Exploiting ortho-substitution effect on formation of oxygen-containing [10]paracyclophane through ring-closing metathesis

The synthesis of strained paracyclophanes is challenging and generally delivers low yields. A novel strategy of installing an ortho-substituent group to the ethereal oxygen is developed to facilitate the formation of oxygen-containing [10]paracyclophane via RCM macrocyclization. By rationally modulating the electronic and steric effects in the single and double ortho-substitution modes, efficient RCM macrocyclization was achieved for different substrates to form the corresponding [10]paracyclophane products, in which all newly generated double bonds were in the E-form. The development of this methodology will enrich the chemistry of ring-closing metathesis related to the formation of strained macrocycles.