coupling strategy for the synthesis of a structurally defined polymer of 1,3-propanediamine, and the polymer can be used for the synthesis of both the initially proposed structure and the revised structure of protoaculeine B isolated from a marine sponge. We first attempted the synthesis of polyamines using “the Ns strategy” but found that a polyamine with eleven Ns groups has solubility problems. We
Winding vine-shaped bithiophene was synthesized through the nosyl (2-nitrobenzenesulfonyl) cyclization protocol. The reaction of bithiophene bearing bromomethyl groups at the 3,3'-positions with nosylated 1,2-ethylenediamine in the presence of potassium carbonate afforded the annulated product in excellent yield. The obtained bithiophene was found to contain a 10-membered ring, which was confirmed by X-ray analysis. The related nosyldiamine bearing a tri- or tetramethylene group also reacted in a similar manner, affording an 11- or 12-membered macrocycle, respectively.