A Continuous Flow Process for LSN647712 via Double Organometallic Additions to Dimethylcarbamyl Chloride.

The ketone intermediate LSN647712 is a key synthetic intermediate for the drug substance lasmiditan manufacturing process. A three-step connected continuous flow process utilizing a Turbo Grignard reagent, N-methylpiperidin-4-ylmagnesium chloride, and lithiated 2,6-dibromopyridine sequentially added to double electrophile (O═C(++) synthon dimethylcarbamyl chloride (DMCC) was developed to deliver the ketone intermediate in a high chemical yield (>85%). This highly productive (>100 g/h lab system) and intensified process (τ ∼ 3 min) yields the product in high purity upon batch reactive crystallization to form a corresponding hydrobromide salt. In addition to the connected plug flow reactor system, the Grignard reagent, N-methylpiperidin-4-ylmagnesium chloride, was also prepared continuously in CSTR as a more soluble LiCl adduct in THF (Turbo Grignard).

Development of a Commercial Process To Prepare AMG 232 Using a Green Ozonolysis-Pinnick Tandem Transformation.

A robust process to manufacture AMG 232 was developed to deliver drug substance of high purity. Highlights of the commercial process development efforts include the following: (i) use of a novel bench-stable Vilsmeier reagent, methoxymethylene- N, N-dimethyliminium methyl sulfate, for selective in situ activation of a primary alcohol intermediate; (ii) use of a new crystalline and stable isopropyl calcium sulfinate reagent ensuring robust preparation of a sulfone intermediate; (iii) development of a safe ozonolysis process conducted in an aqueous solvent mixture in either batch or continuous manufacturing mode; and (iv) control of the drug substance purity by crystallization of a salt rejecting impurities effectively. The new process was demonstrated to afford the drug substance (99.9 LC area %) in 49.8% overall yield from starting material DLAC (1).

Ni-Catalyzed Electrochemical Decarboxylative C-C Couplings in Batch and Continuous Flow.

An electrochemically driven, nickel-catalyzed reductive coupling of N-hydroxyphthalimide esters with aryl halides is reported. The reaction proceeds under mild conditions in a divided electrochemical cell and employs a tertiary amine as the reductant. This decarboxylative C(sp3)-C(sp2) bond-forming transformation exhibits excellent substrate generality and functional group compatibility. An operationally simple continuous-flow version of this transformation using a commercial electrochemical flow reactor represents a robust and scalable synthesis of value added coupling process.

Flow Asymmetric Propargylation: Development of Continuous Processes for the Preparation of a Chiral ß-Amino Alcohol.

The development of a flow chemistry process for asymmetric propargylation using allene gas as a reagent is reported. The connected continuous process of allene dissolution, lithiation, Li-Zn transmetallation, and asymmetric propargylation provides homopropargyl ß-amino alcohol 1 with high regio- and diastereoselectivity in high yield. This flow process enables practical use of an unstable allenyllithium intermediate. The process uses the commercially available and recyclable (1S,2R)-N-pyrrolidinyl norephedrine as a ligand to promote the highly diastereoselective (32:1) propargylation. Judicious selection of mixers based on the chemistry requirement and real-time monitoring of the process using process analytical technology (PAT) enabled stable and scalable flow chemistry runs.

Highly enantioselective, intermolecular hydroamination of allenyl esters catalyzed by bifunctional phosphinothioureas.

Bifunctional phosphinothiourea catalysts have been developed successfully for the highly regio- and enantioselective γ-hydroamination of allenyl and propargyl esters with N-methoxy carbamate nucleophiles to yield α,ß-unsaturated γ-amino acid ester products. In the case of propargyl ester substrates, the reaction proceeds through reversible phosphinothiourea-catalyzed isomerization to the corresponding allenyl ester. The high enantioselectivity of the process is attributed to a cooperative conjugate addition of a thiourea-bound carbamate anion to a vinyl phosphonium ion resulting from covalent activation of the allenyl ester substrate.

Magnesium coordination-directed n-selective stereospecific alkylation of 2-pyridones, carbamates, and amides using α-halocarboxylic acids.

A general inversion-stereospecific, N-selective alkylation of substituted 2-pyridones (and analogues), amides, and carbamates using chiral α-chloro- or bromocarboxylic acids in the presence of KOt-Bu (or KHMDS) and Mg(Ot-Bu)(2) is reported. The resulting α-chiral carboxylic acid products were isolated by crystallization in good chemical yields and in high ee (>90% ee). Mechanistic evidence suggests that the reaction proceeds through 2-pyridone O-coordinated Mg carboxylate intermediates, which afford the product through an intramolecular S(N)2 alkylation.

Cooperative, highly enantioselective phosphinothiourea catalysis of imine-allene [3 + 2] cycloadditions.

A new family of phosphinthiourea catalysts was developed for the highly enantioselective synthesis of 2-aryl-2,5-hydropyrroles via a [3 + 2] cycloaddition of an electron-deficient allene with aryl and heteroaryl diphenylphosphinoylimines. The presence of both H2O and Et3N as additives was found to be important for achieving optimal rates. Dual activation of both nucleophile and electrophile by the bifunctional catalyst is invoked to account for the observed high reactivity and enantioselectivity.

A highly selective tandem cross-coupling of gem-dihaloolefins for a modular, efficient synthesis of highly functionalized indoles.

A highly efficient method of indole synthesis using gem-dihalovinylaniline substrates and an organoboron reagent was developed via a Pd-catalyzed tandem intramolecular amination and an intermolecular Suzuki coupling. Aryl, alkenyl, and alkyl boron reagents are all successfully employed, making for a versatile modular approach. The reaction tolerates a variety of substitution patterns on the aniline leading to indoles with group at C2-C7. The orthogonal approach of the sequential copper- and palladium-mediated synthesis of 1,2-diarylindoles exploited the wide availability of diverse organoboron reagents.

A general and practical method of alkynyl indole and benzofuran synthesis via tandem Cu- and Pd-catalyzed cross-couplings.

A new tandem coupling approach to synthesize 2-alkynyl indoles and benzofurans is described. This reaction utilizes easily accessible gem-dibromovinyl substrates and terminal alkynes and proceeds via Pd/C- and CuI-catalyzed tandem Ullman/Sonogashira couplings.

A general modular method of azaindole and thienopyrrole synthesis via Pd-catalyzed tandem couplings of gem-dichloroolefins.

A palladium-catalyzed reaction of gem-dichloroolefins and a boronic acid via a tandem intramolecular C-N and intermolecular Suzuki coupling process gave corresponding substituted azaindoles or thienopyrroles. This method is a very modular protocol to synthesize all four isomers of azaindole and two isomers of thienopyrroles in good to excellent yield.

Ruthenium(II) complexes with improved photophysical properties based on planar 4'-(2-pyrimidinyl)-2,2':6',2' '-terpyridine ligands.

A series of new tridentate polypyridine ligands, made of terpyridine chelating subunits connected to various substituted 2-pyrimidinyl groups, and their homoleptic and heteroleptic Ru(II) complexes have been prepared and characterized. The new metal complexes have general formulas [(R-pm-tpy)Ru(tpy)]2+ and [Ru(tpy-pm-R)2]2+ (tpy = 2,2':6',2' '-terpyridine; R-pm-tpy = 4'-(2-pyrimidinyl)-2,2':6',2' '-terpyridine with R = H, methyl, phenyl, perfluorophenyl, chloride, and cyanide). Two of the new metal complexes have also been characterized by X-ray analysis. In all the R-pm-tpy ligands, the pyrimidinyl and terpyridyl groups are coplanar, allowing an extended delocalization of acceptor orbital of the metal-to-ligand charge-transfer (MLCT) excited state. The absorption spectra, redox behavior, and luminescence properties of the new Ru(II) complexes have been investigated. In particular, the photophysical properties of these species are significantly better compared to those of [Ru(tpy)2]2+ and well comparable with those of the best emitters of Ru(II) polypyridine family containing tridentate ligands. Reasons for the improved photophysical properties lie at the same time in an enhanced MLCT-MC (MC = metal centered) energy gap and in a reduced difference between the minima of the excited and ground states potential energy surfaces. The enhanced MLCT-MC energy gap leads to diminished efficiency of the thermally activated pathway for the radiationless process, whereas the similarity in ground and excited-state geometries causes reduced Franck Condon factors for the direct radiationless decay from the MLCT state to the ground state of the new complexes in comparison with [Ru(tpy)2]2+ and similar species.

Efficient syntheses of KDR kinase inhibitors using a Pd-catalyzed tandem C-N/Suzuki coupling as the key step.

A family of four potent KDR kinase inhibitors containing an indol-2-yl quinolin-2-one structure was utilizing a Pd-catalyzed tandem C-N and C-C coupling sequence.

Synthesis of 2-vinylic indoles and derivatives via a Pd-catalyzed tandem coupling reaction.

A novel one-step synthesis of valuable 2-vinylic indoles and their tricycle derivatives is described. This reaction, which utilizes a gem-dibromovinyl unit as a readily available starting material, occurs via an efficient Pd-catalyzed tandem Buchwald-Hartwig/Heck reaction.

The multichromophore approach: prolonged room-temperature luminescence lifetimes in Ru(II) complexes based on tridentate polypyridine ligands.

A new family of ruthenium(II) complexes with multichromophoric properties was prepared based on a "chemistry-on-the-complex" synthetic approach. The new compounds are based on tridentate chelating sites (tpy-type ligands, tpy=2,2':6',2''-terpyridine) and most of them carry appended anthryl chromophores. Complexes 2 a and 2 b were synthesized through the Pd-catalyzed Suzuki coupling reaction between 9-anthrylboronic acid and the chloro ligands on the presursor species 1 a and 1 b, respectively. The monocoupling product 2 c was also synthesized as the starting complex for a dimetallic complex under optimized Suzuki coupling conditions. The palladium(0)-catalyzed homocoupling reaction on complexes 1 a and 2 c led to dimetallic Ru(II) species 2 d and 2 e, respectively. The solid structures of complexes 2 a and 2 b were characterized by X-ray diffraction. The absorption spectra, redox behavior, luminescence properties (both at room temperature and at 77 K), and transient absorption spectra and decays of 2 a-e were investigated. The absorption spectra of all new species are dominated by ligand-centered (LC) bands in the UV region and metal-to-ligand charge-transfer (MLCT) bands in the visible region. The new compounds undergo reversible metal-centered oxidation processes and several ligand-centered reduction processes, which have been assigned to specific sites. The complexes exhibit luminescence both at room temperature in fluid solution and at 77 K in rigid matrices; the emission was attributed to (3)MLCT states at room temperature and to the lowest-lying anthracene triplet ((3)An) at low temperature, except for 2 c, which does not contain any anthryl chromophore and whose low temperature emission is also of MLCT origin. The luminescence lifetimes of complexes 2 a-d showed that multichromophoric behavior occurs in these species, allowing the luminescence lifetime of the Ru(II)-based chromophores to be prolonged to the microsecond timescale, with the anthryl groups behaving as energy-storage elements for the repopulation of the (3)MLCT state. Nanosecond transient-absorption spectroscopy confirmed the equilibration process between the triplet MLCT and An levels at room temperature. Thermodynamic and kinetic factors governing the equilibration time and the lifetime of the equilibrated excited state are discussed.

CuI-Catalyzed tandem intramolecular amidation using gem-dibromovinyl systems.

[reaction: see text] Imidazoindolones are present as the key structural motif in the family of antifungals, fumiquinazolines, and the antagonist asperlicin. The first example of a CuI-catalyzed tandem intramolecular amidation forming substituted imidazoindolones from readily accessible ortho gem-dibromovinylanilines is described.

Pd-catalyzed tandem C-N/C-C coupling of gem-dihalovinyl systems: a modular synthesis of 2-substituted indoles.

2-substituted indoles were synthesized via a Pd-catalyzed tandem C-N/Suzuki-Miyaura coupling from readily prepared ortho-gem-dihalovinylanilines. Optimal conditions used a Pd(OAc)(2)/S-Phos catalyst in the presence of K(3)PO(4).H(2)O and an organoboron reagent, which included boronic acids, esters, alkyl 9-BBN derivatives, and trialkylboranes. Yields of the desired indoles were good to excellent using low catalyst loadings (typically 1 mol %). [reaction: see text]

Synthesis and properties of the elusive ruthenium(II) complexes of 4'-cyano-2,2':6',2' '-terpyridine.

The heteroleptic and homoleptic ruthenium(II) complexes of 4'-cyano-2,2':6',2' '-terpyridine are synthesized by palladium catalyzed cyanation of the corresponding Ru(II) complexes of 4'-chloro-2,2':6',2' '-terpyridine. The introduction of the strongly electron-withdrawing cyano group into the Ru(tpy)(2)(2+) moiety dramatically changes its photophysical and redox properties as well as prolongs its room temperature excited-state lifetime.

Synthesis of novel tetracycles via an intramolecular Heck reaction with anti-hydride elimination.

[reaction: see text] The catalytic combination of Pd(2)(dba)(3)/HP(t-Bu)(3).BF(4) and DABCO gives an unusual intramolecular Heck reaction with dihydronaphthalene substrates, yielding formal anti-hydride elimination products in good to excellent yields under mild conditions. For dibromo substrates, multiple Heck reactions are possible when an external acceptor is added to afford more highly functionalized products.

Creating new binding sites in ligands and metal complexes using the Negishi cross-coupling reaction.

The Negishi cross-coupling reaction creates a new binding site in a ruthenium complex with high efficiency as exemplified by the synthesis of a heterodimetallic ruthenium-osmium complex.