Perhydrohelicenes and other diamond-lattice based hydrocarbons: the choreography of inversion.
Perhydrohelicenes and other diamond-lattice based hydrocarbons: the choreography of inversion.
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DOI：
10.1039/c7sc01759f
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发表时间：
2017-09-01
期刊：
影响因子：
8.4
通讯作者：
Sessions RB
中科院分区：
文献类型：
--
作者：
Alder RW;Butts CP;Sessions RB
在稠合环己烷低聚物2、3和4（均基于顺式十氢化萘1）中的整体反转通过在任何时间涉及不超过两个相邻环的扭舟构象的滚动过程发生。在稠合环己烷低聚物2、3和4（均基于顺式十氢化萘1）中的整体反转通过在任何时间涉及不超过两个相邻环的扭舟构象的滚动过程发生。这些反向环沿着低聚物移动，其过程由相邻的椅子精确地编排。与顺式十氢萘一样，实际的转化机制可以是逐步的[CC → TC → TT → C′T → C′C′]，但在2中，则是协同的[CC → TC → C′T → C′C′]。全氢螺烯4的全顺式、反式、顺式异构体基于金刚石晶格并且具有显著低的应变能。比较了4和螺旋烯5中的阻碍反转。对于这两种情况，中间体和过渡态的形状大致上就像老式的电话线。在这两种情况下，势垒随着系统的长度而增加，最终达到ca的平台值。4的分子量为120 kJ mol ~（-1），远低于5的分子量（320-350 kJ mol ~（-1））。虽然滚动反转在任何时刻只需要两个相邻的环处于扭船构象，但螺旋桨烷6中的反转需要所有三个环转化为扭船，并且S4对称烃7需要所有四个环转化为扭船。因此，7可能具有任何非低聚顺式十氢化萘衍生结构的最高势垒（在B3 LYP/6- 31 G * 下为87.3 kJ mol-1）。
Overall inversion in fused cyclohexane oligomers 2, 3, and 4 (all based on cis-decalin 1) occurs by a rolling process involving no more than two adjacent rings in twist-boat conformations at any time. Overall inversion in fused cyclohexane oligomers 2, 3, and 4 (all based on cis-decalin 1) occurs by a rolling process involving no more than two adjacent rings in twist-boat conformations at any time. These inverting rings move along the oligomer in processes that are precisely choreographed by the adjacent chairs. Actual inversion mechanisms can be stepwise [CC → TC → TT → C′T → C′C′], as for cis-decalin, but it is shown that a concerted alternative [CC → TC → C′T → C′C′] is enforced in 2. The all-cis,anti,cis-isomers of perhydrohelicenes 4 are based on the diamond lattice and have remarkably low strain energies. Helix inversion in 4 is compared with that in helicenes 5. For both, the intermediates and transition states have shapes broadly like kinked old-style telephone cables. In both cases barriers increase with the length of the system to eventually reach a plateau value of ca. 120 kJ mol–1 for 4, much lower than that for 5 (320–350 kJ mol–1). While rolling inversion only requires two adjacent rings in twist-boat conformations at any instant, inversion in propellane 6 requires all three rings be converted to twist-boats, and the S 4 symmetric hydrocarbon 7 requires all four rings to be converted to twist-boats. As a consequence, 7 probably has the highest barrier of any non-oligomeric cis-decalin derived structure (87.3 kJ mol–1 at B3LYP/6-31G*).
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影响因子：
15
作者：
BAAS, JMA;VANDEGRAAF, B;VANHEE, P
通讯作者：
VANHEE, P
影响因子：
2.1
作者：
RICHMAN, JE;SIMMONS, HE
通讯作者：
SIMMONS, HE
影响因子：
15
作者：
Janke, RH;Haufe, G;Borkent, JH
通讯作者：
Borkent, JH
影响因子：
15
作者：
DALLING, DK;GRANT, DM
通讯作者：
GRANT, DM
影响因子：
64.8
作者：
Burns, Matthew;Essafi, Stephanie;Bame, Jessica R.;Bull, Stephanie P.;Webster, Matthew P.;Balieu, Sebastien;Dale, James W.;Butts, Craig P.;Harvey, Jeremy N.;Aggarwal, Varinder K.
通讯作者：
Aggarwal, Varinder K.