Selective C-H functionalization methods could provide a valuable tool for synthesizing different steroid derivatives, which is essential not only in contexts of developing novel synthetic methodology but also as a direct way for gathering the analogues needed for studying the structure-activity relationships and obtaining biologically active compounds. The review discusses recent examples of steroid C-H functionalization to various C-X derivatives (C-O, C-C, C-N, C-S, and C-halogen) using available methods emphasizing their scope and limitations.
View Article and Find Full Text PDFA new synthetic route to 25-hydroxy-provitamin D was elaborated. The synthesis consists of direct hydroxylation at C-25 of 7-dehydrocholesterol hetero Diels-Alder adducts. The adducts were prepared by [4 + 2] cycloaddition of azadienophiles to the steroidal diene.
View Article and Find Full Text PDFThe reactions of sterols (androst-5-en-3β-ol-17-one, diosgenin, and cholesterol) and their tosylates with hydroquinone aimed at the synthesis of ,-1,4-phenylene-linked steroid dimers were studied. The reaction course strongly depended on the conditions used. The study has shown that the major reaction products are the elimination products and unusual steroid dimers resulting from the nucleophilic attack of the hydroquinone C2 carbon atom on the steroid C3 position, followed by an intramolecular addition to the C5-C6 double bond.
View Article and Find Full Text PDFSo far, no coherent and comprehensive method has been elaborated allowing investigation of tensile strength of upholstery seams dedicated to upholstered furniture. Producers of this type of furniture are interested in the assessment of the quality of upholstery material joints, which seems to be particularly important for ensuring the appropriate quality of products. Therefore, the objective of this research was to investigate the influence of the type of material used and the direction of the fabric cut on the strength of upholstery covers.
View Article and Find Full Text PDFThe development of both light and strong wood-derived materials is an interesting research area, particularly in terms of usability in, e.g., furniture constructions.
View Article and Find Full Text PDFPurpose: To present an interim analysis of the trial comparing two neoadjuvant therapies for unresectable rectal cancer.
Methods: Patients with fixed cT3 or cT4 or locally recurrent rectal cancer without distant metastases were randomized to either 5 × 5 Gy and 3 courses of FOLFOX4 (schedule I) or 50.4 Gy delivered in 28 fractions given simultaneously with 5-Fu, leucovorin and oxaliplatin (schedule II).
Aims And Background: Minimally invasive biopsy should be a standard practice in the non-operative diagnosis of breast lesions that are suspicious for or highly suggestive of malignancy. The aim of this study was to compare the procedure duration time for different methods of minimally invasive image-guided vacuum-assisted breast biopsy (VABB).
Methods: Six hundred and ninety-one women with nonpalpable breast masses classified as BI-RADS IV or V were studied.