Recently, much attention has been paid to the chemistry of 1,2- allenyl ketones, due to their high and unique reactivity. In this paper we wish to review the synthesis and reaction of 1,2-allenyl ketones. 1,2-Allenyl ketones can be synthesized by the following methods: (1) Oxidation of homopropargylic alcohols to the propargyl ketones, followed by the isomerization; (2) Reaction of appropriate organometallic reagents with esters, acyl chlorides or amides; (3) Oxidation of 2,3-allenyl alcohols; (4) [2,3] or [3,3] Rearrangement of the corresponding functionalized alkynes; (5) Reaction of the corresponding Witting reagents with acyl chloride or ketenes; (6) elimination of β-halogen β,γ or α,β-unsaturated enones; and others. 1,2 allenyl ketones can participate nucleophilic addition, cycloaddition and cyclization reactions. (1) The 1,4-nucleophilic reaction with 1,2-allenyl ketones selectively afforded β,γ -or α, β-unsaturated enones. Nucleophiles could be ROH, RSH, RR'NH, HX. (2) Reaction of LiAH~4, DIBAL or organomagnesium with the carbonyl groups of 1,2-allenyl ketones afforded the 1,2-addition products allenyl alcohols. (3) The cycloaddition of 1,2-allenyl ketones with 1,3- butadienes, 1,3-cyclopentadienes, and furans to provide efficient routes to six-membered products. The 1,3-dipolar cycloaddition of 1,2- allenyl ketones with diazomethane afforded five-membered heterocyclic compounds. (4) 1,2-allenyl ketones can be thermally rearranged to furans. The cyclization reaction can also be catalyzed by silver(Ⅰ) and Pd(Ⅱ). (5) Allenyl ketones bearing an aryl group are prone to proceed a new intramolecular electrophilic substitution reaction using BF~3·OEt~2 or Hg(ClO~4)~2 as the catalyst.

Key words: NUCLEOPHILIC REACTION, ADDITION REACTION, ISOMERIZATION, ESTERS, ACYL CHLORIDES, AMIDES