Alkene Chemoselectivity in Ruthenium‐Catalyzed Z‐Selective Olefin Metathesis

Abstract

Chelated ruthenium catalysts have achieved highly chemoselective olefin metathesis reactions. Terminal and internal Z olefins were selectively reacted in the presence of internal E olefins. Products were produced in good yield and high stereoselectivity for formation of a new Z olefin. No products of metathesis with the internal E olefin were observed. Chemoselectivity for terminal olefins was also observed over both sterically hindered and electronically deactivated alkenes.

Ru-based Z-selective metathesis catalysts with modified cyclometalated carbene ligands

“…Previously, 8 was demonstrated to catalyze the Z -selective cross-metathesis of 39 and 40 with complete chemoselectivity. 31 Under identical reaction conditions, the catalytic abilities of 8 , 19 , and 21 were compared (Table 6). Catalysts 8 and 19 afforded cross-product in similar yields (77% and 64%, respectively), with near perfect Z-selectivities, while 21 was again found to be an ineffective catalyst.…”

Z -Selective ruthenium metathesis catalysts: Comparison of nitrate and nitrite X-type ligands

“…1e High M n can be attributed to a high rate of propagation (k p ) relative to the rate of initiation (k i ) or incomplete catalyst initiation. This was observed for catalyst 2 , which has a slow initiation rate compared to faster initiating catalysts ( 21 ) not containing the Hoveyda chelate.…”

“…1 This process has gained widespread applicability in a variety of fields including organic synthesis, biochemistry, and materials science. 2 Transition metal catalysts that could selectively produce the kinetically favored cis -products remained elusive until the discovery of Group VI-based systems by Schrock and Hoveyda.…”

Recent Advancements in Stereoselective Olefin Metathesis Using Ruthenium Catalysts

“…It was reported by Grubbs and coworkers that 9 was able to differentiate between terminal olefins and internal E-olefins with great discretion, providing 1,4-diene CM products in good yields with excellent selectivities (Table 7) [58]. Carbonyl and amine functionality was also tolerated ( Table 7, entries 2-7).…”