提供容易接近目标化合物的对映体形式的合成途径是特别有价值的。据报道,氧化膦的无结晶双分离度可提供高对映体富集的材料(高达94%ee),且产率极高。两种对映体氧化物均由单一中间体(R P)-烷氧基phosph氯化物制得,该中间体是在选择性动态动力学拆分过程中使用单一薄荷醇对映体作为手性助剂而形成的。双重立体选择性的起源在于该中间体的反应路径的分叉,该中间体充当立体化学铁路开关。在受控条件下,至C这中间所得阿尔布佐夫型崩溃O键裂变并保留在磷中心的构型。相反,PO键的碱性水解会导致相反的S P 对映异构体。
Dynamic Cross-Exchange in Halophosphonium Species: Direct Observation of Stereochemical Inversion in the Course of an S<sub>N</sub>2 Process
作者:Kirill Nikitin、Elizabeth V. Jennings、Sulaiman Al Sulaimi、Yannick Ortin、Declan G. Gilheany
DOI:10.1002/anie.201708649
日期:2018.2.5
bromides and chlorides R3PX+X− (R=Alk, Ar, X=Cl or Br) were studied by NMR techniques. Their energy barriers are typically ca. 11 kcal mol−1, but rise rapidly as bulky groups are attached to phosphorus, revealing the importance of steric factors. In contrast, electronic effects, as measured by Hammett analysis, are modest (ρ 1.46) but still clearly indicate negative charge flow towards phosphorus in
[EN] PROCESSES FOR THE STEREOSELECTIVE PREPARATION OF P-CHIRAL FOUR -COORDINATED PHOSPHORUS BORANE COMPOUNDS AND P-CHIRAL THREE-COORDINATED PHOSPHORUS COMPOUNDS<br/>[FR] PROCÉDÉS POUR LA PRÉPARATION STÉRÉOSÉLECTIVE DE COMPOSÉS DE BORANE DE PHOSPHORE À QUATRE COORDINATIONS P-CHIRAUX ET DE COMPOSÉS PHOSPHORÉS À TROIS COORDINATIONS P CHIRAUX
申请人:UNIV DUBLIN
公开号:WO2012113889A1
公开(公告)日:2012-08-30
Processes for the stereoselective preparation of P-chiral four-coordinated phosphorus borane compounds and P-chiral three-coordinated phosphorus compounds.
Identification of a key intermediate in the asymmetric Appel process: one pot stereoselective synthesis of P-stereogenic phosphines and phosphine boranes from racemic phosphine oxides
作者:Kamalraj V. Rajendran、Declan G. Gilheany
DOI:10.1039/c2cc34136k
日期:——
racemic phosphine oxides with oxalyl chloride and chiral non-racemic alcohol generates the same ratios of diastereomeric alkoxyphosphonium salts obtained in the corresponding asymmetric Appel process, strongly implicating the intermediate chlorophosphonium salt in the stereoselecting step. Subsequent reduction allows a novel synthesis of enantioenriched P-stereogenic phosphines-phosphine boranes.
Lithium Borohydride for Achiral and Stereospecific Reductive Boronation at Phosphorus: Lack of Electronic Effects on Stereoselective Formation of Alkoxyphosphonium Salts
作者:Sulaiman S. Al Sulaimi、Kamalraj V. Rajendran、Declan G. Gilheany
DOI:10.1002/ejoc.201500521
日期:2015.9
as a preferred, simple and effective reagent for reductive boronation of achiral and racemic chlorophosphonium salts (CPS) and for diastereomeric alkoxyphosphonium salts (DAPS), both of which are, in turn, easily generated from either the corresponding phosphane or, more conveniently, the phosphane oxide. Further, we have shown that the DAPS reduction/boronation could be achieved with complete stereocontrol