Ligand Control in Co-Catalyzed Regio- and Enantioselective Hydroboration: Homoallyl Secondary Boronates via Uncommon 4,3-Hydroboration of 1,3-Dienes.

Enantiopure homoallylic boronate esters are versatile intermediates because the C-B bond in these compounds can be stereospecifically transformed into C-C, C-O, and C-N bonds. Regio- and enantioselective synthesis of these precursors from 1,3-dienes has few precedents in the literature. We have identified reaction conditions and ligands for the synthesis of nearly enantiopure (er >97:3 to >99:1) homoallylic boronate esters via a rarely seen cobalt-catalyzed [4,3]-hydroboration of 1,3-dienes.

[2,1,3]-Benzothiadiazole-Spaced Co-Porphyrin-Based Covalent Organic Frameworks for O Reduction.

Designing N-coordinated porous single-atom catalysts (SACs) for the oxygen reduction reaction (ORR) is a promising approach to achieve enhanced energy conversion due to maximized atom utilization and higher activity. Here, we report two Co(II)-porphyrin/ [2,1,3]-benzothiadiazole (BTD)-based covalent organic frameworks (COFs; Co@-PorBTD and Co@-PorBTD), which are efficient SAC systems for O electrocatalysis (ORR). Experimental results demonstrate that these two COFs outperform the mass activity (at 0.

Efficacious and sustained release of an anticancer drug mitoxantrone from new covalent organic frameworks using protein corona.

Solid porous and crystalline covalent organic frameworks (COFs) are characterized by their higher specific BET surface areas and functional pore walls, which allow the adsorption of various bioactive molecules inside the porous lattices. We have introduced a perylene-based COF, PER@PDA-COF-1, which acts as an effective porous volumetric reservoir for an anticancer drug, mitoxantrone (MXT). The drug-loaded COF (MXT-PER@PDA-COF-1) exhibited zero cellular release of MXT towards cancer cells, which can be attributed to the strong intercalation between the anthracene-dione motif of the drug and the perylene-based COF backbone.

Room Temperature Cu-Catalyzed -Arylation of Oxazolidinones and Amides with (Hetero)Aryl Iodides.

,'-Bis(pyridin-2-ylmethyl)oxalamide (BPMO) was found to be an apposite promoter for the Cu-catalyzed -arylation of oxazolidinones and primary and secondary amides with (hetero)aryl iodides at room temperature. Excellent chemoselectivity reached between aryl iodides and aryl bromides, and a wide range of functional groups tolerated the reaction conditions, which led to the formation of greatly diverse -arylation products.

Efficacious Electrochemical Oxygen Evolution from a Novel Co(II) Porphyrin/Pyrene-Based Conjugated Microporous Polymer.

Oxygen evolution reaction (OER) is energetically challenging from the platform of making many photovoltaic devices such as metal-air batteries and water splitting systems because of its poor kinetics even when precious metals are used. Herein, a Co(II)-porphyrin/pyrene-comprised conjugated microporous polymer Co-MPPy-1 has been developed which shows efficient OER in alkaline medium. The material was characterized by Fourier transform infrared, solid-state C cross-polarization magic angle spinning nuclear magnetic resonance, N volumetric adsorption/desorption analysis, scanning electron microscopy, ultra high resolution-transmission electron microscopy, X-ray photoelectron spectroscopy, and other physical studies.

A conjugated microporous polymer based visual sensing platform for aminoglycoside antibiotics in water.

A donor-acceptor based conjugated microporous polymer, PER@NiP-CMOP-1, has been synthesized which can achieve highly sensitive stereo-specific "Turn ON" biosensing of an aminoglycoside up to the ppb level. The coordination-driven inhibition of photo-induced electron transfer (d-PET) for d-electrons and the rotational freezing are the key factors for the recovery of the emission.

An expeditious route to the synthesis of the enantioenriched tetracyclic core of ergot alkaloids via an organocatalytic aldol reaction.

The synthesis of the tetracyclic skeleton of ergot alkaloids has been developed via a key organocatalytic enantioselective aldol reaction using paraformaldehyde as the C1-unit in the presence of thiourea catalyst followed by a key Pd-catalyzed directed coupling accelerated by the DavePhos ligand. Utilizing the aforementioned strategy, we have synthesized a key tetracyclic intermediate in up to 95% ee with high yield.

Catalytic asymmetric formal total syntheses of (+)- and (-)-cycloclavine.

We report an expeditious catalytic asymmetric approach to clavine alkaloids via a key Heck cyclization. This reaction sets the formation of vicinal stereocenters with excellent diastereoselectivity. Utilizing the aforementioned strategy, the formal total synthesis of cycloclavine (1) has been achieved via another key late-stage ester-aminolysis of 6.

Biomimetic Total Syntheses of Clavine Alkaloids.

Biomimetic total syntheses of either enantiomers of a number of ergot alkaloids, chanoclavine I (1b), chanoclavine I aldehyde (1c), pyroclavine (1e), festuclavine (1f), pibocin A (1g), 9-deacetoxyfumigaclavine C (1h), and fumigaclavine G (1i), have been achieved from seco-agroclavine (1a). The advanced intermediate for seco-agroclavine (1a) was synthesized via a key thiourea-catalyzed intramolecular nitronate addition onto α,β-unsaturated ester.

N,N'-Bisoxalamides Enhance the Catalytic Activity in Cu-Catalyzed Coupling of (Hetero)Aryl Bromides with Anilines and Secondary Amines.

N,N'-Bis(furan-2-ylmethyl)oxalamide (BFMO), an inexpensive and conveniently available bidentate ligand, is very effective for promoting Cu-catalyzed N-arylation of anilines and cyclic secondary amines. The method enables coupling of a broad range of (hetero)aryl bromides with various (hetero)aryl amines and cyclic secondary amines at 0.5-5 mol % catalyst loadings at relatively low temperatures.

A new strongly paramagnetic cerium-containing microporous MOF for CO fixation under ambient conditions.

Metal organic frameworks (MOFs) bearing multicarboxylate linkers are in great demand for designing robust heterogeneous catalysts. A new microporous Ce(iii)-based metal organic framework (CeNDC) has been synthesized under solvothermal conditions, which showed strong paramagnetism and a CO uptake capacity of 1.64 mmol g (7.

Total Syntheses of Pyroclavine, Festuclavine, Lysergol, and Isolysergol via a Catalytic Asymmetric Nitro-Michael Reaction.

A catalytic enantioselective construction of vicinal stereocenters is reported. The reaction takes advantage of thiourea-catalyzed intramolecular nitronate addition onto α,β-unsaturated ester to afford exceptional levels of enantioselectivity (up to 97 % ee) with moderate diastereoselectivity (up to 4:1). Using this method, a cross-conjugated ester was synthesized in few steps, from which a 6-endo-trig cyclisation led to the formation of all required functionalities for total syntheses of ergot alkaloids.

Electrochemical Stimuli-Driven Facile Metal-Free Hydrogen Evolution from Pyrene-Porphyrin-Based Crystalline Covalent Organic Framework.

A [2 + 2] Schiff base type condensation between 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (TAP) and 1,3,6,8-tetrakis (4-formylphenyl) pyrene (TFFPy) under solvothermal condition yields a crystalline, quasi-two-dimensional covalent organic framework (SB-PORPy-COF). The porphyrin and pyrene units are alternatively occupied in the vertex of 3D triclinic crystal having permanent microporosity with moderately high surface area (∼869 m g) and promising chemical stability. The AA stacking of the monolayers give a pyrene bridged conducting channel.

Selected Copper-Based Reactions for C-N, C-O, C-S, and C-C Bond Formation.

Metal-catalyzed cross-coupling reactions belong to the most important transformations in organic synthesis. Copper catalysis has received great attention owing to the low toxicity and low cost of copper. However, traditional Ullmann-type couplings suffer from limited substrate scopes and harsh reaction conditions.

Discovery of N-(Naphthalen-1-yl)-N'-alkyl Oxalamide Ligands Enables Cu-Catalyzed Aryl Amination with High Turnovers.

A class of N-(naphthalen-1-yl)-N'-alkyl oxalamides have been proven to be powerful ligands, making a coupling reaction of (hetero)aryl iodides with primary amines proceed at 50 °C with only 0.01 mol % of CuO and ligand as well as a coupling reaction of (hetero)aryl bromides with primary amines and ammonia at 80 °C with only 0.1 mol % of CuO and ligand.

Synthesis of 2-oxindoles via 'transition-metal-free' intramolecular dehydrogenative coupling (IDC) of sp(2) C-H and sp(3) C-H bonds.

The synthesis of a variety of 2-oxindoles bearing an all-carbon quaternary center at the pseudo benzylic position has been achieved via a 'transition-metal-free' intramolecular dehydrogenative coupling (IDC). The construction of 2-oxindole moieties was carried out through formation of carbon-carbon bonds using KOt-Bu-catalyzed one pot C-alkylation of β-N-arylamido esters with alkyl halides followed by a dehydrogenative coupling. Experimental evidences indicated toward a radical-mediated path for this reaction.

Unified Approach to the Spiro(pyrrolidinyl-oxindole) and Hexahydropyrrolo[2,3-b]indole Alkaloids: Total Syntheses of Pseudophrynamines 270 and 272A.

The first enantioselective total syntheses of architecturally interesting prenylated pyrroloindole alkaloids, (-)-pseudophrynamines 272A (3d) and 270 (3b), have been achieved starting from enantioenriched 2-oxindoles having all-carbon quaternary stereocenters. A common strategy involving a thio-urea catalyzed aldol reaction is employed for the total synthesis of both spiro(pyrrolidinyl-oxindole) and hexahydropyrrolo[2,3-b]indole alkaloids.

Zn(ii) assisted synthesis of porous salen as an efficient heterogeneous scaffold for capture and conversion of CO2.

We have designed a unique strategy to obtain a zinc-salen functionalized porous polymer (Zn@SBMMP) with high zinc content (15.3 wt%) by an easy one-step, cost effective and scalable process, which shows unprecedented catalytic efficiency in the CO2 fixation reaction via cycloaddition of CO2 with epoxides. We hypothesize that a high density of Zn-Schiff base/salen units present in the porous polymer network is responsible for the exceptionally high catalytic performance of Zn@SBMMP.

A new hypercrosslinked supermicroporous polymer, with scope for sulfonation, and its catalytic potential for the efficient synthesis of biodiesel at room temperature.

We have designed a new hypercrosslinked supermicroporous polymer (HMP-1) with a BET surface area of 913 m(2) g(-1) by FeCl3 via a catalyzed Friedel-Crafts alkylation reaction between carbazole and α,α'-dibromo-p-xylene. Upon sulfonation HMP-1 yielded a very efficient solid acid catalyst for the production of biodiesels via esterification/transesterification of free fatty acids (FFA)/esters at room temperature.

Porous polyurea network showing aggregation induced white light emission, applications as biosensor and scaffold for drug delivery.

We have designed a urea functionalized novel nanoporous material, POP-PU, which showsaggregation induced white light emission in the presence of suitable polar solvents. This nanomaterial has been explored as a pseudowhite light emitter where the polymeric luminogen moiety can interact with the suitable polar solvent, leading to charge transfer. Thus, solvent assisted rotational freezing of nonrigid polymeric nanoparticles gives radiative emission and the whole solution emits white light with color temperature of 8533 K.

Enantioselective construction of vicinal all-carbon quaternary centers via catalytic double asymmetric decarboxylative allylation.

We report a catalytic stereoconvergent construction of vicinal all-carbon quaternary centers via double stereoablative enantioselective alkylation of a mixture having racemic and meso diastereomers of esters to afford exceptional levels of diastereo- (up to 17 : 1) and enantioselectivity (up to >99% ee). The strategy offers an efficient and general approach to dimeric cyclotryptamine alkaloids sharing a labile C(3a)-C(3a') σ-bond in the hexahydropyrroloindoline core.

Acid-catalyzed reactions of 3-hydroxy-2-oxindoles with electron-rich substrates: synthesis of 2-oxindoles with all-carbon quaternary center.

A Lewis acid catalyzed reaction of in situ generated 2H-indol-2-one () with various 2π and other electron-rich substrates has been developed. A variety of electron-rich substrates such as allyl/methallyltrimethylsilane, phenylacetylene, styrenes, acetophenone, and indoles have been used. The methodology provides a straightforward approach for the synthesis of 2-oxindoles with an all-carbon quaternary center at the pseudobenzylic position.

DDQ-mediated direct intramolecular-dehydrogenative-coupling (IDC): expeditious approach to the tetracyclic core of ergot alkaloids.

An efficient route to 2-oxindoles bearing an all-carbon quaternary center at the pseudobenzylic position has been developed via a DDQ-mediated Intramolecular-Dehydrogenative-Coupling (IDC). The methodology involves a one-pot C-alkylation of β-N-arylamido esters (7) concomitant with dehydrogenative-coupling in the presence of stoichiometric amount of DDQ. A tentative mechanistic route has been proposed for the oxidative coupling.

Intramolecular dehydrogenative coupling of sp2 C-H and sp3 C-H bonds: an expeditious route to 2-oxindoles.

An intramolecular-dehydrogenative-coupling (IDC) using "transition-metal-free" oxidation conditions has been achieved to synthesize a variety of 2-oxindoles bearing an all-carbon quaternary stereogenic center at the benzylic position. The methodology involves a one-pot C-alkylation of β-N-arylamido esters (3, 6) with alkyl halides using potassium tert-butoxide concomitant with a dehydrogenative coupling. A radical-mediated pathway has been tentatively proposed for the oxidative process.

Lewis acid-catalyzed Friedel-Crafts alkylations of 3-hydroxy-2-oxindole: an efficient approach to the core structure of azonazine.

A Lewis acid catalyzed Friedel-Crafts reaction of electron rich aromatics with 3-alkyl-3-hydroxy-2-oxindole (5) has been developed. The methodology provides a straightforward access to the core of azonazine (2) sharing an all-carbon quaternary stereocenter at the tetracyclic ring junction.