Advances in synthetic approach to and antifungal activity of triazoles

• Kumari Shalini,
• Nitin Kumar,
• Sushma Drabu and
• Pramod Kumar Sharma

Beilstein J. Org. Chem. 2011, 7, 668–677, doi:10.3762/bjoc.7.79

• -lactams and terminal alkynes of bile acids in the presence of a Cu(I) catalyst (click chemistry) by Vatmurge et al. The synthesized compounds were evaluated for their antifungal activity against different fungal strains such as Candida albicans, Cryptococcus neoformans, Benjaminiella poitrasii, Yarrowia

One-pot gold-catalyzed synthesis of 3-silylethynyl indoles from unprotected o-alkynylanilines

• Jonathan P. Brand,
• Clara Chevalley and
• Jérôme Waser

Beilstein J. Org. Chem. 2011, 7, 565–569, doi:10.3762/bjoc.7.65

• access to 3-silylalkynyl indoles. To the best of our knowledge, this is the first example of a one-pot process combining a Au(III) and a Au(I) catalyst. Findings 2-Alkynylanilines 2 can be efficiently prepared from 2-iodoanilines 4 and terminal alkynes via Sonogashira reaction with Et3N as solvent

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

• reaction time under much milder conditions. Keywords: 4-aryl-2-methyl-3-butyn-2-ol; deprotection reaction; 2-methyl-3-butyn-2-ol; terminal alkynes; tetrabutylammonium hydroxide; Introduction Terminal arylacetylenes are key precursors for the construction of conjugated oligo- or polyarylacetylenes, which

Synthesis of glycoconjugate fragments of mycobacterial phosphatidylinositol mannosides and lipomannan

• Benjamin Cao,
• Jonathan M. White and
• Spencer J. Williams

Beilstein J. Org. Chem. 2011, 7, 369–377, doi:10.3762/bjoc.7.47

• ) lipophilicity allowing biphasic partitioning between butanol/water or purification by reversed-phase extraction, (ii) ability to be reduced to an aminooctyl chain for use in squarate conjugation chemistry, and (iii) capacity to be conjugated with fluorescent terminal alkynes using the Cu(I)-catalyzed azide

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

• /C–CuI–PPh3 catalytic system facilitated C–C bond formation between 4-chlorothieno[2,3-d]pyrimidines and terminal alkynes in methanol with high selectivity without generating any significant side products arising from C–O bond formation between the chloro compounds and methanol. A variety of novel 4

• halopyrimidines with terminal alkynes [1][2][3] (for a review see [8]). While alkynylation of the thiophene ring of thienopyrimidines under Sonogashira conditions [9] has previously been reported [6], a similar coupling reaction on the pyrimidine ring of thieno[2,3-d]pyrimidines is uncommon in the literature [10

• 6,7,8,9-tetrahydro-5H-cyclohepta[4,5]thieno[2,3-d]pyrimidin-4-one (5) which on treatment with POCl3 under refluxing conditions provided the desired 4-chloro derivative 1d. All the terminal alkynes used were commercially available. Initially, we chose to examine the coupling reaction of 4-chloro-5,6,7,8

Ene–yne cross-metathesis with ruthenium carbene catalysts

• Cédric Fischmeister and
• Christian Bruneau

Beilstein J. Org. Chem. 2011, 7, 156–166, doi:10.3762/bjoc.7.22

• [3] demonstrated that alkyne polymerization could be initiated directly from terminal alkynes without previous preparation of a metal carbene but via the formation of a reactive vinylidene tungsten species. Later on, the efficiency of ruthenium vinylidene precursors was also shown in olefin

• metathesis [4][5][6][7][8][9][10]. It is noteworthy that polymerization of terminal alkynes [11][12][13] and cyclotrimerization of triynes [14][15][16][17][18][19][20] with ruthenium carbene precursors is still a topic of current interest. Then, Fischer tungsten carbene complexes were used by Katz [21], and

• by Blechert that EYCM reactions could be performed starting from either the olefin or the alkyne substrate bound to a support [58][59][60]. An improvement of the EYCM was achieved with the second generation Grubbs catalyst II starting from terminal alkynes, especially sterically hindered ones. More

Recent advances in the development of alkyne metathesis catalysts

• Xian Wu and
• Matthias Tamm

Beilstein J. Org. Chem. 2011, 7, 82–93, doi:10.3762/bjoc.7.12

• specific applications and substrate classes. However, the development in alkyne metathesis has yet to overcome one major obstacle, and that is the impracticability of employing terminal alkynes as substrates, since these tend to form polymers [95] and were also shown to degrade Schrock alkylidynes by

The allylic chalcogen effect in olefin metathesis

• Yuya A. Lin and
• Benjamin G. Davis

Beilstein J. Org. Chem. 2010, 6, 1219–1228, doi:10.3762/bjoc.6.140

• by the potentially labile natural product scaffold. Enhancement effects by an allylic hydroxy group have also been found in ring-closing enyne metathesis. Studies by Takahata et al. revealed that the ring-closing enyne metathesis of terminal alkynes containing an allylic hydroxy group proceeded

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• vinyl silyl ethers were used as nucleophiles in this transformation [110]. The substituted γ-selenopropargyl compounds were readily transformed into the terminal alkynes 103 by treatment with tributyltin hydride or were further functionalized with aldehydes to form the highly substituted allenyl

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

• a carboxylate or an equivalent group in proximity to the triple bond). Thus, isocoumarins have been prepared by reacting o-iodobenzoic acid with terminal alkynes in the presence of a Pd-catalyst [14][15][16]. Recently, we have reported synthesis of thienopyranones following a similar strategy [7][18

• generality of this reaction in the synthesis of other analogues especially varying the substituent at C-6. Accordingly, a variety of commercially available terminal alkynes were reacted with the iodo acid 1 (Table 2) under the optimized conditions as presented in Entry 1 of Table 1. As evident from Table 2

• , all the terminal alkynes participated well in this coupling-cyclization reaction affording the desired products in moderate to good yields. Various substituents such as alkyl, hydroxyalkyl or aryl groups present in the terminal alkyne were well tolerated. The use of arylalkynes (Entries 7 and 8, Table

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