Oxo-Diels-Alder reaction

Acyclic dienes react with glyoxylic acid via an oxo-Diels-Alder reaction to give dihydropyran derivatives (Eq. 12.53). An excellent application of the oxo-Diels-Alder reaction is reported by Lubineau et al. in the synthesis of the sialic acids, 3-deoxy-Z)-manno-2-octulosonic acid (KDO) and 3-deoxy-D-glycero-D-galacto-2-nonulosonic acid (KDN).123... 

HETERO DIELS-ALDER REACTIONS 5.5.1 Oxo Diels-Alder Reactions... 

When aldehyde containing an electron-withdrawing group is employed, or when a Lewis acid promoter is present, C=0 double bonds can readily undergo Diels-Alder-type reactions. This process is referred to as the oxo Diels-Alder reaction, and it has been explored by Danishefsky and DeNinno35 for the synthesis of a wide range of saccharide derivatives. 

An intramolecular oxo-Diels-Alder reaction leads to the synthesis of reduced pyrano[3,4-f]pyrrole esters. When benzene is chosen as reflux solvent, /ra r-substituted products form, whereas air-substituted derivatives are favored in refluxing toluene solvent (see Section 10.06.2.1.2) <2003T8955>. 

As for the oxo-Diels-Alder reaction, not much has been reported other Lewis acids are usually superior [26]. As for the aza-Diels-Alder reaction, enantioselective reactions between imino dienophiles 60 and diene 61, using a chiral binaphtholzirco-nium catalyst 23, are known (Eq. 26) [27]. 

The brief report of Jacobsen s total synthesis starts with a detailed retrosynthetic analysis. The compound was broken into four pieces 21a after removal of the phosphate. The unsaturated lactone 24 (M is a metal) could be made by an asymmetric oxo-Diels-Alder reaction from diene 22 and ynal 23. The epoxide 25 provides a second source of asymmetry. One cis alkene comes from an alkyne 26 and the rest from a dienyl tin derivative 27. 

Heterodiene addition to dienophile or heterodienophile addition to diene. Typical hetero-Diels-Alder reactions are aza-Diels-Alder reaction and oxo-Diels-Alder reaction. 

It should be noted that the aza Diels-Alder and oxo Diels-Alder reactions involve nitrogen- and oxygen-containing components, respectively, to give a variety of six-membered heterocyclic compounds. This book will only address the traditional, all-carbon Diels-Alder reaction. 

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