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1.
Yu‐Long Wang Meng Feng Xian Tao Qing‐Yun Tang Ying‐Zhong Shen 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(1):25-28
The lanthanum(III) complexes tris(3,5‐diphenylpyrazolato‐κ2N,N′)tris(tetrahydrofuran‐κO)lanthanum(III) tetrahydrofuran monosolvate, [La(C15H11N2)3(C4H8O)3]·C4H8O, (I), and tris(3,5‐diphenyl‐1,2,4‐triazolato‐κ2N1,N2)tris(tetrahydrofuran‐κO)lanthanum(III), [La(C14H10N3)3(C4H8O)3], (II), both contain LaIII atoms coordinated by three heterocyclic ligands and three tetrahydrofuran ligands, but their coordination geometries differ. Complex (I) has a mer‐distorted octahedral geometry, while complex (II) has a fac‐distorted configuration. The difference in the coordination geometries and the existence of asymmetric La—N bonding in the two complexes is associated with intramolecular C—H...N/O interactions between the ligands. 相似文献
2.
Two efficient methods for the preparation of 2‐(2‐sulfanyl‐4H‐3,1‐benzothiazin‐4‐yl)acetic acid derivatives 3 under mild conditions have been developed. The first method is based on the reaction of 3‐(2‐isothiocyanatophenyl)prop‐2‐enoates 1a – 1c with thiols in the presence of Et3N in THF at room temperature, leading to the corresponding dithiocarbamate intermediates 2 , which underwent spontaneous cyclization at the same temperature by an attack of the S‐atom at the prop‐2‐enoyl moiety in a 1,4‐addition manner (Michael addition) to give 2‐(2‐sulfanyl‐4H‐3,1‐benzothiazin‐4‐yl)acetates in one pot. The second method involves treatment of 3‐(2‐isothiocyanatophenyl)prop‐2‐enoic acid derivatives 1b – 1d with Na2S leading to the formation of 2‐(2‐sodiosulfanyl‐4H‐3,1‐benzothiazin‐4‐yl)acetic acid intermediates 5 by a similar addition/cyclization sequence, which are then allowed to react with alkyl or aryl halides to afford derivatives 3 . 2‐(2‐Thioxo‐4H‐3,1‐benzothiazin‐4‐yl)acetic acid derivatives 6 can be obtained by omitting the addition of halides. 相似文献
3.
An efficient method for the preparation of 2‐substituted 4‐aryl‐4,5‐dihydro‐3,1‐benzoxazepine derivatives under mild conditions has been developed. The reaction of 2‐(2‐aminophenyl)ethanols 1 with acid chlorides in the presence of excess Et3N in THF at room temperature gave the corresponding N‐acylated intermediates 2 , which were dehydrated by treatment with POCl3 to give 2‐substituted 4‐aryl‐4,5‐dihydro‐3,1‐benzoxazepines 3 in a one‐pot reaction. 相似文献
4.
Xia Li Ying‐Quan Zou Hai‐Bin Song 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(3):m110-m111
Each La3+ ion in the title complex, tetra‐μ‐2‐fluorobenzoato‐κ10O:O′;O:O,O′;O:O′;O,O′:O′‐bis[aqua(4,4′‐bipyridine‐κN)(2‐fluorobenzoato‐κO)lanthanum(II)], [La(C7H4FO2)6(C10H8N2)2(H2O)2], is coordinated by six O atoms from the carboxylate groups of five 2‐fluorobenzoate ligands, one O atom from a water molecule and one N atom from a 4,4′‐bipyridine molecule, thus forming a dimeric molecule. An infinite one‐dimensional dimeric supramolecular chain is formed via intermolecular hydrogen bonds. 相似文献
5.
Chen‐Jun Shi Huai‐Guo Xue Zhi‐Quan Shen Yi‐Feng Zhang Yong‐Fang Li Chun‐He Yang 《中国化学》2001,19(10):976-978
High trans‐l,4‐polybutadiene ( ?96% (trans)) was prepared by lanthanum naphthenate catalytic system. The conductivity of obtained polybutadiene doped with iodine reaches about ?100 s/cm, which is 2 orders of magnitude higher than the value reported.4,5 During the I2‐doping, the conjugated sequence was formed through double bond shifting reaction. According to the relationship between conductivity and temperature, conducting mechanism of doped high trans‐l,4‐polybutadiene is fit on variable range hoping (VRH) model. 相似文献
6.
Xuerui Wang Wenxue Zhang Hongjuan Shen Wei Zhang 《Journal of heterocyclic chemistry》2013,50(3):501-505
A one‐pot synthesis of pyrrolo[1,2‐a]quinolin‐1‐ones has been developed from the reactions of 5‐hydroxy‐1‐arylpyrrolidin‐2‐ones with 1,3‐dicarbonyl compounds under the promotion of H3PO4/P2O5 or HOAc/H2SO4. The pyrrolo[1,2‐a]quinolin‐1‐ones are formed by two‐step reactions, that is, the coupling of N‐acyliminium ion intermediates produced from 5‐hydroxy‐1‐arylpyrrolidin‐2‐ones with 1,3‐dicarbonyls and subsequent Friedel–Crafts reactions of the resulting ketone with the aryl ring. 相似文献
7.
Dr. Aliaksei Putau Dr. Harald Brand Prof. Dr. Konrad Koszinowski 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(36):12868-12876
Conjugate additions of organocuprates are of outstanding importance for organic synthesis. To improve our mechanistic understanding of these reactions, we have used electrospray ionization mass spectrometry for the identification of the ionic intermediates formed upon the treatment of LiCuR2 ? LiCN (R=Me, Bu, Ph) with a series of α,β‐unsaturated nitriles. Acrylonitrile, the weakest Michael acceptor included, did not afford any detectable intermediates. Fumaronitrile (FN) yielded adducts of the type Lin?1CunR2n(FN)n?, n=1–3. When subjected to fragmentation in the gas phase, these adducts were not converted into the conjugate addition products, but re‐dissociated into the reactants. In contrast, the reaction with 1,1‐dicyanoethylene furnished the products of the conjugate addition without any observable intermediates. Tri‐ and tetracyanoethylene proved to be quite reactive as well. The presence of several cyano groups in these substrates opened up reaction pathways different from simple conjugate additions, however, and led to dimerization and substitution reactions. Moreover, the gas‐phase fragmentation behavior of the species formed from these substrates indicated the occurrence of single‐electron transfer processes. Additional quantum‐chemical calculations provided insight into the structures and stabilities of the observed intermediates and their consecutive reactions. 相似文献
8.
Sébastien Georges Fanny Bonnet Pascal Roussel Marc Visseaux Philippe Zinck 《应用有机金属化学》2016,30(1):26-31
Mg(n‐Bu){η2‐HC[C(Me)NMes]2} ( 2 ) (Mes = mesityl, 2,4,6‐Me3C6H2), a new β‐diketiminate‐supported magnesium alkyl, has been synthesized and structurally characterized. The X‐ray analysis of the lanthanum half‐sandwich complex Cp*La(BH4)2(THF)2 ( 1 ) (Cp* = pentamethylcyclopentadienyl; THF = tetrahydrofuran) is also reported. Complex 2 has been assessed as both alkylating agent and chain transfer agent for the lanthanum‐catalysed polymerization and coordinative chain transfer polymerization of isoprene and styrene using 1 as the pre‐catalyst. The results are compared with those for n‐butylethylmagnesium (BEM) which is traditionally used for this purpose. The 1,4‐trans stereospecific polymerization of isoprene shows a more controlled character using 2 versus BEM, and higher activities are observed for the chain transfer polymerization of styrene when 2 is used as chain transfer agent. The activity is in turn lower than that observed using BEM when 1 equiv. of magnesium compound is used for the polymerization of styrene. The combination of 1 , 2 and Al(i‐Bu)3 leads finally to a 1,4‐trans stereoselective coordinative chain transfer polymerization of isoprene, in a similar way to BEM. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
9.
A series of 7‐fluorinated 7‐deazapurine 2′‐deoxyribonucleosides related to 2′‐deoxyadenosine, 2′‐deoxyxanthosine, and 2′‐deoxyisoguanosine as well as intermediates 4b – 7b, 8, 9b, 10b , and 17b were synthesized. The 7‐fluoro substituent was introduced in 2,6‐dichloro‐7‐deaza‐9H‐purine ( 11a ) with Selectfluor (Scheme 1). Apart from 2,6‐dichloro‐7‐fluoro‐7‐deaza‐9H‐purine ( 11b ), the 7‐chloro compound 11c was formed as by‐product. The mixture 11b / 11c was used for the glycosylation reaction; the separation of the 7‐fluoro from the 7‐chloro compound was performed on the level of the unprotected nucleosides. Other halogen substituents were introduced with N‐halogenosuccinimides ( 11a → 11c – 11e ). Nucleobase‐anion glycosylation afforded the nucleoside intermediates 13a – 13e (Scheme 2). The 7‐fluoro‐ and the 7‐chloro‐7‐deaza‐2′‐deoxyxanthosines, 5b and 5c , respectively, were obtained from the corresponding MeO compounds 17b and 17c , or 18 (Scheme 6). The 2′‐deoxyisoguanosine derivative 4b was prepared from 2‐chloro‐7‐fluoro‐7‐deaza‐2′‐deoxyadenosine 6b via a photochemically induced nucleophilic displacement reaction (Scheme 5). The pKa values of the halogenated nucleosides were determined (Table 3). 13C‐NMR Chemical‐shift dependencies of C(7), C(5), and C(8) were related to the electronegativity of the 7‐halogen substituents (Fig. 3). In aqueous solution, 7‐halogenated 2′‐deoxyribonucleosides show an approximately 70% S population (Fig. 2 and Table 1). 相似文献
10.
Carolin Schwehm William Lewis Alexander J. Blake Barrie Kellam Michael J. Stocks 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(12):1161-1168
Bicycle ring closure on a mixture of (4aS,8aR)‐ and (4aR,8aS)‐ethyl 2‐oxodecahydro‐1,6‐naphthyridine‐6‐carboxylate, followed by conversion of the separated cis and trans isomers to the corresponding thioamide derivatives, gave (4aSR,8aRS)‐ethyl 2‐sulfanylidenedecahydro‐1,6‐naphthyridine‐6‐carboxylate, C11H18N2O2S. Structural analysis of this thioamide revealed a structure with two crystallographically independent conformers per asymmetric unit (Z′ = 2). The reciprocal bicycle ring closure on (3aRS,7aRS)‐ethyl 2‐oxooctahydro‐1H‐pyrrolo[3,2‐c]pyridine‐5‐carboxylate, C10H16N2O3, was also accomplished in good overall yield. Here the five‐membered ring is disordered over two positions, so that both enantiomers are represented in the asymmetric unit. The compounds act as key intermediates towards the synthesis of potential new polycyclic medicinal chemical structures. 相似文献
11.
Novel π2s+π2a Electrocyclization of Triethylenic‐Malonic Acids Exemplified for a One‐Pot Synthesis of New γ‐Dilactones cis‐Fused with a Cyclopentene
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Jean‐Marc Dillenschneider Laurent Dufossé Mireille Fouillaud Nuthathai Sutthiwong Roger Labia Alain Valla 《Journal of heterocyclic chemistry》2016,53(4):1017-1021
A new, easy and rapid synthesis of γ‐dilactones is cis‐fused with a cyclopentenic ring via cyclization of 7‐chlorotriethylenic‐malonic acids. The key step implicates an intramolecular cyclization to a cyclopentenyl cation, according to an electrocyclic π2s + π2a conrotatory process. This cyclopentenyl cation led to unstable γ‐lactones intermediates that are rearrange to more stable isomers. δ‐lactones (6Z and 6E‐(3‐chlorobut‐2‐en‐2‐yl)‐5‐methyl‐3,6‐dihydro‐2H‐pyran‐2‐one) were obtained as secondary products. Mechanistic pathways were considered. The structures of the newly synthesized compounds were established by elemental and spectral data. 相似文献
12.
PPh3⋅HBr‐DMSO Mediated Expedient Synthesis of γ‐Substituted β,γ‐Unsaturated α‐Ketomethylthioesters and α‐Bromo Enals: Application to the Synthesis of 2‐Methylsulfanyl‐3(2 H)‐furanones
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Kanchan Mal Abhinandan Sharma Dr. Prakas R. Maulik Dr. Indrajit Das 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(3):662-667
An efficient chemoselective general procedure for the synthesis of γ‐substituted β,γ‐unsaturated α‐ketomethylthioesters from α,β‐unsaturated ketones has been achieved through an unprecedented PPh3?HBr‐DMSO mediated oxidative bromination and Kornblum oxidation sequence. The newly developed reagent system serves admirably for the synthesis of α‐bromoenals from enals. Furthermore, AuCl3‐catalyzed efficient access to 3(2H)‐furanones from the above intermediates under extremely mild conditions are described. 相似文献
13.
Pierre Martin 《Helvetica chimica acta》2003,86(1):204-209
A New Access to 2′‐ O ‐(2‐Methoxyethyl)ribonucleosides Starting from D ‐Glucose A new synthesis of 2′‐O‐(2‐methoxyethyl)ribonucleosides, building blocks for second‐generation antisense oligonucleotides, starting from D ‐glucose is presented. The key‐step is the transformation of 3‐O‐methoxyethylallofuranose to 2‐O‐(2‐methoxyethyl)ribose by NaIO4 oxidation. Together with the 4′‐phenylbenzoyl protecting group, which results in crystalline intermediates, this synthesis provides an easy and cheap access to 2′‐O‐(2‐methoxyethyl)‐substituted ribonucleosides. 相似文献
14.
Anja Siegemund Christine Hartung Sven Baumann Brbel Schulze 《Helvetica chimica acta》2004,87(2):376-381
2‐Aryl‐4,5,6,7‐tetrahydro‐1,2‐benzisothiazol‐3(2H)‐ones 1a – e were synthesized by cyclocondensation of 2‐(thiocyanato)cyclohexene‐1‐carboxanilides 9 as a convenient new method. Their S‐oxides 10 were prepared by two routes, either by oxidation of 1 or dehydration of rac‐cis‐3‐hydroperoxysultims 11 . Furthermore, compounds 1 have been identified by HPLC? API‐MS‐MS as intermediates in the oxidation process of the salts 6 . The hydroperoxides 12b and rac‐trans‐ 11b have been unambiguously detected by HPLC? MS investigations and in the reaction of rac‐cis‐ 13b with H2O2 to the hydroperoxides rac‐trans‐ 11b and rac‐cis‐ 11b . 相似文献
15.
A convenient procedure for the synthesis of 2,N,N‐trisubstituted 1H‐indole‐1‐carbothioamides from 2‐(acylmethyl)phenyl isocyanides has been developed. Thus, these isocyanides are converted into (Z)‐ [1‐alkyl (or phenyl)‐2‐(2‐isothiocyanatophenyl)ethenyl] 1,1‐dimethylethyl carbonates via an easy two‐step sequence. Treatment with secondary amines gave thiourea intermediates which afforded with CF3COOH (TFA) the desired products in fair‐to‐good yields. 相似文献
16.
Synthesis of 1‐Acyl‐3,4‐dihydroquinazoline‐2(1H)‐thiones by Cyclization of N‐[2‐(Isothiocyanatomethyl)phenyl] Amides Generated in situ from N‐[2‐(Azidomethyl)phenyl] Amides
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An efficient method for the preparation of 1‐acyl‐3,4‐dihydroquinazoline‐2(1H)‐thiones 5 has been developed. The reaction of N‐[2‐(azidomethyl)phenyl] amides 3 , easily prepared by a three‐step sequence starting with (2‐aminophenyl)methanols, with Ph3P, followed by CS2, allowed generation of N‐[2‐(isothiocyanatomethyl)phenyl]‐amide intermediates 4 , which underwent cyclization on treatment with NaH to furnish the corresponding desired products in generally good yields. 相似文献
17.
Frank Seela KhalilI. Shaikh Thomas Wiglenda Peter Leonard 《Helvetica chimica acta》2004,87(10):2507-2516
The syntheses of N7‐glycosylated 9‐deazaguanine 1a as well as of its 9‐bromo and 9‐iodo derivatives 1b , c are described. The regioselective 9‐halogenation with N‐bromosuccinimide (NBS) and N‐iodosuccinimide (NIS) was accomplished at the protected nucleobase 4a (2‐{[(dimethylamino)methylidene]amino}‐3,5‐dihydro‐3‐[(pivaloyloxy)methyl]‐4H‐pyrrolo[3,2‐d]pyrimidin‐4‐one). Nucleobase‐anion glycosylation of 4a – c with 2‐deoxy‐3,5‐di‐O‐(p‐toluoyl)‐α‐D ‐erythro‐pentofuranosyl chloride ( 5 ) furnished the fully protected intermediates 6a – c (Scheme 2). They were deprotected with 0.01M NaOMe yielding the sugar‐deprotected derivatives 8a – c (Scheme 3). At higher concentrations (0.1M NaOMe), also the pivaloyloxymethyl group was removed to give 7a – c , while conc. aq. NH3 solution furnished the nucleosides 1a – c . In D2O, the sugar conformation was always biased towards S (67–61%). 相似文献
18.
WolfgangG. Wirschun MartinG. Hitzler JohannesC. Jochims Ulrich Groth 《Helvetica chimica acta》2002,85(9):2627-2635
X‐Ray‐diffraction analysis of tBu2CN SCl ( 4b ) revealed an almost linear CNS unit with an SN bond order of ca. 1.9 (Fig. 1), in agreement with the structure of a 1‐thia‐2‐azoniaallene chloride. With SCl2 and SbCl5, compound 4b was transformed into the imidosulfurous dichloride 6 (Scheme 2). With morpholine, compounds 4b and 6 afforded the sulfenamide 7 and the aminosulfonium salt 8 , respectively. The (diarylmethylene)amidosulfenyl chlorides 4g , h , i reacted with SbCl5 to give SbCl salts of the 1,2‐benzisothiazoles 9a , b , d , most likely via 1‐thia‐2‐azoniaallene intermediates 2 (Scheme 3). 相似文献
19.
A Novel Synthesis of Quinazolines by Cyclization of 1‐(2‐Isocyanophenyl)alkylideneamines Generated by the Treatment of 2‐(1‐Azidoalkyl)phenyl Isocyanides with NaH
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A new and efficient method for the synthesis of quinazolines has been developed. Thus, N‐[2‐(1‐azidoalkyl)phenyl]formamides 1 are dehydrated with POCl3 to give the corresponding 2‐(1‐azidoalkyl)phenyl isocyanides 2 , which are then treated with NaH in DMF at 0° to give quinazolines 6 in satisfactory yields via cyclization of 1‐(2‐isocyanophenyl)alkylideneamine intermediates 4 . This methodology can be applied to the synthesis of the 7‐azaanalogs of quinazolines, i.e., pyrido[3,4‐d]pyrimidines 9 . 相似文献
20.
Guowei Wang Xiaoshan Fan Junlian Huang 《Journal of polymer science. Part A, Polymer chemistry》2010,48(23):5313-5321
4μ‐A2B2 star‐shaped copolymers contained polystyrene (PS), poly(isoprene) (PI), poly(ethylene oxide) (PEO) or poly(ε‐caprolactone) (PCL) arms were synthesized by a combination of Glaser coupling with living anionic polymerization (LAP) and ring‐opening polymerization (ROP). Firstly, the functionalized PS or PI with an alkyne group and a protected hydroxyl group at the same end were synthesized by LAP and then modified by propargyl bromide. Subsequently, the macro‐initiator PS or PI with two active hydroxyl groups at the junction point were synthesized by Glaser coupling in the presence of pyridine/CuBr/N,N,N ′,N ″,N ″‐penta‐methyl diethylenetri‐amine (PMDETA) system and followed by hydrolysis of protected hydroxyl groups. Finally, the ROP of EO and ε‐CL monomers was carried out using diphenylmethyl potassium (DPMK) and tin(II)‐bis(2‐ethylhexanoate) (Sn(Oct)2) as catalyst for target star‐shaped copolymers, respectively. These copolymers and their intermediates were well characterized by SEC, 1H NMR, MALDI‐TOF mass spectra and FT‐IR in details. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献