CYCLIC DIENES .4. THE DIMERIZATION OF THIOPHENE 1-DIOXIDE
CYCLIC DIENES .4. THE DIMERIZATION OF THIOPHENE 1-DIOXIDE
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DOI：
10.1021/ja01636a059
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发表时间：
1954-01-01
影响因子：
15
通讯作者：
CUMMINS, EW
中科院分区：
文献类型：
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作者：
BAILEY, WJ;CUMMINS, EW
噻吩1-二氧化物（I）易于进行二聚化，这表明该环系统几乎没有或没有稳定化。这种芳香性的缺乏可以用两种不同的概念来解释。由于二氧化硫在环中只有4个电子，因此它缺乏根据休克尔的芳香共振所必需的（2+ 4 n）或6个电子。[4]使用另一种方法，对于芳香稳定，必须假设与la和lb类似的共振结构必须是亚胺二烯酮。6后者的二聚体在加热时失去桥接的羰基，产生2，2a，4，5-四苯基-2a，6a-二氢茚酮。后一个例子表明噻吩1-二氧化物（I）环比环戊二烯酮环稍微更稳定，因为3，4-二苯基噻吩1-二氧化物7在类似条件下是稳定的单体。由于本工作最初提出，1 Bordwell，McKellin和Babcock 8认为苯并噻吩1-二氧化物（VIII）在230 ℃下二聚产生不稳定的导管IX，失去二氧化硫得到6 α，11b-二氢萘并-（2，1b）-苯并（d）噻吩1-二氧化物（X）。这项工作清楚地表明，稳定效果的苯环上的噻吩1-二氧化物环。Bordwell和McKellin 9先前从双键VIII的加成反应中得出结论，噻吩二氧化物环不是芳族的，而是表现得更像β-不饱和砜。此外，由于目前的工作提出，1 Backer和Melles 10报道了两个衍生物的II的合成。
The ease with which thiophene1-dioxide (I) un-dergoes dimerization suggests that there is little or no stabilization of this ring system. This lack of aromatic properties can be rationalized by two differ-ent concepts. Since thedioxide possesses only four electrons in the ring, it lacks the (2+ 4n) or 6 electrons necessary for aromatic resonance according to Huckel. 4 Using another approach, it must be assumed for aro-matic stabilization that the resonance structures similar to la and lb must be im-dienone. 6 The dimer of the latter on heating loses the bridged carbonyl group to produce the 2, 2a, 4, 5-tetraphenyl-2a, 6a-dihydroindenone. This latter example would indicate that the thiophene 1-dioxide (I) ring is slightly more stable than the cyclopentadienone ring, since 3, 4-diphenylthiophene 1-dioxide7 is a stable monomer under similar conditions.Since the present work was originally presented, 1 Bordwell, McKellin andBabcock8 reportedthat benzothiophene 1-dioxide (VIII) dimerized at 230 to produce the unstableadduct IX, which lost sul-fur dioxide to give 6a, llb-dihydronaphtho-(2, lb)-benzo (d) thiophene 1-dioxide (X). This work clearly indicates the stabilizing effect of the benzene ring on the thiophene 1-dioxide ring. Bordwell and McKellin9 had previously concluded from the addition reactions to the double bondin VIII that the thiophene dioxide ring was not aromatic but behaved more like an,/3-unsaturated sulfone. Also since the present work was presented, 1 Backer and Melles10 reported the synthesis of two derivatives of II.