Sulfonylisocyanates attack the arylaldehyde N,N-dialkylhydrazones 1-3 at the nitrogen or carbon of the azomethine function leading to the formation of the hexahydro-1, 3,5-triazine-2,4-diones 4-6 or arylglyoxylic acid sulfonamide-N, N-dialkylhydrazones 7-9 (scheame 1). Under equal experimental conditions the position of the electrophilic attack depends on the contribution of the dipolar structures
A palladium‐catalyzed C(sp2)−H difluoromethylation of aldehyde‐derived hydrazones using bromodifluoromethylated compounds to afford the corresponding functionalized difluoromethylketone hydrazones has been established. It is proposed that a radical/SET mechanism proceeding via a difluoroalkyl radical may be involved in the catalytic cycle. Applications of the methodology to the synthesis of α,α‐difluoro‐β‐ketoesters