SYNTHESIS AND REACTIVITY OF CHIRAL TELLURIUM AZOMETHINES - PSEUDOPOLYMORPHISM OF ROXY-2-PHENYL-1-METHYLETHYL)AMINO)METHINYL)PHENYL] TELLURIUM(IV) BROMIDE

A range of novel chiral tellurium compounds having an azomethine funct ional group in the position ortho to tellurium has been synthesized by the reaction of the tellurium-containing aldehydes bis(o-formylphenyl ) telluride (1) and o-(butyltelluro)benzaldehyde (4) with chiral amine s (R)-(+)-(1-pheylethylamine) and (1R,2S)-(-)-norephedrine, respective ly. The precursor aldehydes were prepared by using a reported procedur e with slight but advantageous modifications. During the preparation o f o-(butyltelluro)benzaldehyde, interesting side products, namely bis( o-formylphenyl) ditelluride ethylene acetal 5, bis(o-formylphenyl) tri telluride (6), and bis(o-formylphenyl) ditelluride (7) were isolated i n moderate yields. The ditelluride 7 has been characterized by single- crystal X-ray diffraction studies. The liquid Schiff bases 10 and 11 w ere further characterized by derivatizing with liquid bromine. The tit le compound was obtained in excellent yield by reacting the Schiff bas e 11 with elemental bromine. Detailed NMR studies indicated the presen ce of a rigid environment for the hydroxyl group. Single-crystal X-ray determinations of the crystals obtained from the different batches in dicated. the presence of the two pseudopolymorphic forms 13a and 13b, respectively. In the case of 13a there is one molecule of CH3CN as sol vent of crystallization, whereas in 13b half a molecule of CH3CN per m olecule of the title compound lies along the 2-fold axis. In 13a the h ydroxyl hydrogen is hydrogen-bonded to the nitrogen of the solvent mol ecule, whereas in 13b it is hydrogen-bonded to the bromine of the neig hboring molecule.