Inside Cover: Chemistry of Tertiary Carbon Center in the Formation of Congested C−O Ether Bonds (Angew. Chem. Int. Ed. 8/2021)

Abstract

A stereospecific nucleophilic substitution between tertiary alkyl bromides and tertiary alkyl alcohols is described in the Research Article on page 4329 by Toshiki Nokami, Takashi Koike, Manabu Abe, Eiji Shirakawa, Takashi Nishikata, and co‐workers. The entering alcohol formally attacks the C−Br bond to undergo a retentive substitution with formation of tertiary alkyl ethers.

Oxazaborolidinones: Steric Coverage Effect of Lewis Acidic Boron Center in Suzuki–Miyaura Coupling Reactions

“…Based on these facts described above, we hypothesized that if sterically bulky substituents could cover the sp 2 -hybridized boron center, an organoboron reagent with a vacant p-orbital could be prepared. During the course of our previous studies on α-bromocarbonyl compounds, [15] we discovered sterically bulky OxBs, which possess an α-hydroxycarboxamide moiety and sp 2 -hybridized boron with a vacant p-orbital (Figure 2). The α-alkyl groups (R 2 and R 3 ) of the α-hydroxycarboxamide moiety can dynamically cover the p-orbital of the sp 2 -hybridized boron atom, creating a small space around the boron atom.…”