The copper-catalyzed "click" reaction of an azide with an alkyne has become a popular method to build up 1,4-substituted 1H-1,2,3-triazoles in medicinal chemistry and this approach was used on a laboratory scale during the preparation of novel macrolide 1. However, the manufacture of the key azide component, as well as its subsequent use in the presence of a copper catalyst on a large scale, was associated with potential safety concerns. Therefore, a sequence was developed in which construction of the 1,4-substituted 1H-1,2,3-triazole in 1 was accomplished Wia cyclocondensation of an r,r-dichloro tosyl hydrazone with an amine.

No abstract

No abstract

Isoxazolidines have been synthesized in diastereomeric excess up to 94% via a MgBr2-induced chelation-controlled 1,3-dipolar cycloaddition reaction with N-hydroxyphenylglycinol as a chiral auxiliary. The diastereomerically pure isoxazolidines were further transformed into cyclic and acyclic beta-amino acid derivatives.