Haloalkenes activated by geminal groups in reactions with N-nucleophiles

The Wonderful Chemistry of Trifluoromethyl α‐Haloalkenyl Ketones

“…Evidently, their formation can be easily explained in terms of the same scheme that had previously been proposed for reactions between non‐fluorinated haloenones or ‐enals and secondary amines. The aza‐Michael adducts 4 can undergo either intra‐ or intermolecular halogen substitution via aziridinium salts 5a or diamino derivatives 5b , respectively, to give, finally, captodative aminoenones 6 . In contrast with previous results, we had discovered that in this reaction the benzene ring “bites back” on the carbonyl group within the same molecule.…”

“…The chemistry of α‐haloenones is rich in successful trials and absurd errors, unexpected findings, and annoying delusions . Study of these derivatives apparently started at the beginning of the 20th century, when their reactions with nitrogen nucleophiles were reported for the first time .…”

Experimental and Theoretical Study of an Intramolecular CF3‐Group Shift in the Reactions of α‐Bromoenones with 1,2‐Diamines

“…It has previously been reported that the reaction of bromoenones 1 with secondary amines leads to indenols 6 over several steps 6. First, the nucleophilic substitution of bromine proceeds by an aza‐Michael addition/nucleophilic substitution/elimination sequence, which is generally accepted for gem‐ activated haloalkenes 3a. Next, intramolecular electrophilic aromatic substitution occurs to give 6 (Scheme ).…”

“…a,b-Unsaturated carbonyl compounds as well as a-halogenatedc arbonyl derivatives are classical building blocks for the assembly of variousc arbo-a nd heterocyclic systems. [3] However,t rifluoromethylated piperazines are av ery rare type of heterocycle,m ainly due to the difficulties of their synthesis. [4] with the correspondinga liphatic amines [7] or by the reductive amination of benzaldehyde with ethylenediamine (Scheme 1).…”

Synthesis and reactions of halogen-containing chromones

“…101 The reactions of nucleophilic reagents with 3-halochromones containing two good leaving groups (the halogen atom at the a carbon atom and the phenolic fragment at the b carbon atom) are more diverse than reactions with haloalkenes. Indeed, haloalkenes react with N-nucleophiles along three major pathways including the formation of aziridines and aminoalkenes with a vicinal or geminal (ipso-substitution) activating group.…”