Selenolactams as Synthetic Intermediates for the Synthesis of Polycyclic Amines via Seleno-Claisen Rearrangements

Abstract

A highly diastereoselective α-allylation of selenolactams with allyl halides is reported. DFT analyses and experimental observations suggested that this reaction proceeds via a Se-allylation of the eneselenolates of the lactams followed by a seleno-Claisen rearrangement. The thus-obtained products could be efficiently transformed into polycyclic amines using a previously developed sequential addition of organometallic reagents and ring-closing metathesis.

Reactions of Allylmagnesium Reagents with Carbonyl Compounds and Compounds with C═N Double Bonds: Their Diastereoselectivities Generally Cannot Be Analyzed Using the Felkin–Anh and Chelation-Control Models

“…Five-membered-ring iminium ions also underwent reactions with allylmagnesium reagents with some diastereoselectivity (Scheme ). The only nucleophile that was used to trap these iminium ions was allylmagnesium bromide. The relative configuration of the product was not given.…”

Application of Claisen Rearrangement and Olefin Metathesis in Organic Synthesis

“…Murai and co‐workers described an efficient strategy involving a base‐mediated seleno‐CR, sequential Grignard addition, followed by a RCM protocol to different tricyclic amines scaffolds. To this end, allyl amine 131 was treated with lithium diisopropylamide (LDA) in THF at 0 °C and then with allyl bromide ( 4 ) to generate rearranged product 132 (56 %).…”

Palladium-Catalyzed Cascade 5-endo-dig Cyclization of Ynamides to Form 4-Alkynyloxazolones

“…Nitrogen- and oxygen-containing heterocycles are undoubtedly among the most studied classes of compounds and, consequently, the most cited in the literature. , The high citation of nitrogen- and oxygen-containing heterocycles in the scientific literature is explained by their wide application in medicine, pharmacology, materials science, natural products, and as substrates for new transformations. , Therefore, several methodologies for synthesizing N -( O )-heterocycles have been developed. − Among them, metal-catalyzed intramolecular and intermolecular cyclization reactions are frequently used because of their efficiency, high selectivity, and tolerance to a wide range of functional groups. − In these reactions, alkenes or alkynes have been used as substrates, in which the transition metal activates the carbon–carbon multiple bonds, and a nitrogen or oxygen nucleophile, located in a suitable position, promotes the nucleophilic attack to carbon–carbon, leading to the cyclization process. , Lately, the environmental issues and costs, both from the academic and industrial areas, have required new advances and challenges for transition-metal-catalyzed and metal-free cyclization reactions. − Thus, the transition metal-catalyzed cascade reactions are a rapidly growing research area of cyclization reactions because of the atom efficiency, saving time, energy, and money, meeting requirements of the modern and environmentally benign and sustainable chemical processes. − This paper deals with our investigation concerning the selective synthesis of 4-alkynyloxazolones 2 from ynamides 1 , − readily available starting materials, through the formation of carbon–oxygen and carbon–carbon bonds in a cascade transformation (Scheme , eq b). The oxazolone is a central core present in many compounds, having valuable properties for biological activity and intermediate for the synthesis of more complex structures. − However, despite the great importance of substituted oxazolones, very few straightforward syntheses of 4-alkynyloxazolones have been studied. − Zhu and co-workers described the synthesis of 4-alkynyloxazolone using the iodocyclization of ynamide combined with the Sonogash...…”