Generation and Reactivity of 2-Amido-1,3-diaminoallyl Cations: Cyclic Guanidine Annulations via Net (3 + 2) and (4 + 3) Cycloadditions

Abstract

Toward a method for direct conversion of alkenes to cyclic guanidines, we report that 1,3-dipolar cycloadditions of 2-amido-1,3-diamino allylic cations with alkenes provide a new method for direct cyclic guanidine annulation. Generated under oxidative conditions, the 2-amido-1,3-diaminoallyl cations react as 1,3-dipoles providing rapid access to 2-amino imidazolines through net (3 + 2) cycloadditions. The utility is demonstrated through a concise synthesis of the oroidin alkaloid, phakellin. The described 1,3-dipole also participates in net (4 + 3) cycloadditions with dienes.

A Review of the Synthetic Strategies toward Dihydropyrrolo[1,2-a]Pyrazinones

“…Fair amounts of cycloadduct 93 were obtained together with a minor amount of open chain compound 94. The reduction of 93 with an excess of SmI 2 then gave the rac-phakellin [106] (Scheme 25). Other approaches involving regio-and stereoselective additions of nitrogen species to analogs of 91 have been mentioned in the framework of dibromophakellstatin total syntheses [58,105,[107][108][109].…”

Synthesis of Five-Membered Cyclic Guanidines via Cascade [3 + 2] Cycloaddition of α-Haloamides with Organo-cyanamides

“…Recently, transition-metal-promoted intramolecular C–N bond formation via hydroamination, carboamination, diamination, and haloamination of N -propargylguanidines or N -allylguanidines have become powerful synthetic strategies to construct cyclic guanidines (Scheme A, eq 1). Besides, cycloguanidination of alkenes has emerged as an efficient route for the synthesis of five-membered cyclic guanidines (Scheme A, eq 2) . However, these approaches always afford cyclic guanidines bearing protecting groups on the N2 position, and it is sometimes quite challenging to remove the protecting groups.…”

N-Iodosuccinimide-Promoted [3 + 2] Annulation Reaction of Aryldiazonium Salts with Guanidines To Construct Aminotetrazoles

“…Therefore, we embarked on the project about the selective preparation of 5-amino-2 H -tetrazoles (Scheme c). Herein, we report our efforts in the reaction of aryldiazonium salts with a type of simple N 3 -synthonguanidines for the synthesis of aminotetrazoles . This NIS-promoted [3 + 2] annulation reaction features readily available starting materials, metal-free mild conditions, operational simplicity, and wide substrate scope.…”