Reduction of 2,6-diacetoxy-2′-bromoacetophenone (10) with NaBH4 led to 3,4-diacetoxydihydrobenzofuran (12) in a process involving acyl migration followed by cyclization. Subsequent hydrogenolysis gave 4-acetoxydihydrobenzofuran which, upon saponification, afforded 4-hydroxydihydrobenzofuran (8) in good yield. This approach is shown to be a general method for preparation of substituted dihydrobenzofurans
在涉及酰基转移然后环化的过程中,用NaBH 4还原2,6-二乙酰氧基-2'-
溴乙酰苯(10)会生成3,4-
二乙酰氧基二氢
苯并呋喃(12)。随后的氢解产生4-乙酰氧基二氢
苯并呋喃,其经皂化后以良好收率得到
4-羟基二氢
苯并呋喃(8)。已表明该方法是制备取代的二氢
苯并呋喃的一般方法。