Oxidative (3 + 2) Cycloaddition Reactions of Diaza-Oxyallyl Cationic Intermediates and Indoles for the Synthesis of Imidazoloindolines

Abstract

An oxidative diaza-(3 + 2) cycloaddition reaction of simple urea derivatives with substituted indoles has been developed. This transformation provides rapid access to highly functionalized imidazoloindolines that are represented in bioactive compounds. The reported method is compatible with a wide variety of functional groups and directly provides unique heterocyclic scaffolds from indoles and a simple urea derivative.

4‐Dimethylaminopyridine‐Mediated [3+3] Cycloaddition of Aza‐oxyallyl Cations and Nitrones

“…Actually, the similar phenomenon was previously reported by the Jeffrey group. Consitent with Wu's report, product 3 s–v were generated through a C–O annulation of aza‐oxyallyl cation. The steric hindrance of the alkyl chain or alkyl ring in nitrones probably prohibit the “N“ attack of the aza‐oxyallyl cation.…”

α-Halogenoacetamides: versatile and efficient tools for the synthesis of complex aza-heterocycles

“…The first examples of [3+2] cycloadditions were given by the teams of Jeffrey, 117,133 136 published the total synthesis of (+/-)-minfiensine 126 from the N-protected indole 125 via an efficient [3+2]-cycloaddition between the trichloro acetamide 1' and the indole derivative 124 (Scheme 45). In their paper the authors demonstrated that the protection of indole was crucial to obtain (+/-)-minfiensine 126.…”

A Phosphorus(III)‐Mediated (4+1)‐Cycloaddition of 1,2‐Dicarbonyls and Aza‐o‐Quinone Methides to Access 2,3‐Dihydroindoles

“…Dipolar cycloadditions, specifically the (3+2) assembly of an azomethine ylide and an electron deficient alkene, constitutes a powerful tool in the construction of pyrrolidine derivatives ( Scheme ,a ). However, the potential complications due to the inherent reactivity and lack of chemoselectivity associated with 1,3‐dipoles, combined with the structural requirements (i.e., electron withdrawing substituents) for both components, led us to consider alternative disconnects . One complementary approach involves the (4+1)‐cycloaddition between a 1,3‐heterodiene and a disubstituted, biphilic C 1 subunit to construct the pyrrolidine core.…”

“…419.0735). one(10). NaH (2.3 mg, 0.06 mmol) was added to a stirring solution of 9b (16.5 mg, 0.05 mmol) in DMF (0.25 mL) at room temperature.…”