2-dimethyl-2,3-dihydrochromen-4-one 3. The propargylation of 3 gave rise to 2,2-dimethyl-7-(2-methylbut-3-yn-2-yloxy)-2,3-dihydrochromen-4-one 4. Condensation of 4 with substituted phenyl or benzyl Grignard reagents afforded substituted phenyl or benzylidene chromenes 6a-d and 4-(substitutedbenzylidene)-3,4-dihydro chromenes 8a-e, respectively.
三氟甲磺酸(TFA)被发现为
间苯二酚区域选择性闭环的合适试剂,可提供7-羟基-2,2-二甲基-2,3-二氢色素n-4-酮3。3的炔丙基化产生2,2-二甲基-7-(2-甲基丁-3-yn-2-基氧基)-2,3-二氢
铬基-4-一4。用取代的苯基或苄基
格氏试剂将4缩合,分别得到取代的苯基或亚苄基色烯6a-d和4-(取代的亚苄基)-3,4-二氢色烯8a-e。