Synthesis of imides, N-acyl vinylogous carbamates and ureas, and nitriles by oxidation of amides and amines with Dess-Martin periodinane

Chemoselective Acylation of Primary Amines and Amides with Potassium Acyltrifluoroborates under Acidic Conditions

Current methods for constructing amide bonds join amines and carboxylic acids by dehydrative couplings-processes that usually require organic solvents, expensive and often dangerous coupling reagents, and masking other functional groups. Here we describe an amide formation using primary amines and potassium acyltrifluoroborates promoted by simple chlorinating agents that proceeds rapidly in water. The reaction is fast at acidic pH and tolerates alcohols, carboxylic acids, and even secondary amines in the substrates. It is applicable to the functionalization of primary amides, sulfonamides, and other N-functional groups that typically resist classical acylations and can be applied to late-stage functionalizations.

Water-mediated and promoted eco-friendly one-pot synthesis of azaarene substituted isoxazoles

An efficient and green approach for the sp³ C–H bond functionalization of 2-methyl azaarenes to 3-methyl-4-nitro-5-styrylisoxazoles in water has been described.

Palladium-catalysed hydroamidocarbonylation of 1,3-dienes

Herein, we report our recent result on the development of the selective catalytic method towards the synthesis of β,γ-unsaturated imides via Pd-catalysed hydroamidocarbonylation of conjugated dienes. Note that this reaction proceeds under acid additive free conditions. Various dienes, including those of high industrial value (e.g. isoprene, 1,3-butadiene), are shown to be compatible with our established method (28 examples, 40-99% yield), which leads to the corresponding β,γ-unsaturated imides in a highly efficient and atom-economic fashion.

A facile one pot route for the synthesis of imide tethered peptidomimetics

A simple and efficient method for the synthesis of N,N’-orthogonally protected imide tethered peptidomimetics is presented. The imide peptidomimetics were synthesized by coupling the in situ generated selenocarboxylate of N^α-protected amino acids with N^α-protected amino acid azides in good yields.

Palladium-Catalyzed Hydroamidocarbonylation of Olefins to Imides

Carbonylation reactions allow the efficient synthesis of all kinds of carbonyl-containing compounds. Here, we report a straightforward synthesis of various imides from olefins and CO for the first time. The established hydroamidocarbonylation reaction affords imides in good yields (up to 90 %) and with good regioselectivity (up to 99:1) when applying different alkenes and amides. The synthetic potential of the method is highlighted by the synthesis of Aniracetam by intramolecular hydroamidocarbonylation.

Radical-mediated dehydrative preparation of cyclic imides using (NH4)2S2O8-DMSO: application to the synthesis of vernakalant

Ammonium persulfate–dimethyl sulfoxide (APS–DMSO) has been developed as an efficient and new dehydrating reagent for a convenient one-pot process for the synthesis of miscellaneous cyclic imides in high yields starting from readily available primary amines and cyclic anhydrides. A plausible radical mechanism involving DMSO has been proposed. The application of this facile one-pot imide forming process has been demonstrated for a practical synthesis of vernakalant.

Structure-based design of phthalimide derivatives as potential cyclooxygenase-2 (COX-2) inhibitors: anti-inflammatory and analgesic activities

A group of 30 cyclic imides (1-10a-c) was designed for evaluation as a selective COX-2 inhibitor and investigated in vivo for anti-inflammatory and analgesic activities. Compounds 6a, 6b, 7a and 7b exhibit optimal COX-2 inhibitory potency (IC50 = 0.18, 0.24, 0.28 and 0.36 μM; respectively) and selectivity index (SI) range of 363-668. In vitro COX-1/COX-2 inhibition structure-activity studies identified compound 6a as a highly potent (IC50 = 0.18 μM), and an extremely selective [COX-2 (SI) = 668] comparable to celecoxib [COX-2 (SI) > 384], COX-2 inhibitor that showed superior anti-inflammatory activity (ED50 = 54.0 mg/kg) relative to diclofenac (ED50 = 114 mg/kg). Molecular Docking study of the synthesized compound 6a into the active site of COX-2 revealed a similar binding mode to SC-558, a selective COX-2 inhibitor. Docking study showed that the methoxy moeities of 6a inserted deep inside the 2°-pocket of the COX-2 active site, where the O-atoms of such groups underwent an H-bonding interaction with His(90) (3.02 Å), Arg(513) (1.94, 2.83 Å), and Gln(192) (3.25 Å).

Metal free stereoselective synthesis of functionalized enamides

An efficient and expeditious DABCO-mediated synthesis of functionalized enamides from alkenes is delineated. The reaction proceeds through an unprecedented cascade involving an Aza-Michael addition/α-bromination/elimination and a Morita-Baylis-Hillman type reaction to generate functionalized enamides in a regio- & stereoselective fashion.

Molecular design, synthesis and biological evaluation of cyclic imides bearing benzenesulfonamide fragment as potential COX-2 inhibitors. Part 2

A group of cyclic imides (1-10) was designed for evaluation as a selective COX-2 inhibitors and investigated in vivo for their anti-inflammatory activity. Compounds 6a, 6b, 8a, 8b, 9a, 9b, 10a and 10b were proved to be potent COX-2 inhibitors with IC50 range of 0.1-4.0 μM. In vitro COX-1/COX-2 inhibition structure-activity studies identified compound 8a as a highly potent (IC50=0.1 μM), and an extremely selective [COX-2 (SI)>1000] comparable to celecoxib [COX-2 (SI)>384], COX-2 inhibitor that showed superior anti-inflammatory activity (ED50=72.4 mg/kg) relative to diclofenac (ED50=114 mg/kg). Molecular modeling was carried out through docking the designed compounds into the COX-2 binding site to predict if these compounds have analogous binding mode to the COX-2 inhibitors. The study showed that the homosulfonamide fragment of 8a inserted deep inside the 2°-pocket of the COX-2 active site, where the SO2NH2 group underwent H-bonding interaction with Gln(192)(2.95 Å), Phe(518)(2.82 Å) and Arg(513)(2.63 and 2.73 Å). Docking study of the synthesized compound 8a into the active site of COX-2 revealed a similar binding mode to SC-558, a selective COX-2 inhibitor.

Synthesis of Imides and Benzoylureas by Direct Oxidation of N-methylenes of Amides and Benzylureas

Some amides and benzylureas can be oxidised to imides and benzoylureas, respectively, using silver(I) nitrate (20 mol %), copper(II) sulfate pentahydrate (20 mol %), ammonium persulfate (3.0 equiv.), and potassium fluoride (20 equiv.) in water at room temperature.

The antibiotic CJ-15,801 is an antimetabolite that hijacks and then inhibits CoA biosynthesis

The natural product CJ-15,801 is an inhibitor of Staphylococcus aureus, but not other bacteria. Its close structural resemblance to pantothenic acid, the vitamin precursor of coenzyme A (CoA), and its Michael acceptor moiety suggest that it irreversibly inhibits an enzyme involved in CoA biosynthesis or utilization. However, its mode of action and the basis for its specificity have not been elucidated to date. We demonstrate that CJ-15,801 is transformed by the uniquely selective S. aureus pantothenate kinase, the first CoA biosynthetic enzyme, into a substrate for the next enzyme, phosphopantothenoylcysteine synthetase, which is inhibited through formation of a tight-binding structural mimic of its native reaction intermediate. These findings reveal CJ-15,801 as a vitamin biosynthetic pathway antimetabolite with a mechanism similar to that of the sulfonamide antibiotics and highlight CoA biosynthesis as a viable antimicrobial drug target.

Enantioselective total synthesis of (+)-ibophyllidine via an asymmetric phosphine-catalyzed [3 + 2] annulation

In this study we performed the total synthesis of the terpene indole alkaloid (+)-ibophyllidine through a pathway involving asymmetric phosphine catalysis, with our novel l-4-hydroxyproline-derived chiral phosphine mediating the key [3 + 2] annulation. Hydrogenation of the [3 + 2] adduct allowed the rapid formation of the stereochemically dense pyrrolidine ring of (+)-ibophyllidine in excellent yield with exceptionally high levels of both diastereo- and enantioselectivity. We constructed the remainder of the pentacyclic skeleton through an intramolecular alkylation and an intramolecular aza-Morita-Baylis-Hillman reaction.

Fast and flexible synthesis of pantothenic acid and CJ-15,801

The fast and efficient syntheses of pantothenic acid and the antiparasitic agent CJ-15,801 have been achieved starting from a common imide unit through the selective manipulation of enamide intermediates.

Organoiodine(V) reagents in organic synthesis

Organohypervalent iodine reagents have attracted significant recent interest as versatile and environmentally benign oxidants with numerous applications in organic synthesis. This Perspective summarizes synthetic applications of hypervalent iodine(V) reagents: 2-iodoxybenzoic acid (IBX), Dess-Martin periodinane (DMP), pseudocyclic iodylarenes, and their recyclable polymer-supported analogues. Recent advances in the development of new catalytic systems based on the generation of hypervalent iodine species in situ are also overviewed.

Monitoring the allyl ester deprotection by HR MAS NMR in BAL-solid phase peptide synthesis

The backbone amide linker strategy, in which the growing peptide chain is anchored to a solid support via a backbone amide nitrogen, has proven to be successful for the synthesis of cyclic peptides. Optimisation of the reaction conditions for the synthesis of c(Gly-Trp-βAla-Phe) could be accomplished by the help of high resolution magic angle spinning (HR MAS) NMR and the results are presented here. Signal vanishing of HR MAS NMR resonances were encountered and proven to be originated from interchain aggregations of peptide chains.