Traceless solid phase synthesis of 2-substituted pyrimidines using an 'off-the-shelf' chlorogermane-functionalised resin

Thiazole-5-carbaldehyde Synthesis by Cascade Annulation of Enaminones and KSCN with Dess-Martin Periodinane Reagent

The Dess-Martin periodinane (DMP) reagent-mediated reactions of tertiary enaminones with potassium thiocyanate for the synthesis of thiazole-5-carbaldehydes are developed. The product formation involves cascade hydroxyl thiocyanation of the C═C double bond, intramolecular hydroamination of the C≡N bond, and thiazole annulation by condensation on the ketone carbonyl site, representing novel reaction pathways in the reactions between enaminones and thiocyanate salt. DMP plays dual roles in mediating the free radical thiocyanation and inducing the unconventional selective thiazole-5-carbaldehyde formation by masking the in situ generated formyl group during the reaction process.

Traceless Solid-Phase Organic Synthesis

Traceless solid-phase synthesis represents an ultimate sophisticated synthetic strategy on insoluble supports. Compounds synthesized on solid supports can be released without a trace of the linker that was used to tether the intermediates during the synthesis. Thus, the target products are composed only of the components (atoms, functional groups) inherent to the target core structure. A wide variety of synthetic strategies have been developed to prepare products in a traceless manner, and this review is dedicated to all aspects of traceless solid-phase organic synthesis. Importantly, the synthesis does not need to be carried out on a linker designed for traceless synthesis; most of the synthetic approaches described herein were developed using standard, commercially available linkers (originally devised for solid-phase peptide synthesis). The type of structure prepared in a traceless fashion is not restricted. The individual synthetic approaches are divided into eight sections, each devoted to a different methodology for traceless synthesis. Each section consists of a brief outline of the synthetic strategy followed by a description of individual reported syntheses.

Enaminone-Derived Pyrazoles with Antimicrobial Activity

A series of pyrazoles derived from the substituted enaminones were synthesized and were evaluated for antimicrobial activity. All the compounds were characterized by the spectral data and elemental analysis. The synthesized compounds were initially screened for their antimicrobial activity against ATCC 6538, NCTC 10400, NCTC 10418, and ATCC 27853. During initial screening, compounds (P1, P6, and P11) presented significant antimicrobial activity through disc diffusion assay. These compounds were further evaluated for antimicrobial activity at different time points against Gram-positive and Gram-negative bacteria and presented significant activity for 6 hours. The activity was found to be greater against Gram-positive bacteria. In contrast at 24 hours, the activity was found only against Gram-positive bacteria except compound (P11), showing activity against both types of bacteria. Compound (P11) was found to have highest activity against both Gram-positive and Gram-negative bacteria.

Effect of solvent ratio and counter ions on the morphology of copper nanoparticles and their catalytic application in β-enaminone synthesis

This work reports the synthesis of shape selective copper nanoparticles (NPs) using a microwave irradiation method, using diverse ratios of an ethylene glycol (EG)/water system and their catalytic application in β-enaminones synthesis.

A new method for the enamination of 1,3-dicarbonyl compounds catalyzed by laccase in water

Laccase-catalyzed enamination of 1,3-dicarbonyl compounds in water.

Direct condensation of functionalized sp3 carbons with formanilides for enamine synthesis using an in situ generated HMDS amide catalyst

Functionalized enamines, including β-enaminoesters were synthesized using in situ generated HMDS amide bases via the combination of aminosilanes and fluoride salts.

rac-Ethyl (2Z)-3-{2-[(Z)-4-eth-oxy-4-oxobut-2-en-2-yl-amino]-cyclo-hexyl-amino}-but-2-enoate

The asymmetric unit of the title compound, C(18)H(30)N(2)O(4), contains two independent mol-ecules. In each mol-ecule, the cyclo-hexane ring adopts a chair conformation with equatorial orientation of the substituents, and the conformation is stabilized by two intra-molecular N-H⋯O hydrogen bonds, forming rings of S(6) graph-set motif. One eth-oxy group and one ethyl group are disordered over two sets of sites with refined occupancy ratios of 0.704 (2):0.296 (2) and 0.505 (3):0.495 (3), respectively. In the crystal, a weak inter-molecular C-H⋯O hydrogen inter-action is observed, involving the O atom of the major component of the disordered eth-oxy group.

Towards a general solid phase approach for the iterative synthesis of conjugated oligomers using a germanium based linker - first solid phase synthesis of an oligo-(triarylamine)

The development of a germanium-based linker system for the solid phase synthesis (SPS) of 3-(n-hexyl)thiophene oligomers and the first SPS of triarylamine oligomers via iterative chain extension is described. The efficiency of the key steps in the oligomer syntheses and their compatibility with the germanium linker are demonstrated by the SPS of bi-[3-(n-hexyl)thiophene] 19 and ter-(triarylamine) 50. The use of a germanium-based linker in combination with appropriately selected silicon-based blocking/protecting groups allows double coupling to drive the key cross coupling steps to completion hence minimising deletion sequences and also allows for traceless and potentially functionalisative cleavage from the resin. The latter feature has yet to be fully explored but towards this end the first ipso-borodegermylation reaction of a 2-germyl-3-(n-hexyl)thiophene is presented.

Polystyrene-graft-Polyglycerol Resins: A New Type of High-Loading Hybrid Support for Organic Synthesis

The preparation of a dendritic graft polymer by a very efficient synthesis of polyglycerol directly on a polystyrene resin is presented. This one-step process can be performed on a multigram scale to provide a chemically stable polymeric support. The resulting hybrid polymers were fully characterized by diverse analytical methods (NMR, IR, ESEM, UV detection of cleaved protecting groups, and mass-spectrometric methods). They combine a high loading capacity (up to 4.3 mmol g(-1)) with good swelling properties in a wide range of solvents (including water), which is the major drawback for many existing solid phase supports. In comparison to the widely employed PEGylated resins, these hybrid materials offer a 10-fold higher loading capacity. Their suitability as supports for organic synthesis and for the immobilization of reagents has been demonstrated. These materials also swell in water, and consequently, it should be possible to use these new hybrid materials for synthesis in protic solvents.