Asymmetric organocatalyzed synthesis of coumarin derivatives

• Natália M. Moreira,
• Lorena S. R. Martelli and
• Arlene G. Corrêa

Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128

• reaction between 4-hydroxycoumarins 1 and aromatic imines 63 for the synthesis of α-benzylaminocoumarins 64 [54]. Among the cinchona alkaloid derivatives evaluated in this reaction, cupreine (65) was found to be the best option in terms of yields and enantioselectivities (Scheme 20). Both electron

• -hydroxycoumarins (1) and aromatic imines 63 promoted by cupreine (65). Asymmetric addition of malonic acid half-thioesters 67 to coumarins 66 using the sulphonamide organocatalyst 69. Enantioselective 1,4-addition of azadienes 71 to 3-homoacyl coumarins 70. Michael addition/intramolecular cyclization of 3

Controlling the stereochemistry in 2-oxo-aldehyde-derived Ugi adducts through the cinchona alkaloid-promoted electrophilic fluorination

• Yuqing Wang,
• Gaigai Wang,
• Anatoly A. Peshkov,
• Ruwei Yao,
• Muhammad Hasan,
• Manzoor Zaman,
• Chao Liu,
• Stepan Kashtanov,
• Olga P. Pereshivko and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2020, 16, 1963–1973, doi:10.3762/bjoc.16.163

• of stoichiometric amounts of the chiral promotor that was in an agreement with a two-step reaction mode requiring the initial formation of the asymmetric fluorinating agent. An attempt to use cupreine, a member of the cinchona family featuring free phenolic hydroxy group, met with failure producing

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

• . Keywords: bifunctional; cupreidine; cinchona; cupreine; organocatalysis; Introduction The cinchona alkaloids, comprising quinine (QN), quinidine (QD), cinchonidine (CD), cinchonine (CN, Figure 1), and their derivatives have revolutionized asymmetric catalysis owing to their privileged structures. The

• optimize their stereoselective behaviour has seen their utility burgeon dramatically over the last decade. Of particular note is the use of these cinchona systems within bifunctional thiourea catalysis [3][4][5][6][7][8][9][10][11][12]. Cupreine (CPN) and cupreidine (CPD), the non-natural demethylated

• set up a 4π-electrocyclization, generating second intermediate 27. Elimination of the tertiary amine then gives γ-methylene cyclopentenone 28. 1,2-Addition reactions Henry reaction The use of cupreine and cupreidine derivatives in the addition of nitroalkanes to carbonyl compounds was first

Mechanochemistry assisted asymmetric organocatalysis: A sustainable approach

• Pankaj Chauhan and
• Swapandeep Singh Chimni

Beilstein J. Org. Chem. 2012, 8, 2132–2141, doi:10.3762/bjoc.8.240

• ) [48]. Grinding an equimolar quantity of six/five-membered cyclic β-ketoesters 13 and various nitroalkenes 7, including nitrodienes, in the presence of 5 mol % of cupreine-derived organocatalyst X provided Michael adducts 14 in good to high yield (72–99%) and good to excellent stereoselectivity (85–99

Organocatalytic tandem Michael addition reactions: A powerful access to the enantioselective synthesis of functionalized chromenes, thiochromenes and 1,2-dihydroquinolines

• Chittaranjan Bhanja,
• Satyaban Jena,
• Sabita Nayak and
• Seetaram Mohapatra

Beilstein J. Org. Chem. 2012, 8, 1668–1694, doi:10.3762/bjoc.8.191

• 15:1 dr). In the same year Zhao et al. [70] reported an efficient synthesis of highly functionalized thiochromans having three chiral centers, using a tandem thio-Michael–Henry reaction of 2-mercaptobenzaldehydes 34 with β-nitrostyrenes 46 and using cupreine XXXIXa as catalyst in anhydrous diethyl