Iron-Catalyzed Ortho C–H Homoallylation of Aromatic Ketones with Methylenecyclopropanes

Abstract

We report here a C–H homoallylation reaction of aromatic ketones with methylene­cyclo­propanes (MCPs) only using a catalytic amount of Fe­(PMe3)4. A variety of aromatic ketones and MCPs are applicable to the reaction to form ortho-homoallylated aromatic ketones selectively via regioselective scission of the three-membered rings. The homoallylated products are amenable to further elaborations, providing functionalized 1,2-dihydro­naphthalenes.

An Efficient Route to 3,3′‐Biindolinylidene‐diones by Iron‐Catalyzed Dimerization of Isatins

“…Three-coordinated (Me 3 P) 3 Fe(0) has been proposed as an active catalyst in many carbonyl-assisted functionalization reactions. [19] The intermediate A will be coordinated with one more molecule of isatin, thus generating species B. The iron in complex B would trigger the radical formation leading to di-radical species C followed by concerted CÀ C and OÀ O bond formation through [2 + 2] cycloaddition to intermediate D. The elimination of products 1 and O 2 would complete the catalytic cycle with the regeneration of active catalyst.…”

Transition-metal-catalyzed C–H bond alkylation using olefins: recent advances and mechanistic aspects

“…[1][2][3][4][5][6][7][8][9][10][11] Within the domain, transition metal catalysis forms the largest, ever expanding subset contributing to the broad spectrum of applications that ranges from organic synthesis to petrochemical processing. [12][13][14][15][16][17][18][19][20] In this context, the development of novel methods to access arylation, [21][22][23][24] alkenylation [25][26][27] and alkynylation of C-H bonds 28 has gained tremendous attention. In comparison, alkylative C-H functionalizations have remained fairly scarce in the realm of transition metal catalysis due to the inert nature of the C-H bond, the large kinetic barrier for the C-H bond cleavage and its ubiquitous nature.…”

“…Multiple recent innovations such as Katritzky salts, 13 strained ring systems, 14 alkyl halides, and metal-carbenes 16 as alkylating partners (Scheme 1[B-E]) 15 have allowed access to alkylation of C-H bonds using transition metal catalysts. However, alkylation with widely available and unreactive alkenes as alkylating sources has remained relatively infrequent due to the high probability of polymerization and unwanted side reactions under hydrogen and carbon atoms across acyclic or cyclic alkenes (Markovnikov-vs. anti-Markovnikov-addition or exo-vs. endoaddition) has been a formidable challenge to date.…”

Three-Component Coupling of Arenes, Ethylene, and Alkynes Catalyzed by a Cationic Bis(phosphine) Cobalt Complex: Intercepting Metallacyclopentenes for C–H Functionalization

“…While little is known about the nature of metallacycle-mediated C–H activation, this mechanistic proposal is supported by analogy with organometallic and theoretical investigations on [2+2+2]-cycloadditions using isolated cyclopentadienyl-ligated cobalt­(III) metallacyclopentadiene complexes. , Despite the versatility of the metallacycle-mediated C–H functionalization in being compatible with a range of directing groups, − this mode of C–H activation has only been demonstrated with 1, n -enyne substrates ( n = 6, 7), limiting its application to selected classes of cyclized products . To expand the scope and synthetic utility of this type of transformation, intermolecular coupling of alkene and alkyne components is desirable, resulting in a three-component intermolecular arene-alkene-alkyne coupling reaction to form ortho -homoallylated arene products …”