A Highly Regio- and Stereoselective Nickel-Catalyzed Ring-Opening Reaction of Alkyl- and Allylzirconium Reagents to 7-Oxabenzonorbornadienes
作者:Ming-Si Wu、Masilamani Jeganmohan、Chien-Hong Cheng
DOI:10.1021/jo051660v
日期:2005.11.1
allyl zirconium reagents 4a−c also underwent ring-opening reactions with 1a and 1c to give 5a−d in very good yields. The alkylative ring-opening products from 7-oxabenzonorbornadiene can be further converted to naphthalene derivatives 6a−c, via an acid-mediated dehydration, in good to excellent yields. A possible mechanism for the present catalytic reaction was proposed.
描述了一种通过镍催化的烷基或烯丙基锆试剂向7-氧杂苯并降冰片二烯的高区域和立体选择性开环加成反应来合成顺式-2-烷基-或烯丙基1,2-二氢萘的有效方法。用各种烷基锆试剂2a - j(Cp 2 ZrClCH 2 CH 2 R:R =叔丁基,正丁基,正戊基,-(CH 2)3 CH C(CH 3)处理7-氧杂苯并降冰片二烯1a - c 2,-SiMe 3,-CH在50°C的无水THF中,在NiBr 2(dppe)和Zn粉存在下,在2 SiMe 3,-(CH 2)3 Br,环戊基,环己基和苄基中得到相应的顺式-2-烷基-1,2 -二氢萘衍生物3a - m的产率高。另外,烯丙基锆试剂4a - c也与1a和1c进行开环反应,以非常好的收率得到5a - d。从7-oxabenzonorbornadiene的alkylative开环产物可以被进一步转化为萘衍生物6A -c,通过酸介导的脱水,收率良好至优异。提出了本催化反应的可能机理。