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1.
Alireza Hasaninejad Nooshin Golzar Mohsen Shekouhy Abdolkarim Zare 《Helvetica chimica acta》2011,94(12):2289-2294
A sequential one‐pot four‐component reaction for the efficient synthesis of novel 2′‐aminospiro[11H‐indeno[1,2‐b]quinoxaline‐11,4′‐[4H]pyran] derivatives 5 in the presence of AcONH4 as a neutral, inexpensive, and dually activating catalyst is described (Scheme 1). The syntheses are achieved by reacting ninhydrin ( 1 ) with benzene‐1,2‐diamines 2 to give indenoquinoxalines, which are trapped in situ by malono derivatives 2 and various α‐methylenecarbonyl compounds 4 through cyclization, providing the multifunctionalized 2′‐aminospiro[11H‐indeno[1,2‐b]quinoxaline‐11,4′‐[4H]pyran] analogs 5 . This chemistry provides an efficient and promising synthetic way of proceeding for the diversity‐oriented construction of the spiro[indenoquinoxalino‐pyran] skeleton. 相似文献
2.
Lina M. Acosta Quintero Alirio Palma Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(7):549-554
Compounds containing the tricyclic dibenzo[b,e]azepine system have potential activity in the treatment of a number of diseases. Continuing with our studies on the synthesis of new small and potentially bioactive molecules, a synthetic route, involving acid‐catalysed intramolecular Friedel–Crafts cyclization, to the readily separable diastereoisomers of 11‐ethyl‐6,11‐dihydro‐5H‐dibenzo[b,e]azepine‐6‐carboxamide, a potentially useful precursor in the synthesis of analogues of some anti‐allergenic, antidepressant and antihistaminic drugs currently in use, has been developed starting from 2‐allylphenylamine and methyl 2‐bromo‐2‐phenylacetate and proceeding via racemic methyl 2‐[(2‐allylphenyl)amino]‐2‐phenylacetate (A) and racemic 2‐[(2‐allylphenyl)amino]‐2‐phenylacetamide (B), to give the two diastereoisomers (I) and (II), C17H18N2O. Isomers (I) and (II), and their precursors (A) and (B), have all been fully characterized spectroscopically. Structure analysis of the minor isomer (I) shows that it has the (6RS,11RS) configuration, and that the azepine ring adopts a conformation intermediate between the boat and twist‐boat forms, with the carboxamide and ethyl substituents both occupying quasi‐equatorial sites. The molecules of (I) are linked by a combination of N—H…O, N—H…π(arene) and C—H…π(arene) hydrogen bonds to form complex sheets. Comparisons are made with the structures of some related compounds. 相似文献
3.
Nucleophilic trifluoromethylation of α‐imino ketones 2 , derived from arylglyoxal, with Ruppert–Prakash reagent (CF3SiMe3) offers a convenient access to the corresponding O‐silylated β‐imino‐α‐(trifluoromethyl) alcohols. In a ‘one‐pot’ procedure, by treatment with NaBH4, these products smoothly undergo reduction and desilylation yielding the expected β‐amino‐α‐(trifluoromethyl) alcohols 4 . The latter were used as starting materials for the synthesis of diverse trifluoromethylated heterocycles, including aziridines 5 , 1,3‐oxazolidines 8 , 1,3‐oxazolidin‐2‐ones 9 , 1,3,2‐oxazaphospholidine 2‐oxides 10 , 1,2,3‐oxathiazolidine 2‐oxides 11 , and morpholine‐2,3‐diones 12 . An optically active 5‐(trifluoromethyl)‐substituted 1,3‐oxazolidin‐2‐one 9g was also obtained. 相似文献
4.
Novel and Stereospecific Synthesis of (2S)‐3‐(2,4,5‐Trifluorophenyl)propane‐1,2‐diol from D‐Mannitol
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Derya Aktaş Meryem Fıstıkçı Özlem Gündoğdu Hasan Seçen M. Fethi Şahin Ramazan Altundaş Yunus Kara 《Helvetica chimica acta》2015,98(8):1127-1131
A stereospecific synthesis of (2S)‐3‐(2,4,5‐trifluorophenyl)propane‐1,2‐diol from D ‐mannitol has been developed. The reaction of 2,3‐O‐isopropylidene‐D ‐glyceraldehyde with 2,4,5‐trifluorophenylmagnesium bromide gave [(4R)‐2,2‐dimethyl‐1,3‐dioxolan‐4‐yl](2,4,5‐trifluorophenyl)methanol in 65% yield as a mixture of diastereoisomers (1 : 1). The Ph3P catalyzed reaction of the latter with C2Cl6 followed by reduction with Pd/C‐catalyzed hydrogenation gave (2S)‐3‐(2,4,5‐trifluorophenyl)propane‐1,2‐diol with >99% ee and 65% yield. 相似文献
5.
A simple and efficient enantioselective synthesis of chromene, (?)‐(R)‐cordiachromene ( 1 ), and (?)‐(R)‐dictyochromenol ( 2 ) has been accomplished. This convergent synthesis utilizes intramolecular SNAr reaction for the formation of chroman ring, and Seebach's method of ‘self‐reproduction of chirality’ should establish the (R)‐configuration of the C(2) side chain as key steps. 相似文献
6.
Mohammad Navid Soltani Rad Somayeh Behrouz Fatemeh Karimitabar Ali Khalafi‐Nezhad 《Helvetica chimica acta》2012,95(3):491-501
The ‘click synthesis’ of some novel O‐substituted oximes, 7a – 7t , which contain 1,2,3‐triazolediyl residues, as new analogs of β‐adrenoceptor antagonists is described (Schemes 1–4). The synthesis of these compounds was achieved in four to five steps. The formation of oximes of 9H‐fluoren‐9‐one and benzophenone, i.e., 9a and 9b , respectively, followed by their reaction with propargyl bromide, afforded O‐propargyl oximes 10a and 10b , respectively, which by a subsequent CuI‐catalyzed Huisgen cycloaddition with prepared β‐azido alcohols 11a – 11j (Schemes 2 and 3), led to the target compounds 7a – 7t in good yields. 相似文献
7.
A highly selective synthesis of 1‐substituted (E)‐buta‐1,3‐dienes with 4,4,5,5‐tetramethyl‐2‐vinyl‐1,3,2‐dioxaborolane as building block
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Justyna Szudkowska‐Frątczak Aline Ryba Adrian Franczyk Jędrzej Walkowiak Maciej Kubicki Piotr Pawluć 《应用有机金属化学》2014,28(3):137-139
Highly selective synthesis of 1‐substituted (E)‐buta‐1,3‐dienes via palladium‐catalyzed Suzuki–Miyaura cross‐coupling of (E)‐alkenyl iodides with 4,4,5,5‐tetramethyl‐2‐vinyl‐1,3,2‐dioxaborolane ( 1 ) is reported. The vinylboronate pinacol ester ( 1 ) acts as a vinyl building block to show high chemoselectivity for the Suzuki–Miyaura pathway versus Heck coupling in the presence of biphasic conditions (Pd(PPh3)4, aqueous K2CO3, toluene and ethanol). Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
8.
Christian Chapuis Michel Barthe Carole Cantatore Christine Saint‐Lger Patrick Wyss 《Helvetica chimica acta》2006,89(11):2638-2653
To complete our panorama in structure–activity relationships (SARs) of sandalwood‐like alcohols derived from analogues of α‐campholenal (= (1R)‐2,2,3‐trimethylcyclopent‐3‐ene‐1‐acetaldehyde), we isomerized the epoxy‐isopropyl‐apopinene (?)‐ 2d to the corresponding unreported α‐campholenal analogue (+)‐ 4d (Scheme 1). Derived from the known 3‐demethyl‐α‐campholenal (+)‐ 4a , we prepared the saturated analogue (+)‐ 5a by hydrogenation, while the heterocyclic aldehyde (+)‐ 5b was obtained via a Bayer‐Villiger reaction from the known methyl ketone (+)‐ 6 . Oxidative hydroboration of the known α‐campholenal acetal (?)‐ 8b allowed, after subsequent oxidation of alcohol (+)‐ 9b to ketone (+)‐ 10 , and appropriate alkyl Grignard reaction, access to the 3,4‐disubstituted analogues (+)‐ 4f,g following dehydration and deprotection. (Scheme 2). Epoxidation of either (+)‐ 4b or its methyl ketone (+)‐ 4h , afforded stereoselectively the trans‐epoxy derivatives 11a,b , while the minor cis‐stereoisomer (+)‐ 12a was isolated by chromatography (trans/cis of the epoxy moiety relative to the C2 or C3 side chain). Alternatively, the corresponding trans‐epoxy alcohol or acetate 13a,b was obtained either by reduction/esterification from trans‐epoxy aldehyde (+)‐ 11a or by stereoselective epoxidation of the α‐campholenol (+)‐ 15a or of its acetate (?)‐ 15b , respectively. Their cis‐analogues were prepared starting from (+)‐ 12a . Either (+)‐ 4h or (?)‐ 11b , was submitted to a Bayer‐Villiger oxidation to afford acetate (?)‐ 16a . Since isomerizations of (?)‐ 16 lead preferentially to β‐campholene isomers, we followed a known procedure for the isomerization of (?)‐epoxyverbenone (?)‐ 2e to the norcampholenal analogue (+)‐ 19a . Reduction and subsequent protection afforded the silyl ether (?)‐ 19c , which was stereoselectively hydroborated under oxidative condition to afford the secondary alcohol (+)‐ 20c . Further oxidation and epimerization furnished the trans‐ketone (?)‐ 17a , a known intermediate of either (+)‐β‐necrodol (= (+)‐(1S,3S)‐2,2,3‐trimethyl‐4‐methylenecyclopentanemethanol; 17c ) or (+)‐(Z)‐lancifolol (= (1S,3R,4Z)‐2,2,3‐trimethyl‐4‐(4‐methylpent‐3‐enylidene)cyclopentanemethanol). Finally, hydrogenation of (+)‐ 4b gave the saturated cis‐aldehyde (+)‐ 21 , readily reduced to its corresponding alcohol (+)‐ 22a . Similarly, hydrogenation of β‐campholenol (= 2,3,3‐trimethylcyclopent‐1‐ene‐1‐ethanol) gave access via the cis‐alcohol rac‐ 23a , to the cis‐aldehyde rac‐ 24 . 相似文献
9.
Anthony Linden Tushar S. Basu Baul 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(4):313-325
The diorganotin(IV) complexes of 5‐[(E)‐2‐aryldiazen‐1‐yl]‐2‐hydroxybenzoic acid are of interest because of their structural diversity in the crystalline state and their interesting biological activity. The structures of dimethylbis{2‐hydroxy‐5‐[(E)‐2‐(4‐methylphenyl)diazen‐1‐yl]benzoato}tin(IV), [Sn(CH3)2(C14H11N2O3)2], and di‐n‐butylbis{2‐hydroxy‐5‐[(E)‐2‐(4‐methylphenyl)diazen‐1‐yl]benzoato}tin(IV) benzene hemisolvate, [Sn(C4H9)2(C14H11N2O3)2]·0.5C6H6, exhibit the usual skew‐trapezoidal bipyramidal coordination geometry observed for related complexes of this class. Each structure has two independent molecules of the SnIV complex in the asymmetric unit. In the dimethyltin structure, intermolecular O—H…O hydrogen bonds and a very weak Sn…O interaction link the independent molecules into dimers. The planar carboxylate ligands lend themselves to π–π stacking interactions and the diversity of supramolecular structural motifs formed by these interactions has been examined in detail for these two structures and four closely related analogues. While there are some recurring basic motifs amongst the observed stacking arrangements, such as dimers and step‐like chains, variations through longitudinal slipping and inversion of the direction of the overlay add complexity. The π–π stacking motifs in the two title complexes are combinations of some of those observed in the other structures and are the most complex of the structures examined. 相似文献
10.
Meruva Suresh Babu Akula Raghunadh Konda Ramulu Vilas H. Dahanukar Unniaran K. Syam Kumar P. Kumar Dubey 《Helvetica chimica acta》2014,97(11):1507-1515
A highly enantiospecific, azide‐free synthesis of (?)‐(R)‐ and (+)‐(S)‐piperidin‐3‐ol in excellent yield was developed. The key step of the synthesis involves the enantiospecific ring openings of enantiomerically pure (R)‐ and (S)‐2‐(oxiran‐2‐ylmethyl)‐1H‐isoindole‐1,3(2H)‐diones with the diethyl malonate anion and subsequent decarboxylation. 相似文献
11.
The first synthetic approach to (±)‐Δ3‐2‐hydroxybakuchiol (=4‐[(1E,5E)‐3‐ethenyl‐7‐hydroxy‐3,7‐dimethylocta‐1,5‐dien‐1‐yl]phenol; 14 ) and its analogues 13a – 13f was developed by 12 steps (Schemes 2 and 3). The key features of the approach are the construction of the quaternary C‐center bearing the ethenyl group by a Johnson–Claisen rearrangement (→ 6 ); and of an (E)‐alkenyl iodide via a Takai–Utimoto reaction (→ 11 ); and an arylation via a Negishi cross‐coupling reaction (→ 12e – 12f ). 相似文献
12.
13.
An enantioselective synthesis of (+)‐β‐himachalene ( 2 ) was accomplished starting from (1S,2R)‐1,2‐epoxy‐p‐menth‐8‐ene ( 3 ) in 15 or 16 steps with an overall yield of ca. 6% (Schemes 3, 5, and 6). Key transformations include an Ireland–Claisen rearrangement, a Corey oxidative cyclization, and a ring expansion. 相似文献
14.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(6):1571-1574
The enantioselective total synthesis of (−)‐tetrodotoxin [(−)‐TTX] and 4,9‐anhydrotetrodotoxin, which are selective blockers of voltage‐gated sodium channels, was accomplished from the commercially available p ‐benzoquinone. This synthesis was based on efficient stereocontrol of the six contiguous stereogenic centers on the core cyclohexane ring through Ogasawara's method, [3,3]‐sigmatropic rearrangement of an allylic cyanate, and intramolecular 1,3‐dipolar cycloaddition of a nitrile oxide. Our synthetic route was applied to the synthesis of the tetrodotoxin congeners 11‐norTTX‐6(R )‐ol and 4,9‐anhydro‐11‐norTTX‐6(R )‐ol through late‐stage modification of the common intermediate. Neutral deprotection at the final step enabled easy purification of tetrodotoxin and 11‐norTTX‐6(R )‐ol without competing dehydration to their 4,9‐anhydro forms. 相似文献
15.
Zonglei Zhang Lizhong Wang Xiaoqin Bian Qian Sun Hangxian Xu Cunde Wang 《Helvetica chimica acta》2011,94(1):98-104
(3α,5α)‐3‐Hydroxy‐C‐homopregnane‐11,20‐dione ( 3 ) was prepared in eleven steps from the commercially available pregn‐4‐ene‐3,11,20‐trione ( 4 ) via the 11‐oxo‐13‐formyl‐12,13‐secopregnane intermediate 11 (Scheme 2). Subjection of this secopregnane to an intramolecular aldol condensation afforded the α,β‐unsaturated key intermediate C‐homopregn‐12‐en‐11‐one 12 . 相似文献
16.
2, 4‐Dimethylpenta‐1, 3‐diene and 2, 4‐Dimethylpentadienyl Complexes of Rhodium and Iridium The complexes [(η4‐C7H12)RhCl]2 ( 1 ) (C7H12 = 2, 4‐dimethylpenta‐1, 3‐diene) and [(η4‐C7H12)2IrCl] ( 2 ) were obtained by interaction of C7H12 with [(η2‐C2H4)2RhCl]2 and [(η2‐cyclooctene)2IrCl]2, respectively. The reaction of 1 or 2 with CpTl (Cp = η5‐C5H5) yields the compounds [CpM(η4‐C7H12)] ( 3a : M = Rh; 3b : M = Ir). The hydride abstraction at the pentadiene ligand of 3a , b with Ph3CBF4 proceeds differently depending on the solvent. In acetone or THF the “half‐open” metallocenium complexes [CpM(η5‐C7H11)]BF4 ( 4a : M = Rh; 4b : M = Ir) are obtained exclusively. In dichloromethane mixtures are produced which additionally contain the species [(η5‐C7H11)M(η5‐C5H4CPh3)]BF4 ( 5a : M = Rh; 5b : M = Ir) formed by electrophilic substitution at the Cp ring, as well as the η3‐2, 4‐dimethylpentenyl compound [(η3‐C7H13)Rh{η5‐C5H3(CPh3)2}]BF4 ( 6 ). By interaction of 2, 4‐dimethylpentadienyl potassium with 1 or 2 the complexes [(η4‐C7H12)M(η5‐C7H11)] ( 7a : M = Rh; 7b : M = Ir) are generated which show dynamic behaviour in solution; however, attempts to synthesize the “open” metallocenium cations [(η5‐C7H11)2M]+ by hydride abstraction from 7a , b failed. The new compounds were characterized by elemental analysis and spectroscopically, 4b and 5a also by X‐ray structure analysis. 相似文献
17.
An efficient one‐pot approach to the synthesis of 5,7,8,9,9a,10‐hexahydro‐8‐thioxopyrido[2,3‐d : 6,5‐d′]dipyrimidine‐2,4,6(1H,3H,5aH)‐triones 5 via a four‐component reaction of an aldehyde 1 , an amine 2 , a barbituric acid 3 , and thiouracil ( 4 ) is reported for the first time. This new multicomponent reaction is accomplished in refluxing EtOH in the presence of tungstophosphoric acid (H3PW12O40) as a catalyst. A variety of hexahydropyrido[2,3‐d : 6,5‐d′]dipyrimidinetrione derivatives were successfully synthesized in excellent yields with this protocol (Table 2). 相似文献
18.
Alkyne‐Mediated Approach to the Synthesis of (4R,5R)‐5‐Hydroxy‐4‐decanolide and (−)‐Muricatacin
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The asymmetric synthesis of two naturally occurring 5‐hydroxy‐γ‐butyrolactones, (4R,5R)‐5‐hydroxy‐4‐decanolide ( 1a ) and (?)‐muricatacin ( 2 ), is described using a general alkyne‐mediated strategy. The key steps involved are Sonogashira coupling for the desired carbon‐chain extension followed by Sharpless asymmetric dihydroxylation to construct the hydroxy‐lactone framework. 相似文献
19.
20.
Miyoko Kamigauchi Yukiko Maekawa Chisato Tode Yasuko In Toshimasa Ishida 《Helvetica chimica acta》2010,93(1):25-32
The X‐ray crystal analyses of the two 11‐deoxy‐didehydrohexahydrobenzo[c]phenanthridine‐type alkaloid derivatives 3 and 4 , derived from (±)‐corynoline ( 1 ) and (+)‐chelidonine ( 2 ), established their structures as (±)‐(5bRS,12bRS)‐5b,12b,13,14‐tetrahydro‐5b,13‐dimethyl[1,3]benzodioxolo[5,6‐c]‐1,3‐dioxolo[4,5‐i]phenanthridine ( 3 ) and (+)‐rel‐(12bR)‐7,12b,13,14‐tetrahydro‐13‐methyl[1,3]benzodioxolo[5,6‐c]‐1,3‐dioxolo[4,5‐i]phenanthridine ( 4 ). The conformations of 3 and 4 in CDCl3 were determined on the basis of 1H‐ and 13C‐NMR spectroscopy. 相似文献