Further studies on the [1,2]-Wittig rearrangement of 2-(2-benzyloxy)aryloxazolines

Authors thank EPSRC (UK) for a DTA studentship to ADH (Grant EP/L505079/1), EPSRC (UK) and CRITICAT Centre for Doctoral Training for a studentship to R. A. I. (Grant code: EP/L016419/1) and the EPSRC UK National Mass Spectrometry Facility at Swansea University.The behaviour of 14 ortho-functionalised 2-aryloxazolines, 11 of them prepared and characterised for the first time, with butyllithium has been examined. Significant limitations to the Wittig rearrangement of such systems are revealed. In terms of asymmetric Wittig rearrangement, good diastereoselectivity is obtained with a valine-derived 4-isopropyl oxazoline but this is compromised by racemisation upon hydrolysis. More encouraging selectivity is achieved in the Wittig rearrangement of an acyclic phenylalanine-derived ortho-benzyloxy benzamide.Publisher PDFPeer reviewe

Rationalisation of patterns of competing reactivity by X-ray structure determination : reaction of isomeric (benzyloxythienyl)oxazolines with a base

Funding: We thank EPSRC (UK) for a DTA studentship to ADH (Grant EP/L505079/1) and the EPSRC UK National Mass Spectrometry Facility at Swansea University.Three isomeric (benzyloxythienyl)oxazolines 9 , 11 and 13 have been prepared and are found, upon treatment with strong base, to undergo either Wittig rearrangement or intramolecular attack of the benzylic anion on the oxazoline function to give products derived from cleavage of the initially formed 3-aminothienofuran products. This pattern of reactivity is directly linked to the distance between the two reactive groups as determined by X-ray diffraction, with the greatest distance in 11 leading to exclusive Wittig rearrangement, the shortest distance in 13 giving exclusively cyclisation-derived products, and the intermediate distance in 9 leading to both processes being observed. The corresponding N-butyl amides were also obtained in two cases and one of these undergoes efficient Wittig rearrangement leading to a thieno[2,3-c]pyrrolone product.Publisher PDFPeer reviewe

Access to diarylmethanols by Wittig rearrangement of ortho-, meta- and para-benzyloxy-N-butylbenzamides

Authors thank EPSRC (UK) for a DTA studentship to ADH (Grant EP/L505079/1), EPSRC (UK) and CRITICAT Centre for Doctoral Training for a studentship to RAI (Grant code: EP/L016419/1) and the EPSRC UK National Mass Spectrometry Facility at Swansea University.The N-butyl amide group, CONHBu, has been found to be an effective promoter of the [1,2]-Wittig rearrangement of aryl benzyl ethers and thus allow the two-step synthesis of isomerically-pure substituted diarylmethanols starting from simple hydroxybenzoic acid derivatives. The method is compatible with a wide range of functional groups including methyl, methoxy and fluoro, although not with nitro and, unexpectedly, is applicable to meta as well as ortho and para isomeric series.Publisher PDFPeer reviewe

Διερεύνηση Πλημυρικής Κατάκλυσης σε συνθήκες μη μόνιμης ροής με τη χρήση Λογισμικών Υδραυλικής Προσομοίωση. Εφαρμογή στον Πηνειό Θεσσαλίας.

Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Επιστήμη και Τεχνολογία Υδατικών Πόρων

Demonstration of nonlinear inverse synthesis transmission over transoceanic distances

Nonlinear Fourier transform (NFT) and eigenvalue communication with the use of nonlinear signal spectrum (both discrete and continuous), have been recently discussed as promising transmission methods to combat fiber nonlinearity impairments. In this paper, for the first time, we demonstrate the generation, detection and transmission performance over transoceanic distances of 10 Gbaud and nonlinear inverse synthesis (NIS) based signal (4 Gb/s line rate), in which the transmitted information is encoded directly onto the continuous part of the signal nonlinear spectrum. By applying effective digital signal processing techniques, a reach of 7344 km was achieved with a bit-error-rate (BER) (2.1×10-2) below the 20% FEC threshold. This represents an improvement by a factor of ~12 in data capacity x distance product compared with other previously demonstrated NFT-based systems, showing a significant advance in the active research area of NFT-based communication systems

Transmission comparison of ultra-long Raman fibre laser based amplification with first and dual order Raman amplification using 10×118 Gbit/s DP-QPSK

Experimental investigations of 10×118 Gbit/s DP-QPSK WDM transmission using three types of distributed Raman amplification techniques are presented. Novel ultra-long Raman fibre laser based amplification with second order counter-propagated pumping is compared with conventional first order and dual order counter-pumped Raman amplification. We demonstrate that URFL based amplification can extend the transmission reach up to a distance of 7520 km in comparison with 5010 km and 6180 km using first order and dual order Raman amplification respectively

Detection of two poleroviruses infecting garlic (Allium sativum) in Australia

Two near complete polerovirus genomes were assembled using high throughput sequencing (HTS) data from two separate samples of garlic cultivar ‘Glenlarge’ grown in Gatton, Queensland, Australia. Whole genome sequence comparisons showed that one contig shared 96.7% nucleotide identity with phasey bean mild yellows virus (MT966032.1) and the other, 99.8% nucleotide identity with turnip yellows virus (MT586581.1). Phylogenetic analyses further revealed that the isolates fell within the PBMYV group 2 and TuYV group 2 clades, respectively. This is the first report of these poleroviruses infecting garlic

Experimental demonstration of 72% reach enhancement of 3.6Tbps optical transmission system using mid-link Optical Phase Conjugation

We experimentally demonstrate nonlinear noise compensation in optical phase conjugation assisted 1st order Raman amplified 30x30Gbaud DP-QPSK transmission system with a spectral efficiency of 3.6b/s/Hz. We show that by optimizing the link symmetry, even with only 1st order Raman amplification a single, mid-link, optical phase conjugation compensates for 90% off the signal-signal nonlinear interference resulting in a 2.3dB performance enhancement. We show that increasing the number of optical phase conjugation s in the presence of 10% residual nonlinearity results in a reduction in the performance enhancement owing to an enhancement in the nonlinear noise generation efficiency of the system. We achieve a record 72% optical phase conjugation enabled reach enhancement of the 30x30Gbaud DP-QPSK signals