Asymmetric Au-catalyzed cycloisomerization of 1,6-enynes: An entry to bicyclo[4.1.0]heptene

• Alexandre Pradal,
• Chung-Meng Chao,
• Patrick Y. Toullec and
• Véronique Michelet

Beilstein J. Org. Chem. 2011, 7, 1021–1029, doi:10.3762/bjoc.7.116

• studies. Synthesis of 1,6-enynes We prepared various oxygen-tethered 1,6-enynes according to classic methodologies employing a Williamson alkylation reaction and/or a Sonogashira cross-coupling [60][61] (Scheme 2 and Scheme 3). The known enyne 5 [62][63] was engaged in Pd-catalyzed coupling in the

Au(I)/Au(III)-catalyzed Sonogashira-type reactions of functionalized terminal alkynes with arylboronic acids under mild conditions

• Deyun Qian and
• Junliang Zhang

Beilstein J. Org. Chem. 2011, 7, 808–812, doi:10.3762/bjoc.7.92

• , Chinese Academy of Sciences, Ling Ling Road 345 Shanghai 200032 (P. R. China) 10.3762/bjoc.7.92 Abstract A straightforward, efficient, and reliable redox catalyst system for the Au(I)/Au(III)-catalyzed Sonogashira cross-coupling reaction of functionalized terminal alkynes with arylboronic acids under

• mild conditions has been developed. Keywords: arylboronic acid; gold-catalysis; Sonogashira cross-coupling; Introduction The Sonogashira reaction has become the most important and widely used method for the synthesis of arylalkynes and conjugated enynes, which are precursors for natural products

• cross-coupling, as well as expanding the substrate scope [11][12][13][14]. Various examples have recently been reported for the palladium-catalyzed Sonagashira-type cross-coupling of terminal alkynes with arylboronic acids [13], and the Pd(0)/Pd(II) catalytic cycles have been well studied. Nevertheless

A rapid and efficient synthetic route to terminal arylacetylenes by tetrabutylammonium hydroxide- and methanol-catalyzed cleavage of 4-aryl-2-methyl-3-butyn-2-ols

• Jie Li and
• Pengcheng Huang

Beilstein J. Org. Chem. 2011, 7, 426–431, doi:10.3762/bjoc.7.55

• have been widely used in the preparation of photoelectric devices such as organic light-emitting diodes (OLEDs) [1][2][3][4], field-effect transistors (OFETs) [5][6], and organic photovoltaic cells (OPVCs) [7][8][9]. The palladium-catalyzed Sonogashira cross-coupling of an aryl halide with a mono

Synthesis of novel photochromic pyrans via palladium- mediated reactions

• Christoph Böttcher,
• Gehad Zeyat,
• Saleh A. Ahmed,
• Elisabeth Irran,
• Thorben Cordes,
• Cord Elsner,
• Wolfgang Zinth and
• Karola Rueck-Braun

Beilstein J. Org. Chem. 2009, 5, No. 25, doi:10.3762/bjoc.5.25

• cyanation, carbonylation and Sonogashira cross-coupling starting from bromo-substituted naphthopyran 1 and benzopyrans 2a/b. A novel photoswitchable benzopyran-based ω-amino acid 6 for Fmoc-based solid-phase peptide synthesis is presented. The photochromic behaviour of the 3-cyano-substituted benzopyran 5a

• . Conclusion In conclusion, we have synthesized novel photochromic naphtho- and benzopyrans for applications in the material and life sciences. A mild and efficient palladium-catalyzed cyanation reaction of bromo-substituted naphtho- and benzopyrans using Zn(CN)2 has been developed. Also a Sonogashira cross

• -coupling furnishing naphthopyran 4 and a palladium-catalyzed carbonylation yielding ω-amino acid 6 has been carried out. Detailed studies on nitrile transformations and alternative carbonylation routes in the presence of other protecting groups are currently under way in our laboratory. Time-resolved

Convenient methods for preparing π-conjugated linkers as building blocks for modular chemistry

• Jiří Kulhánek,
• Filip Bureš and
• Miroslav Ludwig

Beilstein J. Org. Chem. 2009, 5, No. 11, doi:10.3762/bjoc.5.11

• . It should be noted here that 5a–c were also accessible via the routine sequence showed for Method B. On the contrary, borylation of 4-bromobiphenyls with pin2B2 (Method C) yielded only traces of 4a–c. Linear phenylethynylphenyl π-linkers 6a–c were gained by a Sonogashira cross-coupling between the

• terminal acetylenes 7c–9c was accomplished by Sonogashira cross-coupling as shown on the Scheme 2 (Method E). The reaction utilizes the 4-bromo derivatives used as precursors for the construction of dioxaborolanes 4–6 and the product of the Sonogashira cross-coupling between 2c and 1,4-diiodobenzene (54

• and Sonogashira cross-coupling. Convenient synthetic methods leading to π-linkers 3–6. Sonogashira cross-coupling leading to π-linkers 7c–9c. Optimized synthetic procedures and yields for the preparation of 3–9. Supporting Information Supporting Information File 13: Experimental procedures and

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48

• synthesis, diastereoselective epoxidation of 72 and spontaneous cyclization afforded the diastereomers 73a and 73b. Protection of the hydroxyl group of 73a as a MOM ether afforded 74, which was coupled with the γ-lactone precursor 75 by a Sonogashira cross-coupling reaction to give compound 76. Catalytic

• , and AD-mix-α for threo-trans-threo THF moiety 124. The α,β-unsaturated γ-lactone segment 127 was synthesized through alkylation of lactone 15 and iodide 126. The THF moiety 123 and γ-lactone 127 were coupled by a Sonogashira cross-coupling reaction to afford 111. The syntheses of 112 and 121 were

• ). 130 was obtained by using the Sharpless epoxidation and dihydroxylation of 129. Compound 130 was then subjected to the Mitsunobu inversion to afford 131, which was transformed into 125. Then the THF moiety 125 and γ-lactone moiety 132 were coupled by a Sonogashira cross-coupling, and diimide reduction