Experimental study on the microreactor-assisted synthesis of phosphinic chlorides with varying steric hindrance

An efficient and catalyst-free method for the preparation of optically active and racemic mono-substituted t-butyl phosphinic chlorides (BuRP)-Bu-t(O)Cl under flow conditions was reported. A variety of mono t-butyl substituted phosphinic chlorides were obtained using this protocol starting from the corresponding phosphine oxide and one equivalent of carbon tetrachloride (CAUTION: hepatotoxic) with reasonable residence times (25-125 min) and excellent conversions (up to 99%). The asymmetric reaction conducted in a glass microreactor chip with an internal volume of 250 mu L leads to the corresponding chloride with 96% enantiomeric excess. It is significant that the protocol works effectively when the phosphine oxide has one bulky group such as t-butyl, which prevent the formation of undesired products. The steric hindrance is proven to be important for the stabilization of the P-Cl products. The key results were compared with the results obtained in batch conditions and it can be concluded that the flow method provides a sustainable, efficient alternative to the existing methods for the preparation of phosphinic chlorides. The isolation of the reaction products is straightforward because of the lack of any additives and the high purity of the obtained products. The results of the asymmetric reaction and the computational studies suggest that the reaction occurs through a mechanism involving a pentacoordinated phosphorus TS, with the apical positions occupied by the incoming CCl3- nucleophile and the t-butyl group

O-4-Chloro­benzoyl diphenyl­seleno­phosphinate

The title compound, C19H14ClO2PSe, was obtained in the reaction of the diphenyl­monoseleno­phosphinic acid ammonium salt with 4-chloro­benzoyl chloride. The dihedral angle between the P-bonded aromatic rings is 72.64 (14)°. Packing of the mol­ecules in the crystal is reinforced by π–π stacking inter­actions between two inversion-related 4-chloro­benzene rings [centroid-centroid separation = 4.189 (2) Å] and a C—H⋯O interaction also occurs

Solid-phase synthesis and structural characterisation of phosphoroselenolate-modified DNA: a backbone analogue which does not impose conformational bias and facilitates SAD X-ray crystallography

Oligodeoxynucleotides incorporating internucleotide phosphoroselenolate linkages have been prepared under solid-phase synthesis conditions using dimer phosphoramidites. These dimers were constructed following the high yielding Michealis-Arbuzov (M-A) reaction of nucleoside H-phosphonate derivatives with 5ʹ-deoxythymidine-5ʹ-selenocyanate and subsequent phosphitylation. Efficient coupling of the dimer phosphoramidites to solid-supported substrates was observed under both manual and automated conditions and required only minor modifications to the standard DNA synthesis cycle. In a further demonstration of the utility of M-A chemistry, the support-bound selenonucleoside was reacted with an H-phosphonate and then after chain extension using phosphoramidite chemistry. Following initial unmasking of methyl-protected phosphoroselenolate diesters, pure oligodeoxynucleotides were isolated using standard deprotection and purification procedures and subsequently characterised by mass spectrometry and circular dichroism. The CD spectra of both modified and native duplexes derived from self-complementary sequences with A-form, B-form or mixed conformational preferences were essentially superimposable. These sequences were also used to study the effect of the modification upon duplex stability which showed context-dependent destabilisation (-0.4 ̶ -3.1 °C per phosphoroselenolate) when introduced at the 5ʹ-termini of A-form duplexes or at juxtaposed central loci within a B-form duplex (-1.0 °C per modification). As found with other nucleic acids incorporating selenium, expeditious crystallisation of a modified decanucleotide A-form duplex was observed and the structure solved to a resolution of 1.45 Å. The DNA structure adjacent to the modification was not significantly perturbed. The phosphoroselenolate linkage was found to impart resistance to nuclease activity

Shall we go to the spa? The spa trends in Gothenburg and its region

The Spa industry is a new and growing phenomenon showing a clear increase during the last decades. The customers are starting to realize how important the health and wellness in today’s society. People of all ages are starting to have higher demands that empower them to take part in new lifestyles such as spa visits. This allows the spa establishments to develop new products and services to fulfil their desires. In order to describe the new trends and the other linking aspects of this phenomenon we have investigated the Gothenburg market and its regions; both urban and rural. Many of the spa establishments take part in the spa branding phenomenon to gain customer loyalty and to achieve a higher recognition. This has created confusion for the current spa customers where they might have a lack of knowledge about the actual spa concept. The result of our investigation shows that people are still not aware of the current spa concept. Therefore, the spa establishments see the necessity in putting more effort in educating their target market. The location is also considered an important issue when it comes to spa planning, while the market is starting to become saturated in the urban area. Our findings allow us to give suggestions for the spa establishments as to how to stay unique and differentiate themselves from their competitors