The regiospecific synthesis of substituted furans by metal-catalyzed methodologies is reviewed. The whole review consists two parts. (1) Methodologies based on preformed furans. Furanyl metal reagents (M=Sn, B, Zn, Mn etc) undergo transition metal-catalyzed cross coupling reaction with organic halides or acyl chlorides to afford the substituted furans. On the another hand, furanyl halides can also undergo cross coupling reaction with orgnometallic reagents or termial alkynes to afford functionalized furans. Under the catalysis of Pd(0), furanyl halides can also react with alkenes to produce alkenyl substituted furans. The C－H activation reaction of furans with RuH~2(CO)PPh~3 directly produced furanyl ruthenium intermediates, which can further react with certain silylsubstituted 1-alkynes to afford 3-substituted furans. The C－H bond activation occurred regiospecifically the 3-positions. (2) Methodologies based on the cyclization reaction of acyclic compounds. The most efficient way to synthesize furans is the cyclization of the corresponding acyclic precursors, which provides the diversity, efficiency, and selectivity for the substituted furans synthesized. Under the catalysis of Ru(Ⅱ) or Ag(Ⅰ), 1,2-allenyl ketone can undergo cycloisomerization to afforded 3-unsubstituted furans. Recently Pd(0)-catalyzed coupling- cyclization reactions of organic halides and 1,2-allenyl ketones were also developed to afford polysubstituted furans. The diversity of furan thus synthesized depends on the type of organic halides as well as the substitution patterns of 1,2-allenyl ketones. Under the catalysis of Pd complexes, β-iodo-β-enone can undergo oxidative addition-cyclization or dimerization reaction to produce furans. Under the catalysis of Pd, another type of acyclic starting material suitable for the synthesis of furan is alkynones, the carbon-carbon triple bond can be located at α, β-, β, γ-, and γ,δ-positions. Both cycloisomerization and two-component coupling-cyclization have be金属催化合成? $609$ADD

Key words: TRANSITION METAL COMPOUND, TRANSITION METAL COMPLEX, METAL CATALYST, FURAN P