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

• possible palladium-catalyzed cross-couplings we performed several Sonogashira-reactions [28][29][30]. As described in Scheme 3, the pyridinyl-bistriflates or -nonaflates 3 were coupled with alkynes like phenylacetylene or (triisopropylsilyl)acetylene using Pd(PPh3)4 or alternatively, Pd(OAc)2/PPh3 as

• (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

• of 3-alkoxypyridinols 1 to pyridine-3,4-diols 2. aMethod a: Pd/C, H2, MeOH, rt, 1 d; bMethod b: BBr3, CH2Cl2, 0 °C to rt, 1 d; cMethod c: TFA:CH2Cl2 (1:2), rt, 1 h. Conversion of pyridine-3,4-diols 2 into pyridinediyl bistriflates or -nonaflates 3. a) Et3N, Rf2O, CH2Cl2, 0 °C to rt, 1 d. Sonogashira

Solvent-free and time-efficient Suzuki–Miyaura reaction in a ball mill: the solid reagent system KF–Al₂O₃ under inspection

• Franziska Bernhardt,
• Ronald Trotzki,
• Tony Szuppa,
• Achim Stolle and
• Bernd Ondruschka

Beilstein J. Org. Chem. 2010, 6, No. 7, doi:10.3762/bjoc.6.7

• comminuting the reactants for just 10 min [40][41] without the presence of any additional stabilizing or activating ligands. Compared to the original published procedure for the Suzuki–Miyaura reaction [36] or the protocols featured by Mack and Frejd and their coworkers for Sonogashira [54] and Heck–Jeffery

Ring strain and total syntheses of modified macrocycles of the isoplagiochin type

• Andreas Speicher,
• Timo Backes,
• Kerstin Hesidens and
• Jürgen Kolz

Beilstein J. Org. Chem. 2009, 5, No. 71, doi:10.3762/bjoc.5.71

• report on the total synthesis of compounds which possess more rigid two-carbon biaryl bridges like stilbene (E or Z) or even tolane moieties which were introduced starting with a Sonogashira protocol. The McMurry method proved to be a powerful tool for the cyclization to these considerably ring-strained

• adopted because they do not give rise to specific double bond geometry or even an alkyne moiety between rings b and c. Our new strategy of synthesis involved a consecutive coupling of the rings a-b-c-d whereby the two-carbon bridge b–c would be introduced by a Sonogashira type reaction yielding an alkyne

• [22]. The aldehyde 13 was transformed into the terminal alkyne 14 by chain extension [23] (Scheme 3). The coupling of the terminal alkyne 14 with the iodoarene 15 [24] as the “c” building block using a typical Sonogashira protocol [Pd(PPh3)4, CuI, Et3N] gave – even under an argon–hydrogen atmosphere

Pd/C-mediated synthesis of α-pyrone fused with a five-membered nitrogen heteroaryl ring: A new route to pyrano[4,3-c]pyrazol-4(1H)-ones

• Dhilli Rao Gorja,
• Venkateswara Rao Batchu,
• Ashok Ettam and
• Manojit Pal

Beilstein J. Org. Chem. 2009, 5, No. 64, doi:10.3762/bjoc.5.64

• reported for the class of compounds represented by B. One of the common methods used for the construction of a pyrone ring fused with benzene or with other heteroaryl moieties is Sonogashira-type coupling followed by electrophilic or transition metal mediated cyclization of the resulting alkyne (possessing

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

• -substituted heterocycles 2a,b with phenylboronic acid in the presence of Pd(PPh3)4 and sodium carbonate at 80 °C in toluene gave the expected 4-phenyl-substituted 6H-1,2-oxazines 8a or 8b in 82 and 77% yield (Scheme 3). 4-Bromo-6H-1,2-oxazine 2a also serves as suitable model substrate for Sonogashira

• 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

• the expected product 9d and a byproduct bearing a 4-enyne moiety at 4-position. This indicates an addition of a second alkyne molecule to the primary product 9. Similar results were observed for the Sonogashira reaction of 2a with propargylic alcohol [33]. After successful simple cross couplings of

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

• 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 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

• the presence of an Fmoc protecting group for the direct synthesis of ω-amino acid 6. Also, a Sonogashira reaction was conducted towards the synthesis of naphthopyran precursor 4, which is suitable for attachment to tripodal linker systems for the immobilization on surfaces [26]. Results and Discussion

• ]. However, only the rearranged and hydrodehalogenated benzofuran 14 was isolated in 65% yield after flash chromatography. Formation of the benzofuran can be rationalized by cleavage of the benzopyran ring and a subsequent rearrangement reaction [29][30]. However, by using standard Sonogashira conditions in

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

• moieties is usually accomplished by cross-coupling reactions, in particular by the Suzuki–Miyaura [26][27] or the Sonogashira [28] reactions. Consequently, the availability of the suitably substituted π-conjugated linkers of various lengths bearing boronic ester functionality or terminal acetylene is

• crucial for such a synthetic approach. Hence, we report here a convenient synthesis as well as characterization of either unsubstituted (R = H) or donor substituted (R = NMe2, OMe) π-conjugated linkers designed for the Suzuki–Miyaura and Sonogashira cross-couplings with a systematically varied 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

• 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

• , 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

Synthesis of 2,3,6,7-tetrabromoanthracene

• Christian Schäfer,
• Friederike Herrmann and
• Jochen Mattay

Beilstein J. Org. Chem. 2008, 4, No. 41, doi:10.3762/bjoc.4.41

• iodinated four times to give 1 in 71% yield by the method of Mattern [16]. The next step is a fourfold Sonogashira-Hagihara coupling reaction with trimethylsilylacetylene. We slightly modified the procedure reported by Vollhardt et al. [17] and used tetrakis(triphenylphosphine)palladium(0) as catalyst

Facile synthesis of two diastereomeric indolizidines corresponding to the postulated structure of alkaloid 5,9E- 259B from a Bufonid toad (Melanophryniscus)

• Angela Nelson,
• H. Martin Garraffo,
• Thomas F. Spande,
• John W. Daly and
• Paul J. Stevenson

Beilstein J. Org. Chem. 2008, 4, No. 6, doi:10.1186/1860-5397-4-6

• -vinyl iodide with a selectivity of 97:3. Finally, Sonogashira reaction [50] of the vinyl iodide with trimethylsilylacetylene followed by removal of the trimethylsilyl group gave synthetic 7. At this stage the C8 diastereoisomers were separated by flash chromatography, though the minor component was

• contaminated with triphenyl phosphine / phosphine oxide residue from the Sonogashira reaction. The two synthetic C8 diastereoisomers were compared to natural 5,9E-259B present in the alkaloid fraction obtained from a bufonid toad, Melanophryniscus stelzneri [51]. The GC mass spectra of the three compounds were

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

Trapping evidence for the thermal cyclization of di-(o-acetylphenyl)acetylene to 3,3'-dimethyl- 1,1'-biisobenzofuran

• Charles P. Casey,
• Neil A. Strotman and
• Ilia A. Guzei

Beilstein J. Org. Chem. 2005, 1, No. 18, doi:10.1186/1860-5397-1-18

• . Oligomeric isobenzofurans are theoretically interesting molecules and their optical and electronic properties have been studied computationally.[2][3] Alkyne 1 was synthesized through two palladium catalyzed Sonogashira couplings (Scheme 2). Coupling of 2'-iodoacetophenone with trimethylsilylacetylene