The evaluation of a biogenetically based approach to the synthesis of octahydro-1h-benzofuro[3,2-e]isoquinolines

A potential synthetic route to octahydro-1$\text{H}$-benzofuro [3,2-e]isoquinoline derivatives by intermolecular oxidative phenolic coupling has been studied. A variety of successful coupling reactions have been effected between 2-naphthol or 4-t-butylphenol and p-cresol, 2-(p-hydroxyphenyl)ethanol, 3,4-dimethylphenol, 5-indanol and 6-hydroxytetralin, but 2-acetyl-7-hydroxytetrahydroisoquinoline failed to participate in such reactions.     

Intramolecular de Mayo Reactions of 3-Acetoxy-2-alkenyl-2-cyclohexenones. Preliminary communication

The photoaddition, hydrolysis, retro-aldol sequences 1 → 2 → 3 and 4 → 5 + 6 → 7 proceeded in high yield and in a regiospecific manner. However, the enol acetate 8 on irradiation furnished the tricyclic ketoacetate 9 as the major product, presumably by a hydrogen shift in the intermediate diradical 11 . Hydrolysis of the minor photoadduct 10 gave the dione 13 .     

A facile synthesis of substituted 3‐amino‐1H‐quinazoline‐2,4‐diones

A new synthesis of a series of 3‐amino‐1H‐quinazoline‐2,4‐diones is described. The 1H‐quinazoline‐2,4‐dione 10 was made starting with fluorobenzoic acid in three high yielding steps. The key step of this synthesis involved the generation of the dianion of urea 7 and the subsequent intramolecular nucleophilic displacement of the 2‐fluoro to form the quinazolinedione ring. The 3‐amino moiety was incorporated using (2,4‐dinitro‐phenyl)‐hydroxylamine as the aminating reagent.     

Metal–insulator transition in quantum dot arrays

We present evidence for a re-entrant metal–insulator transition that arises in quantum dot arrays as the gate voltage is used to sweep their density of states past the Fermi level. The form of the temperature variation of the conductance observed in these arrays can be accounted for using a functional form derived from studies of the metal–insulator transition in two dimensions, although the values obtained for the fit parameters suggest that the behavior we observe here may be quite distinct to that found in two dimensions.     

Comparison of the Reveal 20-hour method and the BAM culture method for the detection of Escherichia coli O157:H7 in selected foods and environmental swabs: collaborative study.

Four different food types along with environmental swabs were analyzed by the Reveal for E. coli O157:H7 test (Reveal) and the Bacteriological Analytical Manual (BAM) culture method for the presence of Escherichia coli O157:H7. Twenty-seven laboratories representing academia and private industry in the United States and Canada participated. Sample types were inoculated with E. coli O157:H7 at 2 different levels. Of the 1,095 samples and controls analyzed and confirmed, 459 were positive and 557 were negative by both methods. No statistical differences (p <0.05) were observed between the Reveal and BAM methods.     

Hydrolysis and Oxidation Products of the Chemical Warfare Agents 1,2-Bis[(2-chloroethyl)thio]ethane Q and 2,2′-Bis(2-chloroethylthio)diethyl Ether T

Syntheses of diols of structure [HOCH₂CH₂S]₂(CH₂)_n in 86–95% yield from the sodium salt of 2-mercaptoethanol and Br(CH₂)_nBr (n = 1 to 5) or in 60–90% yield from 2-chloroethanol and NaS(CH₂)_nSNa (n = 2 to 5) are described. The diol [HOCH₂CH₂SCH₂CH₂]₂O was prepared in 82% yield from the sodium salt of 2-mercaptoethanol and [ClCH₂CH₂]₂O, and in 88% yield from 2-chloroethanol and [HSCH₂CH₂]₂O. Mono- and bis-sulfoxides and bis-sulfones of these species were prepared in generally high yield by treatment with an equivalent of KIO₄ in aqueous methanol, two equivalents of NaIO₄ in aqueous methanol, or four equivalents of H₂O₂ in trifluoroacetic acid respectively. The compounds are important analytical standards for investigating the fate of the chemical warfare agents sesquimustard Q and oxygen mustard T in environmental samples.     

Preparation and spectroscopic characterization of bis(6,8-dimethoxychroman-5-yl)methanes

3,5-Dimethoxyphenylalkan-2-ols react with diethoxymethane and boron trifluoride etherate, or aqueous formaldehyde and hydrochloric acid forming bis(6,8-dimethoxychroman-5-yl)methanes.