The enthalpies of formation ΔHf and the ring strain energies Eg were calculated for the nine isomeric dithiacyclooctynes 1‐‐9 by applying the MNDO method. Reaction Scheme 2 shows the synthesis of 1,4‐dithia‐2‐cyclooctyne (1), which was the highest Eg value in this series. It dimerizes to 13 in the absence of reaction partners. Scheme 4 summarizes the preparation of 1,5‐dithia‐2‐cyclooctyne (2) and its homologue 1,5‐dithia‐2‐cyclononyne (23) and Scheme 6

Meier, Herbert; Dai, Yujia; Schuhmacher, Hans; Kolshorn, Heinz

doi:10.1002/cber.19941271028

Cited by 10 publications

(5 citation statements)

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“…These were obtained under dilution conditions by the use of suitably functionalised cyclisation substrates (dibromides, [35] dithiols [36] ). The introduction of unsaturated elements (a, b in Figure 8) enabled the examination of the influence of etheno and ethyno bridges [37] towards the deformation of the aromatic parts and chiroptical properties. NMR and X-ray-crystallographic studies re- All cyclophanes were separated into their enantiomers and showed similar CD spectra with typical Cotton effects for electron transitions of the aromatic rings with significant contributions of the sulfur atoms.…”

Section: Introductionmentioning

confidence: 99%

Structure/Chiroptics Relationships of Planar Chiral and Helical Molecules

Grimme¹,

et al. 1998

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Section: Introductionmentioning

confidence: 99%

Structure/Chiroptics Relationships of Planar Chiral and Helical Molecules

Grimme¹,

et al. 1998

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“…The hypothetical thiosulfenyl chloride 1r must by necessity be an intermediate in reaction (10) with R = C 6 H 5 , but cannot be observed directly. 5 Ethynyl hydrogen disulfide (1a) 1,2 and 1,2-bis(disulfanyl)ethyne (1s) 1 …”

Section: Methodsmentioning

confidence: 98%

“…1 An MNDO theoretical study of the geometrical ring strain of nine isomeric dithiacyclooctynes showed that 1,2-dithiacyclooct-3-yne 3 is severely strained (E g 17.7 kcal mol −1 ), only surpassed by the isomer 1,4-dithiacyclooct-2-yne (E g 18.4 kcal mol −1 ). 10 The rearrangement of 3 to 8 according to Eq. (16), vide infra, would, of course, relieve this ring strain.…”

Section: The Physical Properties Of Alk-1-yn-1-yl Disulfidesmentioning

confidence: 99%

The Chemistry of Alk-1-yn-1-yl Disulfides—A Review

Senning

2009

Phosphorus, Sulfur, and Silicon and the Related Elements

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“…A sizeable number of derivatives of cyclooctyne is known, and many of these are summarized in compilations by Krebs and Meier and their coworkers [12,[70][71][72].…”

Section: Cyclooctyne and Its Derivativesmentioning

confidence: 99%

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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Cited by 10 publications

References 12 publications

Structure/Chiroptics Relationships of Planar Chiral and Helical Molecules

Structure/Chiroptics Relationships of Planar Chiral and Helical Molecules

The Chemistry of Alk-1-yn-1-yl Disulfides—A Review

Angle‐Strained Cycloalkynes

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