BF_(3)·Et_(2)O催化关环法简便合成黄烷-7-羟基-3’,4’-甲二氧基黄烷和4’-羟基-7-甲氧基黄烷

Facile synthesis of(±)-7-hydroxy-3',4'-methylenedioxyflavan and(±)-4'-hydroxy-7-methoxyflavan by a BF3 Et2O-mediated pyran cyclization

利用BF3·EtO关环形成吡喃合成黄烷化合物是一种新的简便方法,用此方法合成了两种天然化合物7-羟基-3’,4’-甲二氧基黄烷和4’羟基-7-甲氧基黄烷.

A facile approach for the synthesis of flavans was developed by employing a BF3(Et2O-catalyzed pyran cycliza-tion in an aprotic polar solvent as key step, by which facile total syntheses of (±)-7-hydroxy-3' , 4'-methylenedioxy-flavan (1) and (±)-4'-hydroxy-7-methoxyflavan (2), two naturally occurring flavans, were achieved.