Isoxazoline analogues of artemisinin were obtained in low yield and low diastereoselectivity from the 1,3-dipolar cycloaddition of nitrile oxides. Alternatively, starting from the aldehyde 7, a number of transformations--Wittig reaction and reduction, Henry reaction and cyanohydrin formation--were achieved in significantly higher yields. In the cases where a new stereocenter was introduced this...

Alkene cis-trans Ratio, Betaine Mechanism, Cycloaddition Mechanism The cis-trans ratio of the stilbenes formed in Wittig reactions of semistabilised ylides (derived from benzyltri(hetero)arylphosphonium salts in ethanolic ethoxide) with benzaldehyde decreases markedly in the series 2-furyl >2-thienyl >phenyl > 1-methylpyrrol2-yl. The 2-furyl group favours a greater proportion of the ci«-isomer ...

Ruthenium complexes have been shown to perform efficient transfer hydrogenation reactions between alcohols and alkenes; in combination with an in situ Wittig reaction, indirect formation of C-C bonds has been achieved from alcohols.

The aza-Friedel–Crafts (aza-FC) reaction is a very powerful tool for forming C–C and C–N bonds, based on an acid-catalyzed addition of electron-rich aromatic compounds to imines.

Silica ferric hydrogensulfate is an efficient heterogeneous catalyst for the cyclization of 2- aminochalcones to the corresponding 2,3-dihydroquinolin- 4(1H)-ones. This intramolecular aza Michael reaction was carried out in high yields using chalcones bearing of electron donating and electron withdrawing groups. The catalyst is reusable without significant decreases in its activity after four t...