The diastereo‐ and enantioselective diboration of spirocyclobutenes provides a platform for the rapid preparation of a wide variety of chiral spirocyclic building blocks. The chemoselective functionalization of the carbon‐boron bond in the products, including a stereospecific sp3‐sp2 Suzuki–Miyaura cross‐coupling reaction, provides a powerful tool to control the directionality and the nature of the exit vectors in the spirocyclic framework.

Herein, we report a catalytic and stereospecific method for the preparation of enantioenriched a-hydroxy cyclopropylboronates with control in four contiguous stereocenters. The reaction involves the borylation of readily available allylic epoxides using an inexpensive Cu(I) salt and a commercially available phosphine ligand. High diastereocontrol is achieved and different diastereomers can be selectively prepared. Functionalization of the carbon-boron bond provides access to different enantiomerically enriched trisubstituted cyclopropanes from a common intermediate.

We present a strategy for the synthesis of spirocyclic cyclobutanes with modulable exit vectors based on the regioselective monoborylation of spirocyclobutenes. Using an inexpensive copper salt and a commercially available bidentate phosphine, a broad variety of borylated spirocycles have been prepared with complete regiocontrol. The boryl moiety provides a synthetic handled for further functionalization, allowing access to a wide array of spirocyclic building blocks from a common intermediate.

We present an efficient strategy for the formal 1,4-reduction of vinyl epoxides that does not require superstoichiometric amounts of a strong reductant. Using a readily available copper catalyst and a diboron compound, a wide variety of enantioenriched allylic alcohols has been prepared. Additionally, epoxyenynes have been reduced in a 1,4-manner to selectively afford skipped enynes or skipped dienes.

The diastereo‐ and enantioselective diboration of spirocyclobutenes provides a platform for the rapid preparation of a wide variety of chiral spirocyclic building blocks. The chemoselective functionalization of the carbon‐boron bond in the products, including a stereospecific sp3‐sp2 Suzuki–Miyaura cross‐coupling reaction, provides a powerful tool to control the directionality and the nature of the exit vectors in the spirocyclic framework.