1,2-Sulfone rearrangement in organocatalytic reactions
作者:Adrien Quintard、Alexandre Alexakis
DOI:10.1039/c0ob00818d
日期:——
The 1,2-sulfone rearrangement resulting from nucleophilic addition to bis activated vinyl-sulfones has been studied in more detail. Various nucleophiles activated by different types of catalysts (enamine, Brönsted base, thiourea) are able to promote such rearrangement in excellent yields and moderate to excellent enantioselectivities (up to 94% ee). Mechanistic studies have led to a better understanding of the mechanism and allowed its application to other electrophiles such as vinyl-sulfone acrylates.
F rigid cats: The power of conformationallystabilizedcatalysts is demonstrated. By taking appropriate advantage of fluorineinsertion (see scheme), purely conformationalcatalyst design led to a notable improvement in enantioselectivities from around 70 % to 91–98.5 % ee. The other advantage of this approach is the better understanding of the origin of the stereoselectivity in the given catalytic
Joined together, organocatalysts aldehydes and sulfones: A diaryl prolinol silyl ether was found to catalyse efficiently and enantioselectively the conjugate addition of aldehydes to vinyl sulfones (see scheme). The ample synthetic utility of the resulting adducts is illustrated.
Organocatalytic Addition on 1,2-Bis(sulfone)vinylenes Leading to an Unprecedented Rearrangement
作者:Adrien Quintard、Alexandre Alexakis
DOI:10.1002/chem.200901535
日期:2009.10.26
An unprecedentedrearrangement of 1,2‐bis(sulfone)vinylenes used in aminocatalysis led to the formation of highly useful gem‐disulfones (see scheme). By using aminal–pyrrolidine organocatalysts, the 1,2‐sulfone shift was generalised, leading to highly versatile adducts using both ketones and aldehydes. It represents a valuable alternative for the α‐alkylation of carbonyl compounds.