Synthesis of (+)-piclavines A1 and A2

Piclavines AI and A2 have been synthesised for the first time. The route is short with the key step being the reaction of a bicyclic N-acyl iminium ion with 3-trimethysilyl-1-decene. This convergent strategy gave exclusively compounds in which the pendant decenyl group was axial, as a 6:1 mixture of E:Z-alkene diastereoisomers. Reduction of the lactam carbonyl group gave a 6:1 mixture of piclavines Al and A2, (C) 2000 Published by Elsevier Science Ltd.

Expedient synthesis of (+)-trans-5-allylhexahydroindolizidin-3-one

Treatment of the bicyclic iminium ion derived from 5-methoxyhexahydroindolizidin-3-one with allyltrimethylsilane gave exclusively the diastereoisomer in which the allyl group was axial. This substrate is a useful precursor to 5-propyl-3-alkylindolizidine alkaloids. (C) 1999 Elsevier Science Ltd. All rights reserved.

Strengthening Clinical Cancer Research in the United Kingdom

BACKGROUND: In 1999, 270,000 cases of cancer were registered in the United Kingdom, placing a large burden on the NHS. Cancer outcome data in 1999 suggested that UK survival rates were poorer than most other European countries. In the same year, a Department of Health review noted that clinical trials accrual was poor (

Increasing entanglement through engineered disorder in the random Ising chain

The ground-state entanglement entropy between block of sites in the random Ising chain is studied by means of the Von Neumann entropy. We show that in presence of strong correlations between the disordered couplings and local magnetic fields the entanglement increases and becomes larger than in the ordered case. The different behavior with respect to the uncorrelated disordered model is due to the drastic change of the ground state properties. The same result holds also for the random three-state quantum Potts model.

Mid to late Holocene hydrological change in continental eastern Canada: assessing regional trends from ombrotrophic peat records.

ABSTRACT High resolution records of mid-late Holocene hydro-climatic change are presented from Mer Bleue Bog, eastern Ontario. Past climatic changes in this region have previously been inferred from lake sediments, but rain-fed peatlands can offer additional insights into the spatial and temporal pattern of moisture availability. In this study, reconstructed water table depths are based on a testate amoeba-derived transfer function developed for the region and changes in bog surface wetness are compared with plant macrofossil and peat humification data.

RÉSUMÉ Nous présentons les enregistrements hautes résolutions des variations hydrologique durant la second moitié de l’Holocène pour les tourbières Mer Bleue á l’est de l'Ontario. Précédemment, les changements climatiques de cette région ont été dérivés à partir de prélèvement de sédiments de lac. Mais ils s’avèrent que les tourbières ombrotrophes offrir un éclairage supplémentaire sur les schémas de répartition spatiale et temporelle de la disponibilité de l'humidité. Dans cette étude, des profondeurs reconstruites de nappe phréatique sont basées sur un modèle de function de transfert d’amibes (Arcellinida) et des changements de l’humidité de surface de la tourbière sont comparés avec les macrofossils et au humification de tourbe dans une analyse multi-proxy.