Cycloaddition between Electron-Deficient π-Systems, Photochemical and Radical-Induced Reactions: A Novel, General, and Stereoselective Route to Polyfunctionalized Bridged Bicyclo[2.2.2]octanes, Bicyclo[3.3.0]octanes, Bicyclo[4.2.0]octanes, and Tricyclo[4.3.1.03,7]decanes

Gd(III)-Catalyzed Regio-, Diastereo-, and Enantioselective [4 + 2] Photocycloaddition of Naphthalene Derivatives

Catalytic asymmetric dearomatization (CADA) reactions have evolved into an efficient strategy for accessing chiral polycyclic and spirocyclic scaffolds from readily available planar aromatics. Despite the significant developments, the CADA reaction of naphthalenes remains underdeveloped. Herein, we report a Gd(III)-catalyzed asymmetric dearomatization reaction of naphthalene with a chiral PyBox ligand via visible-light-enabled [4 + 2] cycloaddition. This reaction features application of a chiral Gd/PyBox complex, which regulates the reactivity and selectivity simultaneously, in excited-state catalysis. A wide range of functional groups is compatible with this protocol, giving the highly enantioenriched bridged polycycles in excellent yields (up to 96%) and selectivity (up to >20:1 chemoselectivity, >20:1 dr, >99% ee). The synthetic utility is demonstrated by a 2 mmol scale reaction, removal of directing group, and diversifications of products. Preliminary mechanistic experiments are performed to elucidate the reaction mechanism.

Cycloaddition of Spiroepoxycyclohexa-2,4-dienones, Radical Cyclization and 1,3-Acyl Shift in Excited State: Aromatics to Sterpuren-4-one

A stereoselective route to sterpuren-4-one from a simple aromatic precursor is presented. Oxidative dearomatization, π⁴s + π²s cycloaddition of 6,6-spiroepoxycyclohexa-2,4-dienones with ethyl acrylate, radical cyclization and 1,3-acyl shift in excited state are the important aspects of our approach. An interesting effect of a remote substituent on radical cyclization has also been presented.

Construction of Optically Active Isotwistanes and Aminocyclitols Using Chiral Cyclohexadiene as a Common Intermediate

We have developed a new method for synthesizing chiral isotwistane and homoisotwistane skeletons as well as aminocyclitols in a highly stereoselective manner. These results were achieved through the use of a common intermediate, which was derived from the ytterbium-catalyzed asymmetric Diels-Alder reaction of Danishefsky diene.

Efficient construction of the A/C/D tricyclic skeleton of palhinine A

An efficient approach for the synthesis of the 9/6/6 tricyclic structure ofLycopodiumalkaloid palhinine A has been accomplished. This protocol can undergo ring constriction to rapidly construct the highly strained nine-membered azonane ring of palhinine A.

Synphos modified Pt nanoclusters, their heterogenization by silica sol-gel entrapment, and catalytic activity in hydrogenolysis of bicyclo[2.2.2]oct-7-enes and hydrogenation of ethyl pyruvate

Platinum (Pt) colloids modified by the chiral ligand synphos were prepared with the goal of obtaining a catalytic nanomaterial and were subsequently embedded in silica to form a heterogeneous catalyst. The systems were characterized by (31)P-NMR, x-ray diffraction, molecular modeling and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs) measurements. These colloids, both as 'quasi-homogeneous catalysts' (or soluble heterogeneous catalysts) and embedded in silica (heterogeneous catalysts) were employed in the selective hydrogenolysis of highly sterically constrained bicyclo[2.2.2]oct-7-enes and hydrogenation of ethyl pyruvate.