Access to Protected 2-Alkylidene 1,3-diones by Modified Knoevenagel Reaction in the Presence of Thiophenol. A New Approach to Spirocyclopentanol Construction
摘要:
A general procedure is described for trapping the products of Knoevenagel condensation involving 1,3-diketones and aliphatic aldehydes. Simple stirring of a three-component mixture consisting of each reactant and thiophenol in dichloromethane containing silica gel leads to products in which the 2-alkylidene 1,3-dione has been intercepted to give a (most often) crystalline Michael adduct. The yields are usually quite acceptable, especially if the beta-dicarbonyl compound is cyclic. Oxidation of these adducts with sodium periodate regenerates the conjugated enedione, which reacts rapidly with air to give a cyclic peroxide unless protected from the atmosphere. When a monoprotected succinaldehyde is utilized as starting material, hydrolysis of the resultant adduct in aqueous acid results in intramolecular aldolization to give a spirocyclic cyclopentanol.
Access to Protected 2-Alkylidene 1,3-diones by Modified Knoevenagel Reaction in the Presence of Thiophenol. A New Approach to Spirocyclopentanol Construction
摘要:
A general procedure is described for trapping the products of Knoevenagel condensation involving 1,3-diketones and aliphatic aldehydes. Simple stirring of a three-component mixture consisting of each reactant and thiophenol in dichloromethane containing silica gel leads to products in which the 2-alkylidene 1,3-dione has been intercepted to give a (most often) crystalline Michael adduct. The yields are usually quite acceptable, especially if the beta-dicarbonyl compound is cyclic. Oxidation of these adducts with sodium periodate regenerates the conjugated enedione, which reacts rapidly with air to give a cyclic peroxide unless protected from the atmosphere. When a monoprotected succinaldehyde is utilized as starting material, hydrolysis of the resultant adduct in aqueous acid results in intramolecular aldolization to give a spirocyclic cyclopentanol.
Fuchs Klaus, Paquette Leo A., J. Org. Chem, 59 (1994) N 3, S 528-532
作者:Fuchs Klaus, Paquette Leo A.
DOI:——
日期:——
Access to Protected 2-Alkylidene 1,3-diones by Modified Knoevenagel Reaction in the Presence of Thiophenol. A New Approach to Spirocyclopentanol Construction
作者:Klaus Fuchs、Leo A. Paquette
DOI:10.1021/jo00082a007
日期:1994.2
A general procedure is described for trapping the products of Knoevenagel condensation involving 1,3-diketones and aliphatic aldehydes. Simple stirring of a three-component mixture consisting of each reactant and thiophenol in dichloromethane containing silica gel leads to products in which the 2-alkylidene 1,3-dione has been intercepted to give a (most often) crystalline Michael adduct. The yields are usually quite acceptable, especially if the beta-dicarbonyl compound is cyclic. Oxidation of these adducts with sodium periodate regenerates the conjugated enedione, which reacts rapidly with air to give a cyclic peroxide unless protected from the atmosphere. When a monoprotected succinaldehyde is utilized as starting material, hydrolysis of the resultant adduct in aqueous acid results in intramolecular aldolization to give a spirocyclic cyclopentanol.