Synthetic Applications of 3,4-Bis(trimethylsilyl)thiophene: Unsymmetrically 3,4-Disubstituted Thiophenes and 3,4-Didehydrothiophene(,).
Synthetic Applications of 3,4-Bis(trimethylsilyl)thiophene: Unsymmetrically 3,4-Disubstituted Thiophenes and 3,4-Didehydrothiophene(,).
复制标题
3,4-双(三甲基硅基)噻吩的合成应用：不对称3,4-二取代噻吩和3,4-二脱氢噻吩(,)。
作者：
X. Ye;H. Wong
通过3条路线合成了3，4-二(三甲基硅基)噻吩(1a)：(A)1，3-偶极环加成；(B)3，4-二溴噻吩改性；(C)分子间的噻唑-炔基Diels-Alder反应。3，4-二(三甲基硅基)噻吩(1a)可作为一种多功能的构筑基团，利用其区域专一性的单异构体取代和钯催化的交叉偶联反应来构建不对称的3，4-二取代的噻吩类化合物。以这种方式制备了噻吩类化合物15、16、17a-j、19a、b、20、22a-c、23a、b、24a-d、25a-c和27a-j。并通过钯催化的有机硼氧杂多环自偶联反应实现了噻吩二聚体28和噻吩二聚体29的合成。通过硼杂环己烷26c将C-Si键转化为C-Sn键而形成的锡基噻吩31既经历了碳化偶联，又经历了锂化反应，然后用亲电试剂猝灭，也得到了不对称的3，4-二取代噻吩33和36a-c。此外，3，4-二(三甲基硅基)噻吩烯(1a)可以作为合成高应变环状异丁烯3，4-二脱氢噻吩烯(2)的原料，它与几种烯烃的捕获反应证实了它的存在。
3,4-Bis(trimethylsilyl)thiophene (1a) was synthesized by three routes: (a) 1,3-dipolar cycloaddition; (b) modification of 3,4-dibromothiophene; and (c) intermolecular thiazole-alkyne Diels-Alder reaction. 3,4-Bis(trimethylsilyl)thiophene (1a) can function as a versatile building block for the construction of unsymmetrically 3,4-disubstituted thiophenes utilizing its stepwise regiospecific mono-ipso-substitution followed by palladium-catalyzed cross-coupling reactions. In this manner, thiophenes 15, 16, 17a-j, 19a,b, 20, 22a-c, 23a,b, 24a-d, 25a-c, and 27a-j were prepared. The thiophene-3,4-diyl dimer 28 and thiophene-3,4-diyl tetramer 29 were also realized by palladium-catalyzed self-coupling reaction of organoboroxines. The stannylthiophene 31, formed by conversion of the C-Si bond to a C-Sn bond via boroxine 26c underwent both carbonylative coupling and lithiation followed by quenching with electrophiles to afford unsymmetrically 3,4-disubstituted thiophenes 33 and 36a-c as well. Moreover, 3,4-bis(trimethylsilyl)thiophene (1a) can be used as the starting material for the generation of the highly strained cyclic cumulene 3,4-didehydrothiophene (2), whose existence was substantiated by its trapping reaction with several alkenes.