Concepts for ligand design in asymmetric catalysis: a study of chiral amino thiol ligands
摘要:
A series of new chiral sulfur-nitrogen chelate ligands, derived from amino acids, has been synthesised rationally. Fruitless experiments into catalytic asymmetric conjugate additions and desymmetrisation of meso-epoxides led us to analyse our ligands in the catalytic asymmetric addition of diethylzinc to aromatic aldehydes. These latter experiments were successful with chiral benzylic alcohols being obtained in up to 82% enantiomeric excess. (C) 1998 Elsevier Science Ltd. All rights reserved.
Direct biocatalysed synthesis of first sulfur-, selenium- and tellurium- containing <scp>l</scp>-ascorbyl hybrid derivatives with radical trapping and GPx-like properties
作者:Damiano Tanini、Beatrice Lupori、Gianni Malevolti、Moira Ambrosi、Pierandrea Lo Nostro、Antonella Capperucci
DOI:10.1039/c9cc02427a
日期:——
6-O-l-Ascorbyl selenoesters, thioesters and telluroesters can be efficiently and directly prepared from l-ascorbic acid and suitable functionalised chalcogenoesters through lipase-catalysed transesterification reactions.
Metal-free ringopening reactions of activated and unactivated aziridines with different silyl chalcogenides are described. Judicious tuning of the reaction conditions enables the synthesis of chiral enantioenriched N-Ts and N-Boc 1,2-mercaptoamines in good yields from the corresponding aziridines and bis(trimethylsilyl)sulfide. N-Protected and N-H unactivated aziridines are efficiently converted into
Phosphine-Triggered Tandem Annulation between Morita–Baylis–Hillman Carbonates and Dinucleophiles: Facile Syntheses of Oxazepanes, Thiazepanes, and Diazepanes
作者:Rong Zhou、Jianfang Wang、Chong Duan、Zhengjie He
DOI:10.1021/ol302696e
日期:2012.12.21
A new phosphine-triggered tandem [3 + 4] annulation reaction between Morita–Baylis–Hillman carbonates and 1,4-diheteroatom dinucleophiles has been developed, which provides a facile synthetic method for saturated seven-membered 1,4-heterocycles such as 1,4-oxazepanes, 1,4-thiazepanes, and 1,4-diazepanes. Mechanistic investigation implies that this reaction takes place through a phosphine-catalyzed
Bisphosphine-Catalyzed Mixed Double-Michael Reactions: Asymmetric Synthesis of Oxazolidines, Thiazolidines, and Pyrrolidines
作者:Vardhineedi Sriramurthy、Gregg A. Barcan、Ohyun Kwon
DOI:10.1021/ja073754n
日期:2007.10.1
mixed double-Michael reactions have been developed to afford β-amino carbonyl derivatives of oxazolidines, thiozolidines, and pyrrolidines in excellent yields and with high diastereoselectivities. Efficient reactions between amino-acid-derived pronucleophiles, such as β-amino alcohols, β-amino thiols, and γ-amino diesters, as Michael donors and electron-deficient acetylenes, such as propiolates, acetylacetylene
Aziridines Ring Opening by Silyl Chalcogenides: a Stereoselective Access to Polyfunctionalized Molecules as Precursor of Sulfurated and Selenated Heterocycles
Aziridines react efficiently with bis(trimethyl)silyl-sulfide and -selenide to afford a direct access to -amino thiols and selenols. Synthesis of 2,4-disubstituted 1,3-selenazolidines is obtained through reaction of 1,2-amino selenols with aldehydes.