Design and Synthesis of Bicyclo[4.3.0]nonene Nucleoside Analogues.

Nucleoside analogues are effective antiviral agents, and the continuous emergence of pathogenic viruses demands the development of novel and structurally diverse analogues. Here, we present the design and synthesis of novel nucleoside analogues with a carbobicyclic core, which mimics the conformation of natural ribonucleosides. Employing a divergent synthetic route featuring an intermolecular Diels-Alder reaction, we successfully synthesized carbobicyclic nucleoside analogues with high antiviral efficacy against respiratory syncytial virus.

Ni-Catalyzed 1,1- and 1,3-Aminoboration of Unactivated Alkenes.

Alkene borylfunctionalization reactions have emerged as useful methods for chemical synthesis. While much progress has been made on 1,2-borylamination reactions, the related 1,1- and 1,3-borylaminations have not been reported. Herein, a Ni-catalyzed 1,1-borylamination of 1,1-disubstituted and monosubstituted alkenes and a 1,3-borylamination of cyclic alkenes are presented. Key to development of these reactions was the identification of an alkyllithium activator in combination with Mg salts. The utility of the products and the mechanistic details are discussed.

Catalytic Arylboration of Spirocyclic Cyclobutenes: Rapid Access to Highly Substituted Spiro[3.n]alkanes.

A method to achieve the synthesis of highly substituted spirocyclic cyclobutanes is disclosed. The reaction involves the catalytic arylboration of cyclobutenes. Depending on the substitution pattern of the cyclobutene, either a Cu/Pd- or a Ni-catalyzed reaction was utilized. In the case of the Cu/Pd catalyzed reactions, the identification of a Cu-complex for arylboration was crucial to observe high selectivity. The synthetic utility of the products is demonstrated, and the mechanistic details are discussed.

Total Synthesis of Cryptotrione.

The total synthesis of cryptotrione (1) was enabled by substrate-controlled diastereoselective construction of the bicyclo[3.1.0]hexene framework through platinum-catalyzed enyne cycloisomerization and Lewis acid induced polyene cyclization to construct the abietane-type tricyclic diterpene skeleton. The stereogenic tertiary carbon center in the side chain was installed in a diastereodivergent manner by conjugate addition reactions.

Gold(I)-Catalyzed Tandem Cycloisomerization of 1,5-Enyne Ethers by Hydride Transfer.

A novel gold-catalyzed tandem protocol, initiated by hydride transfer in the presence of catalytic (C6 F5 )3 PAuCl/AgSbF6 , for the formation of fused polycyclic ring systems has been achieved. This tandem reaction provides rapid access to various fused polycyclic species in a single chemical operation, leading to stereospecific formation of two carbon-carbon bonds and three rings.