NH₂-Directed C–H Alkenylation of 2-Vinylanilines with Vinylbenziodoxolones

Abstract

The first directing-group-mediated C-H alkenylation with alkenyl-λ-iodanes as electrophilic alkene-transfer reagents has been developed. The application of free aromatic amines as challenging but synthetically valuable directing groups in combination with an Ir catalyst enabled the synthesis of highly desirable 1,3-dienes in excellent yields of up to 98% with high to perfect (Z,E) stereoselectivity. A broad substrate scope and further synthetic modifications are demonstrated.

Fine-tuned organic photoredox catalysts for fragmentation-alkynylation cascades of cyclic oxime ethers

“…Preliminary results for an alkenylation cascade were also obtained using Phenyl Vinyl BenziodoXolone (PhVBX, 14 ), recently introduced by Olofsson and co-workers. 27 Under the optimized reaction conditions, alkene 15 was isolated in 50% yield with a 12 : 1 E / Z selectivity. 28 Changing the base from K 2 CO 3 to CsOBz afforded lower yield (40%), but with enhanced selectivity (17 : 1 E / Z ).…”

Dealkenylative Alkenylation: Formal σ‐Bond Metathesis of Olefins

“…We commenced our investigation by reacting (À)-isopulegol (1a)a samodel alkene with ar ange of structurally diverse vinylation agents:( E)-(2-bromovinyl)benzene (2), [18] cinnamic acid (3), [19] two b-nitrostyrenes 4, [20] (E)-[2-(benzenesulfonyl)vinyl]benzene (5), [21] (E)-1-styryl-1,2-benziodoxol-3(1H)-one (6) [22] (entries 1-6, Table 1). Among them, 4methyl-b-nitrostyrene (4b)performed the best, providing the desired styrylated cyclohexanol 7ab in 47 %y ield (entry 4).…”

Stereospecific Synthesis of Multi-Aryl Substituted Olefins and 1,3-Dienes via 1,4-Palladium Migration/Suzuki Coupling Sequence

“…17 Regarding the use of -NH2 as a directing group, Nachtsheim and co-workers accomplished an iridium catalyzed alkenylation of 2-vinylanilines with very high stereoselectivity. 18 Despite the excellent results obtained in both cases with an ortho-heteroatom directing group, they suffer from inherent limitation that the essential ortho-nitrogen-atom is probably either unwanted in the design of a material molecule or hard to be removed after reaction completion.…”