Tosyl esters of cinchonidine and cinchonine alkaloids: the structure-reactivity relationship in the hydrolysis to 9-epibases.

In the crystal structures of the diastereoisomers of O-tosylcinchonidine [(9R)-cinchon-9-yl 4-methylbenzenesulfonate], (I), and O-tosylcinchonine [(9S)-cinchon-9-yl 4-methylbenzenesulfonate], (II), both C(26)H(28)N(2)O(3)S, both molecules are in an anti-closed conformation and, in each case, the position of the aryl ring of the tosylate system is influenced by an intramolecular C-H···O hydrogen bond. The molecular packing in (I) is influenced by weak intermolecular C-H···O and C-H···π interactions. The crystal structure of (II) features C-H···π interactions and van der Waals forces only.