Diazoaldehyde Chemistry, Part 2: Transdiazotization of β,γ‐ and β,δ‐Dioxoaldehydes

Abstract

AbstractBase induced ring opening reactions of 2‐(substituted)‐4H‐pyran‐4‐ones (R=H, Ph) gave the corresponding 5‐(substituted)‐3,5‐dioxopentanals, which were in turn transdiazotized with 2‐azido‐1‐ethylpyridin‐1‐ium BF4. The reactions gave 5‐(substituted)‐2,4‐bis(diazo)‐3,5‐dioxopentanals and 4‐(substituted)‐1,3‐bis(diazo)‐2,4‐butandiones, the latter being the deformylating diazo transfer products. A two‐fold deformylation product (1,3‐bisdiazo‐2‐propanone) was observed in the reaction of 3‐oxopentandial, which was also synthesized from tosyl azide and 1,5‐bis(N‐methyl‐N‐phenylamino)‐trans,trans‐1,4‐pentadiene‐3‐one in low yield. 4‐(substituted)‐3‐diazo‐2,4‐butandieones also formed as side products. The reactions of 4,4‐dimethoxy‐3‐oxobutanal and ethyl 2,4‐dioxobutanoate with the same azidinium salt gave 1‐diazo‐3,3‐dimethoxy‐2‐propanone and ethyl 3‐diazo‐2‐oxopropanoate respectively.