Synthesis is reported of 2-amino-5-mercapto-5-methylhexanoic acid (2) as a bishomologue of penicillamine (1). In this synthesis, alkylation of diethyl acetamidomalonate gave ethyl 2-acetamido-2-carbethoxy-5-methyl-4-hexenoate (4). Addition of -toluenethiol to 4 using BF3-Et20 then gave ethyl 2-acetamido-2-carbethoxy-5-benzylthio-5-methylhex.anoate (6) in 63-74% yield; this reaction appears to be the first use of BFg-EtaO as a catalyst for effecting Markownikoff-type addition of a thiol to an alkene. The bishomologue 2 was obtained from 6 either by decarboxylation to the amide (5), debenzylation of 5 to 7, and hydrolysis, or (preferably) by decarboxylation and hydrolysis to the amino acid 8 in one step and debenzylation. The bishomologue 2 resisted hot strong acid. It reacts with formaldehyde, Fe(III), or Cu(II) much less readily than does 1 and therefore affords a promising means of probing biological properties of 1 where it is unclear whether these properties depend upon ring formation involving SH and NH2 or upon independent action of functional groups.

No abstract

A convenient method of wide scope for the synthesis of the rare tetrahydroisophosphinolinium and tetrahydrophosphinolinium salts has been developed from readily available starting materials. Treatment of a variety of tertiary phosphines (all containing an aryl group and/or an arylmethyl group) with allylic type halides gave phosphonium salts containing a 3-alkenyl substitutent. Cyclization of these salts occurred in the presence of 115% polyphosphoric acid (PPA) at 160°for 30 min to give the C-P heterocyclic systems in modest to good yields (24-82%). Work-up of the reaction mixtures simply involved addition to ice water. The resulting homogeneous solution was treated with KPFe (saturated aqueous solution) which caused the precipitation of the PF6-salt of the respective isophosphinolinium or phosphinolinium system.NMR, 31P NMR, infrared and mass spectral and elemental analyses support the structures of these phosphorus analogs of the corresponding tetrahydroisoquinoline and tetrahydroquinoline heterocycles. Benzyldiphenylvinylphosphonium bromide (3e) cyclized at 300°with 115% PPA after 1.25 hr to give, after work-up, l,2,3,4-tetrahydro-2,2-diphenylisophosphinolinium hexafluorosphate (4e, 51%). Thus, formation of the six-membered ring was favored over formation of the phospholane ring system. A mechanism is tentatively put forth to involve a rather classic electrophilic substitution in the cyclization process. The role of the anion(s) of PPA is unknown but probably involves direct association with the phosphonium cation prior to addition of KPFe.

No abstract

Before the May 2003 TOPOFF II exercise in Seattle, the U.S. EPA's Laboratory in Las Vegas prepared five spiked samples to be analyzed by the Washington State Department of Health's (WSDOH) Radiation Laboratory. Two of these were simulated deposition samples prepared on packaging tape. Laboratories throughout the world are investigating rapid methods for analyzing plume-borne radioactive materials. While measuring gamma emitters in environmental samples is fairly straightforward, the potential presence of alpha emitters adds complexity. The short range of alpha particles and the high degree of energy interference between nuclides usually require chemical separations and very thin mounts for alpha spectrometry. Work published on Frisch-Grid alpha counting of transuranics in soil and the commercial development of radon-rejection for air filters indicate that alpha spectrometry can be used directly on some media with success. This suggests that plume-borne material sampled from air or freshly deposited surface layers may be counted directly by alpha spectrometry, making it possible to identify both alpha and gamma emitters and determine their relative concentrations. The long-range objective is to propose a sampling method that can be used for rapid qualitative and semi-quantitative analyses using conventional radioanalytical instruments, with minimal preparation. This paper describes experimentation with this approach during a real-time exercise. All samples were prepared by spiking with (137)Cs, (241)Am, (238)Pu, and (239)Pu and presented to the WSDOH's Radiation Laboratory for analysis during TOPOFF II. The laboratory quickly identified and determined the ratios of all four contaminants on the tape samples using sequential alpha spectrometry and gamma-ray spectroscopy without chemical separations.

No abstract

Aus den Phosphinen (I) entstehen mit Alkylierungsmitteln die Phosphoniumsalze (II), die mit Polyphosphorsäure zu den bicyclischen Phosphoniumsalzen (III) cyclisiert werden.

Aus den Benzylaminen(I) entstehen mit Allylbromiden (II) die Salze (IIIa)‐(IIId).