Stereoretentive Olefin Metathesis: An Avenue to Kinetic Selectivity

Abstract

Abstract:Olefin metathesis is an incredibly valuable transformation that has gained widespread use in both academic and industrial settings. Lately, stereoretentive olefin metathesis has garnered much attention as a method for the selective generation of both Eand Z-olefins. Early studies employing ill-defined catalysts showed evidence for retention of the starting olefins at early conversion. However, thermodynamic ratios were reached as the reaction proceeded to equilibrium. Recent studies in olefin metathesis have focused on the synthesis of catalysts that can overcome the inherent thermodynamic preference of an olefin, providing synthetically useful quantities of a kinetically favored olefin isomer. These reports have led to the development of stereoretentive catalysts that not only generate Z-olefins selectively, but also kinetically produce E-olefins, a previously unmet challenge in olefin metathesis. Advancements in stereoretentive olefin metathesis using tungsten, ruthenium, and molybdenum catalysts are presented.

Using stereoretention for the synthesis of E-macrocycles with ruthenium-based olefin metathesis catalysts

“…E -selective cross metathesis using stereoretentive Ru-based catalysts was often marred by low yields in reactions involving functionalized substrates or terminal olefins. Although the low yields observed in reactions with terminal olefins were attributed to decomposition of Ru methylidenes, 6 studies performed in our group showed that a large contributing factor to low activity with functionalized substrates is slow catalyst initiation in reactions of these catalysts with E -olefins. 8 A series of fast-initiating catalysts 1–4 was reported to significantly improve activity of stereoretentive catalysts in highly E -selective reactions ( Fig.…”

“… 5 In 2015, we demonstrated that these catalysts were further capable of cross metathesis between two E -olefins or between an E -olefin and a terminal olefin to generate E -products with high selectivity (>98% E ). 6 This was the first reported example of highly E -selective cross metathesis through kinetic control.…”

Transformations of bio‐sourced 4‐hydroxyphenylpropanoids based on olefin metathesis

“…[58] More recently, new stereoretentive catalysts have been developed that are able to kinetically produce (Z)-and (E)double bonds with excellent selectivities via cross metathesis of pure (Z)-and (E)-olefins. [59] The first and most active catalysts able to achieve this performance were ruthenium dithiolate catalysts such as Ru13, Ru14 and Ru15 presented in Figure 2. [60] These catalysts are (Z)-selective, stereoretentive and tolerant to a variety of functional groups but are not suited for metathesis transformations of terminal alkenes because the in situ generated ruthenium methylidene species are too unstable.…”

Combining enyne metathesis with long-established organic transformations: a powerful strategy for the sustainable synthesis of bioactive molecules

“…Alkene and alkyne metathesis [1][2][3][4], constituting highly versatile and powerful catalytic processes for constructing complex organic molecules [5][6][7][8][9][10][11][12], have found broad application in the fields of pharmaceutical synthesis [13][14][15], materials science [16][17][18][19][20], or in advanced techniques and technologies [21][22][23][24][25][26][27][28][29][30]. Thus, numerous multistep total syntheses of organic compounds, including bioactive molecules [31][32][33][34][35] and natural products [36,37], have been performed in a highly chemo-and stereoselective manner through metathesis routes [38][39][40][41][42][43]. In ingeniously elaborated procedures, olefin metathesis has been frequently employed as such or associated with name reactions like Grignard, Wittig, Diels-Alder, Suzuki-Miyaura, Heck, etc., resulting in the assembly of diverse intricate building blocks of the targeted structures [...…”