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 .     

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.     

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.     

The Synthesis of Some Bifunctionally Substituted [3,3,1] Propellanes

Convenient syntheses of some bifunctionally substituted [3.3.1] propellanes are reported from the readily accessible tricyclo[4.3.1^1,6] dec-3-en-8-ol.     

Some regioselective reactions of photoaldrin and photodieldrin

A study has been made of the regioselectivities of some typical addition reactions of pbotoaldrin and epoxide ring-opening reactions of photodieldrin. The structures of the resulting products have been established by appropriate interconversions and syntheses. The factors responsible for the observed regioselectivities are discussed.