A Versatile Synthesis of 1-Benzoheteroepines Containing Group 14, 15, and 16 Heavier Elements via a Common 1,6-Dilithium Intermediate.
作者:Shuji YASUIKE、Shin-ichi SHIRATORI、Jyoji KURITA、Takashi TSUCHIYA
DOI:10.1248/cpb.47.1108
日期:——
Fully unsaturated group 14 (Si, Ge, and Sn), group 15 (P, As, Sb, and Bi) and group 16 (S, Se, and Te) 2-trimethylsilyl-1-benzoheteropines (16a-j), including the first isolated examples of bismepines, have been prepared by reaction of the corresponding electrophilic metal reagents (MX2 or MX4; M=group 14, 15, and 16 heavier elements) with the key 1, 6-dilithium intermediate (9), generated from the common starting compound (Z, Z)-1-bromo-4-(2-bromophenyl)-1-trimethylsily-1, 3-butadiene (14) by treatment with tert-butyllithium. The trimethylsilyl group in 16b-j was readily removed by treatment with tetrabutylammonium fluoride to give the desired C-unsubstituted 1-benzoheteroepines (1b-j). Single crystal X-ray analyses of 1d (P) and 1f (Sb) revealed that the seven-membered rings exist in boat conformations with the heteroatoms at the bows. All obtained C-unsubstituted group 15 and 16 1-benzoheteroepines (1d-j) were thermolabile in solution towards heteroatom extrusion, while heteroepines (16d-j) having the bulky trimethylsilyl group at the 2-position were much more stable than 1d-j. The half-lives of 1d-j estimated from 1H-NMR spectral analysis indicate that the thermal stabilities of 1d-j decrease in the order 1f (Sb)>1d (P)>1e(As)>1g(Bi) in the group 15 heteroepines and 1j (Te)<1i (Se)>1h (S) in the group 16 heteroepines.
完全不饱和的第14族(Si、Ge、Sn)、第15族(P、As、Sb、Bi)和第16族(S、Se、Te)的2-三甲基硅基-1-苯并杂环戊二烯(16a-j),包括首批分离得到的二甲基乙二酮肼,已通过相应的亲电金属试剂(MX2或MX4;M=第14、15、16族较重元素)与关键的1,6-二锂中间体(9)反应制备而成,后者由常见起始化合物(Z,Z)-1-溴-4-(2-溴苯基)-1-三甲基硅-1,3-丁二烯(14)经特丁基锂处理生成。16b-j中的三甲基硅基团可通过四正丁基氟化铵处理轻易去除,得到所需的C-未取代1-苯并杂环戊二烯(1b-j)。单晶X射线分析显示,1d(P)和1f(Sb)中的七元环以船式构象存在,杂原子位于船首位置。所有获得的C-未取代第15和16族1-苯并杂环戊二烯(1d-j)在溶液中对热敏感,倾向于杂原子排出反应,而2-位带有庞大三甲基硅基团的杂环戊二烯(16d-j)比1d-j稳定得多。从1H-NMR谱分析估算的1d-j半衰期表明,热稳定性按以下顺序递减:在第15族杂环戊二烯中为1f(Sb)>1d(P)>1e(As)>1g(Bi),在第16族杂环戊二烯中为1j(Te)<1i(Se)>1h(S)。