Stereoselective synthesis of trans-fused iridoid lactones and their identification in the parasitoid wasp Alloxysta victrix, Part I: Dihydronepetalactones

• Nicole Zimmermann,
• Robert Hilgraf,
• Lutz Lehmann,
• Daniel Ibarra and
• Wittko Francke

Beilstein J. Org. Chem. 2012, 8, 1246–1255, doi:10.3762/bjoc.8.140

• ruthenium BINAP catalysts ([Ru((S)-BINAP)](OAc)2) [35][36] but reduction occurred only at the side chain. Relative configurations of all substituents of the acetate 26 were confirmed by NOESY experiments (Figure 7). Strong NO-effects were observed between the protons 5-CH3 and 1’-H (protons of the

Palladium-catalyzed substitution of (coumarinyl)methyl acetates with C-, N-, and S-nucleophiles

• Kalicharan Chattopadhyay,
• Erik Fenster,
• Alexander J. Grenning and
• Jon A. Tunge

Beilstein J. Org. Chem. 2012, 8, 1200–1207, doi:10.3762/bjoc.8.133

• the enolate proceeds in highest yield in acetonitrile (2a, Table 1, entry 3). Bidentate ligated palladium complexes gave mixed results: the Pd/dppf complex (Table 1,entry 4) catalyzed the reaction smoothly, while little product was seen on using the Pd/BINAP complex (Table 1,entry 5). Under the best

Synthesis and characterization of Sant-75 derivatives as Hedgehog-pathway inhibitors

• Chao Che,
• Song Li,
• Bo Yang,
• Shengchang Xin,
• Zhixiong Yu,
• Taofeng Shao,
• Chuanye Tao,
• Shuo Lin and
• Zhen Yang

Beilstein J. Org. Chem. 2012, 8, 841–849, doi:10.3762/bjoc.8.94

• smoothly in toluene with NaOt-Bu as base by using a Pd2(dba)3/rac-BINAP catalysis system [50]. Substituent-modifications on the motif D It has previously been shown that the substitution pattern on the nitrogen atom of trans-1,4-diaminocyclohexane moiety plays a critical role in the activity of the

• , PhMe, reflux; (f) acetamidine hydrochloride, Na, EtOH, reflux; (g) 1H-imidazole-4-carbaldehyde, DMF, CuI, Cs2CO3. Chemical modifications on the motif C. Reagents and conditions: (a) Pd(OAc)2, PPh3, 1,4-dioxane, Na2CO3, 100 °C; (b) CuI, DMF, Cs2CO3, 120 °C; (c) (i) Pd2(dba)3, rac-BINAP, NaOt-Bu, PhMe

Bromine–lithium exchange: An efficient tool in the modular construction of biaryl ligands

• Laurence Bonnafoux,
• Frédéric R. Leroux and
• Françoise Colobert

Beilstein J. Org. Chem. 2011, 7, 1278–1287, doi:10.3762/bjoc.7.148

• diphosphine ligands BINAP [3], H8-BINAP [4], BIPHEMP [5], MeO-BIPHEP [6], SEGPHOS [7][8][9], P-Phos [10], SYNPHOS [11][12], Cn-TUNAPHOS [13] and DIFLUORPHOS [14][15][16] and their analogues are well known as highly efficient chiral ligands for a variety of transition metal-catalyzed asymmetric transformations

Chiral gold(I) vs chiral silver complexes as catalysts for the enantioselective synthesis of the second generation GSK-hepatitis C virus inhibitor

• María Martín-Rodríguez,
• Carmen Nájera,
• José M. Sansano,
• Abel de Cózar and
• Fernando P. Cossío

Beilstein J. Org. Chem. 2011, 7, 988–996, doi:10.3762/bjoc.7.111

• gold(I) catalysts in this reaction was established by working with chiral phosphoramidites or with chiral BINAP. The best reaction conditions were used for the total synthesis of the hepatitis C virus inhibitor by a four step procedure affording this product in 99% ee and in 63% overall yield. The

• origin of the enantioselectivity of the chiral gold(I) catalyst was justified according to DFT calculations, the stabilizing coulombic interaction between the nitrogen atom of the thiazole moiety and one of the gold atoms being crucial. Keywords: BINAP; 1,3-dipolar cycloaddition; gold; HCV

• , generated from chiral phosphoramidites or BINAP as ligands, in order to prepare antiviral agent 2a. Results and Discussion The efficiency of the chiral phosphoramidite/silver(I) salts [25][26][29] and BINAP/Ag(I) salts [30][31] in 1,3-DC, following the general pattern shown in Scheme 1, has been

Cationic gold(I) axially chiral biaryl bisphosphine complex-catalyzed atropselective synthesis of heterobiaryls

• Tetsuro Shibuya,
• Kyosuke Nakamura and
• Ken Tanaka

Beilstein J. Org. Chem. 2011, 7, 944–950, doi:10.3762/bjoc.7.105

• Tetsuro Shibuya Kyosuke Nakamura Ken Tanaka Department of Applied Chemistry, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan 10.3762/bjoc.7.105 Abstract It has been established that a cationic gold(I)/(R)-DTBM-Segphos or (R)-BINAP

• palladium(II)/(S)-xyl-H8-BINAP complex showed the highest enantioselectivity (Scheme 3) [43][44]. In this paper, we report the use of the cationic gold(I)/axially chiral biaryl bisphosphine complexes in the catalytic asymmetric intramolecular hydroarylation for the synthesis of axially chiral 4-aryl-2

• -quinolinones and 4-arylcoumarins. Results and Discussion The reaction of N-benzyl-N-(2-naphthyl)propiolamide 1a, bearing a 2-methoxynaphthyl group at an alkyne terminus, was first investigated in the presence of a cationic gold(I)/(R)-BINAP complex (20 mol % Au). Although the reaction proceeded at room

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• ee values have been obtained with thiourea-cinchonine [176], chiral carbene [177], BINAP [178][179][180], and BIPHEP [181][182][183][184][185][186][187][188][189][190] analogs. Monge et al. reported a direct asymmetric one-pot synthesis of optically active 2,3-dihydropyrroles from propargyl

• found chiral carbene–AuCl catalyst precursor 380 gave moderate enantioselectivity of up to 59% (Scheme 61) [177]. In the last 3 years, enantioselective gold-catalyzed reactions with BINAP and BIPHEP analogs have been far more documented compared to other ligands. In 2009, Toste’s group reported the

• application of [(R)-xylyl-binap-(AuOPNB)2] 383 in gold-catalyzed hydroaminations and hydroalkoxylations of allenes with hydroxylamines and hydrazines, which gave ee values of up to 99% [178]. Whereas chiral biarylphosphinegold(I) complexes are suitable catalysts for the enantioselective addition of nitrogen

Synthesis of chiral mono(N-heterocyclic carbene) palladium and gold complexes with a 1,1'-biphenyl scaffold and their applications in catalysis

• Lian-jun Liu,
• Feijun Wang,
• Wenfeng Wang,
• Mei-xin Zhao and
• Min Shi

Beilstein J. Org. Chem. 2011, 7, 555–564, doi:10.3762/bjoc.7.64

• catalysts in chiral induction reactions [19][20][21][22][23][24][25]. The axially chiral biaryl framework, widely used in the design of chiral ligands such as BINAP [26][27], BINOL [28][29], and boxax [30], has proved to be very rigid, and was introduced in the development of NHC ligands by the Hoveyda

Palladium- and copper-mediated N-aryl bond formation reactions for the synthesis of biological active compounds

• Carolin Fischer and
• Burkhard Koenig

Beilstein J. Org. Chem. 2011, 7, 59–74, doi:10.3762/bjoc.7.10

• -aryl bond formation, and many examples illustrate their wide application in organic synthesis. The chelating phosphines BINAP, DPPF [17] and DtBPF [18], commonly used for the Buchwald–Hartwig amination, were recently displaced by the biaryl-(dialkyl)phosphine or arylphosphinepyrrole ligands [18][19][20

• syntheses have been developed in which Pd(OAc)2 proved to be the best catalyst in comparison to the dba complex, and BINAP the best ligand. There was no difference if the racemic or the enantiomeric pure ligand was used. The use of Pd(OAc)2 is advantageous on a larger scale due to low cost and easy handling

• appeared to give the highest stereoselectivity of 18 for the N-arylation of 17 (Scheme 5) [55]. Other conditions were not investigated in this case. Another example for BINAP not being the favoured ligand is the synthesis of the fungal natural product demethylasterriquinone A1 (19). Asterriquinones show

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

• recognition of chiral ammonium ions by crown ethers Chiral ammonium salts are found in many biologically active molecules. The enantioselective discrimination of such molecules is of interest as the biological properties of enantiomers may differ [131]. Since Cram et al. synthesized BINAP-crown ethers, which

Iridium-catalyzed asymmetric ring-opening reactions of oxabicyclic alkenes with secondary amine nucleophiles

• Dingqiao Yang,
• Ping Hu,
• Yuhua Long,
• Yujuan Wu,
• Heping Zeng,
• Hui Wang and
• Xiongjun Zuo

Beilstein J. Org. Chem. 2009, 5, No. 53, doi:10.3762/bjoc.5.53

• and 5 mol % bisphosphine ligand (S)-p-Tol-BINAP. The trans-configuration of 3f was confirmed by X-ray crystallography. Keywords: chiral bisphosphine ligand; iridium catalyst; oxabicyclic alkenes; ring-opening reaction; Introduction Substituted dihydronaphthalenes are important molecules with

• obtained only in low yield (47%) with reasonable enantioselectivity (51% ee) in the iridium-catalyzed system. This suggested that (R,S)-PPF-PtBu2 was not an ideal ligand in iridium-catalyzed reactions, which prompted us to screen other ligands. Among the several chiral ligands we had tested, (S)-BINAP and

• (S)-p-Tol-BINAP were found to give better yields and reasonable enantioselectivities. Moreover, in the case of (S)-p-Tol-BINAP, the enantioselectivity is slightly higher than for (S)-BINAP (52% ee vs 35% ee); therefore, we decided to use (S)-p-Tol-BINAP as the ligand for this ring-opening reaction

DBFOX- Ph/metal complexes: Evaluation as catalysts for enantioselective fluorination of 3-(2-arylacetyl)-2-thiazolidinones

• Takehisa Ishimaru,
• Norio Shibata,
• Dhande Sudhakar Reddy,
• Takao Horikawa,
• Shuichi Nakamura and
• Takeshi Toru

Beilstein J. Org. Chem. 2008, 4, No. 16, doi:10.3762/bjoc.4.16

• availability of commonly used classes of ligands for asymmetric catalysis, such as, TADDOLs [37][39][41][47], BINAPs [38][40][43][44][46][49][51][53][55][56][57] and bis(oxazoline) [33][34][36][42][45]. Of particular importance are BINAP ligands. Sodeoka et al. have used the latter ligands in asymmetric

• fluorination of a wide range of substrates, including β-keto esters, β-keto phosphonates, oxindoles [38][40][43][51][53][56][57]. They have also recently reported the enantioselective fluorination of 3-(2-arylacetyl)-2-thiazolidinones with their extended catalytic system, NiCl2-BINAP/R3SiOTf-lutidine with high

• ) and Ni(ClO4)2-DBFOX-Ph/lutidine (binary system, entries 3–6) are moderately effective in the enantioselective fluorination of 1a. According to the report by Sodeoka using their NiCl2-BINAP/R3SiOTf-lutidine (trinary system, up to 88% ee obtained), the reaction requires both R3SiOTf and lutidine [57

Reaction of benzoxasilocines with aromatic aldehydes: Synthesis of homopterocarpans

• Míriam Álvarez-Corral,
• Cristóbal López-Sánchez,
• Leticia Jiménez-González,
• Antonio Rosales,
• Manuel Muñoz-Dorado and
• Ignacio Rodríguez-García

Beilstein J. Org. Chem. 2007, 3, No. 5, doi:10.1186/1860-5397-3-5

• catalytic amount of a complex formed with AgOTf and (±)-BINAP to give good yields of dihydrobenzofurans. [5] Under the same reaction conditions, the eight membered benzoxasilocines did not react. The cis/trans diastereoisomers could be easily distinguished by means of the coupling constants between the

Asymmetric aza-Diels- Alder reaction of Danishefsky's diene with imines in a chiral reaction medium

• Bruce Pégot,
• Olivier Nguyen Van Buu,
• Didier Gori and
• Giang Vo-Thanh

Beilstein J. Org. Chem. 2006, 2, No. 18, doi:10.1186/1860-5397-2-18

• relation to the asymmetric process. Among them are: the zirconium-binaphthol complexes developed by Kobayashi et al., [8][9][10][11] the silver catalysts of phosphine peptide Schiff bases reported by Snapper and Hoveyda,[12] as well as the copper complexes of BINAP and phosphino-oxazolidines described by