114468-50-7Relevant articles and documents
Retinoids, XI. - Preparation of 13-, 9-, and 11-Methoxyretinoids
Hopf, Henning,Natsias, Konstantinos
, p. 705 - 716 (2007/10/02)
The synthesis of vitamin A derivatives carrying methoxy substituents in positions 13, 9, and 11 is described.The C4-building block 21 and the phosphonate derived from it, 22, serve as key intermediates for these preparations.Several routes leading to 21 are described and compared with each other.Wittig-Horner reaction between 22 and the β-C15-aldehyde 24 provides the 13-methoxyretinoate 25 which is reduced to 13-demethyl-13-methoxyretinal (26).Starting from β-cyclocitral (27), Reformatzky reaction with 21 furnishes the methoxy lactone 31 which is opened stereospecifically to give the carboxylic acid 33 by base treatment.The reduction product of 33, aldehyde 34, is coupled with various phosphonates (36, 37, 22) thus opening up routes to the methoxyretinals 38-40.The β-C12-aldehyde 41 and β-ionone (46) serve as substrates for 9,13-bis(demethyl)-11-methoxyretinal (45) and 13-demethyl-13-methoxyretinal (50); in the former case Wittig-Horner reaction between 42 and 22 serves as the decisive chainelongation step, whereas Reformatzky coupling between 46 and 21 is used for this purpose in the latter.
