The stereoselective synthesis of P-chiral phosphines through the additions onto the P=C double bond of prochiral phosphaalkenes

(1)含邻位苄基杂原子取代基芳基磷杂烯的非对映选择性合成邻苄基杂原子取代芳基磷杂烯的非对映选择性合成这些络合物在空气中对硅胶层析是稳定的。芳基磷杂烯的苄基杂原子取代基作为所得到的钯(II)配合物的配体。该反应的非对映选择性主要由苯基立体中心的杂原子取代基控制。我们发现了一条合成对映体纯P-C-S钳形配位钯配合物的新方法。(2)硫代阴离子与三羰基铬配位的芳基磷烯的亲核加成前手性磷烯的P=C双键上的立体选择性加成是合成P-手性膦的有效方法之一。然而，空间保护的磷杂烯在空气中稳定，其反应活性相当低。三羰基铬配位的芳基磷杂烯有望提高对亲核试剂的反应活性，因为三羰基铬片段具有很强的吸电子能力，可以稳定苄基碳负离子。虽然(E)-2-phenyl-1-(2，4，6-tri-t-butylphenyl)phosphaethene在四氢呋喃中不与硫代锂反应，但相应的铬络合物以极高的产率生成硫代膦。我们发现了一种合成大体积β-手性配体的新方法。

(1) Diastereoselective Synthesis of Phosphapalladacyclopropanes by Alkoxypalladation of Arylphosphaalkenes Bearing ortho-Benzylic Heteroatom SubstituentAlkoxypalladation of the kinetically protected arylphosphaalkenes bearing a coordinative heteroatom substituent at the ortho-benzylic positeion gave the phosphapalladacyclopropane complexes stereoselectively. The complexes were found to be stable to silica gel chromatography in the air. The benzylic heteroatom substituent of arylphosphaalkenes acts as the ligand of the resulting palladium (II) complexes. The diastereoselectivity of this reaction is mainly controlled by the heteroatom substituent at the benzylic stereogenic center. We have found a novel approach for the synthesis of enantio-pure P-C-S pincer ligand coordinated palladium complexes.(2) Nucleophilic Addition of Thiolate Anion to Tricarbonylchromium-Coordinated ArylphospaalkenesThe stereoselective additions onto the P=C double bond of prochiral phosphaalkenes are one of the efficient method for the synthesis of P-chiral phosphines. However, the reactivity of sterically protected phosphaalkenes, which are stable in the air, is rather low. Tricarbonylchromium-coordinated arylphosphaalkenes are expected to increase the reactivity toward nucleophiles, because the tricarbonylchromium fragment stabilizes benzylic carbanions due to its strong electron-withdrawing ability. Although (E)-2-phenyl-1-(2,4,6-tri-t-butylphenyl)phosphaethene did not reacted with lithium thiolate in THF, the corresponding chromium complex gave thiophosphine in excellent yield. We have found a new method for the synthesis of bulky P-chiral ligands.