Ruthenium-catalysed Z-selective cross metathesis of allylic-substituted olefins

Abstract

The Z-selective cross metathesis of allylic-substituted olefins is explored with recently developed ruthenium-based metathesis catalysts. The reaction proceeds with excellent stereoselectivity for the Z-isomer (typically >95%) and yields of up to 88% for a variety of allylic substituents. This includes the first synthesis of Z-α,β-unsaturated acetals by cross metathesis and their elaboration to Z-α,β-unsaturated aldehydes. In addition, the reaction is tolerant of a variety of cross partners, varying in functionality and steric profile.

Tandem Z‐Selective Cross‐Metathesis/Dihydroxylation: Synthesis of anti‐1,2‐Diols

“…Achieving unsymmetrical substitution patterns through hetero‐cross‐metathesis/dihydroxylation is an appealing target, particularly if differentially protected products can be obtained. Z ‐selective hetero‐cross‐metathesis can be achieved by using an excess of one of the olefin partners 21. 25 Tosyl‐ and Cbz‐protected allyl amines were used as coupling partners with allyl butyrate or allyl benzoate (Table 3), generating the corresponding substituted amino triols in up to 63 % yield.…”

The chemistry of the carbon-transition metal double and triple bond: Annual survey covering the year 2014

“…A variety of allylically-substituted alkenes (e.g. 30) were subjected to Z selective cross metathesis using the ruthenium catalyst 28 [232]. Several analogs of catalyst 28 that feature a variety of NHC ligands were tested as Z-selective catalysts [233].…”

Z‐Selektive Kreuzmetathese mit Ruthenium‐Katalysatoren: Anwendung in der Synthese und mechanistische Aspekte

“…B. Verbindung 11, mit sehr guten Z-Selektivitäten (91-> 95 %) umgesetzt werden kçnnen (Schema 5). [17] Die Verwendung von Katalysator 2 resultierte wie erwartet in einer niedrigeren Z-Selektivität (ca. 76 %).…”