The synthesis, structure and properties of diazaphospholes: Reagents and ligands for asymmetric synthesis
摘要:
Reaction of C-2 diamines with PCl3 and Et3N in toluene, followed by water or hydrogen sulfide, gave a series of cyclic phosphorous acid diamides (diazaphosphole oxides) and thiophosphorous acid diamides (diazaphosphole sulfides), respectively. Similarly, reaction of diamines with phenyl dichlorophosphine gave phenyl diazaphospholes. The synthesis, properties, and structure of these diazaphospholes are reported. (C) 1998 Elsevier Science Ltd. All rights reserved.
Supramolecular-Directed Chiral Induction in Biaryl Derivatives
摘要:
A thermodynamically controlled resolution has allowed for the generation of diastereomerically enriched complexes, by chirality transfer from ail enantiopure building block to a dynamically racemic biaryl derivative. A switchable sense of induction could be achieved depending on the substituents of the chiral block.
Enantioselective addition of methyllithium to aromatic imines catalyzed by C2 symmetric tertiarydiamines is described. Eleven diamines have been tested, for which dramatic effect of the nitrogen substitution has been observed. Diamines bearing hindered group close to the nitrogen led to racemic product while homologous hindered diamines led to the best results. Enantiomeric excess up to 74% could
New chiraldiamines were prepared, based on the cyclohexane diamine core. The two different substituents on each nitrogen allow this heteroatom to become a stereogenic center upon chelation with a metal, such as lithium. The enantioselective addition of MeLi to imines, with ee's up to 68%, illustrates the validity of this concept.
In non-racemic (1R,2R)-(1,2-dialkyl)-1,2-diaminocyclohexane palladium dichloride complexes the C2 symmetry of the diamine ligand is broken, resulting in selective R,S-coordination.
Synthesis of Phosphoramides for the Lewis Base-Catalyzed Allylation and Aldol Addition Reactions
作者:Scott E. Denmark、Xiping Su、Yutaka Nishigaichi、Diane M. Coe、Ken-Tsung Wong、Stephen B. D. Winter、Jun Young Choi
DOI:10.1021/jo9820723
日期:1999.3.1
Both chiral and achiral phosphoramides of diverse structure were prepared from diamines by the coupling to phosphorus(V) or phosphorus(III) reagents. Several enantiopure 1,2-diphenyl-1,2-ethanediamine analogues have been prepared by the reductive coupling of the corresponding N-silylimine with NbCl(4)(THF)(2) and subsequent resolution by the formation of diastereomeric menthyl carbamates. (S,S)-N,
Sulfoniumylides derived from chiral N,N'-substituted (benzyl, isopropyl, neopentyl) phosphonamides were prepared by reacting appropriate chiral diamidophosphites with potassium hydride and chloromethyl methyl sulfide, and then with methyl iodide in the presence AgBF4 to give the corresponding sulfonium salts in high yields. One of them was analyzed by X-ray crystallography. The salts upon treatment
由手性 N,N'-取代(苄基、异丙基、新戊基)膦酰胺衍生的锍叶立德是通过将适当的手性亚磷酸二酰胺与氢化钾和氯甲基甲基硫醚反应制备的,然后在 AgBF4 存在下与甲基碘反应得到相应的锍盐高产量。其中之一通过 X 射线晶体学进行了分析。用不同碱(二异丙基胺锂、锂、碳酸钾)处理后的盐被原位转化为叶立德,叶立德与活化的烯烃反应生成膦酰基环丙烷,作为两种非对映异构体的混合物,具有中等至高的非对映选择性。