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1.
A concise approach for the frst total synthesis of two naturally occurring flavanoids,()-malaysianone A(1)and()-tanariflavanones B(2),has been accomplished with total yields of 12.9%and 10.4%,respectively.The key steps were regioselective deprotection and regioselective synthesis of 5-formaldehyde-8-hydroxy-2-[40-methyl-30-penteneyl]-dihydro-1-benzopyran(8).  相似文献   

2.
A short formal stereoselective synthesis of (-)-swainsonine (1) is described. Our synthesis started with the versatile building block (R)-3-benzyloxyglutarimide 5. Through controlled regioselective reduction, Ley's-sulfone chemistry (N-α-sulfonylation and ZnCl2-catalyzed N-α-amidovinylation), an RCM reaction, and an amide reduction, the synthesis of unsaturated indolizidine (8R,8aS)-3 has been achieved in five steps. The indolizidine (8R,8aS)-3 is an advanced intermediate toward the synthesis of (-)-swainsonine (1).  相似文献   

3.
First total synthesis of (±)-abyssinoflavanone V   总被引:1,自引:0,他引:1  
The total synthesis of (±)-abyssinoflavanone V was first achieved through C-prenylation, selective protection of phenolic hydroxyl group, aldol condensation, cyclization and deprotection starting from cheap 4-hydroxybenzaldehyde and 2,4,6- trihydroxyacetophenone, with total yield 24%. All structures of new compounds were confirmed by IR, 1^H NMR and MS.  相似文献   

4.
A simple and effective procedure for the enantioselective synthesis of (R)- and (S)-moprolol was described. The key step was the asymmetric synthesis of enantiopure (R)- and (S)-guaifenesin, which were synthesized from enantioenriched (R)-3-chloro-l,2-propanediol and (S)-epichlorohydrin via kinetics of hydrolysis resolution of racemic epichlorohydrin by chiral Salen-Co^Ⅲ complex. The e.e. values of both the optical compounds were above 98%, and the chemical structures of the target compounds were confirmed by ^1H NMR, ^13C NMR, IR, and MS.  相似文献   

5.
6.
以廉价易得的异戊基溴为起始原料,以烯丙基二异松莰烷基硼烷参与的不对称烯丙基化反应和Yamaguchi酯化反应为关键步骤,实现了对(-)-(3S,6R)-3,6-二羟基-10-甲基十一酸(总收率27.5%)及其三聚体(总收率24.5%)的不对称全合成。  相似文献   

7.
8.
合成了四种含樟脑巯基手性助剂的光学活性的硫亚胺化合物。  相似文献   

9.
Lost in rotation: The concise strategy of the first enantioselective total synthesis of bismurrayaquinone?A utilized traceless stereochemical exchange to form an enantioenriched biphenyl core that was elaborated in a bidirectional manner to the natural product. Observed racemization on an unsuccessful initial route prompted studies into the configurational stability of bismurrayaquinone?A and related biquinones.  相似文献   

10.
The reaction of [Fe2S2(CO)6] with one equiv.of o-OCH3C6H4CH2Br under the re-duction of LiBHEt3 in dry THF afforded a tetranuclear cluster [(μ4-S){(μ-SCH2(o-OCH3)Ph)Fe2(CO)6}2](1).Complex 1 crystallizes in monoclinic,space group P21/n with a = 16.5623(6),b = 12.8265(5),c = 18.2702(7) ,β = 115.95(1)o,V = 3489.9(4) 3,Z = 4,μ = 1.87 mm-1,Dc = 1.709 Mg/m3,T = 296(2) K,C28H18Fe4O14S3,Mr = 898.03,F(000) = 1800,S = 1.10,R = 0.032 and wR = 0.058.Complex 1 consists of two diiron fragments possessing a {Fe2(CO)6} core.The two diiron units are bridged by an inorganic sulfide in a μ4-S binding mode and the sulfide is in a distorted tetrahedral geometry with the four iron atoms at each corner of the distorted tetrahedral.In its solid state,two types of non-classic intermolecular hydrogen bonding interactions plus a weak π-π stacking interaction led to a 2-D network.  相似文献   

11.
3,4-Epoxybisabola-7(14),10-dien-2-one,a natural sesquiterpoind,was first synthesized from(-)-carvone through 7 steps,in an overall yield of 35.9%.The key step was the allylation and then a substrate-directable epoxidation was committed successfully.  相似文献   

12.
Synthesis and Structure Analysis of N-(Dehydroabietyl)maleamic Acid   总被引:1,自引:0,他引:1  
N-(Dehydroabietyl)maleamic acid was synthesized from dehydroabietylamine and maleic anhydride.Its structure was characterized by IR,1 H-and 13 C-NMR spectra.The stereo structure of the title compound was also unambiguously confirmed by X-ray crystal structure analysis.The white crystal crystallizes in the monoclinic system,space group P2 1 with a=12.075(2),b=10.377(2),c=17.840(4),β=100.31(3) °,V=2199.3(8) 3,R=0.0618 and wR=0.1437.Two crystallographically independent molecules with different conformations co-exist in the unit.In each molecule,the two cyclohexane rings form a trans ring junction with chair and half-chair conformations,respectively.The C=C double bond between two carbonyl groups is in a Z configuration.Intermolecular and intramolecular hydrogen bonds coexist to stabilize the structure.  相似文献   

13.
Fe(HSO4)3 has been used as an efficient and recyclable catalyst for the one-pot synthesis of 14-aryl- or alkyl-14Hdibenzo[aj]xanthene derivatives by the reaction of 2-naphtol and aldehydes. Different types of aromatic and aliphatic aldehydes are used in the reaction and in all cases the products were obtained in good to excellent yields.  相似文献   

14.
15.
A series of four novel hydrazine-modified diamine conjugates (7a-b, 8a-b) were synthesized and evaluated for cytotoxicity against Melanoma B 16, α-difluoromethylornithine (DFMO)-treated B 16, spermidine (SPD)-treated B 16, Mouse leukemia L 1210 and Hela cell lines. Both the DFMO-B 16 and SPD-B 16 experiments indicated that conjugates 7a-b and 8a-b could recognize the polyamine transporter (PAT) and enter the cells in part or in whole via PAT, although they were not as efficient as the reference, 9- anthracenemethyl homospermidine (1). 2007 Chao Jie Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.  相似文献   

16.
Homobinuclear complex (HCuL)2 (1) (H3L: N-3-carboxylsalicylidene-N'-salicylaldehyde-1,2-diaminoethane) was obtained from self-organization of the reported complex HCuL, and its crystal structure was determined through X-ray diffraction at room temperature. The crystal of complex 1 belongs to monolinic system, the space group Cc, a=2.5326(5) nm, b=0.88861(18) nm, c=1.3738(3) nm, β=96.95(3)°, Z=4, R1=0.0520, wR2=0.1185. (HCuL)2 is a dimeric molecule and has extended phenolic oxygen-bridged structure. In addition, using mononuclear complex HCuL as building blocks, Cu(Ⅱ)-Mg(Ⅱ)-Cu(Ⅱ) heterotrinuclear complex 2 was synthesized, and its crystal structure also has been determined by X-ray analysis. The crystal of complex 2 is of monoclinic system, space group Pc, a=1.1816(2) nm, b=1.5599(3) nm, c=1.9642 (4) nm, β=98.22°, Z=2, R1=0.0701, wR2=0.1498. Each dissymmetricai cell unit of complex 2 contains two heterotrinucler neutral molecules: {[CuL(H2O)]Mg[CuL(CH3OH)]} and {[CuL]Mg[CuL(H2O)]}.  相似文献   

17.
18.
《Tetrahedron letters》2019,60(22):1471-1475
The total synthesis of four natural products, trigonostemine A, trigonostemine B, pityriacitrin, and hyrtiosulawesine was accomplished. The key intermediates, variously substituted 1-formyl-β-carbolines, were prepared in five steps via a novel synthetic approach using readily available starting materials. These formyl derivatives were then further transformed, providing a general route for the synthesis of the four title alkaloids. The method reported herein represents the first total synthesis of the two trigonostemines and a new pathway to pityriacitrin and hyrtiosulawesine.  相似文献   

19.
Geometries and binding energies were predicted at the B3LYP/6-311+G* level for the guanine-BX3 (X = F, Cl) systems and four isomers with no imaginary frequencies have been obtained for both guanine-BF3 and guanine-BCl3, respectively. Single energy calculations using much larger basis sets (6-311+G(2df,p) and aug-cc-pVDZ were carried out as well. It was found that the most stable isomer of guanine-BF3 is BF3 connected to N3 of guanine with the stabilization energy of –19.93 kcal/mol (BSSE corrected), while that of guanine-BCl3 is BCl3 connected to O10 of guanine having stabilization energy of –15.02 kcal/mol at the same level. The analyses for the combining interaction between BX3 and guanine with the atom-in-molecules theory (AIM) and natural bond orbital (NBO) methods have been performed. The results indicated that all the isomers are formed with σ-p type interactions between guanine and BX3, in which pyridine-type nitrogen or carbonyl oxygen or nitrogen atom of amino group offers its lone pair electrons to the empty p orbital of boron atom and the concomitance of charge transfer from guanine to BX3 has occurred. Still, one or two hydrogen bonds exist in some isomers of guanine-BX3 system and contribute to the stability of complex systems. Frequency analysis suggested that the stretching vibration of BX3 undergoes a red shift in complexes. Guanine-BF3 complex is more stable than guanine-BCl3 although the B–Y (Y=N, O) bond distance in the latter is shorter.  相似文献   

20.
A short 11-step synthesis of the pentacyclic core of the polycyclic xanthone antibiotic citreamicin η has been completed. Although the basic approach was inspired by our previous explorations of polycyclic xanthone chemistry, the present report features some new insights into the Moore rearrangement and offers some improvements to our original methodology that include additions of aryllithiums to squarate esters, additions of cerium acetylides to hindered ketones utilizing PDA as an internal indicator, and the use of cyclic di-tert-butylsilyl (DTBS) ethers to protect electron-rich benzyl alcohols toward ionization under acidic conditions. We also developed an improved protocol for selective o-bromination of phenols utilizing N-bromosuccinimide (NBS) and tetramethylguanidine (TMG) that promises to be generally useful. Finally, we developed a modular approach for the synthesis of isoquinolones and dihydro-5H-oxazolo[3,2-b]isoquinoline-2,5(3H)-diones that features a novel sequence of alkoxycarbonylation, acetone arylation, transamidation.  相似文献   

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