Aza-Michael reaction: achievements and prospects

The Wonderful Chemistry of Trifluoromethyl α‐Haloalkenyl Ketones

“…The presence, in a Michael adduct, of bromine attached to a sp 3 carbon atom and the carbonyl group make it a valuable intermediate for the aza‐Michael‐reaction‐initiated assembly of fluorinated nitrogen heterocycles. These transformations are known as aza‐MIRC (aza‐Michael‐Initiated Ring Closure) processes …”

“…According to the authors, the formation of heterocycle 25 is the result of halophilic attack of hydrazine hydrate on one of the bromine atoms followed by bromide elimination and generation of acetylenic ketone. These are known to be appropriate starting materials for pyrazole synthesis …”

A versatile and efficient approach for the synthesis of chiral 1,3-nitroamines and 1,3-diamines via conjugate addition to new (S,E)-γ-aminated nitroalkenes derived from L-α-amino acids

“…They are reactive in Michael reactions with a wide variety of nucleophiles [5–10], in Friedel–Crafts alkylations [11–14], and Baylis–Hillman reactions [15–18]. Furthermore, nitroalkenes can react as dipolarophiles in [3 + 2] cycloadditions [19–22], as dienophiles in [4 + 2] cycloadditions [23–26], and as heterodienes in hetero-Diels–Alder reactions [27–31] and even participate in cross-coupling reactions [32].…”

3,2-Hydroxypyridinone (3,2-HOPO) vinyl sulfonamide and acrylamide linkers: aza-Michael addition reactions and the preparation of poly-HOPO chelators

“…We were particularly optimistic with piperazine as our substrate, since it is known that cyclic amines react more readily with various Michael acceptors than their acyclic analogs. 29 When piperazine was reacted with sulfonamide 3 (2 eq) in refluxing acetonitrile, the rate of addition was slow (8 days) but the sulfonamide-linked bisHOPO compound 6 was obtained in 48% yield. However, when the same reaction was run in 2:3 THF/water at room temperature for 1 day, the product 6 was isolated in excellent yield after chromatographic purification (Scheme 3).…”