A Crystalline Ready-to-Use Form of Cyclopentadiene

Abstract

Cyclopentadiene (Cpd) is widely used as a starting material in organic and inorganic chemistry. In neat form, Cpd dimerizes, making it necessary to distill it prior to use to obtain fully reactive material. We have screened three different tetraphenyladamantane octaethers for their ability to act as encapsulating organic crystal (EnOC) hosts for Cpd. To this end, we also synthesized 1,3,5,7-tetrakis(3,5-dimethoxyphenyl)adamantane, a new octaether, dubbed iso-TDA. Only one of the octaethers was found to produce inclusion complexes with Cpd in the crystalline state. The encapsulated diene was stable for one month and showed full reactivity in a series of different synthetic transformations.

Advanced crystallisation methods for small organic molecules

“…Examples have included analytes as diverse as [12]crown-4, morpholine and even reactive compounds such as cyclohexyl isocyanide. [95][96][97][98][99] 4.1. Absolute stereochemistry determination of (R)methylbenzylamine using a TEO Inclusion chaperone More recently, Richert and co-workers have applied TAA inclusion chaperones to absolute stereochemistry determination, as exemplified by (R)-methylbenzylamine.…”

“…Examples have included analytes as diverse as [12]-crown-4, morpholine and even reactive compounds such as cyclohexyl isocyanide. 95–99…”

Click Chemistry with Cyclopentadiene

“…The Richert group developed a crystalline ready-to-use form of cyclopentadiene. 129 They showed that cyclopentadiene can be encapsulated as a guest molecule in the crystalline matrix of 1,3,5,7-tetrakis(2,4-dimethoxyphenyl)adamantane (TDA), which is shown in Scheme 28. The crystallization occurs in a stoichiometric ratio of 5 cyclopentadienes for every 4 TDAs.…”

“…Bench-stable sources of cyclopentadienes eliminate the need to distill cyclopentadiene from the dimer prior to use. The Richert group developed a crystalline ready-to-use form of cyclopentadiene . They showed that cyclopentadiene can be encapsulated as a guest molecule in the crystalline matrix of 1,3,5,7-tetrakis­(2,4-dimethoxyphenyl)­adamantane (TDA), which is shown in Scheme .…”

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

“…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.…”