-Photocycloaddition of Cyclohexene to 2-Acetyl-5,5-dimethyl-1,3-cyclohexanedione and 3-Acetyl-1,5,5-trimethyl-2,4-pyrrolidinedione

Article abstract of DOI:10.1007/BF01045301

Irradiation of solutions of excess cyclohexene and 2-acetyl-5,5-dimethyl-1,3-cyclohexanedione (1) and 3-acetyl-1,5,5-trimethyl-2,4-pyrrolidinedione (4) results mainly in the formation of 1,5-diones 2 and 5.These originate from intermediate cycloadducts of cyclohexene and the exo-enols of the cyclic 1,3-diketones.The yields decrease with increasing polarity of the solvent.In solution 2 and 5 are in equilibrium with the cyclic hemiacetals 3 and 6.Keywords: <2+2>-Photocycloaddition; 2-Acetyl-5,5-dimethyl-1,3-cyclohexanedione; 3-Acetyl-1,5,5-trimethyl-2,4-pyrrolidinedione; 2-(2'-Acetyl-cyclohexyl)-5,5-dimethyl-1,3-cyclohexanedione; 3-(2'-Acetyl-cyclohexyl)-1,5,5-trimethyl-2,4-pyrrolidinedione.