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以2,4-二羟基苯乙酮为原料,经C-异戊烯基化和酚羟基保护制得中间体2-羟基-4-甲氧甲氧基-3,5-二异戊烯基苯乙酮(4)。以对羟基苯甲醛为原料,经C-异戊烯基化和催化环化制得中间体2,2-二甲基-5-甲酰基-2H-1-苯并吡喃(7);4和7经羟醛缩合反应得2’-羟基-3’,5’-二异戊烯基-4’-甲氧甲氧基-4,5-(2,2-二甲基-苯并吡喃)-查尔酮(8);8经分子内的迈克尔加成反应得6,8-二异戊烯基-7-甲氧甲氧基-4’,5’(2,2-二甲基-苯并吡喃)-二氢黄酮(9);在对甲苯磺酸的催化下,9脱去保护基,首次完成了天然异戊烯基黄烷酮(±)-Lespeflorins A3的全合成。其中8和9为新化合物,其结构经1H NMR,IR和EI-MS表征。
Using 2,4-dihydroxyacetophenone as raw material, the intermediate 2-hydroxy-4-methoxymethoxy-3,5-diisoprenyl was obtained by C-isoprenylation and phenolic hydroxyl protection Acetophenone (4). The intermediate 2,2-dimethyl-5-formyl-2H-1-benzopyran (7) was synthesized from p-hydroxybenzaldehyde by C-isoprenylation and catalytic cyclization. And 7 by aldol reaction 2’-hydroxy-3 ’, 5’-diisoprenyl-4’-methoxymethoxy-4,5- (2,2-dimethyl-benzopyridine (8); 8 Michael intramolecular addition reaction of 6,8-diisoprenyl-7-methoxymethoxy-4 ’, 5’ (2,2-dimethyl -benzopyran) -flavanone (9). The synthesis of (±) -Lespeflorins A3 was completed for the first time under the catalysis of p-toluenesulfonic acid. . Among them, 8 and 9 are new compounds whose structures are characterized by 1H NMR, IR and EI-MS.