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1.
The reactions of GeCl4, GeBr4, and MeGeCl3 with O-trimethylsilyl derivatives of N,N-disubstituted amides of 2-hydroxycarboxylic acids afforded pentacoordinate and hexacoordinate neutral (O,O)-mono- and (O,O)-bischelates. The reactions of glycolic acid derivatives with GeX4 produced bischelates X2Ge[OCH2C(O)NR2R3]2 7a,c,d (X = Cl, R2 = R3 = Me (a), (CH2)5 (c), (CH2CH2)2O (d)) and 8a (X = Br). By contrast, the reactions of lactic and mandelic acid derivatives with GeCl4 and MeGeCl3 gave monochelates Cl3Ge[OCH(R1)C(O)NR2R3] (S)-9a–c (R1 = Me) and Cl2MeGe[OCH(R1)C(O)NR2R3] 10a (R1 = H), (S)-11a,b (R1 = Me), and (S)-12a (R1 = Ph) (R2R3 = (CH2)4 (b)), respectively. According to the X-ray diffraction data, the Ge atom in bischelates 7c,d and 8a has a coordination number 6, and its coordination polyhedron can be described as a slightly distorted octahedron. In monochelates (S)-9a-c, 10a, (S)-11a,b, and (S)-12a, the Ge atom has a coordination number 5, and its coordination polyhedron can be described as a trigonal bipyramid with two halogen atoms or one halogen atom and one ethereal oxygen atom in equatorial positions and the halogen atom and the amide oxygen atom in the axial positions. The bonds in the axial positions are somewhat longer than the corresponding bonds in tetracoordinate Ge compounds.  相似文献   

2.
Lithiation of O-functionalized alkyl phenyl sulfides PhSCH2CH2CH2OR (R = Me, 1a; i-Pr, 1b; t-Bu, 1c; CPh3, 1d) with n-BuLi/tmeda in n-pentane resulted in the formation of α- and ortho-lithiated compounds [Li{CH(SPh)CH2CH2OR}(tmeda)] (α-2ad) and [Li{o-C6H4SCH2CH2CH2OR)(tmeda)] (o-2ad), respectively, which has been proved by subsequent reaction with n-Bu3SnCl yielding the requisite stannylated γ-OR-functionalized propyl phenyl sulfides n-Bu3SnCH(SPh)CH2CH2OR (α-3ad) and n-Bu3Sn(o-C6H4SCH2CH2CH2OR) (o-3ad). The α/ortho ratios were found to be dependent on the sterical demand of the substituent R. Stannylated alkyl phenyl sulfides α-3ac were found to react with n-BuLi/tmeda and n-BuLi yielding the pure α-lithiated compounds α-2ac and [Li{CH(SPh)CH2CH2OR}] (α-4ab), respectively, as white to yellowish powders. Single-crystal X-ray diffraction analysis of [Li{CH(SPh)CH2CH2Ot-Bu}(tmeda)] (α-2c) exhibited a distorted tetrahedral coordination of lithium having a chelating tmeda ligand and a C,O coordinated organyl ligand. Thus, α-2c is a typical organolithium inner complex.Lithiation of O-functionalized alkyl phenyl sulfones PhSO2CH2CH2CH2OR (R = Me, 5a; i-Pr, 5b; CPh3, 5c) with n-BuLi resulted in the exclusive formation of the α-lithiated products Li[CH(SO2Ph)CH2CH2OR] (6ac) that were found to react with n-Bu3SnCl yielding the requisite α-stannylated compounds n-Bu3SnCH(SO2Ph)CH2CH2OR (7ac). The identities of all lithium and tin compounds have been unambiguously proved by NMR spectroscopy (1H, 13C, 119Sn).  相似文献   

3.
Two of the 12 possible oxide-bridged phenylmorphans, were synthesized, rac-(3R,6aS,11aS)-2-methyl-1,3,4,5,6,11a-hexahydro-2H-3,6a-methanobenzofuro[2,3-c]azocine-10-ol (7) (the ortho-c compound), and rac-(3R,6aS,11aS)-2-methyl-1,3,4,5,6,11a-hexahydro-2H-3,6a-methanobenzofuro[2,3-c]azocine-8-ol (8) (the para-c compound). Single-crystal X-ray diffraction studies indicated that the dihedral angle between the least squares planes through the phenyl ring and the atoms C1, C11a, C12, and C3 in the piperidine ring in both 7·CHCl3 and 8·HBr was 6.9°. The C12-C6a-C6b-C10a torsion angle was found to be 139.3° for both compounds. The angular relationship between the phenolic ring and the piperidine ring in phenylmorphans that interact with specific opioid receptors as agonists or antagonists is of considerable theoretical interest.  相似文献   

4.
The interaction of optically pure 1R,2R-diammoniumyclohexane mono-(+)-tartrate and 1S,2S-diammoniumcyclohexane mono-(−)-tartrate with 2 equiv. of o-(diphenylphosphino)benzaldehyde in the presence of 2 equiv. of potassium carbonate in a refluxing ethanol/water mixture gave the optically pure condensation products N,N′-bis[o-(diphenylphosphino)benzylidene]-1R,2R-diiminocyclohexane[1R,2R-cyclohexyl-P2N2, (R,R)-I] and N,N′-bis[o-(diphenylphosphino)benzylidene]-1S,2S-diiminocyclohexane [1S,2S-cyclohexyl-P2N2, (S,S)-I], respectively, in good yield. Reduction of optically pure (R,R)-I and (S,S)-I with NaBH4 in ethanol gave the optically pure reduced products N,N′-bis[o-(diphenylphosphino)benzylidene]-1R,2R-diaminocyclohexane[1R,2R-cyclohexyl-P2N2H4, (R,R)-II] and N,N′-bis[o-diphenylphosphine)benzylidene]-1S,2S-diaminocyclohexane[1S,2S-cyclohexyl-P2N2H4, (S,S)-II], respectively, in good yield. The coordination behaviour of I and II toward salts of CuI and AgI have been examined. The interaction of [Cu(C)3CN)4][X] (X = ClO4, PF6) with 1 equiv. of optically pure L4 [L4 = (R,R)-I, (S,S)-I, (R,R)-II and (S,S)-II] gave the corresponding optically pure [CuL4][X] complexes, III–VI IIIa, L4 = (R,R)-I, X = PF6 IIIb, L4 = (R,R)-I, X = ClO4 IV, X = PF6; Va, L4 = (R,R)-II, X = PF6, Vb L4 = (R,R)-II, X= ClO4, VI L4 = (S,S)-II, X = PF6, in good yield. For the CuI complexes, the L4 ligand acted as a tetradentate ligand. However, a variable-temperature 31P[1H] NMR study of IIIb shows that at ambient temperature one of the imino groups of the tetradentate ligand undergoes rapid dissociation to form a tridentate ligand. The interaction of AgBF4 with 1 equiv. of otpically pure L4 [L4 = (R,R)-I, (S,S)-I, (R,R)-II and (S,S)-II gave the corresponding optically pure [AgL4][BF4] complexes, VII–X VII L4 = (R,R)-I; VIII, L4 = (S,S)-I; IX,L4 = (R,R)-II; X, L4 = (S,S)-II], in good yield. For the AgI complexes, the L4 ligand acted as a tetradentate ligand with the two amino groups coordinated unsymmetrically to the silver. A variable temperature 31P [1H] NMR study of VII suggests that at high temperature the complex exists as a tri-coordinated complex. The structurers of IV and IX were established by X-ray diffraction studies.  相似文献   

5.
Reaction of (R,R)-(−)- and (S,S)-(+)-1,2-bis(pyrrol-2-ylmethyleneamino)cyclohexane with K2PtCl4 afforded chiral, neutral platinum(II) Schiff base complexes of (R,R)-PtL and (S,S)-PtL with high yields. The rare C–HPt(II) intermolecular interaction was found to show considerable strength and directionality for controlling M and P helical supramolecular architectures of (R,R)-PtL and (S,S)-PtL, respectively, in crystal lattices. More importantly, the open square-planar geometry of platinum(II) complexes allows axial C–HPt(II) interaction, resulting in the 3(ππ*) excited state with some mixing of the Pt(II) metal character observed both in concentrated solutions and in the solid state at room temperature.  相似文献   

6.
Treatment of the η1-acetylide complex [(η5-C5H5)(CO)(NO)W---CC---C(CH3)3]Li (4) with 1,2-diiodoethane in THF at −78 °C, followed by the addition of Li---CC---R [R=C(CH3)3, C6H5, Si(CH3)3, 6a6c] or n-C4H9Li and protonation with H2O, afforded the corresponding oxametallacyclopentadienyl complexes (η5-C5H5)W(I)(NO)[η2-O=C(CC---R)CH=CC(CH3)3] (7a7c), 8c and (η5-C5H5)W(I)(NO)[η2-O=C(n-C4H9)CH=CC(CH3)3] (9). The formation of these metallafuran derivatives is rationalized by the electrophilic attack of 1,2-diiodoethane onto the metal center of 4 to form first the neutral complex [(η5-C5H5)(I)(CO)(NO)W---CC---C(CH3)3] (5). Subsequent nucleophilic addition of Li---CC---R 6a6c or n-C4H9Li and a reductive elimination step followed by protonation leads to the products 7a7c and 9. One reaction intermediate could be trapped with CF3SO3CH3 and characterized by a crystal structure analysis. The identity of another intermediate was established by infrared spectroscopic data. The oxametallacyclopentadienyl complex 10 forms in the presence of excess 1,2-diiodoethane through an alternative pathway and crystallizes as a clathrate containing iodine.  相似文献   

7.
《Tetrahedron: Asymmetry》2006,17(16):2377-2385
Separation of diastereomeric and enantiomeric mixtures of 2,2′-[1,2- and 1,3-phenylenebis(oxy)]dicyclohexanols rac-3a and meso-3a, and rac-3b and meso-3b—resulting from the reactions of pyrocatechol 1a and resorcinol 1b with cyclohexene oxide 2—were performed using acetylation catalyzed by the highly stereoselective Candida antarctica lipase B (Novozym 435). The absolute configurations of the resulting diols (S,S,S,S)-3a,b, monoacetates (R,R,S,S)-4a,b and diacetates (R,R,R,R)-5a,b were assigned on the basis of the steric analogy to the acetylation of racemic trans-2-phenoxycyclohexanol rac-6 with the same enzyme resulting in the known acetate (−)-(R,R)-7.  相似文献   

8.
The rate of the thermal rearrangement of (S) 2 chloromethyl-1-ethylpyrrolidine [(S)-1a] to (R)-3-chloro-1-ethylpiperidine [(R) 2a] has been examined at three temperatures in benzene by PMR and polarimetry. The rearrangement was shown to be completely stereospecific and to obey a simple first order rate law. The calculated Ea ΔH3 and ΔS3 were 22 ± 2 kcalmole (25°), 21 ± 2.5 kcalmole (25°) and - 10 ± 2 e.u. (0°K) respectively. The effect of solvents having differing dielectric constants was also studied. A transition state 9'a and an ion pair intermediate 3a are suggested for the rearrangement. The stereochemical course of the reactions of (S)-1a, (R)-2a and (S)-2a with hydroxide and methoxide ions have been shown to be 100% stereospecific with an uncertainty of about 1%. The absolute configurations of all optically active reactants and products [(S)- and (R)-4a, (S)-4b (R)- and (S)-5a, (R)-5b, (S,S')-6a, (S,R')-7a and (R,R')-8a] were established by chemical correlations with known compounds or by ORD and chemical inference. The ring opening of both the primary and secondary aziridinium ion positions of 1-azonia-1-ethylbicyclo [3.1.0]hexane [(S)-3a] by nucleophiles proceeds entirely by SN2 processes. The conversion of (R)-1-ethyl-3-hydroxypiperidine [(R)-5a] to (S)-2a. HCl with thionyl chloride in chloroform proceeds by inversion with 4.8% racemization, whereas the thermal rearrangement of (S)-1a to (R)-2a occurs with complete retention of absolute configuration.  相似文献   

9.
《Tetrahedron: Asymmetry》2000,11(19):4009-4015
The asymmetric allylic alkylation of rac-1,3-diphenyl-2-propenyl acetate 1 with dimethyl malonate 2a proceeded smoothly in the presence of lithium acetate, BSA (N,O-bis(trimethylsilyl)acetamide), [Pd(η3-C3H5)Cl]2, and the chiral ligand (R)-i-Pr2N-PHEST (R)-5a to give the allylic alkylation product (R)-3a in 89% yield with 99% ee. Furthermore, the asymmetric allylic amination of 1 with potassium phthalimide 2c has been carried out using the same ligand to give the allylic amination product (S)-3c in 10% yield with 66% ee.  相似文献   

10.
The resolution by Lipase PS of rac-5 (from reduction of ketone 6, obtained from dicyclopentadiene with a new environment-friendly synthesis) gives (2S)-5, which was further reduced to the endo(2R)-1a alcohol. The endo(2S)-1b alcohol was obtained from camphor with a multistep synthesis. Pinacol couplings of 3a,b, carried out with Mg/Hg or Corey's general procedure respectively, afforded with high diastereoselectivity the C2 symmetry diols (2R,2′R)-2a and (2S,2′S)-2b, with endo oriented OH functions. The enantiogenic power of the endo alcohol (2R)-1a and (2S)-1b and of the diols (2R,2′R)-2a and (2S,2′S)-2b was tested towards the LiAlH4 reduction of acetophenone. The C2 symmetry appears to play a fundamental role.  相似文献   

11.
The first synthesis of tadalafil 1 (Cialis) from l-tryptophan is described. The title compound 1 was synthesized via seven steps from l-tryptophan methyl ester hydrochloride in 42.3% overall yield. Two characteristic steps involved in this synthesis are the base-catalyzed epimerization of the C-3 position of (1S,3S)-1,2,3-trisubstituted-tetrahydro-β-carboline 3a and the acid-catalyzed epimerization of the C-1 position of (1S,3R)-1,3-disubstituted-tetrahydro-β-carboline 5. The (S)-configurations at C-1 and C-3 were inverted to (R)-configurations during the epimerization reactions. The base-catalyzed epimerization of C-3 of (1S,3S)-1,2,3-trisubstituted-tetrahydro-β-carbolines 3a3e was also studied in detail.  相似文献   

12.
《Tetrahedron: Asymmetry》1998,9(12):2065-2079
rac-α-Chlorocarboxylic acids, rac-9ae, were formally deracemized by reaction of the corresponding acyl chlorides with the chiral auxiliaries (R)- and (S)-3-hydroxy-4,4-dimethyl-1-phenyl-2-pyrrolidinone, (R)- and (S)-4, followed by mild alkaline hydrolysis. The highest o.p. (99%) was obtained in the case of (S)-α-chloropropanoic acid, a known precursor for the synthesis of (R)-α-aryloxypropanoic acid herbicides such as dichlorprop-P, (R)-3a, or mecoprop-P, (R)-3b, which, together with their enantiomers, were also obtained in moderate e.e.s by dynamic kinetic resolution from (αRS,3S)-4,4-dimethyl-2-oxo-1-phenylpyrrolidin-3-yl α-bromopropanoate, (αRS,3S)-6, by reaction with the corresponding phenoxide followed by mild acid hydrolysis.  相似文献   

13.
A novel and simple process for the preparation of enantiomerically pure (SS)-benzenesulfinamide (SS)-3a, (SS)-p-toluenesulfinamide (SS)-3b, (SS)-p-chloro-benzenesulfinamide (SS)-3c and (SS)-p-fluorobenzenesulfinamide (SS)-3d has been developed. The treatment of arylsulfinyl chlorides with (R)-N-benzyl-1-phenylethanamine in the presence of excess triethylamine gave diastereomeric mixtures of N-benzyl-N-(1-phenylethyl)-arylsulfinamides 1, which underwent spontaneous crystallization to furnish diastereomerically pure (R,SS)-N-benzyl-N-(1-phenylethyl)-arylsulfinamides (R,SS)-1a-1d in 28%, 29%, 27% and 31% yields, respectively. The diastereomerically pure compounds (R,SS)-1 were then converted into four enantiopure (RS)-methyl arylsulfinates (RS)-2, and finally into four enantiopure (SS)-arylsulfinamides (SS)-3 in good yields.  相似文献   

14.
Treatment of [(1,5-C8H12)PtCl(X)] (X=Cl, CH3, CH2CMe3) with C2 chiral cyclopentane-1,2-diyl-bis(phosphanes) C5H8(PR2)2, either as racemic mixtures or as resolved enantiomers, afforded the chelate complexes [C5H8(PR2)2Pt(Cl)(X)] (X=Cl: R=Ph (1), N-pip (2), OPh (3); X=CH3: R=Ph (4), N-pip (5), OPh (6); X=CH2CMe3: R=Ph (7), N-pip (8), OPh (9); ‘N-pip’=N(CH2)5), (+)-[(1R,2R)-C5H8{P(OPh)2}2PtCl2] [(R,R)-3], (−)-[(1S,2S)-C5H8{P(OPh)2}2PtCl2] [(S,S)-3], (−)-[(1R,2R)-C5H8(PPh2)2Pt(Cl)(X)], and (+)-[(1S,2S)-C5H8(PPh2)2Pt(Cl)(X)] (X=CH3: (R,R)-4, (S,S)-4; X=CH2CMe3: (R,R)-7, (S,S)-7). Reacting 4, 6, and 7 with AgO3SCF3 led to triflate derivatives [C5H8(PR2)2Pt(X)(OSO2CF3)] [X=CH3: R=Ph (11), OPh (12); X=CH2CMe3: R=Ph (13)] with covalently bonded OSO2CF3 ligands. The unusual Pt2 complex [μ-Cl{C5H8(PPh2)2PtCH3}2]O3SCF3 (14) containing an unsupported single Pt---Cl---Pt bridge was also isolated. In the presence of SnCl2, complexes 1, 3, 4, 6, 7, and 9 are catalysts for the hydroformylation of styrene forming 2- and 3-phenylpropanal together with ethylbenzene. Except for 1, they also catalyze the consecutive hydrogenation of the primary propanals to alcohols. High regioselectivities towards 2-phenylpropanal (branched-to-normal ratios ≥91:9) were obtained in hydroformylations catalyzed by 3 and 4, for which the influence of varied CO/H2 partial pressures, catalyst-to-substrate ratios and different reaction temperatures and times on the outcome of the catalytic reaction was also studied. When tin-modified complexes (R,R)-3, (S,S)-3, and (S,S)-4 were used as optically active Pt(II) catalysts, an only low stereoselectivity for asymmetric hydroformylation (e.e.<18%) was observed. The Pt---Sn complexes [C5H8(PR2)2Pt(CH3)(SnCl3)] [R=Ph (15), OPh (17)], resulting from SnCl2 insertion into the Pt---Cl bonds of 4 or 6, undergo rapid degradation in solution, forming mixtures composed of [C5H8(PR2)2Pt(X)(Y)] with R=Ph or OPh and X/Y=Cl/SnCl3 (16, 18), Cl/Cl (1, 3), and SnCl3/SnCl3 (19, 20), respectively. In the presence of SnCl2, triflate complex 11 also becomes a catalyst for styrene hydroformylation and consecutive hydrogenation of the aldehydes to alcohols. The crystal structures of 11 complexes — 2, 5, 7, 8, 9, 10 (the previously prepared [C5H8{P(N-pip)2}2Pt(CH2CMe3)2]), 13, 14, 16, (R,R)-3, and (S,S)-3 — were determined by X-ray diffraction.  相似文献   

15.
The thermolysis of (3R,9bS)-5-oxo-2,3,5,9b-tetrahydrothiazolo[2,3-a]isoindole-3-carboxylic acids in Ac2O led to novel 3-methylene-2,5-dioxo-3H,9bH-oxazolo[2,3-a]isoindoles and chiral (9bS)-5-oxo-2,3,5,9b-tetrahydrothiazolo[2,3-a]isoindoles were obtained on FVP. Starting from l-cysteine methyl ester (3R,10bR)-5-oxo-2,3-dihydro-10bH-[1.3]thiazolo[3,2-c][1,3]benzoxazines were obtained as single stereoisomers. The thermolysis of (3R,10bR)-5-oxo-2,3-dihydro-10bH-[1.3]thiazolo[3,2-c][1,3]benzoxazine-3-carboxylic acid in Ac2O gave 5-acetyl-2-phenyl-2,3-dihydrothiazole. The structures of methyl (3R,9bS)-5-oxo-2,3,5,9b-tetrahydrothiazolo[2,3-a]isoindole-3-carboxylate 1a and methyl (2R,4R)-N-chlorocarbonyl-2-(2-hydroxyphenyl)thiazolidine-4-carboxylate 9 were determined by X-ray crystallography.  相似文献   

16.
A practical and enantiopure synthesis for the preparation of key intermediates of conformationally locked γ-amino acid and nucleoside analogues is described. First, a highly stereoselective aziridine ring-opening reaction with phenylselenide anion was employed for the stereoselective synthesis of the chiral aminoselenide (1S,2S,1′S)-8, which after N-benzylation was transformed into the corresponding allyl amine (1S,1′S)-7 by oxidation with H2O2. Then, dihydroxylation–dehomologation of (1S,1′S)-7 with (OsO4/NMO, NaIO4) selectively afforded the desired γ-aminocyclopentene aldehyde (S)-1 and its corresponding γ-amino acid (S)-2 via an intramolecular selective aldol-condensation catalyzed by an internal base.  相似文献   

17.
The complex [Rh(CO)2Cl]2 reacts with two molar equivalent of pyridine carboxylic acids ligands Py-2-COOH(a), Py-3-COOH(b) and Py-4-COOH(c) to yield rhodium(I) dicarbonyl chelate complex [Rh(CO)2(L/)](1a) {L/ = η2-(N,O) coordinated Py-2-COO(a/)} and non-chelate complexes [Rh(CO)2ClL//](1b,c) {L// = η1-(N) coordinated Py-3-COOH(b), Py-4-COOH(c)}. The complexes 1 undergo oxidative addition (OA) reactions with different electrophiles such as CH3I, C2H5I, C6H5CH2Cl and I2 to give penta coordinated Rh(III) complexes of the types [Rh(CO)(CORn)XL/], {n = 1,2,3; R1 = CH3(2a); R2 = C2H5(3a); X = I and R3 = CH2C6H5 (4a); X = Cl}, [Rh(CO)I2L/](5a), [Rh(CO)(CORn)ClXL//] {R1 = CH3(6b,c); R2 = C2H5(7b,c); X = I and R3 = CH2C6H5 (8b,c); X = Cl} and [Rh(CO)ClI2L//](9b,c). The complexes have been characterized by elemental analysis, IR and 1H NMR spectroscopy. Kinetic data for the reaction of 1a–b with CH3I indicate a first order reaction. The catalytic activity of 1a–c for the carbonylation of methanol to acetic acid and its ester is evaluated and a higher turn over number (TON = 810–1094) is obtained compared with that of the well-known commercial species [Rh(CO)2I2] (TON = 653) at mild reaction conditions (temperature 130 ± 5 °C, pressure 35 ± 5 bar).  相似文献   

18.
The double addition of bis(trimethylsilyl) ketene acetals [R1, R2 = CH3, -(CH2)5-] to pyridine N-oxide promoted by triflic anhydride under mild conditions generates N-[(trifluoromethane)sulfonyl-1,2-dihydropyridine-2,4-dicarboxylic acids 2a-b. Subsequent reaction of these acids upon iodolactonization conditions affords tetrahydrofuro[3,2-b]pyridine-2(3H)-ones 3a-b containing an exo-insaturation on the products as a result of an unexpected decarboxylation.  相似文献   

19.
2,2,2-Trifluoroethanol, 1,1,1,3,3,3-hexafluoro-2-propanol, and nonafluoro-tert-butyl alcohol were used as precursors for the preparation of the appropriate bis(polyfluoroalkoxymethyl)carbinols [(RFHOCH2)2CHOH, 1a-c, RFH = (a) CF3CH2, (b) (CF3)2CH, and (c) (CF3)3C] and the corresponding mesylates [(RFHOCH2)2CHOSO2CH3, 2a-c]. This novel design paradigm is introduced to eliminate the persistence and bioaccumulation problems of fluorous chemistry, which are associated with the use of longer linear perfluoroalkyl groups (e.g. Rfn ≥ n-C8F17, n-C7F15). Secondary mesylates 2a,b and the primary tosylate [(CF3)3COCH2CH2OTs, 2d] displayed acceptable reactivity towards azide and imidazole nucleophiles to allow the syntheses of novel fluorous azides, which on hydrogenolysis with H2/Pd-C offered fluorous amines [(RFHOCH2)2CHNH2, 8a,b], and 1-(polyfluoroalkyl)imidazoles (5a,b,d), respectively, while 2c showed no reactivity due to steric hindrance. The reaction of 8a,b with formaline, glyoxal and hydrochloric acid gave symmetrical 1,3-dialkylated imidazolium chlorides (9a,b), while 5a,b,d were effectively alkylated using n-C8F17(CH2)3I, methyl iodide, 2-bromoethanol, and 2d to yield the corresponding 1,3-dialkylimidazolium iodides, bromides, and tosylates (7aa-ec). Some physical properties of new compounds including mp, bp and solubility patterns were also analyzed; and the fluorophilicity values of 1a-c, and 2a-c were experimentally determined by GC and/or 19F NMR spectroscopy.  相似文献   

20.
Mikio Fujii  Hiroyuki Akita 《Tetrahedron》2008,64(22):5147-5149
The concise synthesis of (8aR)-(−)-albaconol (1) from (8aR)-albicanol (2) obtained from the lipase-assisted asymmetric acetylation of rac-2, was achieved in 45% overall yield (eight steps). By comparison of the sign of specific rotation of between synthetic (8aR)-(−)-albaconol (1) and natural (+)-albaconol (1), the absolute structure of natural (+)-1 was determined to be 1R,2R,4aS,8aS configuration.  相似文献   

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