TMSOTf-mediated synthesis of skipped dienes through the addition of olefins to imines and semicyclic N,O-acetals

Abstract

A novel approach to skipped dienes has been developed through the TMSOTf-mediated one-pot addition-substitution of olefins 2a, 2f-2g with imines 1a-1g, and a series of aryl substituted skipped dienes 3aa-3gf...

Palladium-Catalyzed Sequential Heck Reactions of Olefin-Tethered Aryl Iodides with Alkenes

“…Several groups reported a metal-catalyzed cyclization strategy to construct a dihydrobenzofuran skeleton. − For example, Lamaty and co-workers combined O -allylation with methyl bromomethylacrylate into a Pd-catalyzed one-pot process, and a variety of functionalized 3,3-disubstituted-2,3-dihydrobenzofurans were obtained when the subsequent Heck reaction or Suzuki coupling was properly added into the synthetic sequence (Figure a). − Later on, two different enantioselective syntheses of 3,3-disubstituted-2,3-dihydrobenzofurans were achieved through Ni-catalyzed aryl alkylation of arylboron reagents that bear a pendant olefin and Cu-promoted diarylation of pendant olefins tethered on aryl boronates by Fu and Brown, respectively (Figure b). On the basis of our continuous efforts in establishment of heterocyclic building blocks, we envisioned that the metal-catalyzed cyclization of olefin-tethered aryl iodides with styrenes and α,β-unsaturated ketones could also lead to 3,3-disubstituted-2,3-dihydrobenzofurans. To the best of our knowledge, substituted styrenes and α,β-unsaturated ketones have never been studied in this system under classical conditions, in addition to the photocatalytic free radical pathway .…”