Catalytic arylation of carbon-carbon double bond followed by N- or O-cyclization

Abstract

Under the catalytic action of palladium, o-hydroxy-or o-amino-substituted aryl iodides oxidatively add to palladium(0), insert strained or rigid olefins, and close the ring between the atiphatic carbon and the ortho-functional group. This reaction occurs under mild conditions in the absence of phosphine ligands in a DMF solution and affords fused dihydrofurans or -pyrroles.Key words: palladium complexes, catalysis; formation of C--C, C--O, and C--N bonds, cyclization.It is well known that alkylation or arylation of rigid olefins with organic halides RX (X = Br, I) and palladium(0) complexes leads to norbornylpalladium species containing cis-oriented alkyl (or aryl) and PdX groups.t For steric reasons, these complexes do not undergo reductive elimination of the hydrogen atom from the generally favored anti-position z (Scheme I, the ligands are omitted for simplicity). Some years ago we showed that tile substituted norbornyl group attached to palladium can be trapped in several ways, for example, by hydride transfer. 3 Later, we studied the behavior of the arylnorbomylpalladium complexes obtained from aryl halides, norbornene, and palladium(0). These complexes gave palladacycles, which are converted into hexahydromethanobiphenytenes upon reductive elimination. A catalytic cycle, which is showta in Scheme 2 for iodobenzene and norbomene, 4 was also worked out.We further observed that the palladium-bonded arylalkyl intermediates can be trapped by carbon monoxide and nucleophiles. 5 Using o-iodophenol we were

Palladium-catalyzed heteroannulation of cyclic alkenes by functionally substituted aryl iodides

“…Like Catellani and Del Rio [14], our initial results on the heteroannulation of norbornene and bicyclo [2.2.2]octene by o-iodophenol and o-iodoacetanilide were quite promising (Eq. (2)).…”

“…The base Na 2 CO 3 provided excellent results and, unlike much of our earlier annulation chemistry and CatellaniÕs procedure [14], we only needed to use catalytic amounts of n-Bu 4 NCl to get high yields.…”

“…Perhaps DMG is performing the same function here. This ''optimal'' amide procedure for sulfonamide-containing aryl iodides produces good to excellent yields with the alkenes indene, acenaphthalene and 1,2-dihydronaphthalene (entries [11][12][13][14]. Table 1 Palladium (0) The mechanism proposed for these reactions (Scheme 1) involves: (1) oxidative addition of the carbon-iodide bond of the o-substituted aryl iodide to the palladium catalyst, (2) syn-arylpalladation of the olefin carboncarbon double bond, (3) possible coordination of the internal oxygen or nitrogen nucleophile to the palladium, (4) loss of hydrogen iodide with formation of a six-membered ring palladacycle, and (5) reductive elimination of the palladium intermediate to produce the heteroannulation product and regenerate the Pd(0) catalyst.…”

Cross‐Coupling of Organyl Halides with Alkenes – The Heck Reaction

“…o-Iodoamino-and o-iodohydroxyarenes such as 172-XH also react with various alkynes [347], alkenes [348], and enol triflates with or without incorporation of carbon monoxide to yield versatile heterocyclic compounds (Scheme 8.41).…”

Highly Regioselective Indoline Synthesis under Nickel/Photoredox Dual Catalysis

“…17 C–N bond formation also presumably proceeds via external nucleophilic attack on a π-allyl intermediate. Other intermolecular annulation approaches involve the use of alkenes without available β-H atoms, first reported by Catellani and coworker, 18 or forego use of alkenes altogether. 19 Perhaps the most general approach thus far was disclosed by Glorius and coworkers earlier this year.…”