The intriguing methoxycarbonylation of trimethylsilylacetylene in the presence of Drent's catalytic system

Abstract

The alkoxycarbonylation of trimethylsilylacetylene has been studied in order to develop an atom economic sustainable synthesis of 2‐(trimethylsilyl)acrylates, a family of valuable intermediates. Pd(OAc)2 in combination with CH3SO3H and diphenyl‐(pyridin‐2‐yl)phosphine or diphenyl‐(6‐methyl‐pyridin‐2‐yl)phosphine is an active catalyst for the reaction affording mixtures of the sought 2‐(trimethylsilyl)acrylate and the isomeric 3‐(trimethylsilyl)acrylate. The phosphine ligand has a dramatic effect on the reaction. When employing diphenyl‐(pyridin‐2‐yl)phosphine, it is necessary to carry out the reaction at 80°C in order to observe a modest catalytic activity, and the product is an almost equimolecular mixture of the two isomeric esters. On the contrary, when employing diphenyl‐(6‐methyl‐pyridin‐2‐yl)phosphine, the reaction proceeds under much milder conditions affording with high rate (turnover frequency [TOF] up to 1200 h−1) and selectivity (>95%) of the sought 2‐(trimethylsilyl)acrylate. The reaction conditions have been optimized, and the effects of phosphine/palladium, acid/palladium, reaction time, temperature, and CO pressure have been investigated.

A sustainable route for the synthesis of alkyl arylacetatesviahalogen and base free carbonylation of benzyl acetates

“…Summing up, given our interest in palladium catalysed carbonylation reactions 14 and sustainability, 15 we realized that the identification of a halogen-free synthetic strategy for the synthesis of alkyl arylacetates from benzyl acetates could represent a valuable alternative to industrial practices adopted to date. With this in mind, the unprecedented carbonylation of benzyl acetates is herein discussed (Scheme 1e).…”

Synthesis of 2-Alkylaryl and Furanyl Acetates by Palladium Catalysed Carbonylation of Alcohols

“…Considering the achievements recently reported on the carbonylation of benzyl alcohols for the synthesis benzyl acetates (Scheme 2a) [8], and given our interest in the development of sustainable products and processes [36][37][38] and in palladium-catalysed carbonylation reactions [39][40][41][42][43], in this work, we deemed it interesting to verify whether the two-step strategy developed by us for the synthesis of alkylaryl acetates could be further implemented into a one-pot strategy starting from alkylaryl and furanyl alcohols (Scheme 2b). Benzyl, piperonyl and furfuryl alcohol have been tested, the first as a standard substrate for reaction condition optimization, and the latter two as interesting examples of building blocks for fine chemical synthesis.…”