Determining the Relative Configuration of Propargyl Cyclopropanes by Co-Crystallization

Krupp, Felix; Picher, Marie-Idrissa; Frey, Wolfgang; Plietker, Bernd; Richert, Clemens

doi:10.1055/a-1293-9867

Cited by 8 publications

(12 citation statements)

References 14 publications

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“…Some tetraaryladamantane ethers have attracted interest because of their ability to include other molecules in their crystalline lattice. 24 25 26 27 28 29 30 31 32 Building on earlier work on diaryladamantanes 17 we recently showed that 1,3,5,7-tetrakis(2,4-dimethoxyphenyl)adamantane (TDA), 1,3,5,7-tetrakis(2,4-diethoxyadamantane (TEO), and 1,3,5,7-tetrakis(2-bromo-4-methoxyphenyl)adamantane (TBro) are able to act as crystalline hosts for liquid compounds. This property makes them useful as crystalline coats for hazardous or reactive compounds, 30 or reversible uptake of volatile organic compounds from the gas phase.…”

Section: Introductionmentioning

confidence: 99%

“…Perhaps the most interesting crystallization chaperone, co-crystallizing with analytes up to a molecular weight of 242 g/mol, is TBro. 28 Unfortunately, TBro is accessible in modest yields only, not exceeding 20% for the Friedel–Crafts alkylation step starting from TOA and bromoanisole. Unlike the aryl starting materials for TDA and TEO, bromoanisole 3 contains two different substituents on its phenyl ring, either of which is ortho / para -directing, so that regioisomers are likely to be formed in the alkylation step.…”

Section: Introductionmentioning

confidence: 99%

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Kinetic or Thermodynamic Product? Case Studies on the Formation of Regioisomers of Tetraphenyladamantanes

Richert¹,

Frey²,

Berking³

2023

Synthesis

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Tetraaryldamantanes (TAAs) with alkoxyphenyl groups are interesting synthetic targets because they can act as crystallization chaperones for liquid compounds. Their carbon framework is set up by Friedel-Crafts alkylation, using adamantane-1,3,5,7-tetraol and anisole derivatives as starting materials. One successful chaperone is 1,3,5,7-tetrakis(2-bromo-4-methoxyphenyl)adamantane (TBro). This compound was initially considered the thermodynamic product of alkylation. We now report that exposure of TBro to strong Brønsted acid leads to its regioisomer 1,3,5,7-tetrakis(4-bromo-2-methoxyphenyl)adamantane (iTBro) as the dominant product, obtained in a yield of 68%, far surpassing the 20% yield reported earlier for TBro. We also investigated the reactions of 3-iodo-, 3-chloro-, and 3-fluoroanisole to the corresponding TAAs and obtained yields of 66%, 26% and 52% for the main regioisomer. While 3-iodoanisole gave the same regioisomer as bromoanisole, 3-chloroanisole gave complex mixtures and 3-fluoroanisole gave 1,3,5,7-tetrakis(2-fluoro-4-methoxyphenyl)-adamantane (TFM) in 52% yield as the main product. When mixtures of regioisomers were isomerized with an excess of triflic acid, the thermodynamic products were obtained in 76-91%. These results show how subtle effects govern the regioisomeric product distribution of aryladamantanes. They also help to make novel crystallization chaperones accessible in yields.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Kinetic or Thermodynamic Product? Case Studies on the Formation of Regioisomers of Tetraphenyladamantanes

Richert¹,

Frey²,

Berking³

2023

Synthesis

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“…[14] Lastly, we have recently reported tetraaryladamantanes (TAAs) that can encapsulate liquid organic and inorganic compounds in their crystal lattices. [15][16][17][18][19][20] Three tetraaryladamantane ethers have been shown to readily crystallize as solvates when a hot solution in the liquid of interest is allowed to cool to room temperature. Encapsulation has been observed for a broad range of organic liquids.…”

Section: Introductionmentioning

confidence: 99%

“…[17] A third TAA with an unusually high propensity to crystallize as solvate from solutions of different liquids is 1,3,5,7-tetrakis(2bromo-4-methoxyphenyl)adamantane (TBro), which was identified in our study on the determination of the absolute configuration of chiral analytes upon encapsulation. [18] In many cases, at least one guest molecule was found to be well ordered when encapsulated in TDA, TEO or TBro, so that the relative [19] or absolute stereochemistry can be revealed, qualifying the TAAs as a crystallization chaperone. [18] Still, for all TAA chaperones identified thus far, there is also a solvate-free form with similar crystallographic density as the solvates.…”

Section: Introductionmentioning

confidence: 99%

Transitions in Solvate Crystals of a Tetraaryladamantane

Frey,

Schwenger,

Berking

et al. 2023

Helvetica Chimica Acta

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Obtaining high‐resolution structures of liquid compounds can be difficult. Encapsulating them in the lattice of a larger organic molecule acting as crystallization chaperone is one option to overcome this difficulty. Tetraaryladamantane ethers can play the role of chaperones, accommodating a range of different guest molecules in their crystals. How well ordered crystalline arrangements for molecules of different shape are achieved is not clear. Cases in which more than one structure is found may shed light on this phenomenon. Here we report low order cubic crystal structures of 1,3,5,7‐tetrakis(2,4‐dimethoxyphenyl)adamantane (TDA) encapsulating ortho‐xylene or cyclohexane, together with better ordered structures obtained after warming the crystals to 60 °C. Evidence for cubic crystal systems was also found for limonene, hexachlorobutadiene and eucalyptol, with a transition to a triclinic system for the former two, but no transition up to 70 °C for the latter. These findings indicate that some solvate structures of TDA can readily undergo structural transitions to less solvated, better ordered systems. Crystals obtained by rapid thermal crystallization may be kinetically trapped states, and the transition to a solvate‐free crystal system appears to have a kinetic barrier that depends strongly on the structure of the liquid guest molecules encapsulated in the lattice.

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“…Three tetraaryladamantanes (TAAs) were found to show this behavior as hosts, namely 1,3,5,7-tetrakis(2,4-dimethoxyphenyl)adamantane (TDA), 1,3,5,7-tetrakis(2,4-diethoxyphenyl)adamantane (TEO), and 1,3,5,7-tetrakis(2-bromo-4-methoxyphenyl)adamantane (TBro). The X-ray crystal structures of over 100 EnOCs have been reported thus far [13][14][15][16], including structures with chiral guests that allow for the determination of the absolute [17] or relative configuration [18]. One limitation of the EnOC method was that the guest compound to be encapsulated had to be a liquid, so that it could act as solvent for the TAA, which would rapidly crystallize upon cooling of a hot, saturated solution.…”

Section: Introductionmentioning

confidence: 99%

Co-crystallization of an organic solid and a tetraaryladamantane at room temperature

Rami¹,

Nowak²,

Krupp³

et al. 2021

Beilstein J. Org. Chem.

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Tetraaryladamantanes have proven useful as chaperones for the co-crystallization of small molecules that do not readily crystallize by themselves. The co-crystals are often useful for structure elucidation. Usually, the small molecules are encapsulated in the crystal lattice of the aryladamantane that forms during rapid thermal crystallization. Thus far, co-crystallization has been limited to liquids as guest molecules. Here we report the co-crystal structures of phenol, which is solid at room temperature, with both 1,3,5,7-tetrakis(2,4-dimethoxyphenyl)adamantane (TDA) and 1,3,5,7-tetrakis(2,4-diethoxyphenyl)adamantane (TEO). The co-crystals were obtained from solutions in dichloromethane by slow evaporation or diffusion. The implications for generating other co-crystals of two solids are briefly discussed.

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Determining the Relative Configuration of Propargyl Cyclopropanes by Co-Crystallization

Cited by 8 publications

References 14 publications

Kinetic or Thermodynamic Product? Case Studies on the Formation of Regioisomers of Tetraphenyladamantanes

Kinetic or Thermodynamic Product? Case Studies on the Formation of Regioisomers of Tetraphenyladamantanes

Transitions in Solvate Crystals of a Tetraaryladamantane

Co-crystallization of an organic solid and a tetraaryladamantane at room temperature

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