Haifeng Zhou

Iron-catalyzed C(sp3)–H functionalization of methyl azaarenes: a green approach to azaarene-substituted α- or β-hydroxy carboxylic derivatives and 2-alkenylazaarenes

Bioactive azaarene-substituted lactic acids, β-hydroxy esters, 3-hydroxy-2H-indol-2-ones, and 2-alkenylazaarenes were prepared in moderate-to-excellent yields via C(sp3)–H functionalization of methyl azaarenes with carbonyl compounds in the presence of iron(II) acetate as an inexpensive, nontoxic, efficient catalyst. The application of this atom-, step-economic, and environmentally friendly method was demonstrated by a gram-scale synthesis of 3-[(E)-2-(7-chloroquinolin-2-yl)vinyl]benzaldehyde, a key intermediate of leukotriene receptor antagonist (Montelukast).

Brønsted acid-catalyzed selective C–C bond cleavage of 1,3-diketones: a facile synthesis of 4(3H)-quinazolinones in aqueous ethyl lactate

A facile and green approach was developed for the synthesis of 4(3H)-quinazolinones by using camphorsulfonic acid as a catalyst in an aqueous solution of biodegradable ethyl lactate. Various 2-aryl-, 2-alkyl-, and 2-(4-oxoalkyl)quinazolinones were obtained by cyclization of 2-aminobenzamides with a wide range of acyclic or cyclic 1,3-diketones via C–C bond cleavage in satisfactory to excellent yields.

Bifunctional Oxo-Tethered Ruthenium Complex Catalyzed Asymmetric Transfer Hydrogenation of Aryl N-Heteroaryl Ketones

A facile asymmetric transfer hydrogenation of ortho-substituted aryl N-heteroaryl ketones and non-ortho-substituted N-oxide of aryl N-heteroaryl ketones using a readily available oxo-tethered ruthenium complex as a catalyst and sodium formate as a hydrogen source in an aqueous solution has been discovered. A variety of chiral aryl N-heteroaryl methanols were obtained with up to 99.9% ee.

Iridium-Catalyzed Highly Enantioselective Transfer Hydrogenation of Aryl N-Heteroaryl Ketones with N-Oxide as a Removable ortho-Substituent

A highly enantioselective transfer hydrogenation of non-ortho-substituted aryl N-heteroaryl ketones, using readily available chiral diamine-derived iridium complex (S,S)-1f as a catalyst and sodium formate as a hydrogen source in a mixture of H2O/i-PrOH (v/v = 1:1) under ambient conditions, is described. The chiral aryl N-heteroaryl methanols were obtained with up to 98.2% ee by introducing an N-oxide as a removable ortho-substituent. In contrast, no more than 15.1% ee was observed in the absence of an N-oxide moiety. Furthermore, the practical utility of this protocol was also demonstrated by gram-scale asymmetric synthesis of bepotastine besilate in 51% total yield and 99.9% ee.

Transformation of Alkynes into Chiral Alcohols via TfOH-Catalyzed Hydration and Ru-Catalyzed Tandem Asymmetric Hydrogenation

A novel full atom-economic process for the transformation of alkynes into chiral alcohols by TfOH-catalyzed hydration coupled with Ru-catalyzed tandem asymmetric hydrogenation in TFE under simple conditions has been developed. A range of chiral alcohols was obtained with broad functional group tolerance, good yields, and excellent stereoselectivities.

B2(OH)4-mediated one-pot synthesis of tetrahydroquinoxalines from 2-amino(nitro)anilines and 1,2-dicarbonyl compounds in water

A practical one-pot synthesis of tetrahydroquinoxalines from readily available 2-amino(nitro)anilines and 1,2-dicarbonyl compounds mediated by diboronic acid with water as both a solvent and a hydrogen donor under metal-free conditions has been discovered. The deuterium labeling experiments with D2O were also performed to demonstrate that water acts as the hydrogen donor.

One-pot synthesis of chiral alcohols from alkynes by CF3SO3H/ruthenium tandem catalysis

A practical one-pot synthesis of chiral alcohols from readily available alkynes via tandem catalysis by the combination of CF3SO3H and a fluorinated chiral diamine Ru(II) complex in aqueous CF3CH2OH is described. Very interestingly, the combination of fluorinated catalysts and solvent exhibits a positive fluorine effect on the reactivity and enantioselectivity. A range of chiral alcohols with wide functional group tolerance was obtained in high yield and excellent stereoselectivity under simple and mild conditions.