Steuerung der Bildungsselektivität vielgliedriger Oligomerer durch Templat‐ und Caesium‐Effekt

Steering of the Selectivity of Formation of Many‐membered Oligomers by Template and Cesium Effects Cyclization of the bis(bromomethyl) compounds 1 and 2 with thioacetamide in the presence of carbonates M 2 CO 3 leads to mixtures of dimers ( 3, 4 ) and trimers ( 5, 6 ) in yields ranging from 40 to 60%. Increasing cation size in the added carbonate raises the amount of trimers 5, 6 relative to the dimers 3, 4 . In the pyridine series sodium carbonate leads to predominant formation of the trimer 6 , indicating a template effect. In the pyridine and the xylylene series the cesium effect leads to an approx. 40:60 ratio of dimer and trimer, which shows that a template effect seems not to be effective in this cesium assisted cyclization.