Asymmetric Organocatalytic Direct Aldol Reactions of Ketones with α-Keto Acids and Their Application to the Synthesis of 2-Hydroxy-γ-butyrolactones
作者:Xiao-Ying Xu、Zhuo Tang、Yan-Zhao Wang、Shi-Wei Luo、Lin-Feng Cun、Liu-Zhu Gong
DOI:10.1021/jo701868t
日期:2007.12.1
of organocatalysts for the asymmetric direct aldolreactions of ketones with α-keto acids were designed on the basis of molecular recognition and prepared from proline and aminopyridines. The organic molecule 8e, derived from proline and 6-methyl-2-amino pyridine, was the best catalyst, affording excellent enantioselectivities (up to 98% ee) for the direct aldolreactions of acetone or 2-butanone with
Novel N-formyl hydroxylamine compounds and their derivatives are disclosed. These N-formyl hydroxylamine compounds inhibit peptidyl deformylase (PDF), an enzyme present in prokaryotes. The compounds are useful as antimicrobials and antibiotics. The compounds of the invention display selective inhibition of peptidyl deformylase versus other metalloproteinases such as MMPs. Methods of preparation and use of the compounds are also disclosed.
Various ligands for the ruthenium-catalyzed enantioselective reduction of ketones in water have been investigated. Multi-substrate reactions have been carried out for the comparison of various proline amides and aminoalcohol ligands. Two sets of six aromatic ketones have been selected in order to evaluate the enantiomeric excesses of all the resulting alcohols by a single chromatographic analysis.
Enantioselective biomimetic cyclization of 2′-hydroxychalcones to flavanones
作者:Yan-Lei Zhang、Yong-Qiang Wang
DOI:10.1016/j.tetlet.2014.04.032
日期:2014.5
developed and shown to catalyze the direct and highly enantioselective cyclization of 2′-hydroxychalcones in imitation of the natural process of chalcone cyclization. The straightforward synthetic process occurs under mild reaction conditions, tolerates moisture and air, and gives an enantiomeric excess up to 99%. This approach provides a facile and efficient access to chiral flavanones.
benzenesulfonic acid (DBSA) leads to highly effective and selective organocatalysts in water. The in situ generated catalysts catalyze highly stereoselective desymmetrization of prochiral ketones via directaldol reactions (up to >16:1 dr, >99% ee) in water using micelle as reaction media. The current strategy was also applied in asymmetric Michael addition leading to a catalytic system with good activity