C₂-symmetric bisamidines: Chiral Brønsted bases catalysing the Diels- Alder reaction of anthrones

• Deniz Akalay,
• Gerd Dürner,
• Jan W. Bats and
• Michael W. Göbel

Beilstein J. Org. Chem. 2008, 4, No. 28, doi:10.3762/bjoc.4.28

• bisamidine-mediated organocatalytic transformations. Kinetic measurements of 1a with 2a catalyzed by 5 mol% of 8a·H+·TFPB- (black line) and 1 mol% 8a (free base; red line). Molecular structure of 3m (C: black; N: blue; O: red; Cl: green; hydrogen atoms are omitted for the sake of clarity). Diels-Alder

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

• reactions. Stoichiometric approaches based on cinchona alkaloid/Selectfluor® combinations [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32], chiral ligand/metal-catalyzed [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57] or organocatalytic [58

The first organocatalytic carbonyl- ene reaction: isomerisation- free C-C bond formations catalysed by H-bonding thio- ureas

• Matthew L. Clarke,
• Charlotte E. S. Jones and
• Marcia B. France

Beilstein J. Org. Chem. 2007, 3, No. 24, doi:10.1186/1860-5397-3-24

• interest in hydrogen bond mediated catalysis,[11] we have investigated thioureas as H-bonding additives for organocatalytic carbonyl ene reactions and report these results here. Despite the explosive growth in organocatalytic reactions in recent years, [12][13][14][15][16] this represents, to the best of

• our knowledge, the first example of an organocatalytic carbonyl ene reaction. [17] Findings We first carried out a thermal ene reaction of α-methyl styrene 1 with ethyl trifluoropyruvate under microwave heating to produce racemic product 3 (Scheme 1). This reaction was accompanied by several side

• % catalyst. Lower catalyst loadings required longer reaction times. Thus, in common with most organocatalytic procedures, turnover frequency is low. In order to explore if an asymmetric variant of this reaction was possible, we elected to employ a chiral thio-urea. It is almost certain that these reactions

Beilstein Journal of Organic Chemistry

• Jonathan Clayden

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

• still to be discovered. Four years ago, the Nobel prize in chemistry celebrated chemists' achievements in asymmetric catalysis – and even since then the face of catalysis is changing, with for example metathesis and organocatalytic methods constantly breaking into new areas. Synthesis is changing too