Palladium-Catalyzed Ortho-Arylation of Carbamate-Protected Estrogens

Abstract

The palladium-catalyzed ortho-arylation of diethyl carbamate-protected estrone and estriol with aryl iodides gives the 2-arylated analogues. Subsequent removal of the carbamate directing group furnishes 2-arylated estrone, estradiol, or estriol depending on the method used.

Modular bismacycles for the selective C–H arylation of phenols and naphthols

“…The most widely used strategies involve metalcatalyzed arylation of a hydroxyarene-derived substrate via either cross-coupling 12 or C-H functionalization. 13,14,15,16,17,18,19,20 However, although extremely powerful, the atom and step economy of these approaches is impacted by the need to prefunctionalize the substrate. For example, cross-coupling typically requires challenging ortho-selective halogenation or borylation of the hydroxyarene, 13 whereas C-H functionalization demands installation and subsequent removal of Lewis-basic directing groups.…”

“…The preference of Bi(V) for arylation of estrone at the 4-position is apparently unique in the literature, and provides a direct complement to metal-catalyzed directed C-H arylations which favor functionalization of the 2-position. 17,71,72,73,74 Both 2-and 4-arylated estrones exhibit biological activity, 75 so the ability to access both regioisomers in a single operation is of potential utility in discovery projects.…”

Transition metal-catalysed A-ring C–H activations and C(sp2)–C(sp2) couplings in the 13α-oestrone series and in vitro evaluation of antiproliferative properties

“…was used with Pd(OAc) 2 (10 mol%) catalyst in TFA solvent. In earlier studies, this methodology proved to be suitable for ortho-arylation of anilides and Ocarbamoylphenols 5,10,36 . The reaction of compound 13 with iodobenzene was performed under both conventional heating and in a microwave reactor at different temperatures.…”

“…An alternative methodology, based on C-H activation, might circumvent the inconveniences of cross-coupling reactions, such as halogenation of the substrates and the use of organometallic nucleophilic coupling partners. Regioselective C-H bond arylation of 3-carbamoylestrone with aryl iodides was described by Bedford et al 36 In this transformation, Pd(OAc) 2 was used as a catalyst, AgOAc as a base in TFA solvent, and the mixture was stirred at 60 C for 18 h. Arylation occurred at the C-2 ortho-position owing to the directing ability of the carbamate group. The removal of the DG was achieved in a subsequent step, by treatment with LiAlH 4 followed by acidic hydrolysis.…”

Oxidative Heck Reaction as a Tool for Para-selective Olefination of Aniline: A DFT Supported Mechanism

“…Furthermore, using a halide promoter results in the formation of halide salts as a byproduct . In order to overcome this disadvantage, an atom-economic strategy is in high demand, and this is possible via direct olefination of C­(sp 2 )–H. − Therefore, C–H activation is a suitable candidate to control the regioselectivity. , Hydroarylation of alkynes via transition metal catalysis is another way to introduce an olefin into arenes. , Recently, using different directing groups such as carbamate, , pyrimidine, pyridine, , and carbonyl , has attracted much attention to put a functional group in a special region. By this strategy, one C–H bond in a molecule can be preferentially activated over other present C–H bonds by forming cyclometalates.…”