A facile synthesis of 3-allyl-4-hydrazinocyclopentenes by the palladium/Lewis acid mediated ring opening of bicyclic hydrazines with allyltributyltin and allyltrimethylsilane

Palladium Catalyzed Ring-Opening of Diazabicylic Olefins with 4-Halo-1,3-Dicarbonyl Compounds: Accessing 3(2H)-Furanone-Appended Cyclopentenes

We have realized a Pd-catalyzed ring-opening of diazabicyclic olefins with 4-halo-1,3-dicarbonyl compounds. This reaction resulted in the formation of 3(2H)-furanone-appended hydrazino cyclopentenes. The reaction proceeds via the formation of a π-allylpalladium intermediate which is attacked by the active methylene species, and an intramolecular nucleophilic substitution in the 4-halo-1,3-dicarbonyl moiety furnishes the 3(2H)-furanone-substituted cyclopentene. We could extend this methodology to cyclopropane-appended spirotricyclic olefin for synthesizing 3(2H)-furanone-substituted spiro[2.4]hept-5-ene.

Trapping the Lewis acid generated transient species from pentafulvene derived diazanorbornenes with ortho-functionalized aryl iodides and aliphatic alcohols

Herein we describe our efforts on the Lewis acid catalyzed stereoselective ring-opening of pentafulvene derived diazabicyclic olefins using various ortho-functionalized aryl iodides such as 2-iodoanilines, 2-iodophenols and 2-iodobenzene thiols to access trans-1,2 disubstituted alkylidenecyclopentenes. The scope of the reaction was also explored with a range of easily available aromatic and aliphatic alcohols. Furthermore, the palladium catalyzed intramolecular Heck cyclization of trans-1,2 disubstituted alkylidenecyclopentenes would provide an easy approach for the synthesis of highly functionalized spiropentacyclic frameworks consisting of a cyclopentene fused to an indoline/benzothiophene and pyrazolidine.

Pd-NHC catalyzed cyclopentannulation of diazabicyclic alkenes with ortho-aryl halides

Pd-NHC catalyzed cyclopentannulation of diazabicyclic alkenes with ortho- functionalized aryl halides is described. In all the reactions, a single diastereomer of the cyclopentannulated product is observed, and this reaction is very efficient under microwave irradiation.

Palladium catalyzed tandem ring opening-ring closing reaction of diazabicyclic alkenes: a facile one pot strategy for cyclopentannulation of heterocycles

A novel palladium catalyzed protocol for the synthesis of cyclopentene fused heterocycles from diazabicyclic alkenes and ortho-functionalized aryliodides has been elaborated. The reaction can be tuned toward the formation of either 3,4-disubstituted cyclopentenes or cyclopentene fused heterocycles by careful manipulation of the reaction parameters. A number of cyclopentene fused benzofurans and indole derivatives were prepared in excellent yield by utilizing the developed methodology.

Iodine assisted modified Suzuki type reaction of bicyclic hydrazines: stereoselective synthesis of functionalized cyclopentenes

Bicyclic hydrazines undergo a facile palladium/iodine mediated stereoselective ring opening on reaction with organoboronic acids affording trans-3,4-disubstituted hydrazino cyclopentenes in good to excellent yield.