Synthesis of 4-methoxy-1H-phenalen-1-one: a subunit related to natural phenalenone-type compounds

4-Methoxy-1H-phenalen-1-one (4-methoxyperinaphthenone, 1), a subunit found in some Musa phytoalexins and related natural products from the Haemodoraceae, was synthesized starting from 2-methoxynaphthalene in five steps and an overall yield of 36%. A Heck–Fujiwara coupling between ethyl acrylate and 1-bromonaphthalene afforded the corresponding (E)-naphthylpropanoic acid which, after hydrogenolysis, was subjected to a one-pot Friedel–Crafts acylation–DDQ dehydrogenation procedure to furnish 1.     

Bestimmung von Kalziumoxyd, Magnesiumoxyd und Phosphors?ure mit dem Zeiss'schen Eintauchrefraktometer

Ohne ZusammenfassungMitteilung aus dem öffentlichen Nahrungsmitteluntersuchungsamt Sondershausen.     

Synthesis and Reactivity of Phenylimidorhenium(V) Complexes with N‐[(N′,N′‐Dialkylamino)(thiocarbonyl)]benzamidines. Observation of a pH‐Dependent Isomerisation of Related Oxorhenium(V) Compounds

Reactions of [Re(NPh)Cl₃(PPh₃)₂] with N‐[(N′,N′‐dialkylamino)(thiocarbonyl)]benzamidines (H₂R₂tcb) (R₂ = Et₂, (CH₂)₂O(CH₂)₂) in methanol give mono‐chelates of the composition [Re(NPh)Cl₂(PPh₃)(HR₂tcb)] as the sole products independent of the amount of the added H₂R₂tcb. Addition of a supporting base such as NEt₃ results in hydrolysis of the Re=NPh bonds and partial hydrolysis of the thiocarbamoylbenzamidines. Orange‐brown, cationic oxorhenium(V) compounds of the formula [ReO(HR₂tcb)₂]Cl were isolated from such reaction mixtures in good yields, and the formation of small amount of the unusual sulfido/persulfido‐bridged Re^V dimer [{ReO(HEt₂tcb)}₂(μ‐S)(μ‐S₂)] give evidence for a considerable degree of ligand decomposition under such conditions. The products have been characterized by spectroscopic methods and X‐ray crystallography. Acidification of orange‐brown solutions of the five‐coordinate Re^V oxo complex [ReO(HEt₂tcb)₂]Cl causes an immediate change of the color and deep blue crystals of the neutral, six‐coordinate [ReOCl(HEt₂tcb)₂] can be isolated from the resulting mixture. Alternatively, the product can be prepared by a ligand‐exchange protocol starting from (NBu₄)[ReOCl₄] and H₂Et₂tcb. The pH‐dependent isomerization between [ReO(HEt₂tcb)₂]Cl and [ReOCl(HEt₂tcb)₂] is reversible.     

1p hole-states in 16O and 16N and the mass dependence of the 1p spin-orbit splitting

The 1p hole strength distributions in mass 16 nuclei, measured in parallel ¹⁷O(d,t)¹⁶O and ¹⁷O(d,τ)¹⁶N experiments, exhibit differences of the effective $\text{1d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{1p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{and}\text{1d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{1p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ interactions which lead to a 1p orbit splitting increasing strongly with the number of $\text{1d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ nucleons.     

Minimal covers of finite sets

We enumerate the minimal covers of a finite set S, classifying such covers by their cardinality, and also by the number of elements in S which they cover uniquely.