172
F. Glorius, K. Hirano
Scheme 12. α-Methyl cinnamaldehyde as challenging substrate
7
Intramolecular Variants
The aforementioned intermolecular reactions generate a γ-butyrolactone with up to three contiguous stereocenters. An intramolecular
variant of this reaction would be attractive, because more complex systems form, higher stereoselectivities are expected and fewer reactive
electrophiles could potentially be used, thereby significantly expanding the scope of this transformation. However, an often complex, multistep substrate synthesis decreases the attractivity of intramolecular reactions. Consequently, our investigation commenced with the design of
readily accessible cyclization precursors.
2-Butenediol 13 was envisioned to be an ideally suited building
block, allowing the synthesis of substrates for the conjugate umpolung
cyclization reaction in only two steps. A highly regioselective epox-
F. Glorius, K. Hirano
Scheme 12. α-Methyl cinnamaldehyde as challenging substrate
7
Intramolecular Variants
The aforementioned intermolecular reactions generate a γ-butyrolactone with up to three contiguous stereocenters. An intramolecular
variant of this reaction would be attractive, because more complex systems form, higher stereoselectivities are expected and fewer reactive
electrophiles could potentially be used, thereby significantly expanding the scope of this transformation. However, an often complex, multistep substrate synthesis decreases the attractivity of intramolecular reactions. Consequently, our investigation commenced with the design of
readily accessible cyclization precursors.
2-Butenediol 13 was envisioned to be an ideally suited building
block, allowing the synthesis of substrates for the conjugate umpolung
cyclization reaction in only two steps. A highly regioselective epox-