Dimethyl propargylmalonate

Cyclization ofl,6-enynes to 1,3- and 1,4-dienes.1 The 1,6-enynes are prepared by Pd(0)-catalyzed alkylation of allylic carboxylates with the anion of dimethyl propargylmalonate. The products cyclize in the presence of this Pd(II) catalyst or [(o-CH3C6H4)3P]2Pd(OAc)2 to 1,3- or 1,4-dienes. 

In an alternative strategy for making bis-annulated pyranoid derivatives, addition of sodio dimethyl propargylmalonate to benzyl 2-0-tosyl-3,4-dideoxy-a-D-g/ycero-pent-3-enopyranoside gave unsaturated compound 28 as the major product. This, on treatment with the reagent Co2(CO)s (to produce a... 

Allylic acetates couple with dimethyl propargylmalonate anion in the presence of [(Ph2P)i Pd] to give 1,6-enynes. In the presence of [(o-tolyl )P]2Pd(0Ac)2 these 1,6-enynes isomerize to 1,4-dienes unless the 1,4-diene product would contain a trisubstituted olefin in which case 1,3-dienes are obtained (Scheme 13). 1,3-Dienes... 

Williams has shown that the use of non C2-synimetric ligands is equally effective. The regiochemical approach of the nucleophile is influenced by the relative trans effect of the two coordinating atoms in the optically pure ligand (i.e. approach trans to sulfur and phosphorus is favoured over nitrogen). Protocol 6, which involves the reaction of epoxycyclopentadiene 33 with dimethyl propargylmalonate 38, demonstrates the excellent stereochemical control that can be obtained using this reaction. 

Allyiic alkylation of epoxycyclopentadiene (Structure 33) with dimethyl propargylmalonate ( ucture 38)... 

During the course of our studies on the Pd-catalyzed allylic alkylation in which we were examining tandem alkylation-cyclization, we examined the use of dimethyl propargylmalonate as the nucleophile with the intention to explore a subsequent thermal ene reaction to constitute an overall cyclopentane annulation as shown in Eq. 3 [81, 82]. While the alkylation proceeded well to give the cis product 1,... 

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