A synthesis of 1, 2, 3, 4-tetrahydroquinolines (TQs) 13 with two and three methoxyl groups on the benzene ring, was achieved via intramolecular cyclization of N-aryl-N-[(phenylsulfinyl)propyl]formamides 7 utilizing the Pummerer reaction as a key step. The reaction was carried out by using trifluoroacetic anhydride (TFAA)(method A) or TFAA-BF3·Et2O (method B). The cyclization to 4-PhSTQs 8 proceeded effectively when the reaction center at the benzene ring was electronically activated by a methoxyl group. In the reaction of sulfoxide 7e having two OMe groups in the ortho- and para-positions, a different cyclization reaction leading to 1, 5-benzothiazepine derivative 9 was observed, indicating that the high uncleophilicity of the benzene ring caused the unexpected reaction prior to cyclization to 4-PhSTQs 8. This route starting from methoxyanilines provides an efficient and convenient method of TQ synthesis.
以 N-芳基-N-[(
苯亚磺酰基)丙基]甲
酰胺 7 的分子内环化为关键步骤,利用 Pummerer 反应合成了
苯环上带有两个和三个甲
氧基的 1、2、3、4-
四氢喹啉(TQs)13。反应采用
三氟乙酸酐(
TFAA)(方法 A)或
TFAA-
BF3-Et2O(方法 B)进行。当
苯环上的反应中心被甲
氧基电子激活时,4-Ph
STQs 8 的环化反应进行得非常有效。在正位和对位有两个 OMe 基团的
亚砜 7e 的反应中,观察到了不同的环化反应,生成了 1,5-
苯并
硫氮杂卓衍
生物 9,这表明
苯环的高不亲
水性导致在环化生成 4-Ph
STQs 8 之前发生了意想不到的反应。这条从
甲氧基苯胺开始的路线提供了一种高效、便捷的 TQ 合成方法。