Parts–per–million of ruthenium catalyze the selective chain–walking reaction of terminal alkenes

Abstract

The chain–walking of terminal alkenes (also called migration or isomerization reaction) is currently carried out in industry with unselective and relatively costly processes, to give mixtures of alkenes with significant amounts of oligomerized, branched and reduced by–products. Here, it is shown that part–per–million amounts of a variety of commercially available and in–house made ruthenium compounds, supported or not, transform into an extremely active catalyst for the regioselective migration of terminal alkenes to internal positions, with yields and selectivity up to >99% and without any solvent, ligand, additive or protecting atmosphere required, but only heating at temperatures >150 °C. The resulting internal alkene can be prepared in kilogram quantities, ready to be used in nine different organic reactions without any further treatment.

Solid-catalyzed synthesis of isomers–free terpinen–4–ol

“…Fig. 6 also shows that the reaction can be run solventless at higher temperature, with a slight decrease in yield [41].…”

Iron‐Catalyzed Positional and Geometrical Isomerization of Alkenes

“…[140] Despite this, the catalytic activity and catalyst loading were far from those of the more efficient noble metal systems. [29,36,56,65] The latter ligand-free catalyst in the presence of either B 2 (pin) 2 or PhMe 2 SiB(pin) and a base had the rare ability to drive CÀ C double bond migration over multiple position (up to 9 positions) for terminal and even internal alkenes (Scheme 9). The methodology was tolerant to a wide range of functional groups embedded into an aryl moiety, simple heteroaryl derivatives or N-containing heterocycles, and led to the formation of the coresponding isomerized product with high E/Z selectivity of > 49/1.…”

“…For decades, precious metal-based catalysts such as Ru, [29][30][31][32][33][34][35][36][37][38][39][40][41] Rh, [42][43][44][45][46][47][48] Pd, [49][50][51][52][53][54][55][56][57] Ir, [58][59][60][61][62][63][64][65][66][67][68][69][70][71] Pt, [72][73][74] and Mo, [75,76] have been at the forehead of metal-catalyzed alkene isomerization to address the challenges and selectivity issues and to enrich the reaction applications pertaining to scope and synthetic usefulness. However, the low abundance, high cost and high toxicity of these metals have stimulated the exploration of earth-abundant firstrow late transition metals as sustainable a...…”

“…For decades, precious metal‐based catalysts such as Ru, [29–41] Rh, [42–48] Pd, [49–57] Ir, [58–71] Pt, [72–74] and Mo, [75,76] have been at the forehead of metal‐catalyzed alkene isomerization to address the challenges and selectivity issues and to enrich the reaction applications pertaining to scope and synthetic usefulness. However, the low abundance, high cost and high toxicity of these metals have stimulated the exploration of earth‐abundant first‐row late transition metals as sustainable alternatives that could additionally feature distinct and complementary reactivity behaviors thanks to a large set of redox and spin states [77] .…”

Synthesis of Dehydromuscone by an Alkene Metathesis Macrocyclization Reaction at 0.2 M Concentration

“…In particular, the use of an RCM macrocyclization reaction at a >0.1 M concentration with the relatively inexpensive Grela-type catalysts provides an opportunity for the synthesis of 1 at an industrial level. 21…”