Fine-tuning alkyne cycloadditions: Insights into photochemistry responsible for the double-strand DNA cleavage via structural perturbations in diaryl alkyne conjugates

• Wang-Yong Yang,
• Samantha A. Marrone,
• Nalisha Minors,
• Diego A. R. Zorio and
• Igor V. Alabugin

Beilstein J. Org. Chem. 2011, 7, 813–823, doi:10.3762/bjoc.7.93

• corresponding lysine conjugates shown in Figure 4. Results and Discussion Synthesis The regioisomeric diaryl alkynes were synthesized following the synthetic strategy previously outlined by us for compound 1 [25]. The Sonogashira coupling of the corresponding iodonitrobenzene with trimethylsilyl (TMS) acetylene

C–C (alkynylation) vs C–O (ether) bond formation under Pd/C–Cu catalysis: synthesis and pharmacological evaluation of 4-alkynylthieno[2,3-d]pyrimidines

• Dhilli Rao Gorja,
• K. Shiva Kumar,
• K. Mukkanti and
• Manojit Pal

Beilstein J. Org. Chem. 2011, 7, 338–345, doi:10.3762/bjoc.7.44

• ]pyrimidines C (Figure 1). These derivatives are attractive due to the synthetic potential of C-4 alkynyl fragments for further use in library construction. A number of methods have been reported for the synthesis of alkynyl substituted pyrimidines and most of which involve the use of Sonogashira coupling of

• ]. The use of Pd/C–CuI–PPh3 as a less expensive catalyst system for efficient Sonogashira coupling has been explored earlier. Due to our continuing interest in Pd/C-mediated alkynylation of aryl and heteroaryl halides we decided to investigate the Pd/C-based methodology for the synthesis of our target

First synthesis of 2-(benzofuran-2-yl)-6,7-methylene dioxyquinoline-3-carboxylic acid derivatives

• Wentao Gao,
• Jia Liu,
• Yun Jiang and
• Yang Li

Beilstein J. Org. Chem. 2011, 7, 210–217, doi:10.3762/bjoc.7.28

• construction of the benzofuran moiety from intermediate 5. For the construction of 2-substituted benzofurans, the most widely used approach involves the palladium-catalyzed heteroannulation of 2-halophenols with a terminal alkyne via a tandem Sonogashira coupling-5-endo-dig-cyclization, largely based on the

Donor-acceptor substituted phenylethynyltriphenylenes – excited state intramolecular charge transfer, solvatochromic absorption and fluorescence emission

• Ritesh Nandy and
• Sethuraman Sankararaman

Beilstein J. Org. Chem. 2010, 6, 992–1001, doi:10.3762/bjoc.6.112

• (2) with 1,1-dimethylpropargyl alcohol followed by deprotection with KOH in refluxing toluene (Scheme 2). 2-Phenylethynyltriphenylene (1a) and those bearing electron withdrawing substituent (1b–e) were synthesized by the Sonogashira coupling of 2-iodotriphenylene (2) with the corresponding

• phenylacetylene derivatives. Although 1f–g were also synthesized by this procedure, their purification proved difficult due to an inseparable minor product formed in these reactions. Therefore compounds 1f–g were synthesized via the Sonogashira coupling of 2-ethynyltriphenylene (4) and the corresponding

Conjugated polymers containing diketopyrrolopyrrole units in the main chain

• Bernd Tieke,
• A. Raman Rabindranath,
• Kai Zhang and
• Yu Zhu

Beilstein J. Org. Chem. 2010, 6, 830–845, doi:10.3762/bjoc.6.92

• polycondensation reactions such as Suzuki [17], Stille [18] and Heck [19] coupling are especially useful. Other suitable reactions are Ni-mediated Yamamoto coupling [20], Sonogashira coupling [21], or electrochemical polymerization [22]. In the following, a brief review of recently prepared DPP based polymers is

• -sensitized solar cells were fabricated with P-12 as active layer. A power conversion efficiency of 1.43% was reached. G. Zhang et al. [52] synthesized diphenylDPP-containing polyphenylene-vinylene (PPV)- and polyphenylene-ethynylene (PPE)-type conjugated polymers via Heck- and Sonogashira coupling

• Suzuki coupling and their characteristic properties. List of DPP-polymers prepared upon Stille, Heck and Sonogashira coupling and their characteristic properties. List of DPP-based polyiminoarylenes and their characteristic properties [37]. List of DPP-polymers prepared upon electrochemical

One-pot three-component synthesis of quinoxaline and phenazine ring systems using Fischer carbene complexes

• Priyabrata Roy and
• Binay Krishna Ghorai

Beilstein J. Org. Chem. 2010, 6, No. 52, doi:10.3762/bjoc.6.52

• ] using palladium catalyzed Sonogashira coupling reactions as depicted in Scheme 2. Iodoketone 6A was prepared in 80% yield from (3-chloro-2-pyrazinyl)phenylmethanone [35] by halogen exchange with NaI in acetonitrile. The three component coupling reaction of pyrazinyl ketone 1A, carbene complex 2 and N

Preparation of pyridine-3,4-diols, their crystal packing and their use as precursors for palladium-catalyzed cross-coupling reactions

• Tilman Lechel,
• Irene Brüdgam and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2010, 6, No. 42, doi:10.3762/bjoc.6.42

• (C-H), 1600–1575 (C=C) cm−1. C12H10F9NO6S2 (499.3): calcd. C, 28.86; H, 2.02; N, 2.81; found: C, 28.89; H, 1.68; N 2.87. Sonogashira coupling reaction, typical procedure A mixture of pyridinediyl bistriflate 3b (245 mg, 0.491 mmol), Pd(PPh3)4 (79 mg, 0.069 mmol), CuI (9.4 mg, 0.049 mmol

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

• contrast, when the same reaction conditions were applied to the coupling of 2a and methyl propargyl ether, product 9d was obtained only in very low yield. In addition, Sonogashira coupling of 2a and methyl propargyl ether performed by an alternative protocol (Pd(OAc)2, CuI, PPh3, NHiPr2 in DMF) afforded

• single product in 65% yield. When the Sonogashira coupling was performed with trimethylsilylethyne under the same reaction conditions an inseparable 85:15-mixture of mono-alkynylated product 10b and bis-alkynylated compound 11b was obtained in reasonable yield. These reactions certainly deserve further

• , Ph, C-4), 157.7 (s, C-3) ppm. IR (KBr): 3040–2930 (=C–H, C–H), 1620 (C=N), 1600 (C=C) cm−1. C18H17NO2 (279.3): calcd. C, 77.39; H, 6.13; N, 5.01; found: C, 77.82; H, 6.37; N, 5.08. Sonogashira-coupling of 4-bromo-substituted 6H-1,2-oxazine 2a, typical procedure 6H-1,2-Oxazine 2a (0.850 g, 3.19 mmol

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

• . (a) arylation at C-4 followed by alkynylation at C-2 or (b) alkynylation at C-2 followed by arylation at C-4. Methodologies based on strategy ‘a’ have been reported earlier. For example, Sonogashira coupling of a terminal alkyne with 2-chloro-4-aryl substituted quinoline [3] in the presence of (PPh3

• singlet at δ 8.03 assigned to the C-3 hydrogen of the quinoline ring. If the alkyne was at C-4, NOE enhancement at C-5 is expected in addition to C-3. It is note worthy that the use of the Sonogashira coupling or its modified form has been employed for the preparation of 2-alkynylquinolines or related

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

• transformations. Synthesis of the 2-bromo-3H-naphtho[2,1-b]pyran 1 and the 3-bromo-2H-1-benzopyrans 2a/b. Ring contraction observed during the cyanation approach towards the synthesis of 3. Palladium-catalyzed Sonogashira-coupling of 2-bromo-3H-naphtho[2,1-b]pyran 1. Palladium-catalyzed cyanation and

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

• use as building blocks in Suzuki–Miyaura or Sonogashira coupling reactions. Keywords: boronic acid; donor/acceptor; linker; Sonogashira reaction; property tuning; push-pull; Suzuki–Miyaura reaction; Introduction Development of new organic compounds with improved and advanced properties is one of the

• . Overall 12 extended π-linkers have been easily synthesized (8 of them are new compounds) utilizing procedures such as a lithiation/reaction with triisopropyl borate/esterification with pinacol, Mizoroki–Heck coupling with vinylboronate pinacol ester, borylation with bis(pinacolato)diboron or Sonogashira

• coupling. Further application of the above boronic esters as well as terminal acetylenes for the construction of imidazole-based D-π-A systems by Suzuki–Miyaura and Sonogashira reaction is currently in progress in our laboratory. Basic and newly proposed π-conjugated linkers designed for the Suzuki–Miyaura

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

• constructed with excellent stereoselectivity by asymmetric alkynylation of α-tetrahydrofuranic aldehyde 114 with 1,6-heptadiyne (115). Then Sonogashira coupling of 116 and the iodide 117 followed by hydrogenation and deprotection provided murisolin (111). The spectroscopic data of synthetic 111 (1H NMR, 13C

Shape- persistent macrocycle with intraannular alkyl groups: some structural limits of discotic liquid crystals with an inverted structure

• Sigurd Höger,
• Jill Weber,
• Andreas Leppert and
• Volker Enkelmann

Beilstein J. Org. Chem. 2008, 4, No. 1, doi:10.1186/1860-5397-4-1

• compared to macrocycle 1. 3,5-Diiodo-4-methylbenzene (2) was treated with trimethylsilyl(TMS)acetylene under standard Hagihara-Sonogashira coupling conditions and subsequently deprotected with K2CO3 in MeOH/THF. As expected, the Pd-catalyzed coupling reaction runs under milder conditions and with higher

• (model reactions with 4-methylanisole showed that a direct diiodination could not be obtained under the conditions we used; for example, with N-iodosuccinimide and FeCl3 we could obtain cleanly 2-iodo-4-methylanisole). Pd-catalyzed Hagihara-Sonogashira coupling with 15, deprotection of the

• PAH substituents (Scheme 3). Pd-catalyzed coupling of the diiodo compound 14 with the mono protected bisacetylene 20, deprotection of the acetylenes with TBAF and subsequent coupling with an excess of the diiodo compound 5c gave the diiodide 23. Hagihara-Sonogashira coupling of 23 with an excess of

Flexible synthesis of poison- frog alkaloids of the 5,8-disubstituted indolizidine- class. II: Synthesis of (-)-209B, (-)-231C, (-)-233D, (-)-235B", (-)-221I, and an epimer of 193E and pharmacological effects at neuronal nicotinic acetylcholine receptors

• Soushi Kobayashi,
• Naoki Toyooka,
• Dejun Zhou,
• Hiroshi Tsuneki,
• Tsutomu Wada,
• Toshiyasu Sasaoka,
• Hideki Sakai,
• Hideo Nemoto,
• H. Martin Garraffo,
• Thomas F. Spande and
• John W. Daly

Beilstein J. Org. Chem. 2007, 3, No. 30, doi:10.1186/1860-5397-3-30

• the resulting aldehyde under Stork's conditions [11] provided the Z-iodoolefin 5 in a highly stereoselective manner. The Sonogashira coupling reaction [12] of 5 with TMS-acetylene followed by cleavage of the trimethylsilyl group with K2CO3 afforded (-)-231C. Although the rotation of the natural