本實驗室主要研究以兩對卡賓配位基穩定中心碳的同碳雙碳烯 (carbodicarbene, CDC) 及其衍生物的反應性和配位性質。卡賓能夠提供強 供給能力，也因碳上具備空軌域因此亦有 π 電子接受能力。我們將卡賓 的性質應用於膦化學之中，藉此延伸配位基的種類以及應用性。 葉立德膦配位基 (YPhos) 為 Gessner 教授近期研究中發表的新一類膦配位基，其應用在金和鈀催化中，表現出顯著的反應活性。眾多深入的研究 表明了YPhos的特殊性來自膦葉立德 (phosphoniumylide)的強推電子能力， 但適用之葉立德化合物仍然僅限於亞烷基膦化物。含氮雜環碳烯 (NHC)為 相似於膦之常用配位基，含氮雜環烯烴膦配位基首先被 Beller 教授應用而 後被 Rivard 教授單獨分離出來，其電子性質有別於電荷分離的葉立德膦， 更傾向以烯烴的共振形式。本論文我們成功合成了含氮雜環碳烯葉立德膦 (Carbene ylide phosphine, CYPhos)，借助結構中的強拉電子取代基，使得烯 烴結構更能趨近極化的兩性離子。以理論計算 (NBOanalysis)和晶體結構， 證實 CYPhos 性質更接近葉立德，並透過 Tolman 電子參數 (TEP) 和掩埋 體積 (%Vbur)描述新型配位基的電子性質以及立體效應。此外，借助理論計 算 (NCI index)以及核磁共振光譜數據得知 CYPhos 具備 secondary interaction，但因其彈性 (flexible)的性質，使得 CYPhos 反應性異於 Buchwald-type 配位基，從金(I)催化的炔類氫氨化反應和炔丙基醯胺的環化 反應證實了這一觀察結果。;The main research interest in our group is the synthesis and application of diversified carbodicarbene: a divalent carbon(0) species ligated by two flanking carbene ligands. The importance of using carbene moieties to provide sufficient sigma donating strength and pi accepting ability in stabilizing active species inspires us a new project of application in phosphine chemistry. In very recent works by Gessner and co-workers, ylide-substituted phosphines (YPhos) were introduced as a new class of phosphine ligands which exhibited remarkable reactivity in gold and palladium catalysis. Aside from the growingly important YPhos ligands, using a carbene-olefin as the analog of phosphonium ylide, however, is less studied. The first N-heterocyclic olefin phosphine (NHOP) ligand was applied in palladium-catalyzed coupling reactions by Beller and later the free ligand was isolated and studied by Rivard. Inspired by the efficient YPhos gold(I) catalysis, we synthesized the variation of NHOP with an electron-withdrawing -SO2 group. According to NBO analysis and X-ray crystallography, the new ligand presents the charge-separated, zwitterionic form instead of the neutral olefin form so it is better to describe as carbene ylide phosphine (CYPhos). Tolman electronic parameter (TEP) and the buried volume (%Vbur) was calculated to determine donor strength and steric profile of CYPhos. In addition, NCI index and NMR experiments discovered that the ligand backbone of CYPhos has weak secondary interaction with Au. The smaller average buried volume as well as the flexible characteristic of CYPhos makes it less like a Buchwald-type phosphine. This observation was confirmed by testing the gold(I)- catalyzed hydroamination and cycloisomerization.
