A series of naturally occurring hemiacetals 2a-d was synthesized by the chemoselective diisobutylaluminum hydride reduction of 2,3-dioxo-4H-1, 4-benzoxazines 1a,b and their N-hydroxy derivatives 1c,d precursors. The procedure described represents a new general approach to the 2-hydroxy-2H-1,4-benzoxazin-3(4H)-one skeleton giving rise to the bioactive natural hydroxamic acids 2,4-dihydroxy-2H-1, 3(4H)-one (2c) and 2,4-dihydroxy-7-methoxy-2H-1, 4-benzoxazin-3(4H)-one (2d) in only three steps starting from nitrophenols.
一系列天然半
肟2a-d是通过
化学选择性
二异丁基氢化铝还原2,3-二氧代-4H-1,4-苯并恶嗪1a,b及其N-羟基衍
生物1c,d前体合成的。所描述的工艺是一种新的通用方法,从2-羟基-2H-1,4-苯并恶嗪-3(4H)-酮骨架出发,仅通过三个步骤,从
硝基苯酚开始,即可生成
生物活性天然羟
肟酸2,4-二羟基-2H-1,3(4H)-酮(2c)和2,4-二羟基-7-甲氧基-2H-1,4-苯并恶嗪-3(4H)-酮(2d)。