Divergent Reactivity of Nitrocyclopropanes with Huisgen Zwitterions and Facile Syntheses of 3‑Alkoxy Pyrazolines and Pyrazoles

A novel annulation reaction of <i>trans</i>-2-substituted-3-nitrocyclopropane-1,1-carboxylates with in situ generated Huisgen zwitterions is reported, providing facile synthesis of 3-alkoxy pyrazolines in good yields and high diastereoselectivities. This reaction unveils the divergent reactivity of the nitrocyclopropanes as a kind of versatile donor–acceptor cyclopropanes. It is also demonstrated that the prepared 3-alkoxy pyrazolines from di-<i>tert</i>-butyl azodicarboxylate can be readily transformed into the corresponding 3-alkoxy 1<i>H</i>-pyrazoles in moderate yields

Annulation Reaction of 3‑Acylmethylidene Oxindoles with Huisgen Zwitterions and Its Applications in the Syntheses of Pyrrolo[4,3,2-<i>de</i>]quinolinones and Marine Alkaloids Ammosamides

A novel annulation reaction of 3-acylmethylidene oxindoles with Huisgen zwitterions is unveiled that leads to an unprecedented synthetic method for complex pyrrolo­[4,3,2-<i>de</i>]­quinolinones and marine alkaloids ammosamides A–C. This method features simplicity, high efficiency, and broad substrate scope and is accordingly anticipated to significantly facilitate the preparation and bioassay of the relevant pyrroloquinoline alkaloids and their analogues

Divergent Reactivity of Nitrocyclopropanes with Huisgen Zwitterions and Facile Syntheses of 3‑Alkoxy Pyrazolines and Pyrazoles

A novel annulation reaction of <i>trans</i>-2-substituted-3-nitrocyclopropane-1,1-carboxylates with in situ generated Huisgen zwitterions is reported, providing facile synthesis of 3-alkoxy pyrazolines in good yields and high diastereoselectivities. This reaction unveils the divergent reactivity of the nitrocyclopropanes as a kind of versatile donor–acceptor cyclopropanes. It is also demonstrated that the prepared 3-alkoxy pyrazolines from di-<i>tert</i>-butyl azodicarboxylate can be readily transformed into the corresponding 3-alkoxy 1<i>H</i>-pyrazoles in moderate yields

Diastereoselective Synthesis of Functionalized Spirocyclopropyl Oxindoles via P(NMe₂)₃‑Mediated Reductive Cyclopropanation

A P­(NMe₂)₃-mediated reductive cyclopropanation reaction of α-keto esters or amides with isatin-derived alkenes has been developed, providing efficient and diastereoselective synthesis of highly functionalized spirocyclopropyl oxindoles bearing two all-carbon quaternary centers. This reaction also represents a complementary and nonmetal-involving protocol for the challenging cyclopropanation of electron-deficient alkenes