Rapid and diverse route to natural product-like biaryl ether containing macrocycles

A two-step sequence involving an Ugi four-component reaction and an intramolecular nucleophilic aromatic substitution (S_NAr) has been developed for the rapid access to biaryl-ether containing macrocycles. In the course of this study, we documented that ammonium chloride can promote the Ugi-4CR in non-polar aprotic solvent (toluene) without the interference of an alternative Passerini reaction. Solid phase synthesis of macrocycles by this two-step sequence was also developed using polymer (Wang resin) supported α-(4′-fluoro-3′-nitro)phenethyl isocyanoacetate as one of the inputs.     

胶束催化体系中的对映选择性环醚化反应

The enantioselective cycloetherification of substituted keto phenols into their corresponding dihydrobenzofuran derivatives was carried out using hydrogen peroxide and chiral quaternary ammonium iodide in micellar media. This approach increased the conversion rate of cycloetherification and also widened the scope of this particular reaction for various substituted keto phenols with electron withdrawing as well as electron donating functionalities. The use of a surfactant in the cycloetherification reaction ...     

The intramolecular S = O···H-O hydrogen bond in a chiral cyclic sulfite ester: How it affects the reaction behavior and spectral properties

The intramolecular S = O···H?O hydrogen bond in a chiral cyclic sulfite ester, which affects the reaction behavior and spectral properties considerably, was studied.     

Kinetic Resolution of Acylsilane Cyanohydrins via Organocatalytic Cycloetherification

An asymmetric cyanation of acylsilanes involving the in‐situ formation of chiral acylsilane cyanohydrins followed by their kinetic resolution via organocatalytic cycloetherification is described. The highly enantio‐ and diastereoselective cycloetherification was crucial for achieving a high efficiency in the kinetic resolution. Consequently, acylsilane cyanohydrins containing a tetrasubstituted chiral carbon atom bearing silyl, cyano, and hydroxy groups were obtained in an enantioenriched form. This protocol therefore offers an efficient catalytic approach to optically active acylsilane cyanohydrins, which exhibit potential as chiral building blocks for the synthesis of pharmaceutically relevant chiral organosilanes.     

Solid-phase synthesis of natural product-like macrocycles by a sequence of Ugi-4CR and SNAr-based cycloetherification

An on-resin Ugi four-component reaction followed by an intramolecular nucleophilic aromatic substitution (S_NAr) has been developed for the rapid access to biaryl-ether containing macrocycles.     

A highly stereocontrolled and efficient synthesis of α- and β-pseudouridines

A five-step practical and stereocontrolled synthesis of α- and β-pseudouridines from d-ribonolactone is described. The key step involves a highly stereoselective reduction of a hemiketal C-nucleoside intermediate in each case. Multi-gram quantities of β-pseudouridine can now be made available.