3,9-Di-tert-butyl-2,4,8,10-tetra­oxaspiro­[5.5]undeca­ne

The title compound, C15H28O4, was prepared by the condensation of pivalaldehyde with penta­erythritol. In the crystal, the two halves of the mol­ecule are related by a crystallographic twofold rotation axis passing through the central spiro-C atom. The two non-planar six-membered heterocycles both adopt chair conformations with the two tert-butyl groups both located in the equatorial positions

3,9-Bis(2,4-dichlorophenyl)-2,4,8,10-tetraoxaspiro[5.5]undecane

In the title compound, C19H16Cl4O4, the two halves of the molecule are related by a crystallographic twofold rotation axis passing through the central spiro-C atom. The two non-planar six-membered heterocycles both adopt chair conformations, and the dihedral angle between the two benzene rings is 76.6 (1)°. In the crystal structure, intermolecular C—H...O hydrogen bonds link the molecules into chains along the c axis

Re/Mg Bimetallic Tandem Catalysis for [4+2] Annulation of Benzamides and Alkynes via C‑H/N‑H Functionalization

A rhenium-magnesium cocatalyzed [4+2] annulation of benzamides and alkynes via C-H/N-H functionalization is described. The reaction features a divergent and high level of diastereoselectivities, which are readily switchable by subtle tuning of reaction conditions. Thus, a wide range of both <i>cis</i>- and <i>trans</i>-3,4-dihydroisoquinolinones is expediently synthesized in a highly atom-economical manner. Moreover, mechanistic studies unraveled a tandem mode of action between rhenium and magnesium in the catalytic cycles