Varda Usieli

Reactions of dicyclopropylacetylene with iron carbonyls

Abstract Dicyclopropylacetylene has been brought into reaction under photolytic conditions with Fe(CO) 5 and under thermal conditions with Fe 2 (CO) 9 and with Fe 3 (CO) 12 . It was possible to obtain primarily monoacetylene adducts or bis(acetylene) adducts by modification of the reaction conditions. In addition to products normally obtained from reactions of acetylenes with iron carbonyls, products derived from cyclopropane ring opening were important. Of particular interest are products which resulted from ring opening and carbonyl insertion to yield cyclopentenone derivatives. Experiments were attempted to show the interrelationships between the various products obtained.

Prianicin A and B, nor-sesterterpenoid peroxide antibiotics from Red Sea sponges

The antibiotic properties of 2 acidic C24H40O4 nor-sesterterpenoid peroxides, prianicin A (1) and B (2), against gram-positive and gram-negative bacteria, and against fungi are herein described. They are 4–10 times more effective than tetracycline againstbeta hemolytic Streptococcus, but significantly non-effective against a variety of gram-negative bacteria.

Phosphonoformate inhibits synthesis of epstein-barr virus (EBV) capsid antigen and transformation of human cord blood lymphocytes by EBV☆

Abstract Phosphonoformic acid trisodium salt (PF) and ethyl diethylphosphonoformate (Et-PF) inhibited Epstein—Barr virus (EBV) viral capsid antigen (VCA) synthesis in B.95-8 cells, at concentrations which were nontoxic to cells. PF inhibited 96.7% of VCA synthesis when used at 500 μM whereas Et-PF inhibited only 68.9% of VCA synthesis when used at 2000 μM. The synthesis of EBV nuclear antigen (EBNA) was not inhibited by PF or Et-PF. PF inhibited the transformation of human cord blood lymphocytes (CBL) by EBV as detected by [ 3 H]thymidine uptake. The inhibition of transformation was a function of the dose of PF used. A concentration of 2000 μM PF completely inhibited the transformation; the same concentration of ET-PF had almost no effect.

The synthesis of hexacyclopropylbenzene via cyclotrimerization of dicyclopropylacetylene by Fe3(CO)12

Di-cyclopropyl-acetylen (I) reagiert in Gegenwart von Trieisen-dodecacarbonyl (II) zum Hexakis-cyclopropyl-benzol (III) neben dem Tetrakis-cyclopropylcyclopentadienon (IV) und zwei weiteren Eisen-Komplexen (V) und (VI).

Reductive dehalogenation in Fe(CO)5-mediated photolysis of 3-halo- and 3,4-dihalo-2,5-dimethylthiophene 1,1-dioxides

Abstract Irradiation of 3,4-dibromo-, 3,4-dichloro- and 3-chloro-2,5-dimethylthiophene 1,1-dioxide in the presence of pentacarbonyliron caused successive reductive dehalogenation of the substrates, and π-complexation of the parent compounds and of the reduced products to tricarbonyliron. A mechanism for the dehalogenation is suggested. The mass spectral fragmentation patterns of the thiophene dioxides and of the complexes are discussed.