Theoretical Calculation of Paternó-Büchi reaction between methanal and (2,2-dimethyl-1,3-dioxan-5-ylidene)methanamine in twisted-boat conformation

This paper is investigated the Paternó-Büchi reaction between methanal and (2,2-dimethyl-1,3-dioxan-5-ylidene)methanamine. The conformer is confirmed twisted boat dominant by global optimizer algorithm. Hence, it affects the stereochemistry of the product when 2+2 photocycloaddition reaction between carbonyl group and alkene. The stereochemistry of product A is major S configuration rather than R configuration. The 2nd version of this preprint manuscript also includes investigated 2,2-dimethyl-4-methylene-hexahydropyrimidine and acetone. The better enantiomer excess compare to previous one. As S and R product are diastereomer, therefore it has different in energy.