The Hantzsch Synthesis with 6-Aminouracils: One Step Synthesis of Pyrido[2,3-d]pyrimidines
摘要:
A one-step synthesis of new pyrido [2,3-d]pyrimidine derivatives (III) was achieved through the Hantzsch synthesis using 6-aminouracils (I) as enamine nucleophiles.
Photocyclization of 2-(dialkylamino)ethyl acetoacetates: Remote proton transfer and Stern-Volmer quenching kinetics in the system involving two reactive excited states
摘要:
Upon irradiation, 2-(dibenzylamino)ethyl and 2-(N-benzyl-N-methylamino)ethyl acetoacetate (1a and 1b) undergo photocyclization via remote proton transfer from the benzyl group to the acetyl carbonyl oxygen to give eight-membered azalactones. Irradiation of the corresponding (diisopropylamino)- and (dimethylamino)ethyl esters gave no azalactones. Introduction of the methyl group on C-2 of 1a brought about a complicated photoreaction, probably due to competition of alpha-cleavage, The Stern-Volmer plots for the photoreaction of la did not show the linear relationship, indicating that the photoreaction proceeds from two reactive excited states, The Stern-Volmer quenching equation for the system was obtained by applying the steady-state approximation and was used for the analysis of the photoreaction of 1a. The triplet lifetime was determined to be 1.6 x 10(-8) s.