No abstract

Photooxygenation of 1,5-dihydroxynaphthalene to Juglone was studied in a falling film microreactor. Moderate conversion rates of up to 31% were achieved after just 160 s of exposure to visible light. In contrast, batch reactions gave much lower conversions of up to 14% after a prolonged time period of 10 min. The difference in performance is explained by the superior light penetration in the microfilm and the large gasYliquid contact area.

The borane complexes cyclo-1,4-(BH3)2(P4Ph4CH2) (3) and cyclo-1,2-(BH3)2(P5Ph5) (4) were prepared by reaction of cyclo-(P4Ph4CH2) and cyclo-(P5Ph5) with BH3(SMe2). Only the 2:1 complexes 3 and 4 were isolated, even when an excess of the borane source was used. In solution, 3 exists as a mixture of the two diastereomers (R(P)*,S(P)*,S(P)*,R(P)*)-(+/-)-3 and (R(P)*,R(P)*,R(P)*,R(P)*)-(+/-)-3. However, in the solid state the (R(P)*,S(P)*,S(P)*,R(P)*)-(+/-) diastereomer is the major stereoisomer. Similarly, while only one isomer of 4 is observed in its X-ray structure, NMR spectroscopic investigations reveal that it forms a complex mixture of isomers in solution. 3 may be deprotonated with tBuLi to give the lithium salt cyclo-1,4-(BH3)2(P4Ph4CHLi) (3 x Li), though this could not be isolated in pure form.

The primary aminoalkyl(bisphosphanyl)ferrocenes 2-(N,N-dimethylaminomethyl)-1,1'-bis(phosphanyl)ferrocene (3a) and N,N-dimethyl-1-[1',2-bis(phosphanyl)ferrocenyl]ethylamine (3b) are readily available in two steps from the corresponding aminoalkylferrocenes. Deprotonation of 3a gave the first alkali metal aminoalkyl(bisphosphanido)ferrocene (4) as a one-dimensional polymer.

The dichlorophosphanyl-substituted ferrocene complexes 1-dichlorophosphanyl-2-N,N-dimethylaminomethyl-3-diphenylphosphanylferrocene (2a) and 1-dichlorophosphanyl-2-N,N-dimethylaminomethyl-3,1′-bis(diphenylphosphanyl)ferrocene (2b) have been prepared by the reaction of phosphorus trichloride with the corresponding lithiated aminoalkylferrocene precursors. The crystal structure of 2a reveals a short N···P distance, which is suggestive of a weak N→P dative bond. Using diethyl chlorophosphite instead of phosphorus trichloride as electrophile gave 1-diethoxyphosphanyl-2-N,N-dimethylaminomethyl-3-diphenylphosphanylferrocene (3a) and 1-diethoxyphosphanyl-2-N,N-dimethylaminomethyl-3,1′-bis(diphenylphosphanyl)ferrocene (3b), respectively. The latter was converted to the corresponding dimethoxy compound 4b by reaction with methanol. Crystal structures of 3 and 4b have been determined. Reduction of 2, 3, and 4b with LiAlH4 or LiAlH4/SiMe3Cl yielded the primary phosphanes 1-diphenylphosphanyl-2-N,N-dimethylaminomethyl-3-phosphanylferrocene (5a) and 1,1′-bis(diphenylphosphanyl)-2-N,N-dimethylaminomethyl-3-phosphanylferrocene (5b). The latter was also structurally characterized by X-ray diffraction.