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1-3). The reaction of thienyl selenides 1k with 4-
methoxyphenyl zinc chloride afforded the thiophene derivative
3q in a moderated 45% yield (Table 2, entry 4). The reaction
was also tested with pyridyl selenides through the reaction
with 4-methoxyphenyl zinc chloride and thienyl zinc chloride
which gave piridyl derivatives 3o and 4c in high yields (Table 2,
entries 5 and 6). The reaction with Z-vinilyc selenide 1h
proceeded with high selectivity toward the double bond to
afford Z-styrylbenzene 3n in 64% yield, as the only isomer
(Table 2, entry 7).
cross-coupling of selenoacetylenes
1
DOI: 10.1039/C5C1Ca06(304.27G5
(Scheme 4). We found that the use of selenoacetylene
mmol) with 2-methylbutynol in the presence of PdCl2(PPh3)2
(10mol%), Cu(OAc)2.H2O (20 mol%), Et3N (4 equiv) in DMF (3
mL), at 80 °C was the most efficient condition to deliver the
Sonogashira products in good yields (for additional information
of the reaction condition optimization, see Supporting
Information, Table S1). As illustrated in scheme 4, the best
reaction condition was very efficient with selenoacetylenes
having neutral, electron rich and electron poor aromatic rings
Table 2 Cross-coupling Reactions of Organo Selenides with Organo Zinc directly bonded to alkyne giving the diynes 5a-e in good yields.
Reagents.[a]
entry
organo
selenides
boronic
acids
product
1
2
Scheme 4 The reactions were performed by using organo selenides
(0.25 mmol), terminal alkynes (4 equiv), Pd(PPh3)4 (10 mol %),
1
3
4
o
Cu(OAc)2.H2O (20 mol%), Et3N ( 4 equiv) in DMF (3 mL) at 80 C for 24
h.
5
6
Conclusions
In conclusion, we demonstrated that alkynyl, vinyl, aryl and
heteroaryl selenides are suitable substrates to palladium cross-
coupling reactions. In general Pd(PPh3)4 (10 mmol %), in DMF
at 80 °C demonstrated to be efficient for the coupling of
organoselenides with boronic acids, terminal alkynes, ogano
zinc and Grignard reagents. It was confirmed that Z-vinylic
selenides gave the corresponding Z-styrylbenzene products
with complete retention of the double bond geometry proving
the high selectivity of this methodology. The simple and easy
preparation of organoselenides, their chemo-, region- and
stereoselectivity reactions and the generality of the reaction
sequences make this transformation a powerful tool for
constructing new carbon-carbon bonds.
7b
a
The reactions were performed by using organo selenides 1 (0.25 mmol),
organo zinc reagents (2 equiv), Pd(PPh3)4 (10 mol %) in THF (3 mL) at 60 oC
for 3 h.
The synthetic potential of organo selenides was next
applied to cross-coupling reaction with Grignard reagents.
Thus the reaction of alkynyl, vinyl and heteroaryl selenides
with 4-methoxyphenyl magnesium bromide catalyzed by
o
Notes and references
Pd(PPh3)4 (10 mmol %) in THF (3 mL) at 60 C gave the cross-
coupled products in good yields (Scheme 3).
1
a) J. Yamaguchi, A. D. Yamaguchi, K. Itami, Angew. Chem.,
Int. Ed. 2012, 51, 8960. b) C. -J. Li, Acc. Chem. Res. 2009, 42
,
335. c) C. Bolm, J. Legros, J. L. Paih, L. Zani, Chem. Rev. 2004,
104, 6217.
a) R. Chinchilla, C. Nájera, Chem. Soc. Rev. 2011, 40, 5084. b)
2
C. E. I. Knappke, A. J. Wangelin, Chem. Soc. Rev. 2011, 40
4948. c) E. Negishi, Z. Huang, G. Wang, S. Mohan, C. Wang,
,
H. Hattori, Acc. Chem. Res. 2008,
Nájera, Chem. Rev. 2007, 107
Organomet. Chem. 1999, 576, 147.
a) The Chemistry of Organic Selenium and Tellurium
Compounds; Rappoport, Z., Ed.; John Wiley Sons:
4
,
, 1474. d) R. Chinchilla, C.
874. e) A. Suzuki, J.
Scheme 3 The reactions were performed by using organo selenides
(0.25 mmol), organo magnesium reagents (2 equiv), Pd(PPh3)4 (10 mol
%) in THF (3 mL) at 60 oC for 2 h.
1
3
&
Chichester, 2014, Vol. 4, pp 1-1522. b) The Chemistry of
Organic Selenium and Tellurium Compounds; Rappoport, Z.,
Ed.; John Wiley & Sons: Chichester, 2012, Vol. 3, pp 1-1370.
The final step of this work was to explore the reactivity of
organo selenides as substrate in Sonogashira cross-coupling
reactions. In the first instance, we developed a set of
experiments to determine the best reaction conditions to the
4
5
a) C. W. Nogueira, J. B. T. Rocha, Arch. Toxicol. 2011, 85
1313.
J.-M. Becht, C. L. Drian, J. Org. Chem. 2011, 76, 6327.
,
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