C–C Bond formation catalyzed by natural gelatin and collagen proteins

• Dennis Kühbeck,
• Basab Bijayi Dhar,
• Eva-Maria Schön,
• Carlos Cativiela,
• Vicente Gotor-Fernández and
• David Díaz Díaz

Beilstein J. Org. Chem. 2013, 9, 1111–1118, doi:10.3762/bjoc.9.123

• 33071, Spain 10.3762/bjoc.9.123 Abstract The activity of gelatin and collagen proteins towards C–C bond formation via Henry (nitroaldol) reaction between aldehydes and nitroalkanes is demonstrated for the first time. Among other variables, protein source, physical state and chemical modification

• salmon testes DNA [11] and chitosan [12], as well as various enzymes [13][14][15][16], have been reported to catalyze this type of reaction. However, to the best of our knowledge, the role of natural gelatin or collagen proteins as potential biocatalysts for C–C bond formation has not been yet described

• ]. Very interestingly, even the direct use of edible gelatin obtained from the supermarket (either in powdered or cooked form) promoted the C–C bond formation in good yields (Table 2, entries 6 and 7). On the other hand, although the use of gelatin in hydrogel form did not afford a higher yield than in

A computational study of base-catalyzed reactions of cyclic 1,2-diones: cyclobutane-1,2-dione

• Nargis Sultana and
• Walter M. F. Fabian

Beilstein J. Org. Chem. 2013, 9, 594–601, doi:10.3762/bjoc.9.64

• imaginary frequency of TS3a is larger (ν = 410i cm–1) than that of TS2 (ν = 246i cm–1) with C–C bond formation as the associated mode. Path C Similar to path B, all attempts to locate the initially proposed intermediate Int3 were unsuccessful. Instead a more complicated pathway involving a high-energy

Tandem aldehyde–alkyne–amine coupling/cycloisomerization: A new synthesis of coumarins

• Maddi Sridhar Reddy,
• Nuligonda Thirupathi and
• Madala Haribabu

Beilstein J. Org. Chem. 2013, 9, 180–184, doi:10.3762/bjoc.9.21

• moderate yields. Keywords: A3 coupling; cooperative catalysis; coumarin synthesis; cycloisomerization; transition-metal catalysts; Introduction An alkyne, an aldehyde and an amine coupling, referred to as A3 coupling [1], has been found as an efficient method for C–N and C–C bond formation that results

Rh(III)-catalyzed directed C–H bond amidation of ferrocenes with isocyanates

• Satoshi Takebayashi,
• Tsubasa Shizuno,
• Takashi Otani and
• Takanori Shibata

Beilstein J. Org. Chem. 2012, 8, 1844–1848, doi:10.3762/bjoc.8.212

• -formation reactions [13]. Recently, several reports of cationic Cp*Rh(III)-catalyzed nonoxidative C–C-bond-formation reactions have been disclosed [14][15][16][17][18][19][20][21][22]. For example, Ellman et al. and Shi et al. reported that Cp*Rh(III) complexes catalyzed the reaction of aryl C–H bonds to

• communication describes a metal-catalyzed directed electrophilic C–H activation of an electron-rich Cp ring of ferrocene. Pentamethylcyclopentadienyl (Cp*)Rh(III) is known to catalyze electrophilic activation of aryl C–H bonds, typically in the presence of an acetate ligand, and is used for oxidative C–C-bond

Synthesis and evaluation of new guanidine-thiourea organocatalyst for the nitro-Michael reaction: Theoretical studies on mechanism and enantioselectivity

• Tatyana E. Shubina,
• Matthias Freund,
• Sebastian Schenker,
• Timothy Clark and
• Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2012, 8, 1485–1498, doi:10.3762/bjoc.8.168

• for its ability to mediate the enantioselective C–C bond-formation reactions. As an initial model transformation we studied the Henry reaction of 3-phenylpropionaldehyde (8) with nitromethane (9) in the presence of 10 mol % of 7, with the reaction proceeding for 48 h at room temperature in toluene

• reaction, the C–C bond formation. We found four transition states, three of which lead to the R product and only one to the S equivalent (Figure 6). Compared to the initial complexes INIT1–INIT12, the energy difference between the initial complexes INIT13–INIT16 is much higher (between 4.6 and 8.0 kcal·mol

Enantioselective Michael addition of 2-hydroxy-1,4-naphthoquinones to nitroalkenes catalyzed by binaphthyl-derived organocatalysts

• Saet Byeol Woo and
• Dae Young Kim

Beilstein J. Org. Chem. 2012, 8, 699–704, doi:10.3762/bjoc.8.78

• ][7][8][9]. The stereoselective formation of C–C bonds is of great importance for the synthesis of enantiomerically pure, biologically active organic compounds [10][11]. It is widely recognized that the Michael addition is one of the most versatile and general methods for C–C bond formation in organic

Stereoselective, nitro-Mannich/lactamisation cascades for the direct synthesis of heavily decorated 5-nitropiperidin-2-ones and related heterocycles

• Pavol Jakubec,
• Dane M. Cockfield,
• Madeleine Helliwell,
• James Raftery and
• Darren J. Dixon

Beilstein J. Org. Chem. 2012, 8, 567–578, doi:10.3762/bjoc.8.64

• -99,994 [68][69], inhibitors of farnesyltransferase [70][71], selective dipeptidyl peptidase IV inhibitors [72][73], and functionalised bispidines [74]. Very recently, a related cascade inspired by the original work of Jain incorporating C–C bond formation was accomplished through a nitro-Mannich reaction

Branching out at C-2 of septanosides. Synthesis of 2-deoxy-2-C-alkyl/aryl septanosides from a bromo-oxepine

• Supriya Dey and
• Narayanaswamy Jayaraman

Beilstein J. Org. Chem. 2012, 8, 522–527, doi:10.3762/bjoc.8.59

• 114.3 ppm. Analyses of 1H and 13C NMR spectra and mass spectra confirmed the constitution of 8–10. The reactivity of bromo-oxepine, the key intermediate of the septanoside synthesis earlier, was explored further in the context of C–C bond formation at C-2, through another versatile C–C bond forming

• bond formation with alkyl and aryl substituents. Keywords: C–C bond formations; 2-deoxy sugars; organometallic reactions; septanosides; unsaturated sugars; Introduction Septanoses and septanosides are unnatural, seven-membered cyclic sugars [1]. Methods of preparation and the exploration of the

• septanosides. Deprotection and reduction of the 2-deoxy-2-alkenyl derivative afforded the corresponding 2-deoxy-2-C-alkyl septanoside free of protecting groups. The present study illustrates the reactivity of bromo-oxepine in the synthesis of hitherto unknown septanosides, branching out at C-2, through C–C

Synthesis of fluoranthenes by hydroarylation of alkynes catalyzed by gold(I) or gallium trichloride

• Sergio Pascual,
• Christophe Bour,
• Paula de Mendoza and
• Antonio M. Echavarren

Beilstein J. Org. Chem. 2011, 7, 1520–1525, doi:10.3762/bjoc.7.178

• triaryl substituted diacenaphtho[1,2-j:1',2'-l]fluoranthenes (decacyclenes) 2a and 2b in very good overall yields after aromatization of the crude products with DDQ. Remarkably, this triple hydroarylation occurs efficiently with an average yield per C–C bond formation that is greater than 90%. Conclusion

Use of mixed Li/K metal TMP amide (LiNK chemistry) for the synthesis of [2.2]metacyclophanes

• Marco Blangetti,
• Patricia Fleming and
• Donal F. O'Shea

Beilstein J. Org. Chem. 2011, 7, 1249–1254, doi:10.3762/bjoc.7.145

• substituted m-xylenes is described. The strategy employs a selective benzylic metalation and oxidative C–C bond formation for both synthetic operations. Regioselective benzylic metalation is achieved using the BuLi, KOt-Bu, TMP(H) (2,2,6,6-tetramethylpiperidine) combination (LiNK metalation conditions) and

• from C(8) to C(16) is as expected for [2.2]metacyclophanes at 2.66(1) Å [29]. Conclusion A new two-step general approach to [2.2]metacyclophane synthesis was described from substituted m-xylenes. Our strategy employs a selective benzylic metalation and oxidative C–C bond formation for both synthetic

Microphotochemistry: 4,4'-Dimethoxybenzophenone mediated photodecarboxylation reactions involving phthalimides

• Oksana Shvydkiv,
• Kieran Nolan and
• Michael Oelgemöller

Beilstein J. Org. Chem. 2011, 7, 1055–1063, doi:10.3762/bjoc.7.121

• (ET) from the carboxylate function to the triplet excited phthalimide furnishes an unstable carboxy radical, which undergoes rapid decarboxylation to the corresponding carbon radical. Protonation and C–C bond formation yields compounds 4 and 9, and the latter undergoes further dehydration to 10

• alkyl- and arylthioacetic acids [48][56], respectively. With compound 6 or in the presence of 2, successive electron transfer generates the corresponding phthalimide radical anion. Subsequent decarboxylation, protonation and C–C bond formation furnish products 7 and 12. In the absence of N

• -methylphthalimide 2, protonation and C–C bond formation to 14 or photopinacolization to 15 operate instead (not shown). Conclusion DMBP mediated photodecarboxylation reactions involving phthalimides can be successfully transferred from batch to microflow conditions. While DMBP allows for the application of UVA

Asymmetric synthesis of tertiary thiols and thioethers

• Jonathan Clayden and
• Paul MacLellan

Beilstein J. Org. Chem. 2011, 7, 582–595, doi:10.3762/bjoc.7.68

• (C–S bond formation). Alternatively, stereoselective alkylation, arylation or acylation of a secondary sulfur-based substrate could generate the quaternary centre (C–C bond formation). Review 1 Carbon–sulfur bond formation 1.1 SN2 displacement of a leaving group Stereospecific nucleophilic attack on

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

• –CuI–PPh3 proved to be an efficient and selective catalytic system for the C–C bond formation between 4-chlorothieno[2,3-d]pyrimidine and terminal alkynes in methanol providing a general and practical method for the preparation of these novel compounds. The reaction proceeds well with both hydrophobic

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

• Introduction C–C bond formation is one of the most important types of reaction in organic synthesis. Transformations employing organometallic compounds as catalysts have achieved a significant role because of their advantages such as simplicity (fewer reaction steps) and efficiency (higher yields) in

C-Arylation reactions catalyzed by CuO-nanoparticles under ligand free conditions

• Mazaahir Kidwai,
• Saurav Bhardwaj and
• Roona Poddar

Beilstein J. Org. Chem. 2010, 6, No. 35, doi:10.3762/bjoc.6.35

• aryl halides. The products were obtained in good to excellent yield. The catalyst can be recovered and reused for four cycles with almost no loss in activity. Keywords: active methylene compounds; C-arylation; heterogeneous catalyst; recyclability; Introduction Carbon-carbon (C–C) bond formation is

• catalyze Ullmann-type C–C bond formation, which potentially offers an efficient protocol for accessing a variety of α-arylated dicarbonyl compounds. Experimental General The materials were purchased from Sigma-Aldrich and Merck and were used without further purification. Mass spectra were recorded in a TOF

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

• the extension or shortening of the π-conjugated path between the donor and acceptor [19][21][23][24][25]. Thus, the latter modular synthetic approach seems to be more suitable for the property tuning described above. The final combination, C–C bond formation, of the donor and acceptor chromophore

Reduction of arenediazonium salts by tetrakis(dimethylamino)ethylene (TDAE): Efficient formation of products derived from aryl radicals

• Mohan Mahesh,
• John A. Murphy,
• Franck LeStrat and
• Hans Peter Wessel

Beilstein J. Org. Chem. 2009, 5, No. 1, doi:10.3762/bjoc.5.1

• vinblastine (58a) and vincristine (58b) contain such a system. Aryl C-C bond formation As a final extension of this methodology, we probed the feasibility of this methodology in aryl-aryl C-C bond formation reactions. Accordingly, the diazonium salt 62 was prepared from indoline (59), and treated with one

• reaction conditions for greater efficiency. A preliminary study on TDAE-mediated aryl-aryl C-C bond formation reaction has also been discussed. TDAE possesses a distinct advantage over other organic reducing agents as the oxidized products of TDAE are water soluble – thus the purification process is highly

Mixtures of monodentate P-ligands as a means to control the diastereoselectivity in Rh-catalyzed hydrogenation of chiral alkenes

• Manfred T. Reetz and
• Hongchao Guo

Beilstein J. Org. Chem. 2005, 1, No. 3, doi:10.1186/1860-5397-1-3

• using a 1:1 mixture of triphenylphosphine and a certain phosphinine (substituted phospha-benzene), 95% regioselectivity in favor of C-C bond formation at the higher substituted C-atom was achieved, whereas the use of the pure ligands as traditional homo-combinations led to low degrees of