Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• the stereogenic centers formed during the cascade cyclization was secured by the use of benzothiophene-based TADDOL thiol 166 as chiral catalyst. They obtained in one single step a 5.3:1 and 3.4:1 diastereomeric ratio for C14 and C15, respectively, while forming the desired trans [5-8] ring junction

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Stereoselective Biginelli-like reaction catalyzed by a chiral phosphoric acid bearing two hydroxy groups

• Xiaoyun Hu,
• Jianxin Guo,
• Cui Wang,
• Rui Zhang and
• Victor Borovkov

Beilstein J. Org. Chem. 2020, 16, 1875–1880, doi:10.3762/bjoc.16.155

• BINOL, 2,2-dimethyltetraphenyl-1,3-dioxolane-4,5-dimethanol (TADDOL) was also widely used as a C2 chiral diol. However, TADDOL-derived phosphoric acids were not comprehensively investigated as catalysts in Biginelli and Biginelli-like reactions yet. The first example of their successful application was

Catalytic asymmetric oxo-Diels–Alder reactions with chiral atropisomeric biphenyl diols

• Chi-Tung Yeung,
• Wesley Ting Kwok Chan,
• Wai-Sum Lo,
• Ga-Lai Law and
• Wing-Tak Wong

Beilstein J. Org. Chem. 2019, 15, 955–962, doi:10.3762/bjoc.15.92

• acid catalysts for over three decades [15][16][17][18][19][20][21][22][23][24][25][26]. Comparatively, interest in the utilization of metal-free organocatalytic oxo-DA reactions began to grow only after Rawal’s group reported a ground-breaking contribution in using a diol molecule, TADDOL, as a

• groups of the TADDOL and the carbonyl oxygen of the aldehyde was proposed to be a crucial factor for the success of this organocatalyst in the reaction. Two years later, they reported another efficient diol-based hydrogen bonding organocatalyst, BAMOL, for catalyzing the same oxo-DA reactions with a

• form strong hydrogen bonds could perform the same catalytic role in oxo-DA reactions as reported in the literature. Inspired by Rawal’s work on TADDOL and BAMOL organocatalysts, we, in this work, have adopted a similar reaction of Rawal’s diene with benzaldehyde as a starting point of our study and

Gold(I)-catalyzed enantioselective cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2013, 9, 2250–2264, doi:10.3762/bjoc.9.264

• demonstrated that a phosphoramidite–gold complex like Au8, containing an acyclic Taddol-based backbone, was also an excellent catalyst to perform the same type of [2 + 2] cycloadditions of allenenes 11 [52][53]. This catalyst performs equally well with carbon-based and nitrogen-based tethers, and excellent

• + 2] cycloadditions [67]. Moreover, Fürstner and co-workers also showed that the Taddol-based phosphoramidite–gold complex Au8, which was effective in the [2 + 2] cycloadditions of allenenes, was also able to induce good enantioselectivities in these higher order annulations (Scheme 9) [52]. Although

Thiourea-catalyzed Diels–Alder reaction of a naphthoquinone monoketal dienophile

• Carsten S. Kramer and
• Stefan Bräse

Beilstein J. Org. Chem. 2013, 9, 1414–1418, doi:10.3762/bjoc.9.158

• of one equivalent of Brønsted acid 8 had no effect (Table 2, entry 4), the addition of TADDOL (9) improved the reaction speed (Table 2, entry 5). By the use of Schreiner's catalyst 10 [7], the highest conversion speed was observed (Table 2, entry 6). After this finding, Jacobsen's thioureas 11 [13

Development of the titanium–TADDOLate-catalyzed asymmetric fluorination of β-ketoesters

• Lukas Hintermann,
• Mauro Perseghini and
• Antonio Togni

Beilstein J. Org. Chem. 2011, 7, 1421–1435, doi:10.3762/bjoc.7.166

• Lewis acids catalyze the α-fluorination of β-ketoesters by electrophilic N–F-fluorinating reagents. Asymmetric catalysis with TADDOLato–titanium(IV) dichloride (TADDOL = α,α,α',α'-tetraaryl-(1,3-dioxolane-4,5-diyl)-dimethanol) Lewis acids produces enantiomerically enriched α-fluorinated β-ketoesters in

• TADDOL ligand structure on the catalytic activity and enantioselectivity were investigated. The absolute configuration of several fluorination products was assigned through correlation. Evidence for ionization of the catalyst complex by chloride dissociation, followed by generation of titanium β

• -ketoenolates as key reaction intermediates, was obtained. Based on the experimental findings, a general mechanistic sketch and a steric model of induction are proposed. Keywords: Asymmetric catalysis; fluorination; fluoroorganic compounds; TADDOL; titanium; Introduction Fluoroorganic compounds have peculiar

Directed ortho,ortho'-dimetalation of hydrobenzoin: Rapid access to hydrobenzoin derivatives useful for asymmetric synthesis

• Inhee Cho,
• Labros Meimetis,
• Lee Belding,
• Michael J. Katz,
• Travis Dudding and
• Robert Britton

Beilstein J. Org. Chem. 2011, 7, 1315–1322, doi:10.3762/bjoc.7.154

• The discovery of new chiral ligands and auxiliaries continues to expand the frontiers of catalytic asymmetric synthesis. In particular, C2-symmetric diols, such as (S)-BINOL (1) [1] and (−)-TADDOL (2) [2] (Figure 1), have garnered considerable attention owing to the wide variety of asymmetric

Lithium phosphonate umpolung catalysts: Do fluoro substituents increase the catalytic activity?

• Anca Gliga,
• Bernd Goldfuss and
• Jörg M. Neudörfl

Beilstein J. Org. Chem. 2011, 7, 1189–1197, doi:10.3762/bjoc.7.138

• comparison of fluorinated and nonfluorinated TADDOL phosphonates (which were used by Johnson's group) as precatalysts in benzoin coupling does not show any difference in reactivity (Scheme 2). In contrast the enantioselectivity is clearly higher with the fluorinated TADDOL precatalyst (Scheme 2). Here, we

Recent developments in gold-catalyzed cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2011, 7, 1075–1094, doi:10.3762/bjoc.7.124

• coworkers [105], are also capable of inducing excellent enantioselectivities in these (4 + 2) cycloaddition reactions of allenedienes. More recently, the group of Fürstner has also reported that Taddol-based phosphoramidite–gold complexes such as Au12 (Scheme 29) are excellent catalysts for these (4 + 2

Asymmetric reactions in continuous flow

• Xiao Yin Mak,
• Paola Laurino and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2009, 5, No. 19, doi:10.3762/bjoc.5.19

• on the use of Ti-TADDOL-functionalized monolithic columns for Diels-Alder cycloaddition of cyclopentadiene and 3-crotonyl-1,3-oxazolidin-2-one [39]. In this case, a complete reversal of topicity was observed, switching from a monolithic catalyst to the one grafted on a polymer matrix. Kirschning and

A superior P-H phosphonite: Asymmetric allylic substitutions with fenchol- based palladium catalysts

• Bernd Goldfuss,
• Thomas Löschmann,
• Tina Kop-Weiershausen,
• Jörg Neudörfl and
• Frank Rominger

Beilstein J. Org. Chem. 2006, 2, No. 7, doi:10.1186/1860-5397-2-7

• Leeuwen's bulky, monodentate TADDOL based phosphoramidite gave rise to intriguing memory effects [28b] and yielded 6% branched product with 25% ee (Scheme 2) [9]. We have recently employed modular, chelating fencholates, [10][11][12][13][14] in enantioselective organozinc catalysts, [15][16][17][18][19] and

Chiral trimethylsilylated C₂-symmetrical diamines as phosphorous derivatizing agents for the determination of the enantiomeric excess of chiral alcohols by ¹H NMR

• Anne-Sophie Chauvin and
• Alexandre Alexakis

Beilstein J. Org. Chem. 2006, 2, No. 6, doi:10.1186/1860-5397-2-6

• determination of ee by integration. The area around 0 ppm usually fulfils these criteria. We already reported the use of TADDOL phosphorus derivatives, where the determination of ee can be performed by integration of the TADDOL isopropylidene-methyl signals [29]. Herein we report the use of CDAs 1, 2 and 3

An exceptional P-H phosphonite: Biphenyl- 2,2'-bisfenchylchlorophosphite and derived ligands (BIFOPs) in enantioselective copper- catalyzed 1,4-additions

• T. Kop-Weiershausen,
• J. Lex,
• J.-M. Neudörfl and
• B. Goldfuss

Beilstein J. Org. Chem. 2005, 1, No. 6, doi:10.1186/1860-5397-1-6

• = fenchyl-aryl dihedral angle between C1'-C2'-C3'-O2). Monodentate phosphorus ligands, e.g. BINOL-based phosphoramidites or TADDOL-based phosphites, are highly efficient in copper catalyzed enantioselective conjugate additions. Modular phosphoramidites (R= NR'2) or phosphites (R= OR') from reactive