Propellanes—XLIII: Inhibition of secondary orbital control in diels-alder reactions of certain propellanes with 4-substituted-1,2,4-triazoline-3,5-diones

A number of propellane substrates were prepared with special structural features, such that attack by dienophiles would be (a) from below—due to repulsive interactions, both electronic and steric, or (b) if the electronic influence from above was less efficient, than the attack would be from both directions. The predicted course of all the reactions has been realised experimentally.     

Photodynamic effects of antioxidant substituted porphyrin photosensitizers on gram-positive and -negative bacterial

Photodynamic treatment of the gram-negative bacteria Escherichia coli B and Acinetobacter baumannii and the gram-positive bacterium Staphylococcus aureus was performed using two newly devised and synthesized antioxidant carrier photosensitizers (antioxidant carrier sensitizers-2 [ACS-2] and antioxidant carrier sensitizers-3 [ACS-3]), which are butyl hydroxy toluene and propyl gallate substituted haematoporphyrins, respectively. It was found that ACS-2 is less reactive than other photosensitizers previously used for the same purpose, whereas ACS-3 is very effective against the multidrug-resistant bacterium A. baumannii, causing its complete eradication at a low fluence (approximately 7.5 J/cm2) of blue light (407-420 nm) and a low concentration (10 microM). At a higher fluence (approximately 37.5 J/cm2) complete eradication of E. coli B can be obtained under the same conditions. Furthermore, X-ray microanalysis and ultrastructural changes indicate that ACS-3, especially in the case of photodynamic treatment of A. baumannii, interferes with membrane functions and causes the inactivation of the bacterium. ACS-3 may be suggested as a specific photosensitization agent for photoinactivation of gram-negative bacteria.     

Propellanes-LXXVI: Stepwise reduction of (4.3.3)propellane-8,ll-dione

The title diketone 1 was converted via the diketal 5into a monoketal 6which was then reduced to afford a mixture of two epimeric ketal-alcohols 7and 8. Each of the corresponding keto-alcohols 9 and 10 was then reduced to give a mixture of syn-anti-diol 2 on the one hand and either the syn-syn-diol 3 or the anti-anti-diol 4, respectively, incidentally proving the configurations of the ketal-alcohols. Catalytic reduction of 1 with Rh and Ru gives a mixture of 9 and 10, and a mixture of 2, 3, and 4, respectively.     

Propellanes. Part LXXII. The structure of the 4-methyl-1,2,4-triazoline-3,5-dione adduct of the propellane lactone obtained by oxidation of biphenylene

The title compound reacts with the dienophile by attacking the face of a cyclo-hexadiene ring which is syn- to the lactone ring.