Biomedical subjects

Vincent Levacher

Publications and source records attributed to Vincent Levacher.

5 recordsLinked to original sources

PubMed2006

Solid phase synthesis of a redox delivery system with the aim of targeting peptides into the brain.

A solid phase approach for the preparation of peptides attached to a redox chemical delivery system derived from stable annulated NADH models is reported. The synthesis starts with the grafting on a Merrifield resin of quinoline 4b, precursor of the redox carrier. From the resulting quinoline supported resin 4d, the stepwise SPPS of both octapeptide OP (RPGLLDLK) and octadecaneuropeptide ODN (QATVGDVNTDRPGLLDLK), two neuropeptides exhibiting anorexigenic effects, was successfully achieved by conventional methods. Quaternization of the quinoline moiety prior to cleavage of the modified OP and ODN peptides from the resin, led to the expected quinolinium salt 8a and 8b respectively linked to OP or ODN peptides. Finally, the reduction with NaBH4 monitored by UV-vis, provided the desired annulated NADH models as peptides carriers with either the OP (11a,b) or ODN (12a,b) moiety.

Amino Acid Sequence↗

PubMed2005

Amine capture strategy for peptide bond formation by means of quinolinium thioester salts.

A new and unprecedented exploitation of quinolinium thioester salts 2 in peptide bond formation is reported. These synthetic tools were assessed during the preparation of a number of dipeptides 3a-f obtained in good yields with complete stereochemical integrity. A sequential mechanism related to a prior amine capture strategy is well-established. Additionally, a tripeptide 3g was prepared according to a "safety-catch" approach, thus demonstrating the important potential of these new synthetic tools in the design of new safety-catch linkers exploitable in Solid-Phase Peptide Synthesis (SPPS).

Amines↗

PubMed2003

Novel extension of Meyers' methodology: stereoselective construction of axially chiral 7,5-fused bicyclic lactams.

A novel extension of Meyer's lactamization is reported for the preparation of seven-membered ring lactams 1a-d incorporating a biaryl unit. The required keto-esters 2a-c were readily accessible via the Suzuki coupling reaction. A borylation-Suzuki coupling (BSC) sequence was successfully developed for the high-yielding preparation of keto-ester 2d. Cyclization of the resulting keto-esters 2a-d or keto-acids 5a,c,d in the presence of (R)-phenylglycinol afforded the desired lactams 1a-d in high yields (72-93%) and excellent diastereoselectivities (>95%). This methodology provides a facile stereoselective access to new axially chiral bridged biaryls.

Combinatorial Chemistry Techniques↗

PubMed2003

A novel traceless solid-phase Friedländer synthesis.

[reaction: see text] A new solid-phase synthesis of quinolines based on a Friedländer-type reaction between the resin-bound azomethine 1b and ketones 2 is described. This cyclative cleavage approach affords quinolines 3a-f in 50-81% yields. The polymer-bound aniline equivalent is easily recycled and may be reused with comparable performance.

Journal Article↗

PubMed2002

Atropoisomeric quinolinium salt promoting the access to both enantiomeric forms of methyl mandelate: a versatile NADH mimic.

Asymmetric reduction of methyl benzoylformate by a new NADH mimic is reported; depending on the hydride source used to reduce the NAD+ precursor, NADH mimics so obtained lead to an inversion of enantioselectivity, affording either (R)-methyl mandelate in 88% ee or (S)-methyl mandelate in 78% ee.

Molecular Mimicry↗