A new ferrocenyl oxazaphospholidine oxide 3 was synthesized together with its P-epimer 2 in the reaction of ferrocene lithium with phosphoramidite chloride 1. 3 was successfully derivatized into planar chiral 1,2-ferrocenes, including phosphine ligands, via highly diastereoselective ortho-lithiation and subsequent functionalization; these compounds display opposite planar chirality to those obtained from 2. Some of these 1,2-ferrocenes were further lithiated, allowing for the introduction of a free phosphine group at the oxazaphospholidine ring. The X-ray structures of the compounds 2 and 3 as well as those of the new 1,2-ferrocenes 4 and 7 have been determined.
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http://dx.doi.org/10.1039/c2ob25187f | DOI Listing |
Curr Protoc Nucleic Acid Chem
March 2017
Institute of Bioorganic Chemistry Polish Academy of Sciences, Poznań, Poland.
Application of 2-pyridinyl thermolabile protecting groups (2-PyTPGs) for protection of hydroxyl, phosphate, and carboxyl functions is presented in this unit. Their characteristic feature is a unique removal process following the intramolecular cyclization mechanism and induced only by temperature rise. Deprotection rate of 2-PyTPGs is dependent on certain parameters, such as solvent (aqueous or non-aqueous medium), pH values, and electron distribution in a pyridine ring.
View Article and Find Full Text PDFJ Org Chem
April 2016
Department of Medicinal and Life Sciences, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
Stereocontrolled solid-phase synthesis of phosphate/phosphorothioate chimeric oligodeoxyribonucleotides (PO/PS-ODNs) was achieved by integrating the conventional phosphoramidite method into a previously developed oxazaphospholidine method for the stereocontrolled synthesis of P-chiral oligonucleotides. P-Stereodefined PO/PS-ODNs with mixed sequences (up to 12-mers) were obtained in good yields and high stereoselectivities by reacting different combinations of monomers (conventional phosphoramidites/diastereopure nucleoside 3'-O-oxazaphospholidines), activators (ETT/CMPT), capping reagents (Pac2O/CF3COIm), and oxidizing/sulfurizing reagents (TBHP/POS) on an automated synthesizer. A thermal denaturation study examined the resultant diastereopure PO/PS-ODN 12-mers with three consecutive (Rp)- or (Sp)-PS-linkages at the internal or terminal regions of the molecules.
View Article and Find Full Text PDFOrg Biomol Chem
September 2015
Institut de Chimie et Biochimie Moléculaires et Supramoléculaires (ICBMS-UMR CNRS 5246), Université Claude Bernard Lyon 1, Bâtiment Curien (CPE) 43, Bd du 11 Novembre 1918, 69622 Villeurbanne cedex, France.
D-Glucosamine was successfully employed as a chiral auxiliary for the enantioselective synthesis of phosphine oxides. The influence of the anomeric position was also investigated and revealed the excellent ability of the α-anomer to perform this transformation in a highly selective fashion. The methodology employed consisted of three steps: diastereoselective formation of the oxazaphospholidine followed by subsequent selective cleavage of P-N and P-O bonds by reaction with two Grignard reagents.
View Article and Find Full Text PDFChemistry
June 2015
Institut de Chimie et Biochimie Moléculaires et Supramoléculaires (ICBMS-UMR CNRS 5246), Université Claude Bernard Lyon 1, Bâtiment Curien (CPE) 43, Bd du 11 Novembre 1918, 69622 Villeurbanne cedex (France), Fax: (+33) 472-44-6264 http://www.icbms.fr/casyen/45-casyen-andrioletti/23-andrioletti.
An efficient enantioselective strategy for the synthesis of variously substituted phosphine oxides has been developed, incorporating the use of (1S,2S)-2-aminocyclohexanol as the chiral auxiliary. The method relies on three key steps: 1) Highly diastereoselective formation of P(V) oxazaphospholidine, rationalized by a theoretical study; 2) highly diastereoselective ring-opening of the oxazaphospholidine oxide with organometallic reagents that takes place with inversion of configuration at the P atom; 3) enantioselective synthesis of phosphine oxides by cleavage of the remaining P-O bond. Interestingly, the use of a P(III) phosphine precursor afforded a P-epimer oxazaphospholidine.
View Article and Find Full Text PDFJ Org Chem
September 2012
Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznań, Poland.
Acceleration of H-phosphonate diester oxidation with iodine accompanied by a thermolabile protecting group (TPG) is presented. It is shown that the intermediate product of this reaction is an oxazaphospholidine oxide which forms a phosphate diester only when a 2-pyridyl TPG is applied. The intermediate product is formed with exocyclic nitrogen.
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