OBSERVATION OF PSEUDOROTAMERS OF TWO UNCONSTRAINED WITTIG INTERMEDIATES, (3RS, 4SR)- AND (3RS, 4RS)-4-CYCLOHEXYL-2-ETHYL-3,4-DIMETHYL-2,2-DIPHENYL-1,2 LAMBDA 5-OXAPHOSPHETANE, BY DYNAMIC 31P NMR SPECTROSCOPY : LINE-SHAPE ANALY SES, CONFORMATIONS, AND DECOMPOSITION KINETICS
OBSERVATION OF PSEUDOROTAMERS OF TWO UNCONSTRAINED WITTIG INTERMEDIATES, (3RS, 4SR)- AND (3RS, 4RS)-4-CYCLOHEXYL-2-ETHYL-3,4-DIMETHYL-2,2-DIPHENYL-1,2 LAMBDA 5-OXAPHOSPHETANE, BY DYNAMIC 31P NMR SPECTROSCOPY : LINE-SHAPE ANALY SES, CONFORMATIONS, AND DECOMPOSITION KINETICS
复制标题
两种无约束 Wittig 中间体 (3RS, 4SR)- 和 (3RS, 4RS)-4-环己基-2-乙基-3,4-二甲基-2,2-二苯基-1,2 Lambda 5-氧杂磷酸的假异构体的观察，
DOI：
10.1021/ja974332o
复制
发表时间：
1998
影响因子：
15
通讯作者：
P. Skrabal
中科院分区：
文献类型：
--
作者：
F. Bangerter;M. Karpf;L. Meier;P. Rys;P. Skrabal
通过（1 RS，2SR）-（6）和（1 RS，2 RS）-（2-环己基-2-羟基-1-甲基丙基）乙基二苯基碘化鏻（7）的去质子化反应，选择性地合成了两种典型的非稳定和非约束的氧杂磷杂环丁烷非对映异构体（3RS，4SR）-（3）和（3RS，4 RS）-4-环己基-2-乙基-3，4-二甲基-2，2-二苯基-1，2 λ5-氧杂磷杂环丁烷（5）。7的X射线结构分析确定了6和7的相对构型，从而确定了3和5的相对构型。用~（31）P核磁共振谱研究了1，2-氧杂磷杂环己烷3和5的赝旋转及其烯烃的形成。解析的伪旋转异构体在五配位三角双锥磷原子的构象，确定由1H，13 C，和31 P NMR数据。对于两种非对映异构体，具有乙基取代基的赤道位置的两种旋转异构体在假旋转中占主导地位。线形分析提供了伪旋转的速率常数和激活参数。这些结果代表了第一个伪旋转的实验数据。
The two typical, that is unstabilized and unconstrained, oxaphosphetane diastereomers (3RS,4SR)- (3) and (3RS,4RS)-4-cyclohexyl-2-ethyl-3,4-dimethyl-2,2-diphenyl-1,2λ5-oxaphosphetane (5) have been prepared selectively by deprotonation of (1RS,2SR)- (6) and (1RS,2RS)-(2-cyclohexyl-2-hydroxy-1-methylpropyl)ethyldiphenylphosphonium iodide (7). The X-ray structure analysis of 7 established the relative configurations of 6 and 7 and consequently those of 3 and 5. Pseudorotation of the 1,2-oxaphosphetanes 3 and 5 and their alkene formations have been studied by 31P NMR spectroscopy. The conformations of the resolved pseudorotamers at the pentacoordinate trigonal bipyramidal phosphorus atom are identified by 1H, 13C, and 31P NMR data. For both diastereomers, the two rotamers with equatorial position of the ethyl substituent dominate in pseudorotation. Line-shape analyses provided the rate constants and activation parameters of pseudorotations. The results represent the first experimental data for pseudorotation ...