Abstract:The acid-catalysed thermal rearrangements of a family of N-aryl 2-azabicyclo[3.1.0]hexanes is described. These substrates, designed in such a way that the aromatic system is conjugated with an alkene group located at the ortho position relative to the nitrogen atom, have been prepared by using an intramolecular Kulinkovich-de Meijere reaction. The rearrangements can then be conducted either under standard thermal conditions or with microwave activation. Depending on the conditions applied and the substitution … Show more
“…The use of paratoluenesulfonic acid (pTSA) reduced the reaction times by increasing the rate of the protonation of the substrate 5a 15 but also appeared to slightly favour the production of the by-products 14 and 16 (entry 2 vs entry 1, entry 4 vs entry 3, entry 6 vs entry 5 and entry 8 vs entry 9). With this respect, heating the reaction mixtures in a microwave reactor proved very interesting: 15 the reactions were complete after 5 to 10 minutes only, with a better selectivity in favour of the simple cycloaddition adducts (entry 7 vs entries 3 and 4; entry 9 vs entry 8).…”
Two types of bicyclic N-cyclopropyl glycine ester derivatives have been prepared and put under scrutiny as possible precursors of azomethine ylides. The results demonstrate that they can indeed participate in 1,3-dipolar cycloaddition reactions with dipolarophiles, as illustrated in the cases of phenyl vinyl sulfone, N-phenylmaleimide, diethyl fumarate and diethyl maleate. The relative configurations of the major diastereoisomers produced are consistent with the predicted generation of azomethine ylide species, reacting in concerted cycloaddition processes. This unprecedented way of generating such 1,3-dipoles provides access to functionalised pyrrolizidines and pyrrolidines, that would be difficult to make directly by more classic methods. It was also found that using phenyl vinyl sulfone or N-phenylmaleimide as the dipolarophile reactant, a domino nucleophilic conjugate addition / 1,3-dipolar cycloaddition process may operate competitively.
“…The use of paratoluenesulfonic acid (pTSA) reduced the reaction times by increasing the rate of the protonation of the substrate 5a 15 but also appeared to slightly favour the production of the by-products 14 and 16 (entry 2 vs entry 1, entry 4 vs entry 3, entry 6 vs entry 5 and entry 8 vs entry 9). With this respect, heating the reaction mixtures in a microwave reactor proved very interesting: 15 the reactions were complete after 5 to 10 minutes only, with a better selectivity in favour of the simple cycloaddition adducts (entry 7 vs entries 3 and 4; entry 9 vs entry 8).…”
Two types of bicyclic N-cyclopropyl glycine ester derivatives have been prepared and put under scrutiny as possible precursors of azomethine ylides. The results demonstrate that they can indeed participate in 1,3-dipolar cycloaddition reactions with dipolarophiles, as illustrated in the cases of phenyl vinyl sulfone, N-phenylmaleimide, diethyl fumarate and diethyl maleate. The relative configurations of the major diastereoisomers produced are consistent with the predicted generation of azomethine ylide species, reacting in concerted cycloaddition processes. This unprecedented way of generating such 1,3-dipoles provides access to functionalised pyrrolizidines and pyrrolidines, that would be difficult to make directly by more classic methods. It was also found that using phenyl vinyl sulfone or N-phenylmaleimide as the dipolarophile reactant, a domino nucleophilic conjugate addition / 1,3-dipolar cycloaddition process may operate competitively.
ortho-C–H bond halogenation of anilides and N-aryl carbamates using easily available N-halosuccinimides (NXS) as the active halogenation reagent in the presence of nickel or silver catalyst has been developed. This method provides a new approach to 2-haloanilides and carbamates, which may serve as starting materials for the synthesis of pharmaceutically and biologically active compounds.
“…In the past few years, several synthetic methods have been explored on the construction of the tetrahydropyrrolo-[1,2- a ]quinoline scaffold 4 – 6 . In particular, Liu et al .…”
Section: Introductionmentioning
confidence: 99%
“…However, the tedious procedure to prepare starting materials also restricts its widespread application (Fig. 2c ) 6 . Figure 2 Synthesis of tetrahydropyrrolo[1,2- a ] quinolines.…”
A synthetic method for diversely substituted tetrahydropyrrolo[1,2-a]quinolines was developed via CuCl-catalyzed cascade transformation of internal aminoalkynes with alkynes under microwave- irradiation.
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