Hetero-Diels–Alder reaction of photochemically generated α-hydroxy-o-quinodimethanes with trifluoromethyl ketones
作者:Ken Takaki、Toshifumi Fujii、Hosei Yonemitsu、Makoto Fujiwara、Kimihiro Komeyama、Hiroto Yoshida
DOI:10.1016/j.tetlet.2012.05.082
日期:2012.8
Hetero-Diels–Alder reaction of α-hydroxy-o-quinodimethanes photochemically generated from o-tolualdehydes with trifluoromethyl ketones gave a mixture of hemiacetals and hydroxyaldehydes in fairly good yields. Their subsequent oxidation with PCC provided 1-isochromanones as formal oxidative [4+2] cycloaddition products. In contrast, similar reaction of aromatic ketones such as o-methylbenzophenone,
由邻甲苯甲醛与三氟甲基酮光化学合成的α-羟基邻邻喹啉甲烷的Hetero -Diels-Alder反应得到了相当好的收率的半缩醛和羟基醛的混合物。随后用PCC氧化可提供1-异色酮类化合物,为正式的氧化性[4 + 2]环加成产物。相反,芳族酮如邻甲基二苯甲酮,1-茚满酮和α-四氢萘酮的类似反应仅得到在邻位具有(三氟甲基)羟甲基的相应酮。