title: α-Borylcarbonyl compounds: from transient intermediates to robust building blocks.
abstract: α-Borylcarbonyl species (C-bound boron enolates) are typically unstable due to their kinetic and thermodynamically favourable rearrangement to their O-bound isomers. Direct evidence of α-borylcarbonyl compounds is sparse despite the multitude of transformations in which they have been implicated as reactive intermediates. In recent years, a few examples have emerged of reactive α-borylcarbonyl intermediates that can be observed using spectroscopic methods. Other reports have shown that certain compounds containing the α-borylcarbonyl motif can be isolated under ambient conditions. Installation of electron-rich, tetracoordinate sp(3)-boron centers is a particularly viable strategy to improve the stability of α-borylcarbonyl systems as it imposes a barrier to the otherwise rapid 1,3-boron shift from carbon to oxygen. Among stable α-borylcarbonyl compounds, α-boryl aldehydes, equipped with a tetracoordinated N-methyliminodiacetyl (MIDA) boryl group, have been demonstrated to be versatile building blocks in the synthesis of a wide range of functionalized organoboron compounds.
authors.affiliation: Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto M5S 3H6, Canada. ayudin@chem.utoronto.ca.
authors.forename: Zhi
authors.initials: Z
authors.lastname: He
authors.forename: Adam
authors.initials: A
authors.lastname: Zajdlik
authors.forename: Andrei K
authors.initials: AK
authors.lastname: Yudin