| 摘要 |
3-Alkoxy-pentadiene-2,4-one-1 cpds., which react with acids to form gamma-unsatd. alpha,beta-dicarbonyl cpds. useful as starting materials for heterocycles, have formula: R3-CH=CH-C(OR2)=CR1-C(=O)R (I) (where R and R3 are (hetero)aryl, 1-4C alkoxy or alkyl; R1 is alkyl or (hetero)aryl and R2 is 1-4C alkyl, and if R and R1 are alkyl, both substituents can be members of an alicyclic ring of opt. size). They are prepd. by reacting alkoxycarbonylmethylene-triphenyl phosphorane with trialkylphosphonium tetrafluoroborate to give 2,2-dialkoxy-ethylene-triphenyl phosphonium tetrafluoroborate ((C6H5)3P-CH=C(OR2)2)BF4 (II); reacting (II) with alkali amides, -alkyl or -aryl cpds. to (C6H5)3P=C=C(OR2)2 (III); reacting (III) with R-CO-CH2-R1 (IV) to yields (C6H5)3P=CH-C(OR2)=CR1-CO-R (V) and reacting (V) with anhydrous R3CHO. |
