ASINGER Thiazoline Synthesis

A synthesis of an enantiomerically and diastereomerically pure 3-thiazoline 214 from 215 has been reported via a modified Asinger reaction. The use of a galactose-derived chiral auxiliary 216 was involved (Scheme 85) <2000TL7289>. 

Schlemminger, I, Janknecht, H H, Maison, W, Saak, W, Martens, J, Synthesis of the first enantiomerically pure 3-thiazolines via Asinger reaction. Tetrahedron Lett., 41, 7289-7292, 2000. 

Asinger zl -thiazoline ring synthesis from 2 ketone molecules... 

The list of secondary sources reviewing the chemistry of thiazoles previously given is supplemented by the following publications. Prijs Card Index of Thiazole Compounds provides swift access to information on individual compounds, but its appearance has unfortunately not continued. Asinger and Oflfermanns have reviewed the chemistry of A -thiazolines, within the framework of a full account of their versatile synthesis of heterocyclic compounds by the simultaneous action of sulphur and amines on ketones. Ohta and Kato s comprehensive survey on sydnones includes a section on mesionic thiazoles. 

The production of substituted thiazolines from ketones, sulphur, and ammonia under restrained conditions is well documented. - Asinger et have successfully employed ethyleneimine as one of the reactants in this versatile synthesis. Thus, slow addition of sulphur to a mixture of ethyleneimine and diethyl ketone, heptan-4-one, or an alicyclic ketone at ca. 20 °C yields 5,6-dihydro-4JT-l,4-thiazines (284) as main products (60—90%) and 2,2-dialkylthiazolidines (285) as by-products (10— 23%). ... 

---