A building block method for the synthesis of higher cycloamides

Series of cyclic amides containing optically active helicene, (P)-1,12-dimethylbenzo[c]phenanthrene, are synthesized using a building block method. The building block consists of one (P)-helicene unit and one dianiline unit with its amino-terminal-protected with benzyloxycarbonyl and its acid terminal activated as acid chloride. The coupling with (P,P....)-[(n - 3) + (n - 2)]diamine followed by deprotection gives (P,P....)-[(n - 1) + n]diamine, which possesses n - 1 parts of (P)-helicene and n parts of dianiline. Cyclization of the (P,P....)-[(n - 1) + n]diamine with helicenediacid dichloride gives (P,P....)-[n + n]cycloamide. All the members of (P,P)-[2 + 2]cycloamide to (P,P,P,P,P,P,P,P,P,P)-[10 + 10]cycloamide are synthesized using this method, and are compared spectroscopically.