164025-07-4

Photoorganocatalysis constitutes a powerful domain of photochemistry and organic synthesis. The scaffold of pyrrolo[3,4-c]quinolinoles exhibits interesting and potent inhibition against various enzymes, making them really promising pharmaceutical targets. Herein, we describe a photochemical methodology for the reaction of N,N-dimethylanilines with N-substituted maleimides, utilizing benzaldehyde as the photoinitiator. A variety of substituted N,N-dimethylanilines and N-substituted maleimides were converted into the corresponding adducts in moderate to high yields.

We have investigated a diastereoselective self-replicating system based on a cycloaddition of a fulvene derivative and a maleimide using a two-pronged approach of combining NMR spectroscopy with computational modelling. Two diastereomers are formed with identical rates in the absence of replication. When replication is enabled, one diastereomer takes over the resources as a "selfish" autocatalyst, while exploiting the competitor as a weak "altruist", resulting in a diastereoselectivity of 16:1. We applied 1D and 2D NMR spectroscopic techniques supported by ab initio chemical shifts as well as ab initio molecular dynamics simulations to study the structure and dynamics of the underlying network. This powerful combination allowed us to decipher the energetic and structural rationale behind the observed behaviour, while static computational methods currently used in the field did not.

The [3+2] dipolar cycloaddition between an azide and maleimide can be accelerated by a factor of more than 100 simply by attaching complementary recognition sites to the reactive partners. This rate acceleration derives from the formation of a reactive bi

(Chemical Equation Presented) Crown ether amino acids (CEAAs) with a luminescent phthalic ester or phthalimide moiety have been prepared. Simple peptide chemistry covalently tethers the macrocycles to give ditopic ammonium-ion binders. The binding events

Maleyl amino acid derivatives were prepared from maleic anhydride and cyclized by reaction with ZnCl2 and hexamethyldisilazane yielding maleoyl derivatives. These derivatives were used as dienophiles in cycloadditions with cyclopentadiene. The

The rate of reaction and the selectivity of a Diels - Alder cycloaddition between a furan and a maleimide can be enhanced by the introduction of complementary recognition sites on the reactant species. Subtle manipulation of other structural elements allows the generation of the observed rate enhancements and selectivities through either self-replication or formation of a pre-reactivc binary complex.

In the field of our research programs concerning novel antimicrobial agents, a series of N-substituted imides was synthesized. These compounds were obtained by cyclization of amido-acids in acetic anhydride/sodium acetate or hexamethyldisilazane/zinc bromide for the hydroxy-aromatic derivatives. The hydroxy-alkyl maleimides were directly prepared by condensation of the corresponding amino-alcohol with maleic anhydride in boiling toluene. Most of N-substituted maleimides showed an interesting antimicrobial activity towards bacteria from the ATCC collection (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853) but the MIC values for P. aeruginosa were always high (128 μg/ml). The imides with alkyl substituents showed higher activities than aromatic analogues with MIC values in the range of 8-32 μg/ml. Comparatively, succinimides were practically inactive.

The scope of a recently discovered (Yoon, E.C. et al.J.Am.Chem.Soc. 1995, 117, 2698), azomethine ylide-forming photoreaction has been explored by probing the excited state chemistry of several N-trimethylsilylmethyl substituted cyclic and acyclic imides and amide analogs.Photolysis of N-maleimide (4) in acetonitrile leads to efficient production of the tricyclic product 16, formed by trapping of the photogenerated azomethine ylide intermediate 15 through cycloaddition with 4.Irradiation 4 in solutions containing high concentrations of the dipolarophiles, acrylonitrile or fumaronitrile, results in production of the products (19-21 and 23-24, respectively) arising by cycloaddition of the ylide 15 with the added dipolarophiles.In contrast, photolysis of the nonconjugated cyclic imide, N-succinimide (5), brings about N-acyl migration resulting in the exclusive production of the unstable, iminolactone 30.On the other band, acyclic, N-trimethylsilylmethyl aroyl imides 6-8 undergo the excited state C to O silyl migration reaction to produce azomethine ylide intermediates 35.Both in the presence or absence of added dipolarophiles, these ylides undergo electrocyclization to form transient aziridine intermediates 36 which react further by ring opening to generate N-phenacylamide products 32-34.In contrast, the nonconjugated imide, N--N-acetylacetamide (9), is unreactive upon irradiation.Similarly, simple N-amides 10-13, while being photochemically labile, do not react to form "trappable" ylide intermediates upon irradiation.The results outlined above are presented and discussed in terms of the scope and limitations of the new, azomethine ylide-forming photoreaction of silylmethyl imides.