Diels-Alder reaction ring-closing metathesis

Pauson-Khand reaction ring-closing metathesis ring-opening metathesis reticulated vitreous carbon anode transannular Diels-Alder reaction terf-butyldiisopropylsilyl terf-butyldimethylsilyl tert-butyllithium triethylsilyl... 

The enyne cross metathesis was first developed in 1997 [170,171]. Compared to CM it benefits from its inherent cross-selectivity and in theory it is atom economical, though in reality the aUcene cross-partner is usually added in excess. The inabihty to control product stereochemistry of ECM reactions is the main weakness of the method. ECM reactions are often directly combined with other transformations like cyclopropanation [172], Diels-Alder reactions [173], cychsations [174] or ring closing metathesis [175]. 

Interestingly, treatment of the allylic carbonate 23, which had proven problematic in the previous study, under analogous reaction conditions with the copper enolate derived from 24 furnished the a,/9-disubstituted ketone. Subsequent ring-closing metathesis furnished the 1,2-cyclohexenes 25a/25b in 75% overall yield favoring the trans-dia-stereomer 25a (2° 1°=30 1, ds=10 l) [14]. Overall, this reaction provides an alternative approach to an exo-selective Diels-Alder cycloaddition, and indicates that a-substituted enolates are even more tolerant nucleophiles than the unsubstituted derivatives. 

It has been shown that the combination of ring-closing metathesis and Diels-Alder reaction sequences is a useful synthetic tool for the asymmetric synthesis of... 

During the present decade, a wide variety of polycyclic carbacephem derivatives have been reported starting from readily available monocyclic /3-lactams, which after transformation in more functionalized compounds and further cyclization yielded different fused carbacephems. Several approaches for the preparation of fused carbacephem derivatives including cycloaddition reactions such as the [2+2], 1,3-dipolar, and Diels-Alder reactions, as well as transition metal-catalyzed reactions such as the Pauson-Khand and ring-closing metathesis (RCM) reactions have been reported in the literature. 

Synthesis of carbocyclic systems intramolecular free-radical cyclization, the Diels-Alder reaction, and ring-closing metathesis... 

On the basis of the original studies [111-113], the DoM-cross-coupHng sequence represents a significant entry into chiral binaphthol (BINOL) and achiral biphenol (BIPOL) ligands (Table 14.18) [111-119], which are outside the scope of this review but are widely used for enantioselective reactions, for example, Et2Zn addition to aromatic aldehydes, the Mannich-type reactions, and the Diels-Alder as well as asymmetric ring-closing metathesis (ARCM) reactions. 

Diels-Alder reactions to construct the cis-decalin system. Metathesis of triene 214 in the presence of 5 mol % of 4 in toluene gave the corresponding cw-decalin system 215 in quantitative yields. The authors reported on the ring-closing metathesis of several additional trienes differing only in the stereochemistry of the groups with similar success. 

Deslongchamps and co-workers approach to the synthesis of Kempane diterpenes employed a ring-closing metathesis strategy in the construction of the 13-membered ring carbocycle, which was subsequently subjected to a transannular Diels-Alder reaction to produce the tricyclic... 

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