Highly Efficient Route to Functionalized Tetrahydrocarbazoles Using a Tandem Cross‐Metathesis/Intramolecular‐Hydroarylation Sequence

Abstract

The scope of the novel ruthenium-catalyzed tandem cross-metathesis/intramolecular-hydroarylation sequence is described. This methodology offers a practical and efficient synthesis of structurally diverse and complex tetrahydrocarbazoles in good to excellent yields (up to 98%). Moreover, preliminary efforts towards the development of an enantioselective version of the current process by sequential catalysis with ruthenium complex and chiral amine are presented, with high yields and enantioselectivities (up to 88% yield and 91% ee).

Rh‐Catalyzed Decarbonylative Addition of Salicylaldehydes with Vinyl Ketones: Synthesis of Taccabulins A–E

“…1‐(4‐Hydroxy‐3‐methoxyphenyl)prop‐2‐en‐1‐one (2h) :[18b] Colourless liquid (2.65 g, 49 %). 1 H NMR (400 MHz, CDCl 3 ): δ = 7.57–7.54 (m, 2H), 7.18 (dd, J = 17.0, 10.6 Hz, 1H), 6.96 (d, J = 8.0 Hz, 1H), 6.43 (dd, J = 17.0, 1.8 Hz, 1H), 5.87 (dd, J = 10.5, 1.8 Hz, 1H), 5.56 (s, 1H), 3.95 (s, 3H) ppm.…”

“…1‐(Benzo[d][1,3]dioxol‐5‐yl)prop‐2‐en‐1‐one (2j) :[18c] Colourless liquid (0.42 g, 19 %). 1 H NMR (400 MHz, CDCl 3 ): δ = 7.56 (dd, J = 8.2, 1.6 Hz, 1H), 7.46 (d, J = 1.7 Hz, 1H), 7.12 (dd, J = 17.2, 10.7 Hz, 1H), 6.86 (d, J = 8.2 Hz, 1H), 6.41 (dd, J = 17.2, 1.8 Hz, 1H), 6.05 (s, 2H), 5.87 (dd, J = 10.7, 1.7 Hz, 1H) ppm.…”

Palladium-Catalyzed Decarboxylative Arylation of Benzoylacrylic Acids toward the Synthesis of Chalcones

“…Substituted 3-benzoylacrylic acids 1e – g and 1h and vinyl ketone 5 were prepared according to published procedures. Other starting materials were commercially available.…”

Recent Advances in Catalytic Sequential Reactions Involving Hydroelement Addition to Carbon–Carbon Multiple Bonds

“…An active ruthenium methylene complex, derived from a CM reaction, may serve as a Lewis acid in promoting the final hydroarylation. An alternative asymmetric version was reported by the same group . High enantiomeric excess (84–91% ee ) was achieved.…”