Regiocontrolled benzannulation of diaryl (gem-dichlorocyclopropyl)methanols for the synthesis of unsymmetrically substituted α-arylnaphthalenes:: Application to total synthesis of natural lignan lactones
Regiocontrolled benzannulation of diaryl (gem-dichlorocyclopropyl)methanols for the synthesis of unsymmetrically substituted α-arylnaphthalenes:: Application to total synthesis of natural lignan lactones
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DOI：
10.1021/jo047751u
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发表时间：
2005-04-01
影响因子：
3.6
通讯作者：
Tanabe, Y
中科院分区：
文献类型：
--
作者：
Nishii, Y;Yoshida, T;Tanabe, Y
利用路易斯酸催化的芳基（芳基‘）-2,2-二氯环丙基甲醇（芳基不等于芳基’，缩写为AACMs）的区域控制苯并制得一种高效的高取代-芳基萘类似物。这两种AACM非对映体都是通过高立体选择性的ArLi加成（bbb95 /5）到宝石-二氯环丙基芳基酮中制备的。路易斯酸的选择决定了苯并环化反应的环化区域选择性。TiCl4和SnCl4采用螯合途径，而三氟化硅酯采用非螯合途径得到不对称取代的α -芳基萘，产率为40-91%，具有中等至优异的区域选择性（TiCl4或SnCl4； bbb99 /1-3/1, TBDMSOTf; > 1/99-1/4）。因此，通过选择反应顺序或适当的催化剂，α -芳基或α -芳基'部分（附属芳基）可选择性地引入α -芳基萘。应用该方法合成了不对称取代的天然木脂素内酯，justicidin B, retrojusticidin B， dehydrodesoxypodophylotoxin和相关的类似物5'-甲氧基retrochinensin。采用传统的二醇前体内酯化法合成了木脂素内酯（retrojusticidin B和5′-甲氧基retrochinensin），而采用一种新的单酰化方法合成了正常的木脂素内酯（justicidin B和脱氢脱氧鬼臼毒素）。
An efficient synthesis of highly substituted alpha-arylnaphthalene analogues has been developed utilizing Lewis acid-promoted regiocontrolled benzannulation of aryl(aryl')-2,2-dichlorocyclopropylmethanols (aryl not equal aryl'; abbreviated as AACMs). Both AACM diastereomers were easily prepared via highly stereoselective addition (> 95/5) of ArLi to gem-dichlorocyclopropropyl aryl' ketones. The choice of Lewis acids determined the cyclization regioselectivity of the present benzannulation. TiCl4 and SnCl4 used the chelation pathway, whereas silyl triflates used a nonchelation pathway to give unsymmetrically substituted regioisomeric alpha-arylnaphthalenes in 40-91% yields with moderate to excellent regioselectivity (TiCl4 or SnCl4; > 99/1-3/1, TBDMSOTf; > 1/99-1/4). Thus, the alpha-aryl or alpha-aryl' moiety (accessory aryl group) was alternatively introduced to alpha-arylnaphthalenes by choosing either the order of the reaction sequences or the appropriate catalyst. Application of the present method to the total synthesis for unsymmetrically substituted natural lignan lactones, justicidin B, retrojusticidin B, dehydrodesoxypodophyllotoxin, and a related analogue, 5'-methoxyretrochinensin, was demonstrated. Lignan retrolactones (retrojusticidin B and 5'-methoxyretrochinensin) were synthesized by the conventional lactonization of the diol precursor, whereas a novel Bu2SnO-mediated monoacylation method was applied to the synthesis of normal lignan lactones (justicidin B and dehydrodesoxypodophyllotoxin).