Crystal Structure and Absolute Configuration of (+)-(1S, 2R)-5, 6-Dimethylidene-2exo-norbornyl-exo-irontricarbonyl p-Bromobenzoate

The title complex (+)- 13x has been prepared in an enantiomerically pure form. Its absolute configuration has been determined by single-crystal X-ray diffraction and has been correlated chemically to that of the 5, 6-dimethylidene-2-norbornyl derivatives (—)- 1 , (—)- 2 , (—)- 3 and to (—)-(1S, 2R)-benzonorborn-5-en-2-yl acetate (s. Scheme 1), whose configuration was deduced by indirect techniques. A critical analysis of the chiroptical properties of the exocyclic dienes 1–3 is now possible. These compounds are limiting systems for the application of the allylic axial chirality rule, the generalized octant rule and the symmetry rule for βγ-unsaturated ketones.     

Synthesis,Crystal Structure and Absolute Configuration of (+)-(a-Hydroxybenzyl)phenylphosphinic acid

1 INTRODUCTION a-Hydroxyphosphonic acids and their esters are known to possess broad-based physiological activities and there is close links between biological efficacy and stereochemistry[1~3]. Optical active a-hydroxyphosphonic esters can also serve as useful precursors in organic synthesis[4, 5]. Here we will report the synthesis of optical active a-hydroxyphosphinic acid, (+)-(a-hydroxybenzyl)- phenylphosphinic acid and its crystal structure and the absolute configuration of its a-ca…     

(+)-O-萘基环状磷酰二胺酯的合成、晶体结构及绝对构型

合成了目标化合物(+)-O-萘基环状磷酰二胺酯,其结构由¹HNMR,³¹PNMR及元素分析确定,并在273K下进行了X射线衍射晶体结构分析.该化合物晶体属正交晶系,P2₁2₁2₁空间群,晶胞参数a=1.0028(4)nm,b=1.1406(4)nm,c=2.4455(8)nm,V=2.7971(18)nm₃,Z=4,Dc=1.212g/cm³,F(000)=1088,μ=0.129mm^-1.晶体的结构收敛最终偏离因子R和wR分别为0.0585和0.0827.Flackx参数为0.03(12).目标化合物中磷原子的绝对构型为S.     

Synthesis, Crystal Structure and AbsoluteConfiguration of （＋）-O-Phenyl Cyclophosphorodiamidate

The title compound, ( )-O-phenyl cyclophosphorodiamidate (C28H33N202P, Mr=460.53), has been synthesized and characterized by 31p NMR, 1H NMR and elemental analysis. X-ray diffraction analysis at 273(2) K indicates that it belongs to orthorhombic system, space group P212121 with a=11.518(4), b=13.449(4), c=16.539(5)A, V=2562(1)A3, Z=4, Dc=1.194g/cm3, F(000)=984 and μ(MoKα)=0.134mm-l. The structure parameters were refined by full-matrix least-squares on F2 to R=0.0459 and wR=0.0640. The flack χ parameter is 0.03(10), and the absolute configuration of the phosphorus atom in the title compound is S.     

Synthesis, Crystal Structure and Absolute Configuration of (+)-(а-Hydroxybenzyl)phenylphosphinic acid

The title compound (+)-((-hydroxybenzyl)phenylphosphinic acid (C13H13O3P, Mr = 248.20) has been synthesized and characterized by 31P NMR, 1H NMR and elemental analysis. X-ray diffraction analysis at 293(2) K indicates that the compound belongs to monoclinic system, space group C2 with cell parameters: a = 23.560(8), b = 6.947(2), c = 7.854(3) (A。）, β = 91.273(6)°, V = 1285.2(7) (A。）3, Z = 4, Dc = 1.283 g/cm3, F(000) = 520 and ((MoK() = 0.207 mm-1. The number of independent reflections amounts to 1991, of which 1507 are observed reflections. The crystal structure has been determined by direct methods (SHELXL-97). The structure parameters are refined by full-matrix least-squares on F2 to R = 0.0437 and wR = 0.0893. The flack x parameter is - 0.0001. The absolute configuration of the (-carbon in the title compound is S.     

(+)-Cannabispirenone-A: Synthesis and Absolute Configuration

An efficient asymmetric synthesis of cannabispirenone-A (la) has been accomplished. The absolute configuration of the (+)-(la) is assigned as R. The magnitude of rotation calls the optical purity of the natural product into question.     

Synthesis of 1-alkyl-2-methylazetidin-3-ones and 1-alkyl-2-methylazetidin-3-ols

Several 1-alkyl-2-methylazetidin-3-ones were prepared in good yield by the hydride-induced cyclization of the corresponding β-bromo-α,α-dimethoxyketimines, the resulting 3,3-dimethoxyazetidines being hydrolyzed by acid. Imination of these 1,2-disubstituted azetidin-3-ones, followed by alkylation under kinetic control conditions resulted in regioisomeric mixtures of 2,4- and 2,2-dialkylated compounds. Analytical samples of the major 2,4-disubstituted derivatives were obtained after extensive chromatographic separation. The cis stereochemistry of the major 2,4-dialkylated isomer was demonstrated on the basis of NMR data.     

Absolute configuration of (+)-1-amino-1-methylpropylphosphonic acid

Conclusion The absolute configuration of (+)-1-amino-1-methylpropylphosphonic acid and its (+)-diethyl ester is S in the Cahn -Ingold -Prelog system.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2821–2823, December, 1986.     

Determination of the Absolute Configuration of 1-[(4-(Bromomethyl)phenyl]-2-(prop-2-yn-1-yloxy)ethanol

Russian Journal of Organic Chemistry - The reaction of chloromethyl propargyl ether with 4-(bromomethyl)benzaldehyde in the presence of zinc metal and a chiral ligand,...     

(+)-1R,3R,5S-1,8,8-三甲基-3-硫代-3-(4-甲基苯氧基)-2,4,3-二氮磷杂二环[3,2,1]辛烷的合成和分子绝对构型

合成的标题化合物用X射线衍射方法确定其分子的绝对构型,晶体空间群为P_(2_1 2_1 2_1),晶胞参数:a=0.8365(3)、b=0.8625(3)、c=2.3513(2)nm,Z=4.结构分析表明,分子骨架中存在3个环结构,即含磷、氮原子的船式七元环、椅式六元环以及由碳原子组成的信封式五元环。P—S键为e键,P—O键为a键。     

Synthesis of 5,7-Dihydroxy-6-methoxy-2-(2-hydroxy-4-methoxyphenyl)-4H-1-benzopyran-4-one and Reassignment of Structure of Tamaridone1

The proposed structure of a new flavone, tamaridone, isolated from Tamarix dioica Roxb is untenable on the basis of comparison with its synthetic sample. Its structure has been now revised to 5,7-dihydroxy-8-methoxy-2-(3-hydroxy-4-methoxyphenyl)-4H-1-benzopyran-4-one by careful spectral studies.