120(P-56) 多官性Alleneのパラジウム触媒反応による複素環系骨格の直接構築(ポスター発表の部)

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We have developed a novel strategy for direct construction of tricyclic hetrocycles, indoles and dihydroisoquinolines, by the palladium-catalyzed reactions of functionalized allenes; carbopalladation followed by the intramolecular nucleophilic substitutions. In general, allenes provide π-allylpalladium complexes by the β-functionalization of allenes with aromatic or olefinic halides under palladium-catalyzed reaction conditions, the reactions of which with nucleophiles lead to the facile direct conversion into α,β-difunctionalized products. Likewise, palladium-catalyzed reactions of allenes with iodobenzenes or vinyl halides bearing nucleophilic parts in appropriate sites afford heterocycles or carbocycles by selecting nitrogen anions or carbanions as nucleophiles. The palladium-catalyzed reaction of an optically pure allene ((R)-7) with N-methyl-2-iodobenzylamine (15) was carried out in refluxing THF in the presence of Pd(dba)2 (0.05 equiv.) and triphenylphosphine (PPh3) (0.10 equiv.) using NaH or Et3N (1.5 equiv.) as base to afford an optically active cyclized product, a dihydroisoquinoline derivative, (S)-(E)-16, with slightly low enantiomeric excess (e.e.). We wish to present here a novel and facile synthesis of tricyclic compounds by palladium-catalyzed reactions of 2-iodophenyl allenyl compounds bearing nucleophilic functions at appropriate sites. The palladium-catalyzed reactions of allenes 23a-d were carried out at reflux in THF. CH3CN, or DME in the presence of palladium catalyst, Pd(dba)2 or Pd(OAc)2 (0.1 equiv.), phosphine ligand (0.2 equiv.), and triethylamine (1.5 equiv.) to furnish cyclized indole products 24a-d in fairly good yields.
天然有機化合物討論会の論文
2000-10-01

120(P-56) 多官性Alleneのパラジウム触媒反応による複素環系骨格の直接構築(ポスター発表の部)

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