Pd/C- Mediated synthesis of indoles in water

• Mohosin Layek,
• Udaya Lakshmi,
• Dipak Kalita,
• Deepak K. Barange,
• Aminul Islam,
• K. Mukkanti and
• Manojit Pal

Beilstein J. Org. Chem. 2009, 5, No. 46, doi:10.3762/bjoc.5.46

•  1. We have examined four anilides 1a–d each of which participated well in the present Pd/C-mediated coupling-cyclization process. Substituents such as halogen atoms (1a, 1c and 1d) and alkyl groups (1b) on the aryl ring were well tolerated. A range of terminal alkynes 2 were employed in the present

• present study we have used three equivalents of terminal alkynes to obtain the optimum yields of products. It is possible that the excess equivalents of terminal alkynes might undergo dimerization via oxidative coupling though no significant amount of 1,3-butadiyne derivative was isolated as a side

• product from any of the reactions presented in Table 1. However, to assess the effect of using fewer equivalents of terminal alkynes we conducted an experiment using 1a and 2a in a ratio of 1.0:1.2 without changing the other reaction conditions. The desired indole 3a was isolated in 60% yield (vs 79% of

Palladium- catalyzed cross coupling reactions of 4-bromo- 6H-1,2-oxazines

• Reinhold Zimmer,
• Elmar Schmidt,
• Michal Andrä,
• Marcel-Antoine Duhs,
• Igor Linder and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2009, 5, No. 44, doi:10.3762/bjoc.5.44

• -reactions (Scheme 4). When the coupling reaction of 2a with various terminal alkynes, such as phenylacetylene, trimethylsilylethyne and 1-hexyne, was performed under typical conditions [PdCl2(PPh3)2, CuI, Et3N, toluene], the expected 4-alkynyl-substituted heterocycles 9a–9c were isolated in good yields. In

Regioselective alkynylation followed by Suzuki coupling of 2,4-dichloroquinoline: Synthesis of 2-alkynyl- 4-arylquinolines

• Ellanki A. Reddy,
• Aminul Islam,
• K. Mukkanti,
• Venkanna Bandameedi,
• Dipal R. Bhowmik and
• Manojit Pal

Beilstein J. Org. Chem. 2009, 5, No. 32, doi:10.3762/bjoc.5.32

• Discussion A number of 2-alkynyl-4-chloroquinolines (3) were prepared via coupling of 2,4-dichloroquinoline (1) in the presence of 10% Pd/C (10 mol%), PPh3 (20 mol%) and CuI (5 mol%) as a catalyst system in water. The results are presented in Table 1. Both aryl and alkyl substituted terminal alkynes

• in compound 3. The reaction mechanism of the present stepwise C–C bond forming reactions consisting of alkynylation followed by arylation is shown in Scheme 2. The Pd/C–Cu mediated coupling of 2,4 dichloroquinoline (1) with terminal alkynes (2) in water proceeds via normal Sonogashira pathway [6

Synthesis of 2-substituted 9-oxa-guanines {5-aminooxazolo[5,4-d]pyrimidin- 7(6H)-ones} and 9-oxa-2-thio- xanthines {5-mercaptooxazolo[5,4-d]pyrimidin- 7(6H)-ones}

• Subrata Mandal,
• Wen Tai Li,
• Yan Bai,
• Jon D. Robertus and
• Sean M. Kerwin

Beilstein J. Org. Chem. 2008, 4, No. 26, doi:10.3762/bjoc.4.26

• with benzyl azide or 2-morpholinoethyl azide in the presence of catalytic CuSO4 and sodium ascorbate to afford the triazoles 9 and 10, respectively, in good yield (Figure 5). The copper-catalyzed Huisgen cycloaddition of terminal alkynes and alkyl azides favors formation of the 1,4-triazole

Allylsilanes in the synthesis of three to seven membered rings: the silylcuprate strategy

• Asunción Barbero,
• Francisco J. Pulido and
• M. Carmen Sañudo

Beilstein J. Org. Chem. 2007, 3, No. 16, doi:10.1186/1860-5397-3-16

• -1-ones 15–16 (Scheme 3), which are not easily prepared by classical methods, and for which few methods of synthesis have been reported in the literature. [7][13] Silylcupration of acetylenes is also a powerful tool for cyclopentane annulations. Terminal alkynes 17–19 bearing electron-withdrawing

• the size of the ring. The silylcupration of allenes. Silylcupration of 1,2-propadiene and reaction with oxo compounds. Silicon assisted cyclization of oxoallylsilanes. Silylcupration of terminal alkynes bearing electron-withdrawing functions. The acid-catalyzed cyclization of epoxyallylsilanes