SYNTHESIS AND POLYMERIZATION OF ALPHA,ALPHA-SPIROBICYCLIC BETA-LACTONES

Ethyl α-hydroxymethylacrylate was converted to α-chloromethyiacrylyl chloride, which readily underwent Diels-Alder reactions with butadiene, cyclopentadiene, and anthracene. The adducts 4,8, and 15 were hydrolyzed to the corresponding chloro acids, which cyclized under alkaline conditions to the spiro-β-lactones 6, 10, and 17. Hydrogenation of the bicycloheptene chloro acid and cyclization gave the bicycloheptane lactone 13. When treated with a carboxylate initiator, these polymerized to high-melting polyesters. The cyclohexene and bicycloheptane monomers, perhaps because of their greater reactivity, gave higher molecular weight polymers than the bicycloheptene and anthracene compounds. The methylene protons of many of the intermediates were magnetically nonequivalent. © 1969, American Chemical Society. All rights reserved.