Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

• Alemayehu Gashaw Woldegiorgis and
• Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

• ring [36]. Experiments showed that chiral phosphoric acid CPA 2 acted as a bifunctional organocatalyst, that activates 2-naphthols and quinone derivatives via multiple H-bonds and promotes the first step of the enantioselective conjugative addition to generate intermediate I-1 and transfers the its

N-Sulfinylpyrrolidine-containing ureas and thioureas as bifunctional organocatalysts

• Viera Poláčková,
• Dominika Krištofíková,
• Boglárka Némethová,
• Renata Górová,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2021, 17, 2629–2641, doi:10.3762/bjoc.17.176

• -sulfinylurea as bifunctional organocatalyst [23]. The enantio- and diastereoselective addition of Meldrum’s acids to nitroalkenes via N-sulfinylurea catalysis gave products that were readily converted to pharmaceutically relevant compounds [24][25]. A sulfinylurea organocatalyst catalyzed a highly selective

Bifunctional organocatalysts for the asymmetric synthesis of axially chiral benzamides

• Ryota Miyaji,
• Yuuki Wada,
• Akira Matsumoto,
• Keisuke Asano and
• Seijiro Matsubara

Beilstein J. Org. Chem. 2017, 13, 1518–1523, doi:10.3762/bjoc.13.151

• . Moderate to good enantioselectivities were afforded with a range of benzamide substrates. Mechanistic investigations were also carried out. Keywords: axial chirality; benzamide; bifunctional organocatalyst; molecular conformation; multipoint recognition; Introduction Bifunctional organocatalysts have

Enantioselective addition of diphenyl phosphonate to ketimines derived from isatins catalyzed by binaphthyl-modified organocatalysts

• Hee Seung Jang,
• Yubin Kim and
• Dae Young Kim

Beilstein J. Org. Chem. 2016, 12, 1551–1556, doi:10.3762/bjoc.12.149

• at room temperature (Table 1, entries 1–6). Catalyst III, which is a binaphthyl-modified squaramide bifunctional organocatalyst, was the best catalyst for this enantioselective addition reaction (90% ee, Table 1, entry 3). In order to improve the selectivity, different solvents were tested in the

• isatins has been achieved. This method affords practical and efficient access to chiral 3-amino-3-phosphonyl-substituted oxindole derivatives in high yields with excellent enantioselectivities (up to 99% ee). Keywords: 3-amino-3-phosphonyl-substituted oxindole; α-aminophosphonates; bifunctional

• organocatalyst; ketimines; organocatalysis; squaramide; Introduction α-Aminophosphonate derivatives are important compounds as structural mimics of natural α-amino acids [1][2][3]. Chiral α-aminophosphonates have been shown a wide range of biological activities including antibacterial [4] and anticancer

Towards the total synthesis of keramaphidin B

• Pavol Jakubec,
• Alistair J. M. Farley and
• Darren J. Dixon

Beilstein J. Org. Chem. 2016, 12, 1096–1100, doi:10.3762/bjoc.12.104

• pronucleophile to a substituted furanyl nitroolefin catalysed by a bifunctional cinchonine-derived thiourea has been used as the key stereocontrolling step in a new synthetic strategy to the heavily functionalised piperidine core of keramaphidin B. Keywords: bifunctional organocatalyst; enantioselective Michael

• performed the reaction using the substituted furanyl nitroolefin 9 (Scheme 2). The organocatalysed Michael addition of 8 with substituted furanyl nitroolefin 9 [20] under the control of bifunctional organocatalyst 12 proceeded efficiently and, although the reaction time was slightly increased relative to

Stereoselective amine-thiourea-catalysed sulfa-Michael/nitroaldol cascade approach to 3,4,5-substituted tetrahydrothiophenes bearing a quaternary stereocenter

• Sara Meninno,
• Chiara Volpe,
• Giorgio Della Sala,
• Amedeo Capobianco and
• Alessandra Lattanzi

Beilstein J. Org. Chem. 2016, 12, 643–647, doi:10.3762/bjoc.12.63

• increased to 50% ee for diastereoisomer 7a when using chlorobenzene as the solvent at room temperature (Table 2, entry 5). It is worth noting that bifunctional organocatalyst VII appears to be more effective in terms of diastereocontrol than previously employed Brønsted base/Lewis acid system TMG/ZnI2

• the bifunctional organocatalyst structure and reaction conditions will be required for further improvements of the challenging cascade process. Organocatalysts screened in the cascade reaction. Synthesis of catalyst VIII. Asymmetric sulfa-Michael/nitroaldol reaction of nitroalkenes 1–3 with 1,4

The aminoindanol core as a key scaffold in bifunctional organocatalysts

• Isaac G. Sonsona,
• Eugenia Marqués-López and
• Raquel P. Herrera

Beilstein J. Org. Chem. 2016, 12, 505–523, doi:10.3762/bjoc.12.50

• the high catalytic potential that this versatile motif exhibits [14]. The concept of bifunctionality has been extensively explored in organocatalysis in the last decade [15][16]. The bifunctional organocatalyst contains two chemical groups that interact simultaneously with the substrates. This mode of

• -type alkylation reaction of indoles To the best of our knowledge, the first example of an aminoindanol-containing bifunctional organocatalyst was reported by Ricci and co-workers in 2005 [18]. In this pioneering study, the authors used the easily prepared cis-(1R,2S)-aminoindanol-based thiourea

(Thio)urea-mediated synthesis of functionalized six-membered rings with multiple chiral centers

• Giorgos Koutoulogenis,
• Nikolaos Kaplaneris and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2016, 12, 462–495, doi:10.3762/bjoc.12.48

• trapping of the adducts with trifluoroacetic anhydride (TFAA), in order to make the products more stable. As expected the endo-adduct was the sole product observed. For this transformation, quinine-derived bifunctional organocatalyst 56 was utilized. The authors proposed that the catalyst raises the HOMO

• , Liang, Xu and co-workers developed a domino process in order to construct polysubstituted chromeno[4,3-b]pyrrolidine derivatives 157, utilizing a bifunctional organocatalyst 57 (Scheme 50) [71]. The transformation is quite powerful, utilizing under mild conditions and a very low catalyst loading. The

Asymmetric α-amination of β-keto esters using a guanidine–bisurea bifunctional organocatalyst

• Minami Odagi,
• Yoshiharu Yamamoto and
• Kazuo Nagasawa

Beilstein J. Org. Chem. 2016, 12, 198–203, doi:10.3762/bjoc.12.22

• presence of a guanidine–bisurea bifunctional organocatalyst was investigated. The α-amination products were obtained in up to 99% yield with up to 94% ee. Keywords: α-amination; bifunctional catalyst; guanidine; hydrogen-bonding catalyst; urea; Introduction Asymmetric α-amination of β-keto esters is an

• asymmetric reactions [19][20]. Recently, we disclosed an α-hydroxylation of tetralone-derived β-keto esters 2 using guanidine–bisurea bifunctional organocatalyst 1a in the presence of cumene hydroperoxide (CHP) as an oxidant (Figure 1a) [21]. This reaction provides the corresponding α-hydroxylation products

• expected that guanidine–bisurea bifunctional organocatalyst 1 would be effective in promoting α-amination of β-keto esters as a result of interactions between guanidine and enolate of the β-keto ester, and between urea and azodicarboxylate (Figure 1b). Herein, we describe the catalytic asymmetric α

Catalytic asymmetric formal synthesis of beraprost

• Yusuke Kobayashi,
• Ryuta Kuramoto and
• Yoshiji Takemoto

Beilstein J. Org. Chem. 2015, 11, 2654–2660, doi:10.3762/bjoc.11.285

• nucleophile and relatively unreactive Michael acceptors [27][28][29][30][31][32][33]. We envisioned that our recently developed powerful hydrogen bond (HB)-donor bifunctional organocatalyst [33] could promote the desired reaction of 7 or 8, which can be synthesized from commercial sources 9 or 10. Overall

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

• Organic Chemistry I, University of Erlangen-Nuremberg, Henkestraße 42, 91054, Erlangen, Germany 10.3762/bjoc.8.168 Abstract A new guanidine-thiourea organocatalyst has been developed and applied as bifunctional organocatalyst in the Michael addition reaction of diethyl malonate to trans-β-nitrostyrene

• . Extensive DFT calculations, including solvent effects and dispersion corrections, as well as ab initio calculations provide a plausible description of the reaction mechanism. Keywords: bifunctional organocatalyst; DFT calculations; guanidine-thiourea; Michael addition; organocatalysis; transition states