| 摘要 |
beta -methylene aldehydes of formula (I) are new. R1, R2 = H, or opt. substd. cyclic or non-cyclic hydrocarbons or heterocycles; R3, R4 = as R1, R2 but are not both H. The prepn of retinoids and carotenoids (III) by reaction of (I) with a cpd R5CH2R6 (II) having activatable H, in the presence of an H-activating agent, is also claimed. R5, R6 = H, lower alkyl, or an electro-attracting group, at least one being an electro-attracting group; or R5 = H and R6 = CR7=C(R8)2; R7 = H or lower alkyl; and R8 = electro-attracting gp.
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