ChemInform Abstract: Palladium-Catalyzed Reactions of Aryl Halides with Soft, Non-Organometallic Nucleophiles (original) (raw)
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The Journal of Organic Chemistry, 1996
The reaction of o-ethynylphenols 3 with a wide variety of unsaturated halides or triflates 6 in the presence of Pd(OAc) 2 (PPh 3) 2 , CuI, and Et 3 N (procedure A) gives 2-vinyl-and 2-arylbenzo[b]furans 7, in good to high yield, through a palladium-catalyzed coupling followed by an in situ cyclization step. Small amounts of 2,3-disubstituted-benzo[b]furans 8 are usually isolated as side products. In some cases, however, compounds 8 are generated in significant yield or even as the main products. The formation of 8 can be prevented by employing alternative procedures (B and C) that use o-((trimethylsilyl)ethynyl)phenyl acetates 5 as starting building blocks. Procedure B is based on the palladium-catalyzed reaction of 5 with 6 in the presence of Pd(PPh 3) 4 , Et 3 N, and n-Bu 4 NF, followed by the hydrolysis of the resultant coupling derivative 12 under basic conditions. Procedure C affords 7 through an in situ coupling/cyclization of 5 with 6 in the presence of Pd(PPh 3) 4 and KOBu t. The utilization of o-alkynylphenols 9 as the starting alkynes in the palladium-catalyzed reaction with 6 leads to the formation of 2,3-disubstituted-benzo[b]furans 13 through an annulation process promoted by σ-vinyl-and σ-arylpalladium complexes generated in situ. The best results in this case are obtained by using KOAc and Pd(PPh 3) 4. In the presence of KOAc and Pd(PPh 3) 4 , and under an atmosphere of carbon monoxide, the reaction of o-alkynylphenols with 6 provides 2-vinyl-and 2-aryl-3-acylbenzo[b]furans 14.
Cheminform, 2010
The reaction of o-ethynylphenols 3 with a wide variety of unsaturated halides or triflates 6 in the presence of Pd(OAc) 2 (PPh 3 ) 2 , CuI, and Et 3 N (procedure A) gives 2-vinyl-and 2-arylbenzo[b]furans 7, in good to high yield, through a palladium-catalyzed coupling followed by an in situ cyclization step. Small amounts of 2,3-disubstituted-benzo[b]furans 8 are usually isolated as side products. In some cases, however, compounds 8 are generated in significant yield or even as the main products. The formation of 8 can be prevented by employing alternative procedures (B and C) that use o-((trimethylsilyl)ethynyl)phenyl acetates 5 as starting building blocks. Procedure B is based on the palladium-catalyzed reaction of 5 with 6 in the presence of Pd(PPh 3 ) 4 , Et 3 N, and n-Bu 4 NF, followed by the hydrolysis of the resultant coupling derivative 12 under basic conditions. Procedure C affords 7 through an in situ coupling/cyclization of 5 with 6 in the presence of Pd(PPh 3 ) 4 and KOBu t . The utilization of o-alkynylphenols 9 as the starting alkynes in the palladium-catalyzed reaction with 6 leads to the formation of 2,3-disubstituted-benzo[b]furans 13 through an annulation process promoted by σ-vinyl-and σ-arylpalladium complexes generated in situ. The best results in this case are obtained by using KOAc and Pd(PPh 3 ) 4 . In the presence of KOAc and Pd(PPh 3 ) 4 , and under an atmosphere of carbon monoxide, the reaction of o-alkynylphenols with 6 provides 2-vinyl-and 2-aryl-3-acylbenzo[b]furans 14.
ChemInform, 2000
The reaction of o-ethynylphenols 3 with a wide variety of unsaturated halides or triflates 6 in the presence of Pd(OAc) 2 (PPh 3 ) 2 , CuI, and Et 3 N (procedure A) gives 2-vinyl-and 2-arylbenzo[b]furans 7, in good to high yield, through a palladium-catalyzed coupling followed by an in situ cyclization step. Small amounts of 2,3-disubstituted-benzo[b]furans 8 are usually isolated as side products. In some cases, however, compounds 8 are generated in significant yield or even as the main products. The formation of 8 can be prevented by employing alternative procedures (B and C) that use o-((trimethylsilyl)ethynyl)phenyl acetates 5 as starting building blocks. Procedure B is based on the palladium-catalyzed reaction of 5 with 6 in the presence of Pd(PPh 3 ) 4 , Et 3 N, and n-Bu 4 NF, followed by the hydrolysis of the resultant coupling derivative 12 under basic conditions. Procedure C affords 7 through an in situ coupling/cyclization of 5 with 6 in the presence of Pd(PPh 3 ) 4 and KOBu t . The utilization of o-alkynylphenols 9 as the starting alkynes in the palladium-catalyzed reaction with 6 leads to the formation of 2,3-disubstituted-benzo[b]furans 13 through an annulation process promoted by σ-vinyl-and σ-arylpalladium complexes generated in situ. The best results in this case are obtained by using KOAc and Pd(PPh 3 ) 4 . In the presence of KOAc and Pd(PPh 3 ) 4 , and under an atmosphere of carbon monoxide, the reaction of o-alkynylphenols with 6 provides 2-vinyl-and 2-aryl-3-acylbenzo[b]furans 14.
Tetrahedron Letters, 2000
Palladium-catalyzed synthesis of stereode®ned 3-[(1,1unsymmetrically disubstituted)methylidene]isobenzofuran-1(3H)-ones and stereode®ned 5-[(1,1-unsymmetrically disubstituted)methylidene]furan-2(5H)-ones Abstract Treatment of (hetero)aryl halides with 2-(1-alkynyl)benzoic acids or (Z)-2-en-4-ynoic acids in the presence of K 2 CO 3 and a catalytic amount of Pd(PPh 3 ) 4 provides reaction mixtures in which stereode®ned 3-[(1,1-unsymetrically disubstituted)methylidene]isobenzofuran-1(3H)-ones and stereode®ned 5-[(1,1-unsymmetrically disubstituted)methylidene]furan-2(5H)-ones, respectively, are the major products. # Compounds 7 were separated from the corresponding regioisomers 6 by MPLC on silica gel and were dierentiated from these isocoumarins on the basis of their IR spectra. In fact, compounds 7 displayed a carbonyl absorption band at 1765±1778 cm^1, whereas in compounds 6 the carbonyl absorption frequency was observed at 1722±1724 cm^1. On the other hand, the stereochemistry of compounds 7 was assigned by NOESY experiments.
Journal of the Brazilian Chemical Society, 2014
A reação de acoplamento entre 2,6-diiodoanisóis e alcinos terminais usando Pd(PPh 3) 2 Cl 2 e CuI como catalisadores e diisopropilamina como base em tolueno a temperatura ambiente por 12 h produziu seletivamente 2-iodoanisóis aquinilados, em rendimentos de bons a excelentes (52-95%), os quais são blocos de construção úteis com potencial aplicação na síntese de benzo[b] furanos funcionalizados. The coupling reaction between 2,6-diiodoanisoles and terminal alkynes using Pd(PPh 3) 2 Cl 2 and CuI as catalysts and diisopropylamine as base in toluene at room temperature for 12 h produced selectively alkynylated 2-iodoanisoles, in good to excellent yields (52-95%), which are useful building blocks with potential application in the synthesis of functionalized benzo[b]furans.
Palladium-Catalyzed Synthesis of Lipophilic Benzo[ b ]furans from Cardanol
Synthesis, 2007
o-Iodocardanol, readily available from cardanol by iodination, has been used to prepare a variety of lipophilic benzo[b]furans. 2-Substituted benzo[b]furans have been prepared by a Sonogashira cross-coupling/cyclization process. 2,3-Disubstituted benzo[b]furans have been obtained from o-alkynylcardanols by an oxypalladation/reductive elimination process.
ChemInform, 2004
An efficient one-pot two-step synthesis of polysubstituted furans is described using readily available 4,5-epoxy-2-alkynyl esters as starting materials. In the first step, reduction of these with SmI 2 affords buta-1,2,3-trienyl carbinol intermediates which, in the second step, participate in Pd(0)-catalyzed cyclization reactions with aryl halides and triflates by a mechanism probably involving oxidative addition, intramolecular oxypalladation and reductive elimination steps. In this manner, up to four carbon substituents are incorporated onto the furan ring, with the aryl group being introduced at the furan 3-or 4-positions. These features make the method particularly suitable for regioselective synthesis of tetrasubstituted furans. q