Triazolo[1,5-a]pyridyl phosphines reflecting the influence of phosphorus lone pair orientation on spectroscopic properties

A series of new triazolopyridine-based phosphines has been prepared. These compounds revealed unexpected spectroscopic patterns. In particular, the NMR spectra are highly dependent on the relative conformational preference of the phosphine substituent at C7. Here, we report on their complete NMR analysis, X-ray structures and DFT calculations that confirm the particular arrangement of the phosphorus lone pair orbital related to the substituent pattern of the chosen phosphine. © 2011 The Royal Society of Chemistry.Peer Reviewe

A remarkable solvent effect of fluorinated alcohols on transition metal catalysed C–H functionalizations

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Convergent high stereoselective preparation of the C12-C24 fragment of Macrolactin A.

The convergent synthesis of the C12-C24 fragment (lower part) of macrolactin A is described. The adapted strategy allowed building up the lower moiety by the assembly of three key intermediates via organometallic addition. One hydroxylic stereogenic center was introduced by the application of chiral sulfoxides methodology on fragment C19-C24. The preparation of the versatile 1,3-anti diol synthon C12-C16 was achieved via opening of chiral epoxide and subsequent oxidation to a hydroxy ketone. Finally, reductive elimination of the appropriate allylic dibenzoate with Na/Hg introduced directly the C16-C19 (E,E)-diene unit, in a highly efficient stereoselective fashion

A Concise and Efficient Stereoselective Synthesis of the C1-C11 Fragment of Macrolactin A

A stereoselective synthesis of the C1–C11 fragment of macrolactin A, using original approaches for the introduction of the Z,E-diene stereochemistry and the C-7 stereogenic center, is reported. The adopted strategy has allowed us to build up the fragment by the assembly of three key intermediates via cross-metathesis, Still–Gennari, and Wittig olefinations. Opening of the commercially available chiral benzyl glycidol epoxide to the corresponding homoallylic alcohol introduced the C-7 chiral center. A cross-metathesis reaction was used to create the C5–C4 E double bond. The Still–Gennari reaction introduced the 2Z,4E-diene moiety and finally the Wittig reaction with a propargylic triphenylphosphorane introduced directly the 1,3-enyne unit in a highly efficient stereoselective fashion

Stereoselective Addition of Grignard Reagents to New P-Chirogenic N-Phosphinoylbenzaldimines: Effect of the Phosphorus Substituents on the Stereoselectivity:

Several phosphinoylimines have been synthesized in five steps by starting from the appropriate phosphane oxide and were then treated with methylmagnesium bromide to give both diastereoisomers in high yields and with promising diastereomeric ratios. Then N‐[(tert‐butyl)(phenyl)phosphinoyl]benzaldimine, which displayed the best results, was subjected to the 1,2‐addition of various Grignard reagents to evaluate the best chiral induction due to the stereogenic phosphorus atom. The corresponding adducts were obtained in excellent yields and with moderate to excellent diastereoisomeric ratios