No abstract

Efficient and concise approaches for the synthesis of three bioactive natural products, isohericerin, isohericenone, and erinacerin A, are described in this paper. The key reactions employed include a Mannich reaction with commercially available hydroxybenzoate and subsequent one-pot lactamization to afford the common precursor isoindolinone in 3 steps and a Suzuki-Miyaura coupling reaction to connect geranyl side chains to the isoindolinone core. In addition, the mild and efficient synthesis of the C5'-oxidized geranyl side unit of isohericenone is enabled by developing a highly regioselective and efficient method for the Cu-catalyzed methylboronation of functionalized terminal alkynes.

We present a new and straightforward one-pot process for the synthesis of 3-carbonyl-4-quinolone derivatives through highly efficient Cu-catalyzed aza-Michael addition of 2-aminobenzoates to β-substituted α,β-unsaturated ketones/cyclization/mild oxidation reactions. A broad range of new versatile 3-carbonyl-quinolin-4(1H)-ones is prepared from readily available chemicals under mild reaction conditions with short reaction times, producing good to excellent yields (up to 99%).

An efficient and highly chemo- and stereoselective copper-catalyzed hydroamination of oxa- and azabenzo­norbornadienes with various pyrazole derivatives is described. This catalytic process is promoted by the presence of N-heterocyclic carbene ligands and KOt-Bu under mild and simple reaction conditions, and allows for the direct synthesis of new and versatile functionalized oxa­(aza)­benzo­norbornyl pyrazoles starting from readily available oxa­(aza)­bicyclic alkenes. The synthetic utility of this method was demonstrated by the transformation of the obtained products into pyrazolyl-substituted naphthalenes.

1,2-Diborons with one boron atom each in the allyl and homoallyl positions are of great utility, especially as doubleallylation reagents. However, only a few synthetic methods have been reported to date and have a limited substrate scope. Herein, we developed the Cu-catalyzed regio-and stereoselective synthesis of α-borylmethyl-(E)-allylborons from easily accessible 1-substituted allenols and bis(pinacolato)diboron. Importantly, this method allowed the highly efficient and regioselective formation of doubleallylating diborons with diverse substituents, which would be otherwise cumbersome to synthesize, and could be successfully performed on a gram scale. The synthetic application of α-borylmethyl-(E)-allylborons was demonstrated by the enantio-and (Z)selective allylation of aldehydes via Brønsted acid catalysis. Furthermore, (E)-allyl and (E)-homoallyl diols with excellent diastereoselectivity were generated by the Lewis acid catalyzed diastereo-and (E)-selective allyl transfer of (E)-allyldiborons to aldehydes. Using this strategy, the key intermediate in the construction of the C 7 −C 12 fragment of (−)-discodermolide was also synthesized.