Asymmetric Total Synthesis of (+)-K01-0509 B: Determination of Absolute Configuration

Total Synthesis of (+)-Guadinomic Acid via Hydroxyl-Directed Guanidylation

Protecting-group-free total synthesis of (+)-guadinomic acid is reported using δ-valerolactone as a readily available starting material. The protocol utilizes the recent hydroxyl-directed guanidylation of unactivated alkenes as an approach for direct stereoselective incorporation of the guanidine unit furnishing the natural product in 7 steps.

Unsubstituted Bambusurils: Post-Macrocyclization Modification of Versatile Intermediates

A new bambusuril derivative, (H)BU[6], lacking substituents on the ureidic nitrogen atoms, has been isolated and characterized. This macrocycle was prepared by the deprotection of bambusuril (PMB)BU[6]. (H)BU[6] is attractive for use as a starting compound for the preparation of other bambusuril derivatives, which was demonstrated via propargylation and the copper-catalyzed click reaction performed on the macrocycle.

Synthesis of bicyclic guanidines via cascade hydroamination/Michael additions of mono-N-acryloylpropargylguanidines

A cascade silver(I)-catalyzed hydroamination/Michael addition sequence has been developed to deliver highly substituted bicyclic guanidines. This transformation gives rise to geometrically and constitutionally stable ene-guanidines and generates a remote stereocenter with moderate to high diastereoselectivity.

Ruthenium-catalyzed selective monoamination of vicinal diols

The monoamination of vicinal diols in the presence of in situ generated ruthenium catalysts has been investigated. Among the various phosphines tested in combination with [Ru(3)(CO)(12)], N-phenyl-2-(dicyclohexyl-phosphanyl)pyrrole showed the best performance. After optimization of the reaction conditions this system was applied to different secondary amines and anilines as well as a number of vicinal diols. With the exception of ethylene glycol, monoamination of the vicinal diols occurred selectively and the corresponding amino alcohols were obtained in good yields, producing water as the only side product.

Virulence blockers as alternatives to antibiotics: type III secretion inhibitors against Gram-negative bacteria

In recent years mounting problems related to antibiotic-resistant bacteria have resulted in the prediction that we are entering the preantibiotic era. A way of preventing such a development would be to introduce novel antibacterial medicines with modes of action distinct from conventional antibiotics. Recent studies of bacterial virulence factors and toxins have resulted in increased understanding of the way in which pathogenic bacteria manipulate host cellular processes. This knowledge may now be used to develop novel antibacterial medicines that disarm pathogenic bacteria. The type III secretion system (T3SS) is known to be a potent virulence mechanism shared by a broad spectrum of pathogenic Gram-negative bacteria that interact with human, animal and plant hosts by injecting effector proteins into the cytosol of host cells. Diseases, such as bubonic plague, shigellosis, salmonellosis, typhoid fever, pulmonary infections, sexually transmitted chlamydia and diarrhoea largely depend on the bacterial proteins injected by the T3SS machinery. Recently a number of T3SS inhibitors have been identified using screening-based approaches. One class of inhibitors, the salicylidene acylhydrazides, has been subjected to chemical optimization and evaluation in several in vitro and ex vivo assays in multiple bacterial species including Yersinia spp., Chlamydia spp., Salmonella spp. and Pseudotuberculosis aeruginosa. Reports published up to date indicate that T3SS inhibitors have the potential to be developed into novel antibacterial therapeutics.