Detalle de: Studies on the reactivity of some N ‐aryl‐ and N ‐heteroaryl‐ N' ‐alkylthioureas towards electrophilic reagents. Synthesis of new N ‐pyridylthioureas and thiazolines maría

Here in we describe our findings about the behaviour of some N ‐aryl‐ and N ‐heteroaryl‐ N' ‐alkylthioureas towards electrophilic reagents. In acid medium, the treatment of thioureas bearing aryl groups with 4‐chloropyridine in 2‐propanol yielded N ‐aryl‐ N ‐(4‐pyridyl)‐ N' ‐alk;ylthioureas and N ‐aryl‐ N' ‐alkylureas, whereas the heteroarylthioureas tested under similar reaction conditions afforded N ‐heteroaryl‐ N' ‐alkyl‐ O ‐(2‐propyl)isoureas. The reaction of N ‐(5,6,7,8‐tetrahydronaphth‐1‐yl)‐ and N ‐(2‐benzimidazolyl)‐ N' ‐butyl‐thiourea with propargyl bromide in acid medium led to the formation of 2‐butylimino‐3‐arylthiazolines, in a regioselective way. However, when this reaction was carried out in basic conditions the regioselectivity failed and a mixture of isomeric thiazolines was obtained. The Z‐ or E ‐configuration of the imino group of the synthesized thiazolines was studied by molecular modelling and by selective nuclear Overhauser experiments in nuclear magnetic resonance.