Organocatalytic Asymmetric Synthesis of trans-γ-Lactams
Shunxi Dong1, Marcus Frings1, Duo Zhang1
1Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany.
Abstract:
An N-heterocyclic carbene (NHC)-catalyzed highly diastereo- and enantioselective formal [3+2] reaction of o-hydroxy aromatic aldimines and cinnamaldehydes for the preparation of enantioenriched trans-γ-lactams was developed. An internal hydrogen bond between the o-hydroxy and the imine function was crucial for the reactivity and chemical selectivity. Trans-γ-lactam 3 d was easily oxidized to multifunctional 1,4-benzoquinone 8, which could further be transformed to biaryl 9 in the presence of a phosphoric acid. Finally, preliminary results for a kinetic resolution of (±)-trans-γ-lactam 3 d under asymmetric NHC catalysis are reported.
Related Concept Videos
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
[3,3] Sigmatropic Rearrangement of Allyl Vinyl Ethers: Claisen Rearrangement
Synthesis of α-Substituted Carbonyl Compounds: The Stork Enamine Reaction
Preparation of Epoxides
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
SN2 Reaction: Stereochemistry
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not...


