Trimethyl aconitate

Aconitatc was obtained as a minor product in the carbonylation of propar-gyl alcohol[479]. However, in the two-step synthesis of methyl aconitate (536) from propargyl alcohol in 70% overall yield, the first step is the oxidative carbonylation under CO and air using Pdli and KI to giNe dimethyl hydro-xymethylbutenedioate (535), which is carbonylated further to give trimethyl aconitate (536) by u.sc of [Pd(Tu)4jl2 as a catalyst[480]. 

Reaction of trimethyl aconitate 414 with 3equiv of aryl imines 415 furnished the tricycles 416 in low yields (Equation 111) <2001AGE4212>. 

Trimethyl aconitate can be cyclodimer-ized in 75% yield and a high stereoselectivity to a pentamethyl l-(2-methoxy-2-oxoethyl)- ,2,3,4,5-cyclopentane pentacar-boxylate. Product formation is initiated by an electrogenerated base that induces a catalytic cycle of two successive Michael additions. The most stable out of 16 possible diastereomers is formed, which indicates that the tandem Michael addition is thermodynamically controlled [282]. 

Propargylic alcohols are less reactive than their esters, and their carbonylation has been carried out under somewhat harsh conditions (100 °C, 100 atm) [10,11]. The carbonylation products under these conditions are different from those obtained by the carbonylation of the corresponding carbonates under milder conditions. Carbonylation of propargyl alcohol (82) in methanol without using a phosphine ligand proceeded in the presence of hydrochloric acid to afford dimethyl itaconate (79) as a main product and trimethyl aconitate (83) as a minor product (Scheme 11-24). PdCl2 or Pd/charcoal is an active catalyst [11]. 

The product, trimethyl ester of aconitic acid, was obtained as a mixture of Z- and E-stereoisomers. 

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