Synthesis of branched triangulanes

Lukin, K. A.; Kozhushkov, Sergei I.; Andrievskii, A. A.; Уграк, Б. И.; Зефиров, Н. С.

doi:10.1021/jo00021a041

Cited by 37 publications

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“…In view of the rapidly growing number of possible stereoisomers of these [n]triangulanes with increasing n (e.g., the family of [9]triangulanes consists of four meso diastereomers and 16 pairs of enantiomers), [7] a linear strategy to approach any enantiomerically pure continuously helical [n]triangulane with n ! 4 would not be feasible (there is only one enantiomeric pair of s- [6]helicenes and two additional pairs of enantiomeric [6]triangulanes).…”

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confidence: 99%

“…4 would not be feasible (there is only one enantiomeric pair of s- [6]helicenes and two additional pairs of enantiomeric [6]triangulanes). [7] We therefore conceived a reasonably general convergent strategy, and report herein our first results on its successful application in the synthesis of enantiomerically pure s- [9]helicenes.…”

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“…The addition of dibromocarbene to the double bond in the THP-protected alcohol (1R,3S)-7 or the acetate (1S,3R)-6, [8] adopting a well-established protocol, [9] was followed by deprotection and chromatographic separation to furnish 5,5-dibromodispiro[2.0.2.1]-methanols (1R,3S,4S)-, (1R,3S,4R)-, (1S,3R,4S)-, and (1S,3R,4R)-8 in 27, 25, 32 and 28 % yield, respectively (Scheme 1).…”

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“…After chromatographic separation from the corresponding Z isomers, diols (E)-(3R,3'R,4R,4'R,5S,5'S)-10 and (E)-(3S,3'S,4S,4'S,5R,5'R)-10 were obtained in 33 and 23 % yield, respectively. These products have the appropriate configurations required for the targeted, continuously helical [9]triangulanes. The assigned E configuration of (3S,3'S,4S,4'S,5R,5'R)-10 was confirmed by X-ray crystalstructure analysis.…”

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A Convergent Route to Enantiomerically Pure Higher [n−2]Triangulanedimethanol Derivatives and [n]Triangulanes (n≥7)

et al. 2004

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A Convergent Route to Enantiomerically Pure Higher [n−2]Triangulanedimethanol Derivatives and [n]Triangulanes (n≥7)

et al. 2004

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“…Structure of (R,R)-6 a in the crystal. The enantiomerically pure acid (R)-3 was first transformed to its ethyl ester ((R)-7), [12,17] following a standard procedure, [18] which was then cyclopropanated with the Simmons ± Smith reagent (CH 2 I 2 /Zn) [19] accelerated by ultrasonication [20] to give a mixture of ethyl endo-(1R,3R)-and exo-(1R,3S)-…”

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The First Enantiomerically Pure Triangulane (M)-Trispiro[2.0.0.2.1.1]nonane Is a σ-[4]Helicene

Meijere

Хлебников

Kostikov

et al. 1999

Angewandte Chemie International Edition

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A remarkably high specific rotation, even at 589 nm, is shown by (M)‐1, the first enantiomerically pure unbranched [4]triangulane, although it has no chromophore that would lead to any significant absorption above 200 nm. This outstanding rotatory power is in line with a helical arrangement of its σ bonds, as confirmed by high‐level computations. Thus, it is appropriate to call (M)‐1 a “σ‐[4]helicene”, the first σ‐bond analogue of the aromatic [n]helicenes.

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Das erste enantiomerenreine Triangulan: (M)-Trispiro[2.0.0.2.1.1]nonan ist ein σ-[4]Helicen

Meijere¹,

Хлебников²,

Kostikov³

et al. 1999

Angewandte Chemie

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Professor Hans-Jürgen Quadbeck-Seeger zum 60. Geburtstag gewidmet Enantiomerenreine chirale Verbindungen, die im üblicherweise genutzten UV/Vis-Spektralbereich zwischen 200 und 800 nm nicht optisch aktiv sind, sind als kryptochiral bezeichnet worden. [1] Wie von Wynberg et al. vor fast 35 Jahren belegt wurde, [2] zeigen chirale Kohlenwasserstoffe mit vier verschiedenen Alkylgruppen an ihren Chiralitätszentren selbst in reiner Form keine optische Drehung und sind demnach kryptochiral. Dies geht wahrscheinlich auf die konformative Beweglichkeit der Alkylketten in solchen acyclischen Kohlenwasserstoffen zurück. Im Unterschied dazu sind [n]Triangulane 1, [3] d. h. Kohlenwasserstoffe, die ausschlieûlich aus spiroanellierten und dadurch abwechselnd senkrecht zueinander stehenden Cyclopropanringen bestehen, vollkommen starr. Viele der höheren [n]Triangulane (n ! 4), die keine Chiralitätszentren enthalten, sind symmetriebedingt chiral, [4] und sie sollten sich nicht kryptochiral verhalten, obwohl sie gesättigte Kohlenwasserstoffe sind. Um diese Hypothese zu testen, haben wir eine Synthese des enantiomerenreinen (M)-[4]Triangulans (M)-2, des kleinsten chiralen [n]Triangulans, entwickelt. [4] Racemisches [4]Triangulan rac-2 wurde erstmals 1973 synthetisiert, [5] und in der Zwischenzeit wurden verbesserte Synthesen [6] sowie spek-ZUSCHRIFTEN

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Synthesis of branched triangulanes

Cited by 37 publications

References 0 publications

A Convergent Route to Enantiomerically Pure Higher [n−2]Triangulanedimethanol Derivatives and [n]Triangulanes (n≥7)

A Convergent Route to Enantiomerically Pure Higher [n−2]Triangulanedimethanol Derivatives and [n]Triangulanes (n≥7)

The First Enantiomerically Pure Triangulane (M)-Trispiro[2.0.0.2.1.1]nonane Is a σ-[4]Helicene

Das erste enantiomerenreine Triangulan: (M)-Trispiro[2.0.0.2.1.1]nonan ist ein σ-[4]Helicen

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