[2+2] Cycloadditions of methylene exo-glycal derivatives with chlorosulfonyl isocyanate and dichloroketene were studied in detail, investigating the effect carbohydrate moiety, protecting groups as well reaction temperature on yields transformations. These reactions gave new anomeric spiro-β-lactam spiro-cyclobutanone derivatives, whose structure was established by 1D 2D NMR MS experiments. The...

Spiro compounds are of interest due to their interesting conformational features and their structural implications on biological systems. The asymmetric characteristic of the molecule due to the chiral spiro carbon is one of the important criteria of the biological activities. These structures are a widespread structural motif found as key elements of numerous drugs and designed medicinal agent...

We synthesized two series of androstane derivatives as inhibitors of type 3 and type 5 17β-hydroxysteroid dehydrogenases (17β-HSDs). In the first series, four monospiro derivatives at position C17 were prepared from androsterone (ADT) or epi-ADT. After the protection of the alcohol at C3, the C17-ketone was alkylated with the lithium acetylide of tetrahydro-2-(but-3-ynyl)-2-H-pyran, the triple ...

Abstract. The Ti(OiPr)4/tartaric acid diethyl ester/t-BuOOH complex (Sharpless catalyst) was successfully used for the direct asymmetric oxidation of ketones resulting in lactones from cyclobutanones; α,β-dihydroxy ketones from β-hydroxy ketones; alkyl lactone carboxylic acids from 3-alkylcyclopentane-1,2-diones; and spiro-γ-dilactone from 3-(2-hydroxyethyl)cyclopentane1,2-dione in high enantio...

Microbial b-lactone natural products An annotated selection of World Wide Web sites relevant to the topics in microbial biotechnology. Obafluorin is an antimicrobial b-lactone compound produced by the bacterium Pseudomonas fluorescens. In this study, the compound was synthesized, analysed chemically and tested for biological activity. The triedimycins are a class of spiro b-lactones. They are n...

Email: [email protected]. Protein Data Bank Accession Codes Coordinates have been deposited in the RCSB Protein Data Bank under the accession codes 3DY3 and 3DY4. Supporting Information Available: Table of crystallographic data collection and refinement statistics, and experimental details of the attempted kinetic studies. This information is available free of charge via the intern...

(-)-(4S, 8S)-Foedanolide (1a) and (+)-(4R, 8R)-foedanolide (1b), a pair of new spiro-γ-lactone enantiomers, were isolated from the fermentation broth of the plant endophytic fungus Pestalotiopsis foedan by HPLC using a chiral column, achieving over 7% ee. Their structures and absolute configurations were determined on the basis of extensive analysis of NMR spectra combined with computational me...

Neonectrolide A (1), an oxaphenalenone spiroketal with the previously undescribed (5,8'-dimethyl-5'-oxo-3a',4,5,5'-tetrahydro-3H,3'H-spiro[furan-2,2'-isochromeno[3,4,5-def]chromene]-3'-yl)but-3-enoic acid skeleton, was isolated from cultures of the fungus Neonectria sp. Its absolute configuration was assigned by electronic circular dichroism (ECD) calculations. The skeleton of an oxaphenalenone...