The asymmetric total syntheses of a group of structurally complex Kopsia alkaloids, (-)-kopsine, (-)-isokopsine, (+)-methyl chanofruticosinate, (-)-fruticosine, and (-)-kopsanone, has been achieved. The key strategies for the construction of the molecular complexity in the targets included an asymmetric Tsuji-Trost rearrangement to set the first quaternary carbon center at C20, an intramolecular cyclopropanation by diazo decomposition to install the second and third quaternary carbon centers at C2 and C7, respectively, and a SmI -promoted acyloin condensation to assemble the isokopsine core. A radical decarboxylation of an isokopsine-type intermediate results in a thermodynamic partial rearrangement to give N-decarbomethoxyisokopsine and N-decarbomethoxykopsine, two key intermediates for the syntheses of Kopsia alkaloids with different subtype core structures.

An efficient one-pot synthesis of multisubstituted 9,10-dihydrophenanthrenes from easily available 2-arylazaarenes and cyclohexadienone-tethered terminal alkynes (1,6-enynes) has been successfully achieved. This domino reaction proceeded smoothly through Cp*Rh­(III)-catalyzed C–H activation, direct protonation of alkenyl-Rh intermediates, intramolecular Diels–Alder reaction, alkene isomerization, subsequent ring-opening aromatization, and acetylation. This strategy was pot-economical and tolerated a wide range of functional groups. Moreover, the potent anticancer activities against HepG2 cells were observed for these artificial 9,10-dihydro­phenanthrene derivatives.

The asymmetric total syntheses of ag roup of structurally complex Kopsia alkaloids,( À)-kopsine,( À)isokopsine,( + +)-methyl chanofruticosinate,( À)-fruticosine, and (À)-kopsanone,h as been achieved. The key strategies for the construction of the molecular complexity in the targets included an asymmetric Tsuji-Trost rearrangement to set the first quaternary carbon center at C20, an intramolecular cyclopropanation by diazod ecomposition to install the second and third quaternary carbon centers at C2 and C7, respectively,a nd aS mI 2 -promoted acyloin condensation to assemble the isokopsine core.Aradical decarboxylation of an isokopsine-type intermediate results in at hermodynamic partial rearrangement to give N-decarbomethoxyisokopsine and N-decarbomethoxykopsine,t wo key intermediates for the syntheses of Kopsia alkaloids with different subtype core structures.

Ring strain plays an important role in metalcatalyzed cyclization of 1,6-dienes. Herein, we report a rhodium-(III)-catalyzed asymmetric reductive cyclization of cyclohexadienone-tethered α,β-unsaturated compounds (1,6-dienes), including α,β-unsaturated ketones, esters, amides, sulfone, and phosphonate. The reactions undergo an unusual anti-Michael/Michael addition process, affording cis-bicyclic frameworks with good to high yields and good diastereo-and enantioselectivities. Furthermore, several transformations of the products and a one-pot preparation of bridged polycyclic structure are also presented. Finally, DFT calculations show that the enantioselectivity is determined by the initial olefin insertion step and that the ring strain controls the overall regioselectivity and favors the formation of 5,6-bicyclic products.

A mild and relatively simple way for preparation of 2-(3-hydroxy-1-adamantane)-2-oxoacetic acid (I) was reported. It was prepared from 1-adamantanecarboxylic acid (II) via sulfuric acid/nitric acid to get 3-hydroxy-1-adamantanecarboxylic acid (III); treated with the one-pot method through acylation, condensation, and decarboxylation to obtain 3-hydroxy-1-acetyladamantane (IV); and finally oxidized by potassium permanganate (KMnO4) to get the target compound (I). The overall yield was about 60%, which provides a new idea for commercial production of saxagliptin intermediate.