Sie befinden Sich nicht im Netzwerk der Universität Paderborn. Der Zugriff auf elektronische Ressourcen ist gegebenenfalls nur via VPN oder Shibboleth (DFN-AAI) möglich. mehr Informationen...
Substituent Effects and the Mechanism of Gold to Alkene Benzylidene Transfer Employing a Gold Sulfonium Benzylide Complex
Ist Teil von
Organometallics, 2022-05, Vol.41 (9), p.1106-1114
Ort / Verlag
American Chemical Society
Erscheinungsjahr
2022
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Aliphatic and aromatic alkenes react rapidly and efficiently with the gold sulfonium benzylide complex [(P)AuCHPh(SPh2)]+ {B [3,5-CF3C6H3]4}− [P = P (t-Bu)2 o-biphenyl; 1] at room temperature via the cationic two-coordinate gold benzylidene complex [(P)AuCHPh]+ (I) to form phenyclyclopropanes. The reactivity of p-substituted vinyl arenes toward I decreased with the decreasing electron donor ability of the vinyl arene (ρ = −1.49 ± 0.15), and the reactivity of aliphatic alkenes toward I depended strongly on the number of alkyl groups attached to the more substituted alkene terminus. Benzylidene transfer to cis- and trans-β-methylstyrene occurred with complete retention of the alkene configuration. Benzylidene transfer to vinyl arenes led to predominant formation of cis-cyclopropanes (dr = 4.1: 1 to 13.9:1), whereas benzylidene transfer to aliphatic alkenes was generally less selective (dr = 1.3:1 to 5.1:1). All our experimental observations were consistent with a concerted, asynchronous, electrophilic benzylidene transfer mechanism. The diastereoselectivity of benzylidene transfer was interpreted in the framework of a transition state model involving a near anti-periplanar arrangement of the carbene AuC and alkene CC bonds.