Espinosa Ferao Arturo, Streubel Rainer
Departamento de Quı́mica Orgánica, Facultad de Quı́mica, Universidad de Murcia, Campus de Espinardo, 30100 Murcia, Spain.
Institut für Anorganische Chemie der Rheinischen Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Straße 1, 53121 Bonn, Germany.
Inorg Chem. 2020 Mar 2;59(5):3110-3117. doi: 10.1021/acs.inorgchem.9b03471. Epub 2020 Feb 12.
The potential energy surface for opening and ring-enlargement reactions of 1,2-thiaphosphetane with different oxidation states and coordination at phosphorus has been computationally explored. The most favored [2 + 2] cycloreversions are the so-called normal Wittig-type reactions furnishing an alkene and a P═S-containing component. Somewhat unfavored are reactions involving the P-S bond cleavage and a C-to-P hydrogen shift as well as a ring enlargement to a 1,3,2-dithiaphospholane in the case of high coordinate derivatives. Apart from a two-step P-to-S oxygen transfer in 1,2σλ-thiaphosphetane P-oxide, an interesting reaction is the P-S bond cleavage leading to a thiabetaine which, alternatively, can be formed by the C-attack of a phosphinidene oxide on a thiirane. A similar route, energetically more favored, was found for 1,2σλ-thiaphosphetane starting from thiirane and the corresponding phosphane. For a wide set of P(III) reagents including HPR (R = Me, Ph), PR (R = Me, Ph, NMe, OMe, F, Cl), and HP═O, the competitive direct S-attack was found to be the preferred pathway for the desulfurization of thiiranes, and the relative tendency for these P(III) reagents to act as an S-atom acceptor, the thermodynamic S-transfer potential (TSP) scale, was defined using the S/S couple as a point of reference.
通过计算研究了具有不同氧化态和磷配位的1,2-硫磷杂环丙烷开环和扩环反应的势能面。最有利的[2 + 2]环反转反应是所谓的正常维蒂希型反应，生成烯烃和含P═S的组分。对于高配位衍生物，涉及P-S键断裂和C到P的氢迁移以及扩环生成1,3,2-二硫磷杂环戊烷的反应则不太有利。除了1,2σλ-硫磷杂环丙烷P-氧化物中的两步P到S的氧转移外，一个有趣的反应是P-S键断裂生成硫代甜菜碱，硫代甜菜碱也可以由氧化磷叶立德对硫杂环丙烷的C进攻形成。从硫杂环丙烷和相应的膦开始，发现1,2σλ-硫磷杂环丙烷有一条能量上更有利的类似途径。对于包括HPR（R = Me，Ph）、PR（R = Me，Ph，NMe，OMe，F，Cl）和HP═O在内的一系列P(III)试剂，发现竞争性的直接S进攻是硫杂环丙烷脱硫的首选途径，并以S/S电对为参考点定义了这些P(III)试剂作为S原子受体的相对倾向，即热力学S转移势（TSP）标度。
