Studies on synthesis of 10,11-dihydro-5H-dibenzo[a,d]cycloheptene derivatives. IV. Photoreactions of 5-substituted-5H-dibenzo[a,d]cycloheptenes with 1,2-substituted olefins and the stereostructures of the cycloaddition products.
Studies on synthesis of 10,11-dihydro-5H-dibenzo[a,d]cycloheptene derivatives. IV. Photoreactions of 5-substituted-5H-dibenzo[a,d]cycloheptenes with 1,2-substituted olefins and the stereostructures of the cycloaddition products.
The photoreactions of 5H-dibenzo[a, d]cyclohepten-5-one (la) and its 5-substituted derivatives (lz and ly) with olefins such as maleates, acrylates and crotonate gave the cycloaddition products (3a-e) in yields of 4-82%. Inversion reactions of the adducts (3b and 3c) with bases were carried out for the purpose of investigating the thermodynamic stability of the cycloadducts and the corresponding isomeric products (3b-t and 3c-f) were obtained. The stereostructures of the cycloaddition products and the isomeric products were determined by means of nuclear magnetic resonance (NMR) spectroscopy.