Jean-Erick Ancel

The OSM (oxidation state modification) concept: Application to a new and rapid synthesis of retinoids

The OSM (oxidation state modification) concept for the elaboration of new synthetic pathways is demonstrated for the synthesis of β-ionylidene acetaldehyde 11 and retinal 13. According to this new scheme, electrophilic addition to ω-heterosubstituted enol ethers 5 of the cationic species 9, generated from β-ionol led to aldehydic intermediates 10 which undergo easy elimination to β-ionylidene acetaldehyde 11. Similarly, retinal 13 was obtained from vinyl-β-ionol 14 and dienol ethers 12, via aldehydes 16.

Polyvinylogation reagents : 1-lithio-4-trimethylsiloxy-penta-1,3-diene and 1-lithio-4-ethoxy-2-methyl-buta-1,3-diene

Abstract Title products, lithiodienol ethers 6a and 7a , synthetic equivalents of 4-lithio pent-3-ene-2-one and 4-lithio-senecialdehyde were obtained by bromine-lithium exchange. They are choice reagents for the transformations l → 2 and L → 3 respectively.