| Summary: | The 1-propenyl ethers bearing free hydroxyl groups of CH<sub>3</sub>CH=CH–O–A–OH type (hydroxyalkyl 1-propenyl ethers, 1-propenyloxyalcohols) are the most desired as the reactive diluents for photopolymerizable systems with enhanced reactivity or intermediates for the synthesis of hybrid monomers for special applications. The ruthenium complexes-catalyzed isomerization of allyl ethers under solvent-free conditions is an atom-economical and environmentally sustainable method for their production. Here, the reaction conditions and limitations for the highly productive and selective synthesis of model 4-(1-propenyloxy)butan-1-ol have been investigated. The minimal loading of ruthenium pre-catalysts needed for completion of reaction within reasonable times was priority assumption. It was found that [RuClH(CO)(PPh<sub>3</sub>)<sub>3</sub>] or [RuCl<sub>2</sub>(PPh<sub>3</sub>)<sub>3</sub>] exhibited extremely high catalytic activity under optimized non-oxidative reaction conditions. The key effect of reaction temperature on the activation pre-catalyst and the exothermal effects of isomerization was discovered. The practically quantitative yields of 4-(1-propenyloxy)butan-1-ol were achieved with using of very low loading of [Ru] (5 ppm) and Bu<sub>3</sub>N (to maintain reaction chemoselectivity) at the temperature of 120 °C for only 0.5 h. Consequently, the attained TON (turnover number) and TOF (turnover frequency) values of ca. 198,000 and 390,000 h<sup>−1</sup> were unprecedentedly high and industrial attractive. On the other hand, the direct recycling of ruthenium catalyst is not a reasonable method for improving catalyst productivity.
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