Construction of a <i>cis</i>-Cyclopropane via Reductive Radical Decarboxylation. Enantioselective Synthesis of <i>cis-</i> and <i>trans-</i>1-Arylpiperazyl-2-phenylcyclopropanes Designed as Antidopaminergic Agents
作者:Kazuya Yamaguchi、Yuji Kazuta、Hiroshi Abe、Akira Matsuda、Satoshi Shuto
DOI:10.1021/jo0302206
日期:2003.11.1
Barton reductive radical decarboxylation as the key step. (1S,2R)-1-(tert-Butyldiphenylsilyloxy)methyl-2-carboxy-2-phenylcyclopropane (5), which was prepared from (S)-epichlorohydrin ((S)-7), was converted into its N-hydroxypyridine-2-thione ester 12, the substrate for the reductive radical decarboxylation. When 12 was treated with TMS3SiH in the presence of Et3B or AIBN, the decarboxylation and subsequent
(1S,2S)-,(1S,2R)-和(1R,2S)-1-(2,4-二甲基苯基)哌嗪基-2-苯基环丙烷(分别为2a,3和ent-3)以Barton还原性自由基脱羧为关键步骤,从手性表氯醇合成了被设计为氟哌啶醇(1)(一种临床有效的抗精神病药)的受构象限制的类似物。由(S)-表氯醇((S)-7)制得的(1S,2R)-1-(叔丁基二苯基甲硅烷氧基)甲基-2-羧基-2-苯基环丙烷(5)被转化为其N-羟基吡啶-2-硫酮酸酯12,为还原性自由基脱羧的底物。当在Et3B或AIBN存在下用TMS3SiH处理12时,发生了从大体积甲硅烷氧基甲基部分相反的一侧对环丙基自由基中间体进行脱羧和随后的氢化物攻击,导致选择性地形成具有顺式-环丙烷结构的相应的还原性脱羧产物4-顺式。由4-顺式容易地合成出顺式-环丙烷型目标化合物3。从(R)-表氯醇((R)-7)开始,类似地合成了ent-3。用由Bu2Mg和i-Pr2N