Tandem ring expansion of alkenyl benzocyclobutenol derivatives into substituted naphthols
Tandem ring expansion of alkenyl benzocyclobutenol derivatives into substituted naphthols
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DOI：
10.1002/anie.200602428
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发表时间：
2006-01-01
影响因子：
16.6
通讯作者：
Suzuki, Keisuke
中科院分区：
文献类型：
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作者：
Hamura, Toshiyuki;Suzuki, Takeaki;Suzuki, Keisuke
在我们对聚芳族化合物合成的持续研究中，[1]我们先前报道了通过串联电环化反应将烯基苯并环丁烯A热转化为官能化萘酚C [Eq.①]。[2]我们在本文中报告了一种能够将相同的起始原料A转化为异构体萘酚E的方法[方程式：②]。该过程包括两个连续的环扩大（A！D！D！E）：卤离子（X+）诱导烯基苯并环丁烯A（四元环）扩环为茚满酮D（五元环），而SmI 2促进D扩环为萘酚E（六元环），同时伴随着ROSmI 2的消除。五个！6环放大过程开始与4！通过二醇衍生物1的卤化引发的5环扩大（表1）。[3]当醇1在THF（08 ℃）中用ICl（1.5当量）处理时，RT），环扩大顺利发生，得到碘甲基茚满酮2a，产率90%，为立体异构体的混合物（表1，条目1）。[4]NOE研究表明，2a的主要产物具有相对于碘甲基的顺式构型，
In our continuing studies on the synthesis of polyaromatic compounds,[1] we previously reported thermal conversion of alkenyl benzocyclobutene A into functionalized naphthol C by tandem electrocyclic reactions [Eq.(1)].[2] We report herein a process that is capable of converting the same starting material A into isomeric naphthol E [Eq.(2)]. The process involves two successive ring enlargements (A! D! E): the halonium ion (X+) induces ring expansion of alkenyl benzocyclobutene A (four-membered ring) to indanone D (five-membered ring), and SmI2 promotes expansion of D to naphthol E (six-membered ring) with concomitant elimination of ROSmI2.This tandem 4! 5! 6 ring-enlargement process starts with the 4! 5 ring enlargement triggered by the halogenation of diol derivative 1 (Table 1).[3] When alcohol 1 was treated with ICl (1.5 equivalents) in THF (08C! RT), the ring enlargement occurred smoothly to give iodomethyl indanone 2a in 90% yield as a mixture of stereoisomers (Table 1, entry 1).[4] An NOE study showed that the major product of 2a has the cis configuration with respect to the iodomethyl and the