Alkenylations silver acetate

The direct alkenylation of azoles has been shown to be possible with alkenyl halides " and was later made possible with alkenes via an oxidative Fnjiwara-Moritani reaction." In the presence of palladinm acetate as the catalyst and silver acetate as the oxidant, Miura showed that snbstituted thiazoles and oxazoles 145 could be alkenylated to afford products 146A-D in good yields (Scheme 10.50). 

Alkenylations can also be carried out the optimum conditions for 2-bromopropene with palladium acetate include the use of triphenylarsine with silver carbonate and triethylamine, but the advantages over more amenable conditions, using triphenylphosphine with potassium or cesium carbonate, are marginal. ... 

During the development of the Heck reaction of vinylBhg, silver(i) (or thal-lium(i)) acetate was shown to be a useful stoichiometric additive for enhancing the selectivity in favor of the Heck-product, especially when the coupling partner is an alkenyl system. In the latter case, further improvement can be found in replacing triphenylphosphine with tri(o-tolyl)phosphine and using silver(i) acetate as the sole base. ... 

The conversion of acetylenes into olefinic esters by use of addition reactions has been illustrated by the following two examples, (i) 1-Alkenyl boranes, which are readily prepared by the hydroboration of alkynes, are converted into a,fi-unsaturated carboxylic esters in good yield by reaction with carbon monoxide in the presence of palladium chloride and sodium acetate in methanol the process is carried out at atmospheric pressure and occurs with retention of configuration with respect to the alkenyl borane. (ii) Carboxylic acids add to acetylenes in the presence of silver carbonate to provide a novel synthesis of enol esters, which are formed in an 8 2 mixture of isomers. ... 

Direct Alkenylation of Heteroarenes. Pivalic acid enhanced both yield and selectivity for the C2-selective olefination of pyridine. Other acid additives performed inferiorly to pivalic acid 2.5 equiv of PivOH was the ideal amount to maximize product yield. Silver(I) acetate functioned as a terminal oxidant and also positively influenced yield and selectivity. Only small amounts of C3 product were detected. 

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