New Retinoid Analogs from δ-Pyronene, a Natural Synthon
摘要:
delta-Pyronene (1), a readily available terpenic synthon, is an excellent raw material for the preparation of numerous terpenic intermediates. Original retinoid analogs such as "iso"-retinyl acetate (5), "iso"-retinal (6) and ethyl "iso"-retinoate (7), in which the cyclogeranyl moiety is functionalized in an unusual position, were prepared from delta-pyronene.
Stereospecific palladium-catalyzed 1,4-acetoxychlorination of 1,3-dienes
作者:Jan-E. Bäckvall、Ruth E. Nordberg、Jan-E. Nyström
DOI:10.1016/s0040-4039(00)87173-7
日期:1982.1
Palladium-catalyzed oxidation of 1,3-dienes in acetic acid in the presence of LiCl and LiOAc produces 1-acetoxy-4-chloro-2-alkenes in high selectivity. The 1,4-adducts were stereo- and regioselectively functionalized.
Treatment of secondary allylic chlorides or allylic phosphates in tetrahydrofuran with prenyl Grignard reagent in the presence of CuCN · 2 LiCl gave geraniol or farnesol derivatives with high SN2′ selectivity. Phosphate leaving groups were highly trans-stereoselective for the formation of (E,E)-farnesol derivatives. Furthermore, complete anti-SN2′ selectivity was observed in the alkylation of optically active allylic phosphates. The present method appears to be an excellent carbon-carbon coupling reaction with high regio-, (E)-, and enantioselectivity. Coenzyme Q10 (ubiquinone 10) was efficiently synthesized using this methodology.
Three different routes for the stereoselectivesynthesis of botryodiplodin have been investigated. The intramolecular allylation of acetals proved to be unsatisfactory due to unstable intermediates and poor stereocontrol. Zard intramolecular radical allylation of a 2-iodopropionate derivative allows the development of an expeditious synthesis of racemic botryodiplodin. The relative configuration within
Process for producing a sulfone derivative of vitamin A alcohol
申请人:Hoffmann-La Roche Inc.
公开号:US03960967A1
公开(公告)日:1976-06-01
A process for the preparation of vitamin A and esters thereof from the condensation of a sulfone of 2-methyl-4-hydroxy-but-2-ene and an activated derivative of 3-methyl-5-(2,6,6-trimethyl-cyclohexen-1-yl)penta-2,4-diene including intermediates therein.
(±)-botryodiplodin (1). Several pathways, involving 5-exo-trig ring closure onto allylic sulfones, have been investigated. The iodine atom transfer methodology allowed the preparation of the desired skeleton through intramolecular addition of an α-alkoxycarbonyl radical to the double bond of the appropriate allylic ethyl sulfone. Subsequent deprotonation and kinetic reprotonation led to the key precursor14 with