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1.
A new pyridine synthesis has been found by refluxing certain simple secondary car☐amides in HMPA. Thus 2,6-dimethylpyridine, 2-ethyl-6-methylpyridine, 2,3,6-trimethylpyridine, 2-ethyl-3,6-dimethylpyridine, 2-benzyl-6-methyl-3-phenylpyridine, 2-ethyl-3-methyl-5,6,7,8-tetrahydroquinoline and 2-t-butyl-6-methylpyridine were prepared in 15–40% yield. 相似文献
2.
U. Pedersen M. Thorsen E.-E.A.M. El-Khrisy K. Clausen S.-O. Lawesson 《Tetrahedron》1982,38(22):3267-3269
The easily accessible 2,4-bis (4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide, , has been reacted with salts of N-protected amino acids (Z-Gly-OH, Boc-Gly-OH, Boc-S-Ser(Bzl)-OH, Boc-S-Tyr(Bzl)-OH, Z-S-Arg(Z2)-OH, and Z-S-Pro-OH), at room temperature in CH2Cl2 to give the intermediates , mixed anhydrides. When is treated with two moles of a base and one mole of the salt of an amino acid ester (TosOH·H-Gly-OBzl, HCl·H-Gly-OBzl, HCl·H-Gly-OEt, and HCl·H-S-Phe-OtBu) at 0°C, the expected peptide is isolated in high yields. LR is also found to be a useful reagent in a fragment coupling between Z-Gly-S-Ala-OH and TosOH·H-S-Leu-OBzl). This tripeptide was tested by means of HPLC (deprotection and amino acid analysis according to Izumiya was not necessary), and no epimerization (<0.7 %) was observed. 相似文献
3.
3,1-Benzoxathian-4-ones, 2, when heated with 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2, 4-disulfide, 1, or with P4S10 give one or more of the following products 3,1-benzoxathian-4-thione, 3, 1,3-benzodithian-4-one, 4, 1,3-benzodithian-4-thione, 5, and 3H-1,2-benzodithiole-3-thione, 6. Compounds 2, when heated with primary and secondary amines and with hydrazines, give 2-mercaptobenzamides, 7, and 2-mercaptobenzohydrazides, 8, or their corresponding disulfides, 7' and 8'. 3H-1, 2-Benzodithiol-3-immes, which are in equilibrium with 1,2-benzisothiazole-3(2H)-thiones, (9A ? 9B), are prepared by two new routes (a) by allowing 3 or 5 to react with primary amines or hydrazines, (b) by allowing 7, 8, 7' or 8' to react with 1. 相似文献
4.
A number of 1-allylthio and 1-crotylthio 1-aminoalkenes derived from ketones and active methylene compounds has been prepared and rearranged to the corresponding thioamides (thio-Claisen rearrangement). Besides rearrangement products, small amounts of 1-alkyl-thio-N-alkyl-N-phenyl-1-aminoalkenes have also been isolated. When the ketene derivatives did possess a H-atom on nitrogen, cleavage of the formed thioamide produced phenyl isothiocyanate and substituted active methylene compounds. 相似文献
5.
Secondary car☐amides (R1CONHR2) undergo different reactions when heated in HMPA at about 220°. If R1 or R2 can form stable carbonium ions, fragmentation reactions are observed and the corresponding nitriles R2CN or R1CN, respectively, are formed. Also amidines are produced. N-benzyl-acetamide rearranges when heated in HMPA to give β-phenyl-propionitrile, It is suggested that in all the reactions investigated the first step is the formation of a phosphorodiamidate followed by formation of a nitrilium carbonium ion. The fragmentation reactions can be used as an alternative to the Sandmeyer reaction (nitrile synthesis). 相似文献
6.
4-Substituted-1,2-diphenyl-3,5-pyrazolidinediones (Phenylbutazone analogous) 1a–d react with 2,4-bi-(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-difulside (Lawesson Reagent (LR) with formation of the corresponding 3,3′-dithiobis (1,2-dihydro-3H-pyrazole-5-thione)'s 2a–d. When the 4-substituent contains a sulfoxide group this is deoxygenated to the sulfide by LR at room tmeperature. 1-Phthalazinone-4-thione, 1,4-phthalazine-dithione and ethyl aminothioxoacetate have also been prepared from the corresponding carbonyl compounds. Alkylation or acylation of 2a–d yielded 3H-pyrazole-3-thione derivatives 8 and 9. Alkylation of 1 with MeI in the presence of Et3N at room temp. yielded the C-alkylated products 10 exclusively. X-RAy crystallographic investigations of 2b and 9a are presented. 相似文献
7.
Sten Scheibye Bjarne S. Pedersen S.-O. Lawesson 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2):271-272
Abstract Recent studies have shown that the dimer of p-methoxyphenylthionophosphinesulfide, 1, is a very superior thiation reagent, as ketones, amides, and esters are in most cases quantitatively converted to their thio-analogues. 相似文献
8.
By a charge transfer mechanism for electrophilic aromatic substitution the logarithmic plot of overall rate constants for substitution against ionization potentials is correctly predicted. Also, orientation of substitution is found to be correlated with the hyperfine coupling constants of the aromatic radical cation. The presence of radical cations under the conditions of electrophilic substitution is discussed. 相似文献
9.
J. H. Bowie J.
. Madsen S.-O. Lawesson R. G. Cooks 《Journal of mass spectrometry : JMS》1969,2(4):413-424
The mass spectra of thioglycollic acids and esters are reported and discussed. The spectra of compounds of the type X·CH(Y)·S·CH2·COOR(X > Y) contain skeletal rearrangement fragments with the composition R·Y·C2H3SO+. Ions produced by simple cleavage processes may be usefully correlated with structure. 相似文献
10.
F.C.V. LarssonS.-O. Lawesson 《Tetrahedron》1972,28(21):5341-5357
A number of substituted β-hydroxydithiocinnamic acids have been prepared. By use of so-called ion-pair extraction technique a general method has been found for the preparation of β-hydroxydithiocinnamic esters in high yields. From these esters both symmetrical and unsymmetrical ketene mercaptals have been synthesized, and in some cases thio-Claisen rearrangement and subsequent ring-closure reactions have been observed. 相似文献