共查询到20条相似文献,搜索用时 555 毫秒
1.
A short and convenient synthesis of two series of eight totally new lariat crown ethers is reported in this article. These lariat ethers are derived from triaza‐dibenzo‐27‐crown‐7 and diaza‐dibenzo‐27‐crown‐7 through condensation of appropriate aza‐crown ethers with appropriate substituted compounds in chloroform. The substituted reagents are acetic anhydride, benzoyl chloride, phthalic anhydride, and butanedioic anhydride, respectively. 相似文献
2.
Elena V. Tulyakova Edward V. Rakhmanov Elena V. Lukovskaya Alla A. Bobylyova Andrey V. Khoroshutin Alexander V. Anisimov 《合成通讯》2013,43(16):2329-2337
9(12)‐Hydroxy‐dithia‐13(16)‐crown‐4(6)‐ethers have been prepared by the condensing an oligoethylene glycol dithiol with 2,3‐dibromo‐1‐propanol. Methods of oxidation, halogenation, amination, and esterification of the 9‐hydroxythiacrown ether, producing corresponding oxathiacrown ether derivatives in good yields, have been developed. Cyclic destruction has not been found in the studied reactions. The change of the oxathiamacrocyclic ring size in the course of the halogenation and amination reactions was revealed. 相似文献
3.
Shou‐Ri Sheng Hai‐Rong Luo Wu‐Kang Sun Xiao‐Ling Liu Qin Xin Qiu‐Ying Wang 《合成通讯》2013,43(22):2839-2845
Vinyl ethers were prepared with good yields in a one‐pot, two‐step transformation by O‐alkylation reaction of phenyl 2‐hydroxyalkyl selenides with primary or secondary organic halides followed by oxidation elimination with 30% hydrogen peroxide. 相似文献
4.
Microwave heating of triethylsilyl (TES)‐ and tert‐butyldimethylsilyl (TBS)‐protected 1° and 2° alcohols in a mixture of equal parts acetic acid, tetrahydrofuran (THF), and water allows deprotection in as little as 5 min. tert‐butyldiphenylsilyl (TBDPS)‐ and triisopropylsilyl (TIPS)‐protected alcohols and silyl‐protected phenols are stable in these conditions. Thus, selective deprotection of TES‐ and TBS‐protected alcohols in the presence of TIPS or TBDPS ethers is possible. Similarly, alkyl silyl ethers can be deprotected in the presence of aryl silyl ethers. 相似文献
5.
《合成通讯》2013,43(17):3135-3145
Abstract The heterogeneous catalyst, silica‐supported sodium hydrogen sulfate (NaHSO4 · SiO2) has been found to be highly efficient in carrying out the transformation of p‐hydroxybenzyl alcohols at room temperature to p‐hydroxybenzyl ethers and thioethers in very high yields. 相似文献
6.
The propargyloxydimethylsilyl enol ethers derived from propanone, 2‐butanone, 3,3‐dimethyl‐2‐butanone, 3‐pentanone, 4‐methyl‐2‐pentanone, 2‐heptanone, 4‐heptanone, 2,6‐dimethyl‐4‐heptanone, cyclopentanone, cyclohexanone, cycloheptanone, benzophenone, and propiophenone have been synthesized by two methods: The thermodynamic method is conducted by heating the propargyloxysilyl chloride, triethylamine, and the corresponding ketone in acetonitrile at 40–50°C for less than an hour in the presence of an equimolar amount of sodium iodide; the mixture is maintained at that temperature for an hour. The yields were in the range of 50–95%. In method two (kinetic controlled), lithium diisopropylamide (LDA) was used as a base to abstract the acidic hydrogen, and then the resulted enolate was quenched with silyl chloride, with lower yields than the previous method. NMR, IR, and elemental analysis were used to characterize the products. Some reactions of these compounds have been investigated. 相似文献
7.
The microwave‐assisted synthesis of diaryl ethers directly from aryl halides and arylmethanesulfonates, which as latent phenols obviate a deprotection step prior to the SNAr reaction, in the presence of Cs2CO3 is described. The reaction time was very short (6–9 min), and good to excellent yields (53–90%) with the wide substrate scope were achieved without any catalyst. 相似文献
8.
Robert Łysek Ewa Woźny Marek Chmielewski 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):327-340
Chiral formates derived from propane-1,2-diol, 1,2- O -isopropylidene- f - D -xylo- and f - D -gluco-furanoses were subjected to treatment with cyclopentadienyl [tris(trimethylsilylmethyl)] titanium (IV). A mixture of the corresponding ( E )- and ( Z )- g -silylvinyl ethers were obtained with predominance of the former. It was found that in contrast to ( Z )-vinyl ethers, which give g -lactams with chlorosulfonyl isocyanate, the ( E )-vinyl ethers gave unstable cycloadducts which undergo rapid elimination reaction leading to ( E )- f , g -unsaturated amides. 相似文献
9.
Tarek M. Abou Elmaaty 《合成通讯》2013,43(16):2281-2285
Starting from indan‐1,3‐dione, a novel two‐step synthesis of the oxepine derivatives 5a,b and the pyran derivatives 7 and 8 under very simple reaction conditions is described. 相似文献
10.
11.
Highly selective deprotection of tert‐butyldimethylsilyl ethers at room temperature has been described using sulfated SnO2 as an efficient solid catalyst. 相似文献
12.
《Journal of carbohydrate chemistry》2013,32(5):325-335
Abstract 1‐(Methyl 3‐O‐benzyl‐4,6‐O‐benzylidene‐2‐deoxy‐α‐D‐altropyranosid‐2‐yl)‐4‐phenyl‐but‐3‐yn‐2‐one (4) was synthesized by the reaction of (methyl 3‐O‐benzyl‐4,6‐O‐benzylidene‐2‐deoxy‐α‐D‐altropyranosid‐2‐yl)ethanal (2) with lithium phenylethynide and following oxidation. Compound 4 and hydrazine hydrate provided the 3(5)‐(methyl 3‐O‐benzyl‐4,6‐O‐benzylidene‐2‐deoxy‐α‐D‐altropyranosid‐2‐yl‐methyl)‐5(3)‐phenyl‐1H‐pyrazole (5). The reactions of 4 with amidinium salts and a S‐methyl‐isothiouronium salt, respectively, furnished the pyrimidine C‐nucleoside analogues 6a–6c. Treatment of 4 with 2‐aminobenzimidazole afforded 2‐(methyl 3‐O‐benzyl‐4,6‐O‐benzylidene‐2‐deoxy‐α‐D‐altropyranosid‐2‐ylmethyl)‐4‐phenyl‐benzo [4,5]imidazo[1,2‐a]pyrimidine (7a). Compound 4 and sodium azide yielded 2‐(methyl 3‐O‐benzyl‐4,6‐O‐benzylidene‐2‐deoxy‐α‐D‐altropyranosid‐2‐yl)‐1‐[5(4)‐phenyl‐1H(2H)‐1,2,3‐triazole‐4(5)‐yl]ethanone (8). 相似文献
13.
Hu Liu Leon M. Smith II Yunyu Mao Weitao Pan Yong‐Jiang Xu Sabina Burdzovic‐Wizeman 《合成通讯》2013,43(3):347-354
An improved route for the preparation of highly functionalized 5,6‐dihydro‐pyrimido[4,5‐b][1,4]oxazepine 1a in multigram quantities was developed. This new methodology was highlighted by the proper methoxy disposition via a regioselective methylation of 2,4,5‐trihydroxy‐benzaldehyde followed by a magnesium sulfate–promoted cyclization. 相似文献
14.
Bromination of 4‐dichloromethyl‐4‐methylcyclohexa‐2,5‐dien‐1‐one and 4‐dichloromethyl‐3,4‐dimethylcyclohexa‐2,5‐dien‐1‐one has been studied. The reaction conditions required for the formation of mono‐, di‐, and tribrominated products have been optimized. 相似文献
15.
The Claisen rearrangement of allyl phenyl ethers is a fundamental reaction in organic synthesis with a variety of applications in perfumes, flavors, pharmaceuticals, agrochemicals, polymers, fine chemicals, and intermediate industries. The development of environmentally benign processes using solid acid catalysts is becoming an area of growing interest. It was accomplished in an efficient, economical, environmentally friendly manner and is 100% selective toward alllyl phenols by employing UDCaT‐5 as solid acid catalyst. 相似文献
16.
Reaction of 3‐(2‐bromo‐acetyl)‐chromen‐2‐one with thiosemicarbazide and 2‐acetylbutyro lactone in anhydrous ethanol gave 3‐{2‐[5‐hydroxy‐4‐(2‐hydroxy‐ethyl)‐3‐methyl‐pyrazol‐1‐yl]‐thiazol‐4‐yl}‐chromen‐2‐one in good yields. 相似文献
17.
The reaction of dialkyl acetylenedicarboxylates with alkyl 2‐[3‐oxo‐3,4‐dihydro‐2(1H)‐quinoxadinylidene]ethanoates in the presence of triphenylphosphine leads to trialkyl (E)‐3‐{3‐oxo‐2‐3,4‐dihydro‐2‐(1H)‐quinoxalinylidene}‐prop‐1‐ene‐1,2,3‐tricarboxylates in good yields. 相似文献
18.
G. V. Romanenko D. V. Ovcharenko S. F. Vasilevskii 《Journal of Structural Chemistry》2003,44(2):314-317
The crystal and molecular structures of the stable nitroxide radical 2,4,4,5,5pentamethyl2imidazoline1oxyl3oxide was determined. The N—O bond lengths are 1.279(2) and 1.280(2), respectively. The O-—N+=C—N— O fragment is nearly planar with carbon atoms of the ethyl fragment that deviated from the O—N+=C—N—O plane by –0.204(5) and +0.176(5). The minimum intermolecular distance between the oxygen atoms of NO groups is 4.094. 相似文献
19.
2‐Alkylthio‐3‐alkyl‐5‐phenylmethylidene‐4H‐imidazol‐4‐ones 6 were synthesized by N‐alkylation and S‐alkylation of 2‐thioxo‐5‐phenylmethylidene‐4‐imidazolidinone 5, which was obtained via cyclization of vinyl isothiocyanate 4 with excess ammonium hydroxide (28% NH3 in water). 相似文献
20.
The isothiocyanate 3, obtained from aza‐Wittig reaction of iminophosphorane 2 with CS2, reacts with phenylhydrazine to give thiosemicarbazide 4. Reactions of 4 with alkyl halides in the presence of K2CO3 directly provided 2‐alkylthio‐4H‐imidazol‐4‐ones 6 in good yields. 相似文献