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首页> 外文期刊>Chemistry: A European journal >The first enantiomerically pure [n]trianguanesandanalogues:#sigma#-[n]helicenes with remarkable features
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The first enantiomerically pure [n]trianguanesandanalogues:#sigma#-[n]helicenes with remarkable features

机译：第一个对映体纯的[n] trianguanesandanalogues：具有显着特征的#sigma＃-[n]螺旋

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(M)-(-)-and (P)-(+)-Trispiro[2.0.0.2.1.1.]nonanes[(M)-and(P)-3]as well as (M)-(-)and (P)-(+)-tetraspiro[2.0.0.0.2.1.1.]undecanes[(M)-and(P)-4]-enantiomerically pure unbranched[4]-and[5]triangulanes-have been prepared starting from racemic bicycloprophlidenecarboxylic [(1RS)-12]and exo-dispirol[2.0.2.1]heptane-1-carboxylic[(1RS,2SR)-13]acids.Theopticalresolutions of rac-12 and rac-13furnished enantimerically pure acids (S)-(+)-12,(R)-(-)-12,(1R,3S)-(-)-13,and (1S,3R)-(+)-13.The ethyl ester (R)-25 of the acids (1R,3S)-13 and (1S,3R)-13 were converted into enantiomerically pure consisted of an enzymatic deracemization of endo-[(1SR,3SR)-dispiro[2.0.2.1]hepthl]methanol (rac-20) or anti-[1SR,3RS]-4-methylenespiropentyl (rac-18).This afforded(S)-(-)-and (R)-(+)-28(starting from rac-20),as well as enantimerically pure(M)-(-)-and (P)-(+)-1,4-dimethylene-spiropentanes[(M)-and(p)-23]starting from rac-18.The methylenetriangulanes(S)-(-)-and(R)-(+)-28were cyclopropanated furnishing (M)-and (P)-3.The rhodium-catalyzed onto(S)-(-)-and(R)-(+)-28 yielded four diastereomeric ethyl trispiro[2.0.0.2.1.1]nonane-1-carboxylates in approximately equal proportions.The enantiomerically pure esters (1R,3S,4S)-and (1S,3R,4R)-30 were isolated by careful distillation and then transformed into [5]triangulanes (M)-and (P)-4 using the same sequence of reactions as applied for (M)-and (P)-3.The structures of the key intermediates(R)-12 and rac-31 were confirmed by X-ray analyese.Although[4]-and [5]triangulanes have no chromophore which would lead to any significant absorption above 200nm, they have remarkably high specific rotations even at 589 nm with [#alpha#_3~(20)=-192.7[(M)-3,c-1.18,CHCl_3]]or +373.0[(P)-4,c=1.18.CHCl_3].This remarkable optical rotation is in line with their helical arrangement of #sigma# bonds,as confirmedby a full valence space single excitation configuration interaction treatment(SCI)in conjunction with DFT computations at the B3LYP/TZUP/B3LYP/6-31+G(d,p)level of theory which reproduce the ORD very well.Thus,it is appropriate to call the helically shaped unbranched [#eta#]triangulanes the "#sigma#-[#eta#helicenes]",representing the #sigma#-bond analoguesof the aromatic [#eta#]helicenes.
机译：（M）-（-）-和（P）-（+）-Trispiro [2.0.0.2.1.1。]壬烷[（M）-和（P）-3]以及（M）-（-）和已开始制备（P）-（+）-四螺[2.0.0.0.2.1.1。]十一烷[（M）-和（P）-4]-对映体纯的无支链[4]-和[5]三角烷-外消旋双环亚丙基羧酸[（1RS）-12]和外二螺螺[2.0.2.1]庚烷-1-羧酸[（1RS，2SR）-13]酸的化合物。rac-12和rac-13的对映体纯酸（S）的光学拆分-（+）-12，（R）-（-）-12，（1R，3S）-（-）-13和（1S，3R）-（+）-13。乙酯（R）-25酸（1R，3S）-13和（1S，3R）-13中的一部分被转化为对映体纯的，包括对内[[（1SR，3SR）-双螺[2.0.2.1]庚基]甲醇（rac- 20）或抗[1SR，3RS] -4-亚甲基螺旋戊基（rac-18）。这也提供了（S）-（-）-和（R）-（+）-28（从rac-20开始）以对映体纯（M）-（-）-和（P）-（+）-1,4-二亚甲基-螺旋戊烷[（M）-和（p）-23]从rac-18开始。 -（-）-和（R）-（+）-28分别是环丙烷化的（M）-和（P）-3.T他用铑催化在（S）-（-）-和（R）-（+）-28上生成了大约等比例的四种非对映异构乙基三螺[2.0.0.2.1.1]壬烷-1-羧酸酯。对映体纯的酯（通过仔细蒸馏分离出1R，3S，4S）-和（1S，3R，4R）-30，然后使用与用于（1）相同的反应顺序将其转化为[5] triangulanes（M）-和（P）-4。 M）和（P）-3。关键中间体（R）-12和rac-31的结构已通过X射线分析确定。尽管[4]-和[5]三角烷没有发色团，从而导致任何大于200nm的吸收，即使在589 nm处也具有非常高的比旋光，[[αalpha＃_3〜（20）=-192.7 [（M）-3，c-1.18，CHCl_3]]或+373.0 [[P） -4，c = 1.18.CHCl_3]。这种显着的旋光与其＃sigma＃键的螺旋排列一致，这是通过全价空间单激发构型相互作用处理（SCI）结合B3LYP /处的DFT计算所证实的TZUP / B3LYP / 6-31 + G（d，p）的理论水平ch可以很好地重现ORD。因此，将螺旋形的直链[＃eta＃]三角形称为“ #sigma＃-[＃eta＃helicenes]”是适当的，代表芳香族[＃]的＃sigma＃键类似物eta＃]螺旋。

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