N-methyl-N-alkylsilyltrifluoroacetamide-I2 as a new derivatization reagent for anabolic steroid control.

Analytical methods for the control of growth promoters have to be specific and sensitive. At low concentration levels, it is difficult to identify some molecules unambiguously even with the improved performance of analytical methods. GC-MS analysis of 17 beta-trenbolone and its major metabolite, 17 alpha-trenbolone, is a good example. A new derivatization agent has been developed which is based on silylation of the 3- and 17-oxygenated functions and nucleophilic substitution in the 4-position. The structure of the derivatized products was demonstrated using a simple model, cyclohex-2-en-1-one, by NMR and MS spectrometry. In contrast to data found in the literature, this derivative permitted specific mass spectra for trenbolone, sensitive signals for high mass ions and reproducible gas chromatograms to be obtained. The addition of an N(CH3)COCF3 radical to the steroid nucles allowed highly specific detection in GC-high resolution MS even following extraction from complex matrices; sensitive responses were also observed in the negative chemical ionization mode. Moreover, there are significant differences in the electron ionization mass spectra of the two stereoisomers, 17 alpha- and 17 beta-trenbolone. These preliminary results and those obtained for androsta-1,4-dien-3-one and pregna-4,6-dien-3-one indicate useful advances for the determination of steroids and potential applications for metabolism studies on such compounds.     

Intermolecular [2+2] photocyclization of ethyl 5-oxo-1a,2,5,5a,6,6a-hexahydro-2,6-methano-2aH-indeno-[5,6-b]oxirene-2a-carboxylate

The photodimer, 7, of ethyl 5-oxo-1a,2,5,5a,6,6a-hexahydro-2,6-methano-2aH-indeno-[5,6-b]oxirene-2a-carboxylate has been isolated and structuraally characterized. Triclinic,P ^?1,a=9.7783(6),b=11.2782(7),c=11.3445(7) Å, α=105.461(9), β=113.3759(10), γ=92.9155(11)^o,V=1089.36(12) ų,R=0.049 for 3557 unique observed reflections. Two independent molecules lying on inversion centers occupy the unit cell. The influence of the orientation of the ester group on the polycyclic skeleton is discussed.     

Statistical inference in coupled quantum systems

We discuss the problem of statistical inference in a coupled system. The method is based on the concept of inference introduced in [1].     

Etude cristallographique et magnetique de MnSiN2 par diffraction des neutrons

The Neel temperature (180°C) and magnetic structure of MnSiN₂ have been obtained by neutron diffraction as well as better atomic coordinates than those deduced previously from X-ray data only.     

Specific heat in Erbium and Yttrium Iron garnet crystals

Specific heat measurements have been carried out on single crystals of Erbium and Yttrium Iron garnets between 5 and 210K. The ErIG specific heat presents two anomalies. The first one situated at (77±4)K corresponds approximatively to the compensation temperature at which the bulk magnetization vanishes; the second one was found at (54±2)K below which temperature the |100| direction appears to be the easy direction. Both anomalies are to be associated with second order transitions and correspond to the onset of an umbrella structure and a change of the easy direction.     

Conditional expectations on von Neumann algebras: A new approach

In the framework of non-commutative probability theory on von Neumann algebras the concept of conditional expectation is redefined in such a way that it exists relative to arbitrary a priori distributions and subalgebras. We derive explicit expressions for the expectations relative to Abelian subalgebras and establish their connection with the concept of coarse-graining.     

Synthesis of thioimidates by insertion of TerT-butylisocyanide into the C-S bond of activated sulfides. Rearrangement of thioimidates by 1,3 C to N migration of an alkoxycarbonyl group

Tert-butylisocyanide inserts into the carbon-sulfur bond of α-cyano sulfides $\text{2}$-$\text{6}$ to give thioimidates $\text{10}$-$\text{14}$. The thioimidates can also be obtained via the chlorine substitution of the tert-butylimino chloro sulfides $\text{27}$-$\text{28}$, which is a more general method. These thioimidates rearrange to E and Z isomers of N-vinylcarbamates $\text{16}$-$\text{20}$ via a 1,3 C to N migration of the alkoxycarbonyl group.     

Uncatalyzed insertion reaction of isocyanides into a carbon-sulfur bond

Tert-butylisocyanide and tert-octylisocyanide insert into the carbone-sulfur bond of activated sulfides 2 yielding thioimidates 5 which rearrange to enamines 6.