Disclosed herein is enantioselective synthetic method comprising reacting an enolisable C
4
-C
50
organic anhydride with a second compound selected from the group consisting of an aldehyde, a ketone, an aldimine, a ketimine or a Michael Acceptor in the presence of a bifunctional organocatalyst. The reaction may find particular utility in the enantioselective synthesis of medicinally relevant heterocycles, such as dihydroisocoumarins and dihydroisoquinolinones.
Formal [4 + 2] Cycloadditions of Anhydrides and α,β-Unsaturated <i>N</i>-Tosyl Ketimines
作者:Noah P. Burlow、Sara Y. Howard、Carla M. Saunders、James C. Fettinger、Dean J. Tantillo、Jared T. Shaw
DOI:10.1021/acs.orglett.8b04091
日期:2019.2.15
ketone-derived imines is reported. Cyclic, enolizable anhydrides undergo a base-promoted conjugate addition reaction with α,β-unsaturated N-tosyl ketimines, followed by an intramolecular acylation to give formal [4 + 2] cycloaddition products. The carboxylic acid-containing products are formed with modest selectivity for the cis-diastereomer and can be fully epimerized to the trans-diastereomer upon esterification
Catalytic formal cycloadditions between anhydrides and ketones: excellent enantio and diastereocontrol, controllable decarboxylation and the formation of adjacent quaternary stereocentres
作者:Claudio Cornaggia、Sivaji Gundala、Francesco Manoni、Nagaraju Gopalasetty、Stephen J. Connon
DOI:10.1039/c6ob00089d
日期:——
different types of activated ketone were shown to be compatible with the process – generating a diverse range of structurally distinct and densely functionalised lactone products with the formation of two new stereocentres, one of which is quaternary. In one example, a product incorporating two contiguous quaternary stereocentres (one all carbon) was formed with outstanding enantiocontrol. It has been shown
Catalytic, enantio- and diastereoselective synthesis of γ-butyrolactones incorporating quaternary stereocentres
作者:Francesco Manoni、Claudio Cornaggia、James Murray、Sean Tallon、Stephen J. Connon
DOI:10.1039/c2cc32147e
日期:——
A new, highly enantio- and diastereoselectivecatalytic asymmetric formal cycloaddition of aryl succinic anhydrides and aldehydes which generates paraconic acid (gamma-butyrolactone) derivatives is reported.
investigation has revealed that the base-catalysed Tamura cycloaddition between homophthalic anhydride and activated alkenes/alkynes – a reaction previously thought of as a Diels–Alder type process – proceeds via a stepwise mechanism involving conjugate addition and ring closure; which allowed the first catalytic asymmetric α-substitution reactions to be demonstrated with up to >99% ee.