Dmitry V. Belykh@ and Andrey V. Nikiforov
Institute of Chemistry, Komi Science Center, Ural Division of Russian Academy of Sciences, 167982 Syktyvkar, Russia
@Corresponding author E-mail: belykh-dv@chemi.komisc.ru, belykh-dv@mail.ru
DOI: 10.6060/mhc2011.1.07
It is shown that the exocycle in methylpheophorbide a can act as a methylene component in the Manniсh reaction and the interaction with formaldehyde and dialkylamine leads to the corresponding 13(2)-dialkylaminomethyl derivatives. It was established that aminomethylation proceeds stereoselectively with formation of 13(2)R-diastereoisomers. Stereoselectivity of the reaction and R-configuration of the 13(2) carbon atom are explained by the distortion of the enolic form of the exocycle, arising from the repulsion of the substituents in 13(2) and 17 positions. As a result of such distortion one of the diastereofacing sides of the double bond in the intermediate enol becomes more accessible for the electrophilic attack which leads to formation of 13(2)R-diastereomer.
Keywords: Methylpheophorbide a, aminomethylation, Mannich reaction.
References:
