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11.
V. Z. Shirinian M. M. Krayushkin D. M. Nikalin A. A. Shimkin 《Russian Chemical Bulletin》2005,54(3):738-742
The reaction of alkyl 4-(2-acetylhydrazino)-2-methyl-3-thiophenecarboxylates with 3-methylbutan-2-one was carried out under the Fischer reaction conditions. The influence of Lewis acids and solvents on the process was studied. A convenient method for the synthesis of thieno [3.2-b]pyrrolenine derivatives was proposed.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 725–729, March, 2005. 相似文献
12.
O. M. Radul M. Z. Krimer O. N. Rebrova V. N. Biyushkin I. V. Feofanova A. A. Panasenko 《Russian Chemical Bulletin》1993,42(3):522-527
The rearrangement of enol acylates of aryl 1H-1, 2, 4-triazol-1-ylmethyl ketones at 140–150°C in acetic anhydride is studied. The migration of the acyl group to the C(5) atom of the heterocycle is found to be intramolecular. The characteristics of the original and final products are presented. X-ray structural studies of the enol acetates of 2, 4-dichlorophenyl 1H-1, 2, 4-triazol-1-ylmethyl ketone and 2, 4-dichlorophenyl 5-acetyl-1H-1, 2, 4-triazol-1-ylmethyl ketone are carried out.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 560–564, March, 1993. 相似文献
13.
An efficient synthesis of 6-azapregnane derivatives and their biological activity is described. The nitrogen was introduced into the B ring using Beckmann rearrangement of the (E)-oxime of 6-oxo-B-nor-5α-pregnane derivatives. The required 3α-hydroxyl was produced either by solvolysis of the corresponding 3β-mesyloxy group or by the Meerwein-Ponndorf-Verley reduction of the 3-oxo group; this reduction could be carried out selectively with an unprotected 3,20-dioxo derivative. The binding of the 6-aza-steroids to the γ-aminobutyric acid receptor (GABAA) was measured using [35S]-tert-butyl-bicyclo[2.2.2]phosphorothionate (TBPS) and [3H]flunitrazepam. The only analogue to be slightly active was that lacking any oxygen function in position 3. 相似文献
14.
Vyacheslav Ya. Sosnovskikh Boris I. Usachev Mikhail I. Kodess 《Tetrahedron letters》2004,45(39):7351-7354
Reactions of chromones with dilithiooximes proceed via nucleophilic 1,2-addition to give, on acidification, 4H-chromene-4-spiro-5′-isoxazoline derivatives in high yields. On treatment with concentrated H2SO4 the isoxazoline ring of this novel spiroannulated heterocyclic system opens to give α,β-unsaturated oximes, which undergo nitrosation, bromination, and the Beckmann rearrangement to the corresponding spiroisoxazolines and α,β-unsaturated amides, respectively. The latter can be obtained directly by the Beckmann rearrangement of 4H-chromene-4-spiro-5′-isoxazolines. 相似文献
15.
A convenient method for the two-step synthesis of arenediynes from 1,2-arenedialdehydes is reported. Dibromomethylenation of dialdehydes under Corey-Fuchs conditions (CBr4, Ph3P, Zn) provides the tetrabromides in excellent yields. Treatment of the tetrabromides with n-BuLi or LDA affords 3,4-unsaturated 1,5-diynes, the key structural moiety present in several naturally occurring antitumour antibiotics, in varying yields. The key intermediates in these transformations appear to be vinylidenecarbenes or carbenoids, generated in situ via metal-halogen exchange and elimination. 相似文献
16.
G. G. Danagulyan D. A. Tadevosyan F. S. Kinoyan 《Chemistry of Heterocyclic Compounds》2006,42(6):782-787
Intermediate recyclization products were obtained in a study of the Kost-Sagitullin rearrangement of a series of 1,2-dialkylpyrimidinium
iodides. The initial attack of the nucleophile leads to the formation of products of the addition of the hydroxyl group, namely,
the corresponding pseudo bases. Heating one of these intermediates in ethanol or in the presence of primary amines leads to
rearrangement to give a pyridone derivative. Upon heating in chloroform, the pseudo bases readily lose a water molecule and
are converted to anhydro bases, namely, derivatives of 1-alkyl-1,2-dihydro-2-methylidenepyrimidine.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 894–900, May, 2006. 相似文献
17.
T. Yu. Orlova Yu. S. Nekrasov P. V. Petrovskii M. G. Ezernitskaya T. V. Magdesieva S. V. Milovanov K. P. Butin 《Russian Chemical Bulletin》1998,47(9):1785-1788
The behavior of binuclear “ladder” type complexes FpL, where Fp=Cp(CO)2Fe, L=p-MeC6H4Cr(CO)3 (4), CH2C6H5Cr(CO)3 (5), andp-FpC6H4Cr(CO)3 (6), under conditions of metallation was studied. Unlike compounds5 and6, the σ-bound ligand L in compound4 migrates from the iron atom to the cyclopentadienyl ring to give complexes Me(CO)2FeC5H4−C6H4(p-Me)Cr(CO)3. The electrochemical reduction potentials of the complexes4–6 and the rearrangement products were measured. The migration activity of L is determined by the ease of reductive cleavage
of the Fe−L bond and the susceptibility of the system to undergo intramolecular electron transfer from the Cp ligand to the
aromatic ring.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1832–1835, September, 1998. 相似文献
18.
Richa Pathak 《Tetrahedron》2007,63(2):451-460
Trifluoroacetic acid has been discovered to be a highly effective and efficient reagent for the tandem Claisen rearrangement and cyclization reaction to yield 3-arylmethylene-3,4-dihydro-1H-quinolin-2-ones from compounds obtained from the SN2 reaction between anilines and acetyl derivatives of Baylis-Hillman adducts of acrylates in the presence of DABCO. In contrast, similar compounds obtained from the acetyl derivatives of Baylis-Hillman adduct of acrylonitrile on treatment with trifluoroacetic acid directly furnish 3-arylmethyl-2-amino-quinoline via tandem Claisen rearrangement, cyclization and isomerization. 相似文献
19.
Domino carbocationic rearrangements of α-[bis(methylthio)methylene]alkyl-2-(heteroaryl)cyclopropyl ketones (X=O, S, NMe) bearing five-membered heteroaryl group have been investigated. Although the cyclopropyl ketones (R1=H) gave similar products like their aryl counterparts under these conditions, the corresponding α-methylcyclopropyl ketones (R1=Me) yielded a variety of unexpected products depending on the nature of heteroaryl group in the substrate cyclopropyl ketones and the type of acid catalyst used. A probable mechanism for the formation of various products in these transformations has been proposed. 相似文献
20.
A new C19 hydroxylated enyne 15, as potential A-ring building block of vitamin D analogues, was synthesized in enantiomerically pure form in nine steps from (−)-(S)-limonene. This short synthesis involved ozonolyzis of 1,2-limonene oxide followed by a Criegee rearrangement, epoxide trans diaxial ring opening by lithium acetylide, elimination, epoxidation and syn β-elimination of the resulting homopropargylic oxirane. 相似文献