Cross metathesis (CM) reactions between polyenes, such as beta-carotene, canthaxanthin or retinyl acetate, and various alkenes or dienes in the presence of second generation Hoveyda-Grubbs (H II) or Grubbs (G II) catalysts were investigated. Depending on the cross partner different apocarotenoids were obtained. Cross metathesis reactions of retinyl acetate proved to be fully regioselective. Carotenoid CM reactions afforded mixtures of two products due to competing cleavage of the C11-C12 and C15-C15' double bonds. However, regioselectivity can be controlled by choice of appropriate reaction conditions. The reactions of polyenes with dienes worked better in respect of yields and diastereoselectivities than those with monounsaturated cross partners. (C) 2011 Elsevier Ltd. All rights reserved.
A Highly Stereoselective Synthesis of 11<i>Z</i>-Retinal Using Tricarbonyliron Complex
作者:Akimori Wada、Naoko Fujioka、Yukiko Tanaka、Masayoshi Ito
DOI:10.1021/jo9916030
日期:2000.4.1
A stereoselectivesynthesis of 11Z-retinal 2, which is the chromophore of visual pigment (rhodopsin), was accomplished from the beta-ionylideneacetaldehyde-tricarbonyliron complex 3. The Peterson reaction of 3 using ethyl trimethylsilylacetate smoothly proceeded to afford predominantly the Z-ester 6. Transformation of the Z-ester 6 to the methyl ketone 19, followed by the Emmons-Horner reaction of