An efficient synthetic approach for the construction of fluorine‐containing piperidine γ‐amino acid derivatives has been developed. The synthetic concept was based on oxidative ring opening of an unsaturated bicyclic γ‐lactam (Vince‐lactam) through its ring C=C bond, followed by double reductive amination of the diformyl intermediate performed with various fluoroalkylamines. The method has been extended towards the access of alkylated and perfluoroalkylated substances and for γ‐lactam derivatives. The transformations proceeded with stereocontrol: the configuration of the stereocenters in the products were predetermined by the configuration of the chiral centers of the starting γ‐lactam. The method could be extended for the access to enantiopure piperidine γ‐amino esters.
A novel, convenient procedure has been described for the construction of fluorinecontaining benzazepines. The synthetic protocol starting from readily available dihydronaphthalene regioisomers is based on oxidative ring olefin bond cleavage followed by ring closure of the diformyl intermediates in the presence of some fluorine-containing primary amines across double reductive amination. The applicability of the developed synthetic method was demonstrated by the Graphical abstract: synthesis of 13 benzazepine compounds isolated in 22-35% overall yields.
The current Account gives an insight into the synthesis of some N-heterocyclic β-amino acid derivatives and various functionalized saturated azaheterocycles accessed from substituted cycloalkenes via ring C=C bond oxidative cleavage followed by ring closing across double reductive amination. The ring-cleavage protocol has been accomplished according to two common approaches: a) Os-catalyzed dihydroxylation/NaIO4 vicinal diol oxidation and b) ozonolysis. A comparative study on these methodologies has been investigated. Due to the everincreasing relevance of organofluorine chemistry in drug research as well as of the high biological potential of β-amino acid derivatives several illustrative examples to the access of various fluorine-containing piperidine or azepane β-amino acid derivatives are also presented in the current Account.1 Introduction2 Olefin-Bond Transformation by Oxidative Ring Cleavage3 Synthesis of Saturated Azaheterocycles via Oxidative Ring-Opening/Ring-Closing Double Reductive Amination3.1 Importance of Fluorine-Containing Azaheterocycles in Pharmaceutical Research3.2 Synthesis of Azaheterocyclic Amino Acid Derivatives with a Piperidine or Azepane Framework through Oxidative Ring Opening/Reductive Amination3.2.1 Synthesis of Piperidine β-Amino Esters3.2.2 Synthesis of Azepane β-Amino Esters3.2.3 Synthesis of Fluorine-Containing Piperidine γ-Amino Esters3.3 Synthesis of Tetrahydroisoquinoline Derivatives through Oxidative Ring Opening/Reductive Amination Protocol3.4 Synthesis of Functionalized Benzazepines through Reductive Amination3.4.1 Synthesis of Benzo[c]azepines3.4.2 Synthesis of Benzo[d]azepines3.5 Synthesis of Various N-Heterocycles via Ozonolysis/Reductive Amination3.5.1 Synthesis of Compounds with an Azepane Ring3.5.2 Synthesis of Piperidine β-Amino Acids and Piperidine-Fused β-Lactams3.5.3 Synthesis of γ-Lactams with a Piperidine Ring3.5.4 Synthesis of other N-Heterocycles4 Summary and Outlook5 List of Abbreviations
Fluorine‐containing organic scaffolds are of significant interest in medicinal chemistry. The incorporation of fluorine into biomolecules can lead to remarkable changes in their physical, chemical, and biological properties. There are already many drugs on the market, which contain at least one fluorine atom. Saturated functionalized azaheterocycles as bioactive substances have gained increasing attention in pharmaceutical chemistry. Due to the high biorelevance of organofluorine molecules and the importance of N‐heterocyclic compounds, selective stereocontrolled procedures to the access of new fluorine‐containing saturated N‐heterocycles are considered to be a hot research topic. This account summarizes the synthesis of functionalized and fluorine‐containing saturated azaheterocycles starting from functionalized cycloalkenes and based on oxidative ring cleavage of diol intermediates followed by ring expansion with reductive amination.
An improved, efficient synthesis of some functionalized saturated azaheterocycles has been accomplished by controlled functionalization of various readily available cyclic compounds containing ring C=C bond. The stereocontrolled synthetic concept was based on the oxidative ring cleavage of various unsaturated scaffolds across ozonolysis followed by ring closing with double reductive amination with primary alkylamines or fluorinated alkylamines. The protocol provided versatile azaheterocyclic derivatives with a piperidine or azepane framework.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.