We describe a convergent, enantioselective synthesis of (-)-tetracycline (1) from benzoic acid (17 steps, 1.1% yield). Benzoic acid was transformed into the AB precursor 2 in 10 steps (11% yield), as previously described, and the latter compound was activated toward Diels-Alder cycloaddition by the introduction of an alpha-phenylthio group (two steps, 66% yield). Heating of the resulting alpha-...

Forest soil compaction caused by heavy machines can cause ecosystem degradation, reduced site productivity and increased greenhouse gas (GHG) emissions. Recent studies investigating the plant-mediated alleviation of with black alder showed promising results (Alnus glutinosa). This study aimed to measure recovery GHG fluxes on machine tracks without alders in North-East Switzerland. In 2008, two...

the aim of this study is comparison of soil characteristics and biodiversity in plantation of bald cypress and caucasian alder forest stands in kludeh region (mazandaran province). in order to study biodiversity in forest stands and control region, 10 sample plots (releve) were selected and the name and abundance of plant species of the forest floor were recorded. biodiversity of herbal plants ...

Methods are described by which DNA can be amplified directly from ectomycorrhizal root tip homogenates of a variety of plant species (Picea mariana (black spruce), Betula papyrifera (paper birch), Populus tremuloides (trembling aspen) and Alnus sp.(alder)), including root tips that have been preserved in RNA Later (Ambion, Austin, TX). In most cases for extracts and homogenates diluted 10-fold ...

A fascinating aspect of the Diels–Alder reaction is its endo selectivity. This endo preference is much less pronounced in intermolecular cases compared with the intramolecular and transannular Diels–Alder (IMDA and TADA) reactions. Nevertheless, high endo selectivity is observed in the Diels– Alder additions of (E)-1-O-substituted dienes catalyzed by Lewis acids that lead to cis-1,6-disubstitut...

Consultant Gynaecologist, Department of Paediatric Surgery, Alder Hey Children’s Hospital, Liverpool and Liverpool Women’s Hospital, Liverpool, UK Specialist Registrar, Department of Obstetrics and Gynaecology, Liverpool Women’s Hospital, Liverpool, UK Biomedical Scientist, Department of Biochemistry, Alder Hey Children’s Hospital, Liverpool, UK Consultant Gynaecologist, Department of Gynaecolo...

Attachment of conidia on leaves is a critical first step in the life cycle of aquatic hyphomycetes in streams. In a first series of microcosm experiments, attachment success of three common aquatic hyphomycete species differing in conidial shape (compact, filiform and tetraradiate) was determined on two leaf species, black alder and downy oak. Fungal species identity and leaf surface structure ...

This review is an endeavor to highlight the progress in the inverse-electron-demand hetero-Diels-Alder reactions of 1-oxa-1,3-butadienes in recent years. The huge number of examples of 1-oxadienes cycloadditions found in the literature clearly demonstrates the incessant importance of this transformation in pyran ring synthesis. This type of reaction is today one of the most important methods fo...