Palladium catalyzed reaction of ortho-functionalized aryl iodides with bicyclic hydrazines: facile route toward heteroannulated cyclopentenes and azabicycles

Diazanorbornene: A Valuable Synthon towards Carbocycles and Heterocycles

“…We then extended the reaction to fulvene derived diazabicyclic olefins to yield novel dihydrobenzofuran annulated bicyclic compounds. [38] The annulation reaction was tested with diazabicyclic olefins derived from different pentafulvenes and substituted 2-iodophenols. All reactions proceeded efficiently and delivered the polycyclic heterocycles in moderate to good yields (Scheme 41).…”

“…Finally, a reductive elimination takes place in 109 to furnish the heteroannulated product 106 (Scheme 42). [38]…”

Pentannulation of Heterocycles by Virtue of Precious Metal Catalysis

“…Ap alladium-catalyzed ring opening-ring closing reactiono f diazabicyclic alkenes for the synthesis of cyclopenta-fused heterocycles, was independently described by groups of Radhakrishnan [21] and Gilbertson. [22] Under slightly different conditions, both groups prepared cyclopentene-fused dihydroindole 14 and dihydrobenzofuran 17 in good yields and as single diastereoisomers.…”

“…Scheme7.Pd-catalyzed reaction of azabicyclicolefines and 2-iodoanilines. Reagents and conditions:a)5%P d(OAc) 2 ,LiCl,K 2 CO 3 ,t oluene,1 00 8C, 36 h; [21] b) 5% Pd-NHC 15,DIPEA, DMF,1 30 8C, MW,30min. [22] termediate, formed in the oxidative addition of the Pd 0 to the indoleÀIb ond, underwent an olefin insertion reaction with the proximal allene double bond generatinga na lkylpalladiumi ntermediate 23 which,a fter a b-hydride elimination, gave the product.…”

“…Ah ighly efficient Pd-catalyzedb icyclization of allene-propargylic carbonates 35 and 37 with geminal bis(nucleophile)s was Scheme8.Proposed mechanism for the Pd-catalyzed reaction of azabicyclic olefinsand 2-iodophenoles. Reagents and conditions: a) [Pd(allyl)Cl] 2 , Bu 4 NCl, K 2 CO 3 ,[bmim][PF 6 ], 80 8C, 8h; [21] b) Pd-NHC 15,K 2 CO 3 ,M W, DMF, 120 8C, 30 min. [22] Scheme9.Synthesis of 22 throughcarbocyclization reaction of iodoallenols.…”