4-Yn-1-ols bearing a terminal triple bond undergo oxidative cyclization–alkoxycarbonylation in methanol at 70°C and 100 atm of a 9:1 mixture of carbon monoxide and air in the presence of catalytic amounts of [PdI4]2 in conjunction with an excess of KI to give 2E-[(methoxycarbonyl)methylene]tetrahydrofurans in good yields. A competing reaction, cycloisomerization–hydromethoxylation leading to 2-methoxy-2-methyltetrahydrofurans, can be easily curtailed by increasing the KI excess. The latter products can be prepared from 4-yn-1-ols and methanol in high yields using the same catalytic system and without KI excess in the absence of carbon monoxide.

PALLADIUM-CATALYZED SYNTHESIS OF 2E-[(METHOXYCARBONYL)METHYLENE]TETRAHYDROFURANS: OXIDATIVE CYCLIZATION-METHOXYCARBONYLATION OF 4-YN-1-OLS VERSUS CYCLOISOMERIZATION-HYDROMETHOXYLATION

GABRIELE, Bartolo;
2000

Abstract

4-Yn-1-ols bearing a terminal triple bond undergo oxidative cyclization–alkoxycarbonylation in methanol at 70°C and 100 atm of a 9:1 mixture of carbon monoxide and air in the presence of catalytic amounts of [PdI4]2 in conjunction with an excess of KI to give 2E-[(methoxycarbonyl)methylene]tetrahydrofurans in good yields. A competing reaction, cycloisomerization–hydromethoxylation leading to 2-methoxy-2-methyltetrahydrofurans, can be easily curtailed by increasing the KI excess. The latter products can be prepared from 4-yn-1-ols and methanol in high yields using the same catalytic system and without KI excess in the absence of carbon monoxide.
Carbonylation; Heterocycles; Palladium
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11770/138324
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