The Versatile and Strategic -Carbamate Directed Metalation Group in the Synthesis of Aromatic Molecules: An Update.

The aryl -carbamate (ArOAm) group is among the strongest of the directed metalation groups (DMGs) in directed metalation (DM) chemistry, especially in the form Ar-OCONEt. Since the last comprehensive review of metalation chemistry involving ArOAms (published more than 30 years ago), the field has expanded significantly. For example, it now encompasses new substrates, solvent systems, and metalating agents, while conditions have been developed enabling metalation of ArOAm to be conducted in a green and sustainable manner.

Directed and Remote Metalation-Suzuki-Miyaura Cross Coupling Route to Azafluorenol Core Liquid Crystals.

Two new smectic C* mesogens containing a hexyloxy side chain and an azafluorenone () or azafluorenol () core were synthesized using a combined directed metalation-directed remote metalation-Suzuki-Miyaura cross-coupling strategy. was formed in 10 steps and 25% overall yield based on starting benzamide . forms a nematic phase, while forms a smectic A phase.

Directed and Metalation of Naphthalene 1,8-Diamide: Complementing SAr Reactivity for the Synthesis of Substituted Naphthalenes.

Mono- and dianion species of 1,8-naphthalene diamide were generated under -BuLi/TMEDA conditions and trapped with a variety of electrophiles to give 2- and 2,7- substituted products and . Using Suzuki-Miyaura cross-coupling, mono- and di-iodinated products were converted into the corresponding 2-aryl () and 2,7-diaryl () products, respectively. The amide-amide rotation barrier of was established by VT NMR, and the structure of fluorenone structure , obtained by metalation, was secured.

Tetraethylphosphorodiamidate-Directed Metalation Group: Directed and Remote Metalation, Cross Coupling, and Remote Phospha Anionic Fries Rearrangement Reactions.

The linked directed and remote metalation (DM and DM) and cross-coupling reactions of aryl phosphorodiamidates (Ar-P(O)(NEt)) is reported. The -iodo and -boronato aryl tetraethylphosphorodiamidates , prepared by DM, undergo orthogonal Ni- and Pd-catalyzed Suzuki-Miyaura cross coupling to furnish biaryls and in good to excellent yields. Silicon group protection of biaryl via DM followed by previously unobserved DM phospha anionic Fries rearrangement affords biaryls which, under acidic conditions, furnish oxaphosphorine oxides .

The Tetraethylphosphorodiamidate (P(O)(NEt)) Directed Metalation Group (DMG). Directed and Lateral Metalation and the Phospha Anionic Fries Rearrangement.

We report on the tetraethylphosphorodiamidate (-OP(O)(NEt)) group as an effective directed metalation group (DMG). Lithiation-electrophile quench of provides a general synthesis of -substituted aryl and naphthyl phosphorodiamidates -. We also describe the phospha anionic -Fries (AF) rearrangement of the phosphorodiamidates , → or and its vinylogous counterpart to the -tolyl phosphorodiamidates  → .

Identification of novel dynamin-related protein 1 (Drp1) GTPase inhibitors: Therapeutic potential of Drpitor1 and Drpitor1a in cancer and cardiac ischemia-reperfusion injury.

Mitochondrial fission is important in physiological processes, including coordination of mitochondrial and nuclear division during mitosis, and pathologic processes, such as the production of reactive oxygen species (ROS) during cardiac ischemia-reperfusion injury (IR). Mitochondrial fission is mainly mediated by dynamin-related protein 1 (Drp1), a large GTPase. The GTPase activity of Drp1 is essential for its fissogenic activity.

Purification and Kinetic Characterization of the Essential Condensation Enzymes Involved in Prodiginine and Tambjamine Biosynthesis.

Prodiginines and tambjamines are related families of bioactive alkaloid natural products with pharmaceutical potential. Both compound families result from a convergent biosynthetic pathway ending in the condensation of a conserved bipyrrole core with a variable partner. This reaction is performed by unique condensation enzymes, and has the potential to be manipulated to produce new pyrrolic compounds.

Sodium Methyl Carbonate as an Effective C1 Synthon. Synthesis of Carboxylic Acids, Benzophenones, and Unsymmetrical Ketones.

Reported is the synthesis of carboxylic acids, symmetrical ketones, and unsymmetrical ketones with selectivity achieved by exploiting the differential reactivity of sodium methyl carbonate with Grignard and organolithium reagents.

Regioselective Functionalization of 7-Azaindole by Controlled Annular Isomerism: The Directed Metalation-Group Dance.

The regioselective functionalization of 7-azaindole by controlled annular isomerism employing a directed metalation-group migration is reported. The N7 carbamoyl azaindoles undergo regioselective metalation and quenching with an electrophile to furnish C6-substituted derivatives which, in the presence of a catalytic amount of ClCONR promotes a carbamoyl group shift or dance from N7 to N1. A second directed metalation/electrophile quench sequence leads to 2,6-substituted azaindoles.

Site-Selective and Stereoselective C-H Functionalization of N-Cyclopropylamides via a Directed Remote Metalation Strategy.

A new methodology for site-selective and stereoselective C-H functionalization of aminocyclopropanes via directed remote lithiation has been developed. Treatment of N-directing group (DG = pivaloyl, tetramethylsuccinimidoyl) arylcyclopropanes with t-BuLi results in a clean β-lithiation and, following quench with electrophiles, leads to a range of cyclopropane derivatives. Sequential double lithiation-methylation to give a dimethylated cyclopropane has been achieved.

Biphenyl sulfonic acid ligands for catalytic C-N cross coupling of aryl halides with anilines and secondary amines.

The use of two biphenyl sulfonic acid ligands for the catalytic C-N cross coupling of aryl halides with anilines, 3-aminopyridine, and secondary amines is reported. Our results represent a significant improvement compared to state of the art methods especially with regards to the removal of palladium.

Bacterial Catabolism of Biphenyls: Synthesis and Evaluation of Analogues.

A series of alkylated 2,3-dihydroxybiphenyls has been prepared on the gram scale by using an effective Directed ortho Metalation-Suzuki-Miyaura cross-coupling strategy. These compounds have been used to investigate the substrate specificity of the meta-cleavage dioxygenase BphC, a key enzyme in the microbial catabolism of biphenyl. Isolation and characterization of the meta-cleavage products will allow further study of related processes, including the catabolism of lignin-derived biphenyls.

Pyrimidine as an Aryl C-H Activating Group.

The Pd-catalyzed regioselective C-H activation/arylation, /iodination, and/acetoxylation reactions of 4-arylpyrimidines using aryl iodides, N-iodosuccinimide, and (diacetoxyiodo)benzene respectively as coupling partners are described. Suzuki-Miyaura coupling and Sonogashira reactions of the resulting aryl iodides are demonstrated. The scalability of the C-H activation/functionalization starting with readily accessible 4-aryl pyrimidines is also reported.

Directed Remote Lateral Metalation: Highly Substituted 2-Naphthols and BINOLs by In Situ Generation of a Directing Group.

A general synthesis of highly substituted 2-naphthols based on a new carbanionic reaction sequence is demonstrated. The reaction exploits the dual nature of lithium bases consisting of consecutive ring opening of readily available coumarins with either LiNEt or LiNiPr into Z-cinnamamides, thus generating a directing group in situ and allowing, by conformational freedom, a lateral directed remote metalation for ring closure to give the aryl 2-naphthols in good to excellent yields. These transformations can be combined to provide a more efficient one-pot process.

Amide-Directed Ru-Catalyzed Hydrodemethoxylation of ortho-Methoxy-Benzamides and -Naphthamides: A D oM Reaction Counterpart.

A new ruthenium-catalyzed hydrodemethoxylation of ortho-methoxy-benzamides and -naphthamides involving amide-directed C-OMe bond activation and hydride reduction is disclosed. The reaction is general, proceeding under RuH(CO)(PPh) catalysis using either triethylsilane (EtSiH) or diisobutylaluminum hydride (DIBAL-H) as the reductant. The corresponding C-N hydrodeamination reaction is also briefly reported.

Directed ortho-Metalation and Anionic ortho-Fries Rearrangement of Polycyclic Aromatic O-Carbamates: Regioselective Synthesis of Substituted Chrysenes.

A general method for the regioselective synthesis of a series of ortho-substituted chrysenyl N, N-diethyl- O-carbamates by the directed ortho-metalation (D oM) strategy is reported. The starting O-carbamates were prepared from the corresponding chrysenols, available by oxidative photochemical cyclization or directed remote metalation tactics. Chrysen-1-yl and chrysene-3-yl ring site selectivity of directed ortho-metalation (D oM) and anionic ortho-Fries rearrangement (A oF) protocols, with s-BuLi/TMEDA, followed by electrophilic quench using a selection of electrophiles, were observed, leading to new chrysenyl derivatives.

Atropisomerism in Tertiary Biaryl 2-Amides: A Study of Ar-CO and Ar-Ar' Rotational Barriers.

A rotational barrier study was performed on eight tertiary biaryl 2-amides using variable-temperature (VT) NMR and exchange (EXSY) spectroscopy experiments. Seven out of the eight 2-amido-2'-methylbiphenyls with additional 3- and 6-substitution patterns (1-7) were found to have approximately similar rotational barriers (ΔG = 56.5-67.

Catabolism of the Last Two Steroid Rings in and Other Bacteria.

Most mycolic acid-containing actinobacteria and some proteobacteria use steroids as growth substrates, but the catabolism of the last two steroid rings has yet to be elucidated. In , this pathway includes virulence determinants and has been proposed to be encoded by the KstR2-regulated genes, which include a predicted coenzyme A (CoA) transferase gene () and an acyl-CoA reductase gene (). In the presence of cholesterol, Δ and Δ mutants of either or strain RHA1 accumulated previously undescribed metabolites: 3aα--4α(carboxyl-CoA)-5-hydroxy-7aβ-methylhexahydro-1-indanone (5-OH HIC-CoA) and ()-2-(2-carboxyethyl)-3-methyl-6-oxocyclohex-1-ene-1-carboxyl-CoA (COCHEA-CoA), respectively.

Ester-directed Ru-catalyzed C-O activation/C-C coupling reaction of ortho-methoxy naphthoates with organoboroneopentylates.

A new, catalytic and general synthetic methodology for the construction of biaryls and heterobiaryls by the cross-coupling of ortho-methoxy naphthoates with organoboroneopentylates is disclosed. The reaction proceeds under RuH2(CO)(PPh3)3-catalyzed conditions driven by unreactive C-O bond activation of a proximate ester directing group (DG)-catalyst chelation. This one-step synthesis of 2-aryl and -heteroaryl-1-naphthoates has the features of operational simplicity, minimum waste and convenient scale-up.

A Protocol for the exo-Mono and exo,exo-Bis Functionalization of the Diazocine Ring of Tröger's Base.

An efficient protocol has been developed for the exo-mono and exo,exo-bis functionalization of Tröger's base in the benzylic 6 and 12 positions of the diazocine ring. The lithiation of Tröger's base using s-BuLi/TMEDA followed by electrophilic quench affords exo-mono- and exo,exo-bis-substituted derivatives of Tröger's base in good to excellent yields. The variation of the number of equivalents of s-BuLi/TMEDA and the order of addition of the electrophile strongly govern the outcome of the reaction for each electrophile.

Adding a Structural Context to the Deprotometalation and Trans-Metal Trapping Chemistry of Phenyl-Substituted Benzotriazole.

Organometallic bases are becoming increasingly complex, because mixing components can lead to bases superior to single-component bases. To better understand this superiority, it is useful to study metalated intermediate structures prior to quenching. This study is on 1-phenyl-1H-benzotriazole, which was previously deprotonated by an in situ ZnCl2 ⋅TMEDA/LiTMP (TMEDA=N,N,N',N'-tetramethylethylenediamine; TMP=2,2,6,6-tetramethylpiperidide) mixture and then iodinated.

Beyond Directed ortho Metalation: Ruthenium-Catalyzed Amide-Directed CAr-OMe Activation/Cross-Coupling Reaction of Naphthamides with Aryl Boronates.

A new and general synthetic methodology for the construction of biaryl, heterobiaryl, and polyaryl molecules by the ruthenium-catalyzed cross-coupling of ortho-methoxy naphthamides with aryl boroneopentylates is described. The isomeric 1-MeO-2-naphthamides and 2-MeO-1-naphthamides furnish an expansive series of arylated naphthamides in excellent yields. Competition experiments showed the higher reactivity of 1-MeO-2-naphthamide over 2-MeO-benzamide.

Directed Metalation-Suzuki-Miyaura Cross-Coupling Strategies: Regioselective Synthesis of Hydroxylated 1-Methyl-phenanthrenes.

A general, efficient, and regioselective synthesis of a series of hydroxylated 1-methylphenanthrenes 9 by a combined directed ortho metalation (DoM)-Suzuki-Miyaura cross-coupling-directed remote metalation (DreM) sequence is reported. Diversity to this methodology was achieved by a regioselective DoM rather than DreM reaction, affording more highly substituted phenanthrols ( Table 2 ). Application of the turbo-Grignard reagent (i-PrMgCl·LiCl) in the Ni-catalyzed Corriu-Kumada reaction gave efficient decarbamoylation ( Tables 3 and 4 ).

Resolution and Determination of the Absolute Configuration of a Twisted Bis-Lactam Analogue of Tröger's Base: A Comparative Spectroscopic and Computational Study.

The first reported twisted bis-lactam, a racemic Tröger's base (TB) analogue (2), was resolved into its enantiomers on a chiral stationary phase HPLC column. The absolute configuration of (+)-2 was determined to be (R,R)-2 by comparing experimental and calculated vibrational circular dichroism (VCD) and electronic circular dichroism (ECD) spectra. The absolute configuration of (-)-2 was determined by comparing experimental and calculated electronic circular dichroism (ECD) spectra.