Convenient Synthesis of Bis（oxazoline） Dicarboxylate Derivatives

The synthesis of bis(oxazoline) dicarboxylate derivatives was investigated.Diethyl-aminosulfur trifluoride (DAST) was used as a convenient cyclization reagent in the synthesis of bis(oxazoline) dicarboxylate derivatives,which can not be obtained by the general method using MsC1 and Et3N as dehydrating cyclization reagent.     

C2-symmetric bis(oxazolinato)lanthanide catalysts for enantioselective intramolecular hydroamination/cyclization

C(2)-symmetric bis(oxazolinato)lanthanide complexes of the type [(4R,5S)-Ph(2)Box]La[N(TMS)(2)](2), [(4S,5R)-Ar(2)Box]La[N(TMS)(2)](2), and [(4S)-Ph-5,5-Me(2)Box]La[N(TMS)(2)](2) (Box = 2,2'-bis(2-oxazoline)methylenyl; Ar = 4-tert-butylphenyl, 1-naphthyl; TMS = SiMe(3)) serve as precatalysts for the efficient enantioselective intramolecular hydroamination/cyclization of aminoalkenes and aminodienes. These new catalyst systems are conveniently generated in situ from the known metal precursors Ln[N(TMS)(2)](3) or Ln[CH(TMS)(2)](3) (Ln = La, Nd, Sm, Y, Lu) and 1.2 equiv of commercially available or readily prepared bis(oxazoline) ligands such as (4R,5S)-Ph(2)BoxH, (4S,5R)-Ar(2)BoxH, and (4S)-Ph-5,5-Me(2)BoxH. The X-ray crystal structure of [(4S)-(t)BuBox]Lu[CH(TMS)(2)](2) provides insight into the structure of the in situ generated precatalyst species. Lanthanides having the largest ionic radii exhibit the highest turnover frequencies as well as enantioselectivities. Reaction rates maximize near 1:1 BoxH:Ln ratio (ligand acceleration); however, increasing the ratio to 2:1 BoxH:Ln decreases the reaction rate, while affording enantiomeric excesses similar to the 1:1 BoxH:Ln case. A screening study of bis(oxazoline) ligands reveals that aryl stereodirecting groups at the oxazoline ring 4 position and additional substitution (geminal dimethyl or aryl) at the 5 position are crucial for high turnover frequencies and good enantioselectivities. The optimized precatalyst, in situ generated [(4R,5S)-Ph(2)Box]La[N(TMS)(2)](2), exhibits good rates and enantioselectivities, comparable to or greater than those achieved with chiral C(1)-symmetric organolanthanocene catalysts, even for poorly responsive substrates (up to 67% ee at 23 degrees C). Kinetic studies reveal that hydroamination rates are zero order in [amine substrate] and first order in [catalyst], implicating the same general mechanism for organolanthanide-catalyzed hydroamination/cyclizations (intramolecular turnover-limiting olefin insertion followed by the rapid protonolysis of an Ln-C bond by amine substrate) and implying that the active catalytic species is monomeric.     

Strontium- und Barium-bis[N,N′ -bis(trimethylsilyl)benzamidinate] aus der Additionsreaktion der Erdalkalimetall-bis[bis(trimethylsilyl)amide] mit Benzonitril

Strontium and Barium Bis[N,N′-bis(trimethylsilyl)benzamidinates] from the Addition Reaction of the Alkaline Earth Metal Bis[bis(trimethylsilyl)amides] and Benzonitrile The reaction of strontium bis[bis trimethylsilyl)amide] with benzonitrile yields strontium bis[N,N′- bis(trimethylsilyl)benzamidinate] · 2THF, which crystallizes in the orthorhombic space group Pbcn (a = 1845.4(3); b = 131 1,3(2); c = 1838,(3) pm; Z = 4). During the similar reaction of barium bis[bis(trimethylsilyl)amide] with benzonitrile the benzonitrile adduct barium bis[N,N′-bis(trimethylsilyl)benzamidinate] · 2 THF · benzonitrile is formed. After the addition of diphenylacetylene to the strontium di(benzamidinate) in diglyme a clathrate of the composition strontium bis[N,N′-bis(trimethylsilyl)benzamidinate] · diglyme · diphenylacetylene could be isolated; the spectroscopic data as well as the X-ray structure (monoclinic, C2/c, a = 1492.2(2); b = 1539.1(2); c = 2337.8(3)pm; Z = 4) confirm the isolated appearance of the acetylene molecule without interaction to the metal center in solution and in the solid state, respectively.     

Bis(trimethylsilyl)amide und -methanide des Yttriums — Molekülstrukturen von Tris(diethylether-O)lithium-(μ-chloro)-tris[bis(trimethylsilyl) methyl]yttriat,solvensfreiem Yttrium-tris[bis(trimethylsilyl)amid] sowie dem Bis(benzonitril)-Komplex

Bis(trimethylsilyl)amides and -methanides of Yttrium — Molecular Structures of Tris(diethylether-O)lithium-(μ-chloro)-tris[bis(trimethylsilyl)methyl]yttriate, solvent-free Yttrium Tris[bis(trimethylsilyl)amide] as well as the Bis(benzonitrile) Complex The reaction of yttrium(III) chloride with the three-fold molar amount of LiE(SiMe₃)₂ (E = N, CH) yields the corresponding yttrium derivatives. Yttrium tris-[bis(trimethylsilyl)amide] crystallizes in the space group P3 1c with a = 1 636,3(2), c = 849,3(2) pm, Z = 2. The yttrium atom is surrounded trigonal pyramidal by three nitrogen atoms with Y? N-bond lengths of 222 pm. Benzene molecules are incorporated parallel to the c-axes. The compound with E = CH crystallizes as a (Et₂O)₃LiCl-adduct in the monoclinic space group P2₁/n with a = 1 111,8(2), b = 1 865,2(6), c = 2 598,3(9) pm, β = 97,41(3)° and Z = 4. The reaction of yttrium tris[bis(trimethylsilyl)amide] with benzonitrile yields the bis(benzonitrile) complex, which crystallizes in the triclinic space group P1 with a = 1 173,7(2), b = 1 210,3(2), c = 1 912,4(3) pm, α = 94,37(1), β = 103,39(1), γ = 117,24(1)° and Z = 2. The amido ligands are in equatorial, the benzonitrile molecules in axial positions.     

A New Route to Phosphoryl Thiocarbonyl Mixed Imides - Structure Limitations

Abstract

The rearrangement of N-methyl thiophosphoryl carbonyl mixed imides (I, XYP(S)N(Me)C(O)Z) to N-methyl phosphoryl thiocarbonyl mixed imides (II, XYP(O)N(Me)C(S)Z) was studied as a function of substitution on phosphorus (Ia: X = Y = MeO; Ib: X = Ph, Y = MeO; and Ic: X = Y = Ph) with Z = Ph and as a function of substitution on carbon (Ia: Z = Ph; Id: Z = Me; and Ie: Z = OiBu) with X = Y = MeO. For Ia, Ib, and Id, rearrangement is complete and quantitative. In contrast, Ic rearranges to a 10/90 equilibrium mixture of IIc/Ic and Ie gives no evidence for rearrangement to the phosphoryl thiocarbonyl mixed imide IIe. A relative reactivity order for Ia, Ib, Ic, and Id of 1.00, 0.15, 0.036, and 0.11 respectively, was observed in the rearrangements.     

Asymmetric Diels—Alder Reaction Catalyzed by Novel Chiral Dibenzo[a,c] cycloheptadiene Bis（oxazoline） Metal Complexes

A series of novel chiral C2-symmetric bis (oxazoline) ligands have been synthesized.The copper and magnesium complexes,prepared in situ from copper(Ⅱ)-triflate of magnesium triflate with the new enantiopure oxazoline ligands,were evaluated as chiral catalysts in the enantioselective Diels-Alder reaction of cyclopentadiene with N-crotenoyl-oxazolidin-2-one.Primary results showed that diastereoselectivity up to 94% and enantioselectivity up to 68% ee for endo products were observed respectively with these ligands.     

Umsetzung von 2-Dimethylamino-(1,3,2)-diox-, oxathi- und dithi-arsolanen mit Alkoholen und Thiolen

Reaction of 2-Dimethylamino-(1,3,2)-diox-, oxathi-, and dithi-arsolanes with Alcohols or Thiols The reactions of 2-dimethylamino-(l, 3,2)-diox-, oxathi- and dithi-arsolanes (CH₂)₂XYAs? N(CH₃)₂ (X = Y = O or S; X = S, Y = O) with alcohols and thiols yield by cleavage of the As? N bond in the formation of alkoxy and alkylmercaptoarsolanes (CH₂)₂XYAs? ZR (X = Y = Z = O or S; X = Y: O, Z = S; X = Y = S, Z = O; X = S, Y = O, Z = O or S), respectively. Some of these arsolanes are not stable but rearrange under formation of 1,2-Bis-(arsolanyl)ethane and arsinous acid esters.     

Catalytic and highly enantioselective reactions of alpha-sulfonyl carbanions with chiral bis(oxazoline)s

The enantioselective reactions of lithiated benzyl trifluoromethyl sulfones with a substoichiometric amount of a bis(oxazoline) and various aldehydes is disclosed. The products were formed with excellent diastereo- and enantioselectivities. Fluorination of the sulfone with N-fluorobenzenesulfonimide and a stoichiometric amount of a bis(oxazoline) gave products with extremely high enantioselectivities (up to 99% ee; ee=enantiomeric excess). The enantioselective reaction was confirmed to proceed through a dynamic thermodynamic resolution pathway.     

Enantioselective Direct Alkynylation of Ketones Catalyzed by Chiral CCN Pincer RhIII Complexes

A direct asymmetric alkynylation of ketones with new chiral CCN Rh catalysts containing N‐heterocyclic carbene and oxazoline hybrid ligands is described. The catalytic reaction of fluoroalkyl‐substituted ketones, ArCOCF₂X (X=F, Cl, H), with aromatic and aliphatic alkynes yielded the corresponding chiral propargyl alcohols with high enantioselectivity. Control and kinetic experiments suggested a bis(alkynyl) Rh intermediate as the active species for the C?C bond‐forming step.     

手性双(口恶)唑啉配体-金属配合物在催化不对称环丙烷化反应中的应用研究进展

将用于催化不对称环丙烷化反应中的手性双(口恶)唑啉配体按相应羧酸母体骨架分为丙二酸类,酒石酸类,吡啶二羧酸类,联苯、联萘及双核二茂铁类,将聚合物支载的双(口恶)唑啉配体单独进行了讨论.对各类配体的最新研究进展及其金属配合物在不对称环丙烷化反应中的应用作了总结.     

Rational tuning of the rigidity of a ligand scaffold: synthesis of diphenylsulfide-linked bis(oxazoline) ligands and their application in asymmetric allylic alkylation

The scaffold rigidity of bis(oxazoline) ligands was rationally tuned on the basis of literature information. Diphenylsulfide-linked bis(oxazoline) ligands with a flexible scaffold were efficiently synthesized to test our hypothesis. The improved enantioselectivity in palladium-catalyzed asymmetric allylic alkylation reaction was achieved as we expected.     

Die Kristall- und MolekülStruktur von N,N′-Bis-(trimethylsilyl)-oximidsäure-bis(trimethylsilyl)-ester

The Crystal and Molecular Structure of N,N′-Bis(trimethylsilyl) Oximidic Acid Bis (trimethylsilyl) Ester The X-ray structure analysis of the reaction product of oxalyl chloride with sodium bis(trimethylsilyl) amide formulated by PUMP and ROCHOW as N,N′-bis(trimethylsilyl) oximidic Acid bis (trimethylsilyl) ester shows that the suggested structure is correct for the solid state. The compound crystallizes in the space group P1 with a = 9.948(4), b = 6.612(3), c = 10.370(4) Å, α = 88.87(6), β = 116.95(4), γ = 98.23(6)°, and Z = 1. The molecule manifests symmetry 1 .     

The synthesis of phosphine oxide-linked bis(oxazoline) ligands and their application in asymmetric allylic alkylation

The phosphine oxide-linked bis(oxazoline) ligands were designed and synthesized in two ways. One is the coupling of Grignard reagent derived from 2-(2-bromophenyl)oxazoline with phenylphosphonic dichloride, another route is the condensation of bis(2-formylphenyl)(phenyl)phosphine oxide with chiral amino alcohols followed by NBS oxidation. These new bis(oxazoline) ligands were applied in Pd-catalyzed asymmetric allylic alkylation reactions and good yields and enantioselectivities were obtained with diphenyl substituted ligand (up to 95% ee).     

手性双噁唑啉配体在不对称合成中的应用

双噁唑啉手性配体已广泛用于不对称Henry反应、环丙烷化反应、Aldol反应、烷基化反应、环加成反应中,并表现出很高的对映选择性和催化活性,成为最有用的手性配体之一。文章综述了近10年来双噁唑啉手性配体及高分子受载手性双噁唑啉在不对称合成中的研究进展。     

Reversal of enantioselection in an aldol reaction catalyzed by sterically congested bis(oxazoline)–Cu(II) complexes

The use of sterically congested C₂-symmetrical bis(oxazoline) ligands with methylene and ethylene spacers between the oxazoline rings results in the reversal of the enantioselection for aldol reactions catalyzed by bis(oxazoline)–Cu(II) complexes.     

Synthese von 1, 2-annelierten 1, 4-Benzodiazepinen und 4, 1-Benzoxazepinen

The syntheses of 1, 2-annelated 1, 4-benzodiazepines (IV, Y = N) and 4, 1-benzoxazepines (IV, Y = 0) are described (Scheme 1). The key step is a nucleophilic aromatic substitution of 2-substituted piperazines (II, Z = N? CH₃), piperidines (II, Z = CH₂) or pyrrolidines (II, Z= (CH₂)₀) with activated aryl halides (I).     

Synthese von substituierten Calcium-bis(disilylamiden) mittels der Transmetallierung von Zinn(II)- und Zinn(IV)-amiden

Synthesis of Substituted Calcium-bis(disilylamides) by Transmetalation of Tin(II) and Tin(IV) Amides Stannylenes as well as stannanes with substituted disilylamino groups are valuable synthons for the synthesis of alkaline earth metal bis(disilylamides) via the transmetallation reaction. Whereas bis[2,2,5,5-tetramethyl-2,5-disilaaza-cyclo-pentyl]stannylene 1 is a suitable reagent for this type of reaction, bis[trimethylsilyl-tris(trimethylsilyl)silylamino]stannylene 2 (monoclinic, P2₁/c, a = 1492.6(2), b = 1705.2(2), c = 1865.3(3) pm, β = 109.03(2)º, Z = 4) is not only attacked at the Sn? N-bond but also the N? Si-bond is cleaved by calcium metal. Similar light sensitivity as for 2 is observed for the mercury bis[trimethylsilyl-tris(trimethylsilyl)silylamide] 3 , the homolytic M? N-bond cleavage leads to the formation of the trimethylsilyl-tris(trimethylsilyl)silylamino radical (g = 2.00485; a(N) = 16.2 G). The calcium tin exchange reaction of 1 in THF yields tris(tetrahydrofuran-O)calcium-bis[2,2,5,5-tetramethyl-2,5-disilaaza-cyclo-pentanide] 4 (monoclinic, P2₁/n, a = 1060.9(2), b = 1919.3(5), c = 1686.0(3) pm, β = 90.30(2)º, Z = 4). The stannanes Me_n-4Sn[N(SiMe₃)₂]_n with n = 1 or 2 are also valuable materials for the synthesis of bis(tetrahydrofuran-O)calcium-bis[bis(trimethylsilyl)amide].     

一种计算无机含氧酸pk1的新公式

提出了两个新的拓扑指数：Y＝（DR＋2）／n^0.5＋2N，Z＝[(8-DR)^N(n-1)(ω-1)]^0.05。将主族元素25种单中心无机含氧酸的pκ1实验值与其Y、Z相关联，使用最小二乘法进行线性回归，拟合得：pκ1=19.977-2.430Y-0.944Z(r=0.993）。     

On the intermediates in chiral bis(oxazoline)copper(II)-catalyzed enantioselective reactions--experimental and theoretical investigations

The intermediates in the chiral bis(oxazoline)copper(II)-catalyzed reactions have been investigated by means of experimental and theoretical investigations. It is shown that the absolute configuration of the hetero-Diels-Alder adduct obtained from the reaction of ethyl glyoxylate with 1,3-cyclohexadiene in the presence of the chiral bis(phenyloxazoline)copper(II) is dependent on the solvent. In this case, a linear relationship between the enantiomeric excess (ee) and the dielectric constant of the solvent was observed. However, the enantiomeric excess for the adduct obtained with the chiral bis(tert-butyloxazoline)copper(II) complex is independent of the solvent. The addition of different coordinating solvents to the chiral catalysts was investigated and no effect on the enantioselectivity of the reaction was observed. A series of chiral bis(tert-butyloxazoline)-, bis(phenyloxazoline)-, and bis(indaneoxazoline)copper(II) complexes has been prepared and characterized by X-ray analysis, and the similarity between the structures is discussed. For comparison, two related chiral bis(tert-butyloxazoline)- and bis(phenyloxazoline)zinc(II) complexes were also prepared and characterized. A series of chiral bis(oxazoline)copper(II)-substrate (the substrate being glyoxal or methyl glyoxylate) complexes was investigated by means of ab initio calculations. Calculation of the total energy of the optimized structure of 17-, 19-, and 21-electron bis(oxazoline)copper(II)-substrate complexes give the 17-electron complex as the most stable and the most reactive complex, while the 21-electron complex is less stable and also much less reactive. The optimized structures of both the 17-electron bis(tert-butyloxazoline)- and bis(phenyloxazoline)copper(II)-substrate complexes show that the plane of the substrate molecule is twisted by approximately 40-45 degrees out of the bis(oxazoline)copper(II) plane, in agreement with the X-ray structures. On the basis of the experimental results, X-ray structures, and ab initio calculations, the structure of the intermediate(s) and reactivity of the chiral bis(oxazoline)copper(II)-substrate complexes are discussed.     

Synthesis of Chiral 1,3-Bis(oxazolinyl)benzene

In recent years, C₂-symmetric chiral bis (oxazoline) ligand-metal complexes have received a great of attention through their use in various catalytic processes^[1-2]. Since the early 1990s, many impressive enantioselective carbon-carbon bond forming reactions, aziridination reactions, hydrosilylations, oxidations and reductions have been recorded using bis (oxazoline)-metal complexes with wide structural diversity^[3-4]. The latest review is intended to focus on the recent developments of bis(oxazoline) ligand-metal catalyzed asymmetric reactions and their applications in organic synthesis. Herein we intend to report the synthesis of a new type of chiral bis(oxazoline), 1,3-bis(oxazolinyl)benzene. Application of their asymmetric catalysis is under working.