Penifulvins B-E (2-5), four new sesquiterpenoids with a dioxa[5.5.5.6]fenestrane ring system, have been isolated from cultures of an isolate of Penicillium griseofulvum (NRRL 35584), together with a new silphinene derivative, 12-hydroxysilphinene-15-oic acid (6). Penifulvins B-E (2-5) are oxidized analogues of penifulvin A (1) and were identified by analysis of NMR and MS data. 12-Hydroxysilphi...

Electrocatalytic oxidation of ascorbic acid (AA) at a carbon paste electrode, chemically modified 2,2'-[3,6-dioxa-1,8-octanediylbis(nitriloethylidyne)]-bis-hydroquinone, was thoroughly investigated. The results of cyclic voltammetry, double potential-step chronoamperometry, linear sweep voltammetry and differential pulse voltammetry (DPV) studies were used for the prediction of the mechanism of...

Strained azirinium ylides derived from 2H-azirines and α-diazoketones under Rh(II)-catalysis can undergo either irreversible ring opening across the N-C2 bond to 2-azabuta-1,3-dienes that further cyclize to 2H-1,4-oxazines or reversibly undergo a 1,5-cyclization to dihydroazireno[2,1-b]oxazoles. Dihydroazireno[2,1-b]oxazoles derived from 3-aryl-2H-azirines and 3-diazoacetylacetone or ethyl diaz...

Reaction of tetrafluoropyridazine with catechol gives a tricyclic 9,10-dioxa-1,2-diaza-anthracene system by a sequential nucleophilic aromatic substitution ring annelation process, further extending the use of perfluoroheteroaromatic derivatives for the synthesis of unusual polyfunctional heterocyclic architectures. The tricyclic scaffold reacts with amines and sodium ethoxide providing a short...

The asymmetric unit of (P)-chloridobis[(S)-(+)-5-(3,5-dioxa-4-phosphacyclohepta[2,1-a:3,4-a']dinaphthalen-4-yl)dibenz[b,f]azepine]iridium(I)-benzene-pentane (1/1/1), [IrCl(C(34)H(22)NO(2)P)(2)]·C(6)H(6)·C(5)H(12), contains two formula units. The two symmetry-independent molecules of the Ir complex have similar conformations and approximate C(2) symmetry, with small deviations arising from sligh...