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Catalytic and selective conversion of (Z)-2-en-4-ynoic acids to either 2H-pyran-2-ones in the presence of ZnBr 2 or (Z)-5-alkylidenefuran-2 (5H)-ones in the presence …

L Anastasia, C Xu, E Negishi

文献索引：Anastasia, Luigi; Xu, Caiding; Negishi, Ei-Ichi Tetrahedron Letters, 2002 , vol. 43, # 32 p. 5673 - 5676

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被引用次数: 80

摘要

Treatment of (Z)-5-alkyl-2-en-4-ynoic acids (1), prepared by the Pd-catalyzed alkynylzinc–β- haloacrylic acid coupling, with 5–10 mol% of ZnBr2 can produce 6-alkyl-2H-pyran-2-ones (2) along with minor amounts of (Z)-5-alkylidenefuran-2 (5H)-ones (3) in> 90% combined yields, with often very high (≈ 95/5) pyranone/furanone ratios. On the other hand, lactonization of 1 catalyzed by Ag2CO3 provides a selective synthesis of (Z)-5- ...