Intramolecular reaction

About: Intramolecular reaction is a research topic. Over the lifetime, 5015 publications have been published within this topic receiving 138213 citations.

Synthesis of spiro[4.5]trienones by intramolecular ipso-halocyclization of 4-(p-methoxyaryl)-1-alkynes.

Abstract: A wide variety of 3-halospiro[4.5]trienones are readily prepared in good to excellent yields by the intramolecular ipso-halocyclization of 4-(p-methoxyaryl)-1-alkynes under mild reaction conditions. ICl, I2, and Br2 are all effective electrophiles for this process under carefully optimized reaction conditions.

Synthesis of aryl ketones or ketimines by palladium-catalyzed arene C-H addition to nitriles.

Abstract: The unprecedented palladium-catalyzed C−H addition of arenes to nitriles provides moderate to excellent yields of aryl ketones or the corresponding hindered imines. The addition of a small amount of DMSO increases the yields dramatically. Both intermolecular and intramolecular reactions are successful, although the intramolecular reactions tend to be more sluggish. This novel chemistry is believed to involve palladium-catalyzed C−H activation of the arene by electrophilic aromatic substitution, followed by the unusual carbopalladation of a nitrile. Similar reactions have been successfully developed employing arylboronic acids and nitriles. A concise route to xanthones starting from cheap starting materials has been developed employing this synthetic protocol.

Catalytic asymmetric synthesis of quaternary carbons bearing two aryl substituents. Enantioselective synthesis of 3-alkyl-3-aryl oxindoles by catalytic asymmetric intramolecular heck reactions.

Abstract: A practical sequence involving three consecutive palladium(0)-catalyzed reactions has been developed for synthesizing 3-alkyl-3-aryloxindoles in high enantiopurity. The Heck cyclization precursors 10 and 11a-k are generated in one step by chemoselective Stille cross-coupling of 2'-triflato-(Z)-2-stannyl-2-butenanilide 9 with aryl or heteroaryl iodides. The pivotal catalytic asymmetric Heck cyclization step of this sequence takes place in high yield and with high enantioselectivity (71-98% ee) with the Pd-BINAP catalyst derived from Pd(OAc)(2) to construct oxindoles containing a diaryl-substituted all-carbon quaternary carbon center. A wide variety of aryl and heteroaryl substituents, including ones of considerable steric bulk, can be introduced at C3 of oxindoles in this way (Table 4). The only limitations encountered to date are aryl substituents containing ortho nitro or basic amine functionalities and the bulky N-alkyl-7-oxindolyl group. Asymmetric Heck cyclization of butenalide 22 having an o-(N-acetyl-N-benzylamino)phenyl substituent at C2 provided a approximately 1:1 mixture of amide atropisomers 23 and 24 in high yield and high enantioselectivity. These atropisomers are formed directly upon Heck cyclization of 22 at 80 degrees C, as they interconvert thermally to only a small extent at this temperature.

AuBr3- and Cu(OTf)2-catalyzed intramolecular [4 + 2] cycloaddition of tethered alkynyl and alkenyl enynones and enynals: a new synthetic method for functionalized polycyclic hydrocarbons.

Abstract: Treatment of tethered alkynyl enynones 8, in which a carbon chain is attached to the carbonyl group, with a catalytic amount of AuBr3 in (ClCH2)2 gave the naphthyl ketones 9 in good to high yields (top-down approach). Analogously, the AuBr3-catalyzed benzannulations of 10, in which a carbon tether is extended from the alkynyl terminus, also proceeded smoothly, and the cyclized naphthyl ketones 11 were obtained in high yields (bottom-up approach). Similarly, when two kinds of tethered alkenyl enynones 12 and 14 were treated with Cu(OTf)2 catalyst, the corresponding dihydronaphthyl ketone products 13 and 15 were obtained in high yields, respectively. The present formal [4 + 2] intramolecular cycloaddition proceeds most probably through the coordination of the triple bond at the ortho position of substrates to Lewis acids, the formation of benzopyrylium ate complex 16 via the nucleophilic addition of the carbonyl oxygen atom, the reverse electron demand type Diels−Alder addition of the tethered alkynes or al...

Acyl radicals: intermolecular and intramolecular alkene addition reactions

Abstract: A full study of the use of phenyl selenoesters as precursors to acyl radicals and their subsequent participation in intermolecular and intramolecular alkene addition reactions is detailed. Primary alkyl-, vinyl-, and aryl- substituted acyl radicals generated by Bu 3 SnH treatment of the corresponding phenyl selenoesters participate cleanly un intermolecular addition reactions with alkenes bearing electron-withdrawing or radical-stabilizing substituents at rates that exceed those of the potentially competitive decarbonylation or reduction