Škoch Karel, Daniliuc Constantin G, Kehr Gerald, Ehlert Sebastian, Müller Marcel, Grimme Stefan, Erker Gerhard
Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraβe 40, 48149, Münster, Germany.
Mulliken Center for Theoretical Chemistry Institut für Physikalische und Theoretische Chemie, Universität Bonn, Beringstraβe 4, 53115, Bonn, Germany.
Chemistry. 2021 Aug 19;27(47):12104-12114. doi: 10.1002/chem.202100835. Epub 2021 Jul 16.
Attachment of a pair of P-stereogenic mesityl(alkynyl)phosphanyl groups at the 4- and 5-positions of a 9,9-dimethylxanthene framework gave mixtures of the respective rac- and meso-bisphosphanyl diastereoisomers. They slowly epimerized in a thermally induced reaction with Gibbs activation barriers of about 25 kcal mol at room temperature (measured and DFT calculated). The reaction of the meso-mesityl(tert-butylethynyl)phosphanyl derivative with two molar equivalents of Piers' borane [HB(C F ) ] led to the formation of the alkylidene-bridged geminal bisphosphane/borane-frustrated Lewis pair system. The compound was obtained enriched (>85 %) in the rac diastereoisomer. With a variety of bifunctional donor substrates, the rac-bis-P/B FLP formed macrocyclic compounds. They were all formally derived from meso-configurated diastereoisomers of the bisphosphanylxanthene backbone.
在9,9-二甲基氧杂蒽骨架的4位和5位连接一对P-手性均三甲苯基（炔基）膦基，得到相应的外消旋和内消旋双膦基非对映异构体的混合物。它们在热诱导反应中缓慢差向异构化，在室温下吉布斯活化能垒约为25 kcal mol（测量值和密度泛函理论计算值）。内消旋均三甲苯基（叔丁基乙炔基）膦基衍生物与两摩尔当量的皮尔斯硼烷[HB(CF)]反应，生成亚烷基桥连的偕双膦烷/硼烷受阻路易斯对体系。该化合物以外消旋非对映异构体形式富集（>85%）得到。与多种双功能供体底物反应，外消旋双-P/B FLP形成大环化合物。它们均正式衍生自双膦基氧杂蒽主链的内消旋构型非对映异构体。
