Mass spectra of 1- and 2a-substituted 1,3,5,7-tetramethyl-2,4,6,8-tetrathiaadamantanes

A comparative analysis was made of the mass spectra of monosubstituted 1,3,5,7-tetramethyl-2,4,6,8-tetrathiaadamantanes (TMITA). It is shown that the pathways of monomolecular fragmentation depend on the character of the substituent and the isomeric form of the TMTTA. The principal lines in the mass spectra of the investigated compounds indicate the occurrence of competitive processes of fragmentation of the molecular ions (M⁺) with detachment of the substituent from the M⁺ ion or with cleavage of the cellular structure. The first process makes it possible to form a judgement regarding the mechanism of the fragmentation of the molecular ion and the site of primary localization of the charge on the fragment ions as a function of the donor—acceptor properties of the substituents, and the second process enables one to form a judgement regarding the character of the fragmentation of the cellular structures of the various isomeric forms.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 748–752, June, 1978.     

Synthesis and structure of 2,4,6,8-tetramethyl-3,7-dithia-2,4,6,8-tetraazabicyclo[3.3.0]octane 3,3,7,7-tetraoxide

Condensation of N,N′-dimethylsulfamide with glyoxal gave 2,4,6,8-tetramethyl-3,7-dithia-2,4,6,8-tetraazabicyclo[3.3.0]octane 3,3,7,7-tetraoxide, a sulfur-containing analog of 2,4,6,8-tetramethyl-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-dione (Mebicar). The product structure was studied by X-ray analysis.     

C-Nitroso compounds—XXXV : Reaction of organometallic compounds with 1-chloro-1-nitroso-2,2,6,6-tetramethylcyclohexane

Reaction of Grignard reagents and organolithium compounds (RM) with the congested 1-chloro-1-nitroso-2,2,6,6-tetramethylcyclohexane 1 leads to the formation of significant amounts of the reduction product 2,2,6,6-tetramethylcyclohexanone oxime 3 (61–90%) together with the corresponding oxime O-R ether 4 (0–11%). Attack on nitrogen is unimportant as shown by very low yields of nitrone. Formation of the products is rationalised with a pathway involving transfer of an electron from RM to 1. This leads—after separation of MCI—to a radical pair consisting of R and the relatively stable iminoxy radical 2 (Schemes 1 and 2). Combination of these radicals explains formation of oxime ether 4 and nitrone 5, while reaction of iminoxy radical 2 with excess of RM can give oxime 3. Reactive radicals R (i.e. Me, Ph, and to a minor extent n-Bu) are furthermore capable of abstracting hydrogen from the solvent (diethyl ether, toluene, or cumene), and the solvent derived radicals can also combine with 2 on oxygen, under formation of oxime ether (26% of 6a). The corresponding benzyl- and cumyl ethers 6b and 6c are only formed in trace amounts because dimerisation of benzyl radicals (7%) and cumyl radicals (22%) is favoured.     

Synthesis and biological evaluation of 3-chloro-1-carbacephem compounds

The 3-chloro-1-carbacephem nucleus was prepared for the first time from a 3H-1-carbacephem compound through a sequence of reactions involving addition of thiophenol, oxidation of sulfide to sulfoxide, and alpha-chlorination of the sulfoxide, followed by elimination of phenylsulfinic acid. The 2-beta-methyl analog was similarly prepared, but the 2 alpha-methyl analog was not obtained. Optical resolution of the 3-chloro-1-carbacephem compound was achieved by the employment of penicillin acylase. That is, the 7-phenylacetamido derivative was enantioselectively hydrolyzed to afford the optically active 7-amino-3-chloro-1-carbacephem compound. Carbacefaclor, the carbacephem analog of cefaclor, was directly and efficiently prepared by enzymatic phenylglycylation of the racemic 7-amino-3-chloro-1-carbacephem compound by using immobilized penicillin acylase. Carbacefaclor thus prepared exhibited comparable antibacterial activity against most gram positive bacteria tested and higher activity against typical gram negative bacteria as compared with cefaclor. Moreover, carbacefaclor possessed remarkably high chemical stability.     

Determination of D-penicillamine and tiopronin in human urine and serum by HPLC-FLD and CE-LIF with 1,3,5,7-tetramethyl-8-bromomethyl-difluoroboradiaza-s-indacene

Two rapid and sensitive analytical methods are developed for the determination of D-penicillamine (D-PEN) and tiopronin (TP) through high-performance liquid chromatography with fluorescence detection (HPLC-FLD) and capillary electrophoresis with laser-induced fluorescence detection (CE-LIF). A boron-dipyrrolemethene (BODIPY) fluorescence labeling reagent, 1,3,5,7-tetramethyl-8-bromomethyl-difluoroboradiaza-s-indacene (TMMB-Br) was successfully applied to derivatize these two thiol drugs. Fluorescein was used as the internal standard (IS) for the quantification of D-PEN and TP in CE-LIF. The derivatization and separation conditions were optimized carefully. Under the optimum conditions, the HPLC and CE separation of D-PEN and TP could be achieved within 12?min. The limits of detection were as low as 2.0 nmol/L for HPLC-FLD and 0.47 nmol/L for CE-LIF. The drugs in human urine and serum samples were determined successfully, and the recoveries were 95.0–06.7% and 95.2–104.3%, respectively.     

Determination of the absolute configuration of 1,3,5,7-tetramethyl-1,3-dihydroindol-2-one by optical rotation computation

The absolute configuration of 1,3,5,7-tetramethyl-1,3-dihydroindol-2-one was determined by quantum chemical calculations of specific rotation angles with coupled–perturbed Hartree–Fock methods. The computation used molecular geometries obtained from ab initio calculations as well as from molecular mechanics and semi-empirical optimization. In addition to the dependence on geometry optimization strategies, the basis set dependence of the computed rotation angle was examined.