A chemoenzymatic synthesis of ceramide trafficking inhibitor HPA-12

• Seema V. Kanojia,
• Sucheta Chatterjee,
• Subrata Chattopadhyay and
• Dibakar Goswami

Beilstein J. Org. Chem. 2019, 15, 490–496, doi:10.3762/bjoc.15.42

• (1R,3S)-HPA-12 (2) used the chiral pool approach [15][16], crystallization-induced asymmetric transformation [17], diastereoselective reduction of γ-aryl-γ-oxo-β-amino alcohol [18], cycloaddition of oxime with alkenes [19], enantioselective carbonyl reduction followed by an organocatalyzed α-amination

A survey of chiral hypervalent iodine reagents in asymmetric synthesis

• Soumen Ghosh,
• Suman Pradhan and
• Indranil Chatterjee

Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107

• -oxytosylation of carbonyls. Asymmetric α-oxygenation and α-amination of carbonyls reported by Wirth et al. Asymmetric α-functionalization of ketophenols using chiral quaternary ammonium (hypo)iodite salt reported by Ishihara et al. Oxidative Intramolecular coupling by Gong et al. α-Sulfonyl and α-phosphoryl

Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles

• Johannes Schörgenhumer,
• Maximilian Tiffner and
• Mario Waser

Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170

• precursors and carry out the direct α-amination with a suitable electrophilic N-transfer reagent in the presence of a chiral catalyst to ensure an efficient face-differentiation in the C–N bond formation. This strategy has been investigated under chiral phase-transfer catalysis in the past and the results

• have been rather promising, as will be discussed in the following chapter [61][138][139][140]. One of the key-questions in this field is the nature of the electrophilic N-transfer reagent. One class of reagents that has been employed for α-amination reactions for almost one century now are

• also investigated the use of this catalyst class for asymmetric α-amination reactions of benzofuranones 4 with diazocarboxylates 38 [79]. Very interestingly, the reaction could be carried out under base-free conditions to give the products 40 with excellent enantioselectivities (Scheme 17). Detailed

Experimental and theoretical investigations into the stability of cyclic aminals

• Edgar Sawatzky,
• Antonios Drakopoulos,
• Martin Rölz,
• Christoph Sotriffer,
• Bernd Engels and
• Michael Decker

Beilstein J. Org. Chem. 2016, 12, 2280–2292, doi:10.3762/bjoc.12.221

• structures with various applications in medicinal chemistry [20][21]. The syntheses of tetrahydroquinazolines are well described using different approaches: the majority relies on the direct α-amination of o-aminobenzaldehydes with heating or microwave irradiation [22][23][24], by condensation of diamines

1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

• Antonia Mielgo and
• Claudio Palomo

Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90

• of thiazol-4(5H)-ones as pronucleophiles in asymmetric catalytic reactions has been investigated in the Michael addition reaction to nitroalkenes and α-silyloxyenones, phosphine-catalyzed γ-addition to allenoates and alkynoates, α-amination reactions and iridium-catalyzed allylic substitution

• . 2.2.2 α-Amination reactions. Thiazolones 2 have also been investigated in the α-amination reaction with tert-butyl azodicarboxylate in the presence of the ureidopeptide like catalysts C5 and C8 (Scheme 18) [85]. In these cases better enantioselectivity was observed with catalyst C8, and thiazolones

• mechanism for the C6-catalyzed γ-addition of thiazol-4(5H)-one to allenoates. Adapted from [36], copyright 2015 The Royal Society of Chemistry. Catalytic enantioselective α-amination of thiazolones promoted by ureidopeptide like catalysts C5 and C8 [85]. Iridium-catalized asymmetric allyllation of

Asymmetric α-amination of 3-substituted oxindoles using chiral bifunctional phosphine catalysts

• Qiao-Wen Jin,
• Zhuo Chai,
• You-Ming Huang,
• Gang Zou and
• Gang Zhao

Beilstein J. Org. Chem. 2016, 12, 725–731, doi:10.3762/bjoc.12.72

• , Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, People’s Republic of China 10.3762/bjoc.12.72 Abstract A highly enantioselective α-amination of 3-substituted oxindoles with azodicarboxylates catalyzed by amino acids-derived chiral phosphine

• , the development of more efficient catalytic systems for the asymmetric α-amination of 3-substituted oxindoles with azodicarboxylates is still desirable. Chiral organophosphine catalysis [15][16][17][18] has captured considerable attention over the past decades owing to its high catalytic efficiency in

(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

• of intermediates have been proposed to be the reactive intermediates in many reactions such as aldol, Michael, Mannich, and α-functionalization (α-chlorination, α-amination, α-fluorination) reactions. Proline-type organocatalysts are considered priviliged, because their corresponding enamines exist

Cupreines and cupreidines: an established class of bifunctional cinchona organocatalysts

• Laura A. Bryant,
• Rossana Fanelli and
• Alexander J. A. Cobb

Beilstein J. Org. Chem. 2016, 12, 429–443, doi:10.3762/bjoc.12.46

• HCPN-59 can be used in an asymmetric cyclopropanation. The hydrocupreine and hydrocupreidine-based catalysts HCPN-65 and HCPD-67 demonstrate the potential for phase transfer catalyst derivatives of the 6’-OH cinchona alkaloids to be used in asymmetric synthesis. Jørgensen’s oxaziridination. Zhou’s α

• -amination using β-ICPD. Meng’s cupreidine catalyzed α-hydroxylation. Shi’s biomimetic transamination process for the synthesis of α-amino acids. β-Isocupreidine catalyzed [4 + 2] cycloadditions. β-Isocupreidine catalyzed [2+2] cycloaddition. A domino reaction catalyst by cupreidine catalyst CPD-30. (a

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

• Minami Odagi Yoshiharu Yamamoto Kazuo Nagasawa Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16, Naka-cho, Koganei city, 184-8588, Tokyo, Japan 10.3762/bjoc.12.22 Abstract An asymmetric α-amination of β-keto esters with azodicarboxylate in the

• 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

• particular, catalytic asymmetric α-amination of β-keto esters has been widely explored, using both metal catalysts and organocatalysts [5][6][7][8][9][10][11][12][13][14][15][16][17][18]. We have developed a series of guanidine–bis(thio)urea bifunctional organocatalysts, and have used them in a variety of

N-Heterocyclic carbene-catalyzed direct cross-aza-benzoin reaction: Efficient synthesis of α-amino-β-keto esters

• Takuya Uno,
• Yusuke Kobayashi and
• Yoshiji Takemoto

Beilstein J. Org. Chem. 2012, 8, 1499–1504, doi:10.3762/bjoc.8.169

• , the former methods require a stoichiometric amount of strong bases, and the latter employ inaccessible substrates or multistep protocols. Recently, Zhang and co-workers reported Zn(ClO4)2·6H2O-catalyzed, mild and direct α-amination of β-keto esters with TsNH2, but in this case, a stoichiometric amount

Continuous proline catalysis via leaching of solid proline

• Suzanne M. Opalka,
• Ashley R. Longstreet and
• D. Tyler McQuade

Beilstein J. Org. Chem. 2011, 7, 1671–1679, doi:10.3762/bjoc.7.197

• ]. Achieving this goal would enable us and others to perform proline-catalyzed reactions, aldol [41][42][43] and Mannich [42] reactions as well as α-functionalizations (α-aminoxylation, α-amination or α-halogenations), continuously [44]. We hypothesized that the proline-catalyzed α-aminoxylation could be