
0.2
0.2
0.2
0.2
62
73
60
43
80
72
52
91
48
75
70
95
3
3
hydrazone 12 (Scheme 2).
This synthesis of functionalized benzhydryl esters has one
important limitation. Substrates with sensitive groups such as free
alcohols, amines, and aldehydes did not give the desired esters,
affording probably other oxidation side products.
0
1
2
2
3.5
2
On the other hand, we noted azine formation in most of cases,
1
7
similar to those found by Myers and Furrow, and probably
through a diazoalkane oxidation–dimerization mechanism, as pre-
process. Although calcium hypochlorite is relatively more
stable, the best results were observed using sodium hypochlorite
3
4
35
viously described by Sharma and Shechter and co-workers.
Other kind of reactions that involves diazoalkanes is the
carbenoid insertion to heterocyclic rings. In this regard, our group
(Table 2).
Table 4
Benzhydryl esters prepared via Scheme 4
R1
R2
R3
m.p. (°C)
m.p. lit. (°C)
ref.
Yield (%)
Compound
3
4
5
6
7
8
9
Ph
Ph
Ph
Ph
Ph
Ph
CH
Ph
Ph
Ph
Ph
Ph
CH
CH
CH
Ph
4-NO
3-NO
3-CH
CH
Ph
3
40
89
132
95
79
39–4121
95
81
73
55
79
74
62
88–8922
23
2
C
C
6
H
H
4
4
131–132
2
2
4
4
2
6
ND
ND
Oil
Oil
3
C
6
H
4
25
3
3
3
Oil
Oil
26
3
OCH2
1
0
Ph
Ph
88
89–9027
63
2
8
1
1
1
1
1
1
1
2
3
4
5
6
Ph
Ph
Ph
Ph
4-ClC
4-ClC
Ph
Ph
Ph
Ph
H
2-Naphthyl
4-CH
105
109
87
115
Oil
ND
50
75
70
55
30
38
11029
3
C
6
H
4
86.5–883
0
4-ClC
3-ClC
6 4
H
31
6
H
4
115–117
3
2
2
7
6
H
H
4
4
CH
Ph
3
Oil
Oil
6
H
Oil

3
304
C. Perusquía-Hernández et al. / Tetrahedron Letters 54 (2013) 3302–3305
NNH2
B +
19
BH
N
Cl
N
O
1
8
N
O
N
H
20
Cl2
N
O
N
O
17
Cl
16
Cl2
N
N
OH
N
N
OH
21
23
N
N
22
Scheme 5. Reaction mechanism and catalytic cycle.
reported carbenoid insertions to imidazole rings using p-toluene-
References and notes
36
sulfonylhydrazones as diazo compound sources, as well as the
use of silver nanoparticles as catalysts in these processes.37 There-
1. Doyle, M. P.; McKervey, M. A.; Ye, T. Modern Catalytic Methods for Organic
Synthesis with Diazo Compounds: From Cyclopropanes to Ylides; Wiley: New
York, 1998. p. 10.
2. Zollinger, H. Diazo Chemistry II: Aliphatic, Inorganic and Organometallic
Compounds; VCH: Weinheim, 1995. p. 34.
fore, we attempted to use diazolakanes synthesized by TEMPO cat-
alyzed hydrazone oxidations to the synthesis of alkylpyrazoles. In
this case, diphenyldiazomethane 2 was treated with pyrazole in
3
8
3. (a) Andrews, S. D.; Day, A. C.; Raymond, P.; Whiting, M. C. Org. Synth. Collect. Vol.
the presence of a catalytic amount of iron–copper nanoparticles,
1988, 6, 392; (b) Smith, L. I.; Howard, K. L. Org. Synth. Collect. Vol. 1955, 3, 351.
39
obtaining benzhydryl pyrazole 15 in 50% yield (Scheme 3). This
result shows that 1-alkyl pyrazoles could be synthesized through
metal catalyzed reactions and diazoalkanes prepared in situ from
TEMPO catalyzed oxidations.
4. Schroeder, W.; Katz, L. J. Org. Chem. 1954, 19, 718.
5. Kwang, Y. K.; Ji, Y. K. Bull. Korean Chem. Soc. 1999, 20, 771.
6
7
8
.
.
.
Nakagawa, K.; Onoue, H.; Minami, K. Chem. Commun. 1966, 730.
Lee, K. H.; Ko, K. Y. Bull. Korean Chem. Soc. 2006, 27, 185.
(a) Doyle, M. P.; Yan, M. J. Org. Chem. 2002, 67, 602; (b) Denton, J. R.;
Sukumaran, D.; Davies, H. M. L. Org. Lett. 2007, 9, 2625.
A rational mechanistic explanation of this process should be
4
0
9. Holton, T. L.; Schechter, H. J. Org. Chem. 1995, 60, 4725.
0. (a) Padwa, A.; Rodriguez, A.; Tohidi, M.; Fukunaga, T. J. Am. Chem. Soc. 1983,
05, 933; (b) Barton, D. H. R.; Lester, D. J.; Motherwell, W. B.; Papoula, M. T. B. J.
centered in the role of TEMPO catalyst. According to Ramstrom
1
1
9
and Sheldon, oxoammonium ion 18 is formed when TEMPO ni-
troxyl radical 16 is reacted with chlorine derived from sodium
hypochlorite (Scheme 5). Then, hydrazone 19 is incorporated into
oxoammonium ion 18, generating the intermediate 20. The subse-
quent hydrogen transfer affords the intermediate 21 which is dis-
proportionated to diazocompound 22 and hydroxy TEMPO 23. In
the final step, hydroxy TEMPO 23 is re-oxidized by chlorine to
the intermediates 17 and 18, respectively, completing the catalytic
cycle.
1
Chem. Soc. 1979, 705.
1
1
1
1. Curini, M.; Rosati, O.; Pisani, E. Tetrahedron Lett. 1997, 38, 1239.
2. Morrison, H.; Danishefsky, S.; Yates, P. J. Org. Chem. 1961, 26, 2617.
3. (a) Javed, M. I.; Brewer, M. Org. Lett. 2007, 9, 1789; (b) Javed, M. I.; Brewer, M.
Org. Synth. 2008, 85, 189.
1
1
4. Bedford, C. D.; Bruckmann, E. M.; Smith, P. A. S. J. Org. Chem. 1981, 46, 679.
5. Ter Wiel, M. K. J.; Vicario, J.; Davey, S. G.; Meetsma, A.; Feringa, B. L. Org. Biomol.
Chem. 2005, 3, 28.
16. Li, X. Q.; Zhang, C. Synthesis 2009, 1163.
1
1
1
7. Furrow, M. E.; Myers, A. G. J. Am. Chem. Soc. 2004, 126, 12222.
8. Adam, W.; Saha-Moller, C. R.; Ganeshpure, P. A. Chem. Rev. 2001, 101, 3499.
9. Sheldon, R. A.; Arends, I. W. C. E.; Ten Brink, G. J.; Dijksman, A. Acc. Chem. Res.
2002, 35, 774.
In summary, hydrazones are easily converted into diazoalkanes
through a novel procedure which uses sodium hypochlorite as
green oxidizing agent and TEMPO as catalyst. In addition, diazoalk-
anes prepared in this work were used as starting materials to pre-
pare some esters and benzhydryl pyrazole 15 with moderate–good
yields. This new diazoalkane synthesis is effected under mild con-
ditions, has good functional group tolerance, presents some advan-
tages in comparison with other methods and finally is broad in
scope. These characteristics suggest that this route to diazoalkanes
and esters will enjoy widespread application.
20. Typical procedure for the oxidation of hydrazones-synthesis of benzhydryl
esters. A mixture of the appropriate hydrazone (1 mmol), NaHCO (0.052 g,
.6 mmol), KBr (0.024 g, 0.2 mmol), and TEMPO (0.003 g, 0.02 mmol) in CH Cl
2
3
0
2
(
2 mL) was stirred at À5 °C. A 13% solution of NaOCl (2 mL, 3.5 mmol) was
added, and the resulting reaction mixture was stirred at À5 °C for 1 h. The
violet organic layer was separated and cooled to À5 °C again. Then, the
corresponding carboxylic acid (1 mmol) was added portionwise. A vigorous
evolution of nitrogen occurred, and the mixture was allowed to warm to room
temperature and stirred for 15 min. A saturated solution of NaHCO
was added and the organic layer was extracted with ether (3 Â 5 mL). The
combined organic layers were dried over anhydrous Na SO . The solvent was
removed in vacuo and the product was purified by flash column
chromatography (SiO hexane/ethyl acetate 9:1). Selected spectral data.
Compound 3: H NMR (CDCl , 500 MHz) d: 2.20 (s, 3H), 6.97 (s, 1H), 7.31–
.87 (m, 10H); 13C NMR (CDCl
, 125 MHz) d: 21.3 (CH ), 77.3 (CH), 127 (CH),
27.9 (CH), 127.9 (CH), 128 (CH), 128.3 (CH), 128.6 (CH), 128.7 (CH), 129.3
3
(10 mL)
2
4
2
,
Acknowledgments
1
3
7
1
3
3
Financial support from CONACYT (Project No. 135053) is grate-
fully acknowledged. The authors would like to thank Signa S.A. de
C.V. for some graciously donated solvents and reagents and to N.
Zavala, A. Nuñez, and L. Triana for the technical support.
(
CH), 129.6 (CH), 130 (CH), 140.2 (CC)29.3170.050 (C7); 138.236 (C2);
+
+
1
40.2(C), 159.0(C), 170. 0 (C); MS [EI ] m/z (RI%): 226 [M] (7); IR: (ATR,
cm ) 1750, 1624. Compound 4: 1H NMR (CDCl , 500 MHz) d: 7.17 (s, 1H),
À1
3
7
.31–7.87 (m, 12H), 8.12 (m, 2H); 13C NMR (CDCl
3
, 125 MHz) d: 78.3 (CH),

C. Perusquía-Hernández et al. / Tetrahedron Letters 54 (2013) 3302–3305
3305
1
27.3 (CH), 127.9 (CH), 128.3 (CH), 128.7 (CH), 129.3 (CH), 130.0 (CH), 131.9 127.8, (CH), 128.1 (CH), 128.8 (CH), 129.3 (CH), 129. 8 (CH), 131.8 (CH), 133.8
+
+
+
+
(
C), 134.2 (C), 138.236 (C),168. 3 (C); MS [EI ] m/z (RI%): 288 [M] (10); IR:
(C), 134.25 (C), 139.2 (C),166. 35 (C); [EI ] m/z (RI%): 322 [M] (10); IR: (ATR,
À1
1
À1
cm ) 1715. Compound 15: 1H NMR (500 MHz, CDCl
(
ATR, cm ) 1690, 1650. Compound 5: H NMR (CDCl
3
, 500 MHz) d: 7.14 (s, 1H,
, 125 MHz) d 78.5
CH), 123.6 (CH), 127.1 (CH), 128.3 (CH), 128.3 (CH), 128.7 (CH), 130.7 (CH)
3
) d 2.15 (s, 3H), 5.09 (s,
1
3
13
CH) 7.28–7.48 (m, 12H), 7.89 (d, J = 8 Hz, 2H). C NMR (CDCl
(
3
2H), 7.56 (d, J = 8.2 Hz, 1H), 8.05 (dd, J = 8.2 Hz, 2H). C NMR (127.5 MHz,
CDCl ) d 21.5 (CH ), 65.9 (CH
), 128.5 (2ÂCH), 128.9 (2ÂCH), 134.2 (C), 135.2
(C), 170.1 (C); [EI ] m/z (RI%): 184 [M] (20); IR: (ATR, cm ) 1735. Compound
16: 1H NMR (500 MHz, CDCl
) d 5.30 (s, 2H), 7.34 (m, 4H), 7.41 (m, 2H), 7.56 (d,
J = 7.4 Hz, 1H), 8.05 (dd, J = 8.4 Hz, 2H). C NMRNMR (127.5 MHz, CDCl
65.9 (CH
3
3
+
2
+
À1
1
30.8 (CH), 132.4 (CH), 135.5 (CH), 137.6 (CH), 139.5 (CH), 140.2 (CC), 150.6
+
+
À1
(
CH), 163.7 (C), 176.7 (C); MS [EI ] m/z (RI%): 333 [M] (7); IR: (ATR, cm
)
3
1
13
1
720, 1526, 1493, 1277, 1138. Compound 6: H NMR (CDCl
3
, 500 MHz) d: 7.16
3
) d
1
3
(
s, 1H), 7.23–7.82 (m, 12H), 8.47 (m, 1H), 8.96 (m, 1H). C NMR (CDCl
3
,
2
), 128.5 (2ÂCH), 128.9 (2ÂCH), 129.6 (2ÂCH), 129.8 (2ÂCH), 130.0
+
+
1
25 MHz) d 79.5 (CH), 123.5 (CH), 126.3 (CH), 128.2 (CH), 129.3 (CH), 129.6
(C), 133.2 (CH), 134.2 (C), 134.7 (C), 166.3 (C). MS [EI ] m/z (RI%): 246 [M] (10);
+
À1
(
[
(
(
CH), 131 (CH) 136 (CH), 140.2 (C), 147.8 (C), 169.8 (C); MS [EI ] m/z (RI%): 333
IR: (ATR, cm ) 1694.
+
À1
1
M] (10); IR: (ATR, cm ) 1720, 1526, 1493, 1277, 1138. Compound 7:1 H NMR
21. Herzig, J.; Schleiffer, M. Liebigs Ann. Chem. 1921, 422, 326.
22. Horner, L.; Fernekess, H. Chem. Ber. 1961, 94, 712.
23. Meisenheimer, J.; Schmidt, W. Liebigs Ann. Chem. 1929, 475, 157.
24. Hoefnagel, A. J.; Wepster, B. M. Collect. Czech. Chem. Commun. 1990, 55, 119.
25. Fahey, F. C.; McPherson, C. A. J. Am. Chem. Soc. 1969, 91, 3865.
26. Cohen, S. G. J. Am. Chem. Soc. 1944, 66, 1395.
3
CDCl
CDCl
3
, 500 MHz) d 2.39 (s, 3H) 7.12 (s, 1H) 7.22–7.95 (m, 14H); C NMR
, 125 MHz) d 21.3 (CH ), 77.3 (CH), 127.1 (CH), 127.8 (CH), 127.9 (CH),
28 (CH), 128.2 (CH), 128.3 (CH), 128.5 (CH), 128.6 (CH), 129.3 (CH), 130 (CH),
30.1 (CH) 130.3 (CH), 132.4 (CH) 133.9 (C), 137.6 (C), 138.2 (C), 140.35 (C),
3
3
1
1
1
+
+
À1
65.75 (C); MS [EI ] m/z (RI%): 302 [M] (15); IR: (ATR, cm ) 1719, 1316, 1196.
1
Compound 8: H NMR (CDCl
H), 7.40 (m, 3H), 7.86 (m, 2H); C NMR (CDCl
CH ), 69.9 (CH), 126.5 (CH), 128.3, (CH), 129.5 (CH). 138.4 (C), 168.7 (C); MS
EI+] m/z (RI%): 164 [M] (10); IR: (ATR, cm
3
, 500 MHz) d 1.22 (d, 3H), 2.31 (s, 3H), 3.77 (q,
27. García-Muñoz, A. H.; Tomás-Gamasa, M.; Pérez-Aguilar, M. C.; Cuevas-Yañez,
E.; Valdés, C. Eur. J. Org. Chem. 2012, 3925.
1
3
1
3 3
, 125 MHz) d 15.0 (CH ), 31.0
(
[
3
28. Ananthakrishnanadar, P.; Kannan, N.; Tharumaraj, G. V. Indian J. Chem., Sect. B
1980, 19, 621.
29. Tochtermann, W.; Kirrstetter, R. G. H. Chem. Ber. 1978, 111, 1228.
30. Harris, J. M.; Becker, A.; Fagan, J. F.; Walden, F. A. J. Am. Chem. Soc. 1974, 96,
4484.
+
À1
)
2928, 1741, 1028, 697.
, 500 MHz) d 1.05 (d, 6H), 3.98 (m, 1H), 7.40 (m,
H), 7.89 (m, 2H); 13C NMR (CDCl
, 125 MHz) d 20.7 (CH ), 68.3 (CH), 128.4
CH), 129.5 (CH), 130.1 (CH), 133.6 (C), 172.5 (C); MS [EI ] m/z (RI%): 164 [M]
1
Compound 9: H NMR (CDCl
3
(
3
3
3
+
+
À1
1
(
15); IR: (ATR, cm ) 2964, 1739. Compound 10: H NMR (CDCl
3
, 500 MHz) d
31. Linhardt, R. J.; Murr, B. L.; Montgomery, E.; Osby, J.; Sherbine, J. J. Org. Chem.
1982, 47, 2242.
1
3
4
.83 (s, 2H), 7.00 (s, 1H) 7.21–7.80 (m, 17H); C NMR (CDCl , 125 MHz) d 65.5
3
(
1
CH2),77.8 (CH), 107.2 (CH), 118.6 (CH), 124.1 (CH), 126.4 (CH), 126.9 (CH),
27.1 (CH) 127.6 (CH), 128.13 (CH), 128.2 (CH), 128.5 (CH), 129.7 (CH), 130.6
C), 132.4 (CH), 137.6 (CH), 139.4 (CH), 140.5 (C), 157.2 (C), 196.745 (C); MS
32. Chiarotto, I.; Feroci, M.; Sotgiu, G.; Inesi, A. Eur. J. Org. Chem. 2013, 326.
33. Selected spectral data. Compound 14: 1H NMR (CDCl
, 500 MHz) d: 0.78 (s, 3H),
0.80 (s, 3H),0.92 (s, 3H), 1.03 (m, 1H), 1.04 (m, 1H), 1.09 (m, 1H), 1.82 (m, 2H),
3
(
[
+
+
À1
13
EI ] m/z (RI%): 368 [M] (5); IR: (ATR, cm ) 1737, 1277, 1173. Compound 11:
1.92 (d, 2H), 2.17 (s, 3H), 4.90 (m, 1H); C NMR (CDCl
3
, 125 MHz) d: 11.2
), 35.2 (CH ), 43.9
1
13
H NMR (CDCl
CDCl , 125 MHz) d 77.5 (CH), 125.3 (CH), 126.7 (CH), 127.2 (CH), 127.8 (CH),
28.0 (CH), 128.2 (CH), 128.2 (CH), 128.3 (CH), 128.6 (CH), 131.3 (CH), 132.4
3
, 500 MHz) d 7.19 (s, 1H) 7.24–8.70 (m, 17H, ArH); C NMR
(CH ), 18.6 (CH ), 19.6 (CH ), 27.3 (CH ), 32.5 (CH ), 32.8 (CH
(CH), 47.8 (C), 52.4 (C), 79.3 (CH), 173. 4 (C); MS [EI ] m/z (RI%): 196 [M] (5);
3
3
3
3
2
2
2
+
+
(
3
À1
1
IR: (ATR, cm ) 2966, 2882, 1737.
+
+
(
(
CH), 132.5 (CH), 132.6 (C), 137.2 (C), 165.7 (C); MS [EI ] m/z (RI%): 338 [M]
34. Sharma, T. C.; Lal, A.; Saksena, V. Bull. Chem. Soc. Jpn. 1976, 49, 2881.
35. Bailey, R. J.; Card, P. J.; Shechter, H. J. Am. Chem. Soc. 1983, 105, 6096.
36. Cuevas-Yañez, E.; Serrano, J. M.; Huerta, G.; Muchowski, J. M.; Cruz-Almanza, R.
Tetrahedron 2004, 60, 9391.
37. García, M. A.; García-Muñoz, A.; Peña, J. A.; Trujillo-Reyes, J.; Morales-Luckie, R.
A.; Avalos-Borja, M.; Vilchis-Nestor, A. R.; Sanchez-Mendieta, V.; Corona, D.;
Cuevas-Yañez, E. Lett. Org. Chem. 2012, 9, 2.
38. García-Muñoz, A.; González, J.; Trujillo-Reyes, J.; Morales-Luckie, R. A.;
Sanchez-Mendieta, V.; González, C.; Fuentes, A.; Cuevas-Yañez, E. Lett. Org.
Chem. 2012, 9, 160.
39. Hamze, A.; Treguier, B.; Brion, J. D.; Alami, M. Org. Biomol. Chem. 2011, 9, 6200.
40. Angelin, M.; Hermansson, M.; Dong, H.; Ramström, O. Eur. J. Org. Chem. 2006,
4323.
À1
1
15); IR: (ATR, cm ) 1714, 1278, 1156. Compound 12: H NMR (500 MHz,
) d 2.32 (s, 3H), 7.12 (s, 1H), 7.30 (d, J = 8.4 Hz, 2H), 7.32–7.97 (m, 12 H);
C NMR (CDCl , 125 MHz) d 22.1 (CH ), 77.2 (CH), 127.3 (CH), 127.7 (CH), 1278
CH), 128.1 (CH), 128.3 (CH), 128.5 (CH), 128.6(CH), 128.7 (CH), 129.3 (CH),
CDCl
3
1
3
3
3
(
1
1
1
30.0 (CH), 130.1 (CH) 130.3 (CH), 132.4 (CH) 133.9 (C), 137.6 (C), 138.2 (C),
+
À1
40.35 (C), 165.75 (C); MS [EI+] m/z (RI%): 302 [M] (5); IR: (ATR, cm ) 1720,
1
315, 1196. Compound 13: H NMR (CDCl
3
, 500 MHz) d: 7.15 (s, 1H), 7.31–7.54
, 125 MHz) d: 78.9 (CH), 127.3
CH), 128.1 (CH), 128.8 (CH), 129.3 (CH), 131.5 (CH), 133.9 (C), 134.2 (C), 138.6
1
3
(
(
(
m, 12H), 8.14 (d, J = 8.1 Hz, 2H); C NMR (CDCl
3
+
+
À1
C),166. 35 (C); [EI ] m/z (RI%): 322 [M] (15); IR: (ATR, cm ) 1710; Compound
1
1
8
4: H NMR (CDCl
3
, 500 MHz) d: 7.10 (s, 1H), 7.31–7.67 (m, 12H), 8.02 (m, 1H),
13
.15 (d, J = 8.1 Hz, 1H); C NMR (CDCl , 125 MHz) d: 78.1 (CH), 127.2 (CH),
3