Synthesis of helically twisted [1 + 1]macrocycles assisted by amidinium–carboxylate salt bridges and control of their chiroptical properties†
Abstract
A series of optically active, helically twisted [1 + 1]macrocycles connected via o-, m-, and p-linkages (o-2, m-2, and p-2) was prepared from the corresponding linear duplexes stabilized by complementary amidinium–carboxylate salt bridges bearing two arms with terminal vinyl groups at both ends through the ring-closing metathesis reaction in the good yields of 67, 92, and 96%, respectively. The chiroptical properties of the