Carbon‐rich Cycles with Two and More 1,3‐Butadiyne Units – Syntheses, Structures and Reactivities

Gleiter, Rolf; Werz, Daniel B.

doi:10.1002/3527607994.ch7

Cited by 6 publications

(3 citation statements)

References 38 publications

(87 reference statements)

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“…The p conjugation has attracted synthetic chemists for the construction of conjugated systems by coupling of a,w-polyacetylenes to annulenes [2]. Due to their structural simplicity linear conjugated polyynes have been envisioned as molecular wires [3][4][5][6]. Meanwhile, diacetylene compounds are starting material for the synthesis of heterocyclic compounds.…”

Section: Discussionmentioning

confidence: 99%

Crystal structure of 2-[6-(2-formylphenoxy)-2,4-hexadiynyloxy]- benzaldehyde, C20H14O4

Werz

Balalaie

Rominger

et al. 2006

Zeitschrift Für Kristallographie - New Crystal Structures

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Section: Discussionmentioning

confidence: 99%

Crystal structure of 2-[6-(2-formylphenoxy)-2,4-hexadiynyloxy]- benzaldehyde, C20H14O4

Werz

Balalaie

Rominger

et al. 2006

Zeitschrift Für Kristallographie - New Crystal Structures

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“…Scheme shows one example in which base elimination leads to 36 , a [14]annulene . The main product – 37 – is generated by a transannular ring closure, frequently encountered in cases of larger rings containing double or triple bonds . A similar transannular ring closure is found in the nucleophile‐induced cyclization of octadehydrodibenzo[12]annulene 32b , shown in Scheme .…”

Section: Resultsmentioning

confidence: 93%

“…Carbon‐rich cyclic systems containing two or more buta‐1,3‐diyne units were reviewed in 2006 . From this summary it can be seen that in the 1960s a strong motivation was the synthesis of [12]‐ and [14]annulene derivatives.…”

Section: Resultsmentioning

confidence: 99%

Cyclic Compounds Incorporating Two or Four Alkyne Units in Close Proximity – Theory and Experiments

Gleiter

Haberhauer

2018

Eur J Org Chem

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In the first part we summarize the results of experiments performed with medium‐sized cyclic compounds (10, 12, 14 ring size) incorporating either two opposite acetylene units or two buta‐1,3‐diyne units. The acetylene units in the 10‐membered rings react either thermally or with the aid of AuI catalysis to afford bicyclo[4.4.0]‐1,6‐diene rings. Reduction with H2/Pd or addition of I2 to 12‐membered rings containing two opposite buta‐1,3‐diyne units yield 5–6–5 cycles, whereas 14‐membered rings react with HCl to afford 5–8–5 or 6–6–6 rings. In the second part we discuss the results of calculations relating to 1,6‐transannular ring closure of cyclodeca‐1,6‐diyne derivatives in which the two triple bonds are each flanked either with two oxygen atoms or with two NH groups. For the resulting heterocycles, dicarbenes with singlet ground states are predicted. The extension of these model calculations led us to look at substituted phenylacetylenes (e.g., Ph–C≡C–OMe) for which dimerization to cyclobutadiene derivatives was predicted. This forecast could be verified by trapping the cyclobutadiene products with maleic acid.

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Angle‐Strained Cycloalkynes

Hopf¹,

Grunenberg²

2009

Strained Hydrocarbons

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IntroductionAccording to the sp-hybridization model, the carbon-carbon triple bond possesses a linear structure, and indeed, many alkynes fulfill this prediction. High level ab initio calculations [1] of isolated alkyne molecules, as well as gas phase electron diffraction experiments [2] reveal their linear minimum structure. On the other hand, given that the C C-R bending force constant becomes intrinsically smaller for substituted alkynes and polyynes, crystal packing effects may lead to deviations from strictly linear geometries [3]. From a dynamic point of view even in the case of acetylene one has to include the -albeit reduced -flexibility of the carboncarbon triple bond in order to describe, for example, the vinylidene acetylene rearrangement (see below) [4]. Further, the linear sp-hybrid picture only holds true for the electronic ground state. Cis-and trans-bent configurations are known in the case of low-lying electronic states [5]. Nevertheless, many alkynes correspond to the prediction of linearity due to the sp-hybrid model, and we have collected a selection of typical examples, reaching from the parent compound acetylene 1 via a few alkyl 2-4 and aryl acetylenes 5-7 to a functionalized acetylene, dimethyl acetylenedicarboxylate 8, in Scheme 7.1, together with the appropriate references [1, 2, 6-11], all dating from the recent literature.The easiest way to distort a triple bond is to incorporate it into a sufficiently small ring structure. The question, of course, is what this ring size is, and from what ring size on the respective cycloalkynes can we isolate compounds, that can be worked with under normal laboratory conditions [12]. Rather than using the nonspecific term 'distorted cycloalkyne' Krebs [12] prefers to speak of 'angle-strained cycloalkynes'. Since it is easier to deform a C C-C arrangement than its more hydrogenated olefinic and saturated analogs, relatively large angle deformations are possible in cycloalkynes without significant changes in energy. Krebs arbitrarily considers all cycloalkynes in which the C C-C angle is deformed by more than 10° as angle-strained [12]. Accepting this definition, the stable cyclononyne (see below) is an angle-strained cycloalkyne, whereas cyclodecyne is not.

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Carbon‐rich Cycles with Two and More 1,3‐Butadiyne Units – Syntheses, Structures and Reactivities

Cited by 6 publications

References 38 publications

Crystal structure of 2-[6-(2-formylphenoxy)-2,4-hexadiynyloxy]- benzaldehyde, C20H14O4

Crystal structure of 2-[6-(2-formylphenoxy)-2,4-hexadiynyloxy]- benzaldehyde, C20H14O4

Cyclic Compounds Incorporating Two or Four Alkyne Units in Close Proximity – Theory and Experiments

Angle‐Strained Cycloalkynes

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