42599-89-3Relevant articles and documents
An Enantioconvergent Benzylic Hydroxylation Using a Chiral Aryl Iodide in a Dual Activation Mode
Abazid, Ayham H.,Clamor, Nils,Nachtsheim, Boris J.
, p. 8042 - 8048 (2020/09/21)
The application of a triazole-substituted chiral iodoarene in a direct enantioselective hydroxylation of alkyl arenes is reported. This method allows the rapid synthesis of chiral benzyl alcohols in high yields and stereocontrol, despite its nontemplated nature. In a cascade activation consisting of an initial irradiation-induced radical C-H-bromination and a consecutive enantioconvergent hydroxylation, the iodoarene catalyst has a dual role. It initiates the radical bromination in its oxidized state through an in-situ-formed bromoiodane and in the second, Cu-catalyzed step, it acts as a chiral ligand. This work demonstrates the ability of a chiral aryl iodide catalyst acting both as an oxidant and as a chiral ligand in a highly enantioselective C-H-activating transformation. Furthermore, this concept presents an enantioconvergent hydroxylation with high selectivity using a synthetic catalyst.
Synthesis of 4,4′-biquinazoline alcohols as chiral catalysts in enantioselective alkynylation of aldehydes with phenyl acetylene
Catir, Mustafa,Cakici, Murat,Karabuga, Semistan,Ulukanli, Sabri,Sahin, Ertan,Kilic, Hamdullah
experimental part, p. 2845 - 2853 (2010/04/02)
Optically active propargylic alcohols are important chiral-building blocks in asymmetric synthesis, while the asymmetric addition of a terminal alkyne to an aldehyde is one of the most important procedures to prepare these chiral-building blocks. In this work, a family of chiral 4,4′-biquinazoline alcohols has been conveniently prepared from the easily accessible (S)-2-acetoxycarboxylic acid chlorides by reaction sequences beginning with condensation and followed by key synthetic steps including chlorination, nickel(0)-mediated homocoupling, and deprotection in addition to being examined as potential ligands in the enantioselective addition of phenylacetylene to aldehydes. These chiral ligands can be combined with Ti(OiPr)4 and then used to catalyze the asymmetric addition of zinc acetylide, produced in situ by the reaction of phenylacetylene with diethylzinc, to aldehydes. The best enantiomeric excess obtained in this study was 75%.
Synthesis of chrysogine, a metabolite of Penicillium chrysogenum and some related 2-substituted 4-(3H)-quinazolinones
Bergman, Jan,Brynolf, Anna
, p. 1295 - 1310 (2007/10/02)
Syntheses of both enantiomers of chrysogine, 2-(α-hydroxyethyl)-4(3H)-quinazolinone, 1 from 2-ammobenzamide are reported. Thus reaction of 2-aminobenzamide and optically active α-acetoxypropionyl chloride gave 9, which upon saponification and cyclization induced by aqueous sodium carbonate at room temperature gave chrysogine. The enantiomeric purity of 1 was determined by NMR. Inversion of (-)-(S)-1, using the Mitsunobo reaction, gave (+)-(R)-1. Reduction of 2-acetyl-4(3H)-qumazolinone 2 with baker's yeast gave the S-enantiomer of 1. The cyclization method used could be extended and a number of 2-(a-hydroxy)alkyl-4-(3H)-quinazolinones are also reported.
