Concise approach to γ-(het)aryl- and γ-alkenyl-γ-aminobutyric acids. Synthesis of vigabatrin

γ-Aminobutyric acid (GABA) and GABA derivatives have attracted increased attention over the years in the fields of medicinal chemistry and chemical biology due to their interesting biological properties and synthetic relevance. Here, we report a short synthetic route to γ-(het)aryl- and γ-alkenyl-γ-aminobutyric acids, including the antiepileptic drug vigabatrin, from readily available donor-acceptor cyclopropanes and ammonia or methylamine. This protocol includes a facile synthesis of 2-oxopyrrolidine-3-carboxamides and their acid hydrolysis to γ-aryl- or γ-alkenyl-substituted GABAs, which can serve as perspective building blocks for the synthesis of various GABA-based N-heterocycles and bioactive compounds.

Donor-Acceptor Cyclopropane Ring Expansion to 1,2-Dihydronaphthalenes. Access to Bridged Seven-Membered Lactones

A Lewis-acid-promoted domino ring-opening cyclization of readily available donor-acceptor cyclopropanes with a preinstalled electrophilic center, embedded in a donor group, to functionalized 1,2-dihydronaphthalenes is reported herein. The obtained compounds are transformed to pharmacologically attractive bridged tricyclic esters in a diastereospecific manner.

Synthesis of 1,5-Substituted Pyrrolidin-2-ones from Donor-Acceptor Cyclopropanes and Anilines/Benzylamines

We developed a straightforward synthetic route to pharmacologically important 1,5-substituted pyrrolidin-2-ones from donor-acceptor cyclopropanes bearing an ester group as one of the acceptor substituents. This method includes a Lewis acid-catalyzed opening of the donor-acceptor cyclopropane with primary amines (anilines, benzylamines, etc.) to γ-amino esters, followed by in situ lactamization and dealkoxycarbonylation. The reaction has a broad scope of applicability; a variety of substituted anilines, benzylamines, and other primary amines as well as a wide range of donor-acceptor cyclopropanes bearing (hetero)aromatic or alkenyl donor groups and various acceptor substituents can be involved in this transformation. In this process, donor-acceptor cyclopropanes react as 1,4-C,C-dielectrophiles, and amines react as 1,1-dinucleophiles. The resulting di- and trisubstituted pyrrolidin-2-ones can be also used in subsequent chemistry to obtain various nitrogen-containing polycyclic compounds of interest to medicinal chemistry and pharmacology, such as benz[g]indolizidine derivatives.

Convenient approach to polyoxygenated dibenzo[c,e]pyrrolo[1,2-a]azepines from donor–acceptor cyclopropanes

A convenient approach to polyoxygenated tetrahydrodibenzo[c,e]pyrrolo[1,2-a]azepines from the donor–acceptor cyclopropanes has been developed.