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111.
3-Arylsydnone-4-carbonitrile oxides may undergo 1,3-dipolar cycloadditions with alkenes to produce the corresponding 3-aryl-4-(5-substituted-isoxazolin-3-yl)sydnones. The direct reaction of 3-arylsydone-4-carbohydroximic acid chlorides with alkenes may also give the same products, and with higher yield. 相似文献
112.
S. M. Ramsh A. G. Ivanenko V. A. Shpilevyi N. L. Medvedskiy P. M. Kushakova 《Chemistry of Heterocyclic Compounds》2005,41(7):921-928
Alkaline hydrolysis of 3-tert-butyl-7,7-bis(hydroxymethyl)-3,4-dihydro-2H-thiazolo[3,2-a][1,3,5]-triazin-6(7H)-one can occur in three directions: with cleavage of the tetrahydrotriazine ring, with cleavage of the
thiazolidine ring, and also with opening of both rings. Depending on the process conditions, either the hydrolysis product
corresponding to the first direction or the hydrolytic decomposition products corresponding to the second and third directions
can be obtained in preparative quantities. Hydrolysis of 3,3′-di-tert-butyl-3′,4′-dihydro-2′ H-spiro[(perhydro-1,3-oxazine)-5,7′-thiazolo[3,2-a][1,3,5]triazin]-6′-one in (NH4)2CO3 solution occurs in two steps: in the first step, cleavage of the tetrahydrotriazine ring occurs; and in the second step,
opening of the perhydrooxazine ring occurs.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1089–1097, July, 2005. 相似文献
113.
Dominick Maes Silvia Debenedetti Sven Mangelinckx Norbert De Kimpe 《Tetrahedron》2005,61(9):2505-2511
The synthesis of three highly oxygenated naturally occurring coumarins, 8-methoxy-6,7-methylenedioxycoumarin, 5-methoxy-6,7-methylenedioxycoumarin and 5,8-dimethoxy-6,7-methylenedioxycoumarin is described for the first time, together with a new method for the preparation of ayapin (6,7-methylenedioxycoumarin). Comparison of the spectroscopic data of the synthetic tetraoxygenated coumarin 5,8-dimethoxy-6,7-methylenedioxycoumarin with literature reports resulted in the structural revision of several natural coumarins. Two coumarins, both identified as 5,8-dimethoxy-6,7-methylenedioxycoumarin must have other structures, while the structure of another coumarin, described as the isomeric 7,8-dimethoxy-5,6-methylenedioxycoumarin has to be revised to 5,8-dimethoxy-6,7-methylenedioxycoumarin. 相似文献
114.
K. Bogdanowicz-Szwed M. Krasodomska 《Monatshefte für Chemie / Chemical Monthly》1996,127(12):1273-1281
Summary Reaction of 1,3-diaza-1,3-butadienes (1a–c) with various ketenes and chloroketenes results in the formation of substituted 4-oxo-pyrimido[2,1-b]benzothiazoles (4a–d) and 1,3,4-thiadiazolo[3,2-a]pyrimido-4-ones (4e,f). Reaction of 1,3-diaza-1,3-butadienes1d,e with ketenes and chloroketenes leads to the 2-morpholine-substituted compounds7 and15, respectively. All reactions proceedvia formation of [4+2] cycloadducts that eliminate methylthiol, methylsulfenyl chloride, or morpholine.
Hetero-Diels-Alder-Reaktion einiger 1,3-Diaza-1,3-butadiene mit Ketenen. Synthese funktionalisierter Pyrimido[1,2-b]benzothiazole und 1,3,4-Thiadiazolo[3,2-a]pyrimidine
Zusammenfassung Die Reaktion der 1,3-Diaza-1,3-butadiene1a–c mit verschiedenen Ketenen und Chlorketenen führt zu substituierten 4-Oxo-pyrimido[2,1-b]benzothiazolen (4a–d) und 1,3,4-Thiadiazolo[3,2-a]pyrimido-4-onen(4e,f). Die 1,3-Diaza-1,3-butadiene1d,e ergeben mit Ketenen und Chlorketenen die 2-Morpholin-substituierten Verbindungen7 und15. Alle Reaktionen verlaufen über [4+2]-Cycloaddukte, die Methylthiol, Methylsulfenylchlorid oder Morpholin eliminieren.相似文献
115.
A. Lévai 《Monatshefte für Chemie / Chemical Monthly》1995,126(11):1245-1251
Summary 3-Aroyl-4-aryl-2-pyrazolines (21–40) have been synthesized by the reaction of ,-unsaturated ketones (1–20) with diazomethane. These 2-pyrazolines gave -methyl-,-unsaturated ketones (41–46) on thermal denitrogenation.Dedicated to Prof. Dr.F. Sauter on the occasion of his 65th birthday 相似文献
116.
Drochioiu G 《Talanta》2002,56(6):1163-1165
A very simple, accurate, fast, selective and sensitive assay of cyanide based on its reaction with 2,2-dihydroxy-l,3-indanedione at basic pH is proposed. As little as 0.01 μg ml−1 of cyanide can be determined. The molar absorptivity may reach 5.1–8.0×104 l mol−1 cm−1 depending on the reaction conditions. Thus, 1 ml of sample solution is mixed with 500 μl of 5 mg ml−1 solution of 2,2-dihydroxy-1,3-indanedione monohydrate in 2% sodium carbonate. The absorbance of the purple color is measured at 510 nm in 1-cm glass cuvettes, 10–15 min after mixing the reagents. The procedure could also be used to identify free CN− in natural waters and hydrocyanic acid in the environment. 相似文献
117.
János Szabó Ágnes Katócs Gábor Bernáth Pál Sohár 《Monatshefte für Chemie / Chemical Monthly》1989,120(5):463-471
Summary (±)-4-Thiacarnegin (3) was synthesized by reaction of 6,7-dimethoxy-3-methyl-2H-1,3-benzothiazinium iodide (2) with methyl magnesium iodide, thereby opening a new synthetic route to 4-substituted dihydro-2H-1,3-benzothiazines. Compound3 was also obtained by reduction of 6,7-dimethoxy-3,4-dimethyl-2H-1,3-benzothiazinium iodide (5). In a similar way, reduction of the quaternary salts9 a–c afforded the (±)-4-thia analogues of cryptostilin-I, -II and -III (10 a–c). The isomers of the former compounds (12 a–c) were also synthesized by reduction of the 4H-1,3-benzothiazinium salts11 a–c.
Synthese von 4-Thiaanalogen von Alkaloiden mit Isochinolingerüst
Zusammenfassung Aus 6,7-Dimethoxy-3-methyl-2H-1,3-benzothiaziniumjodid (2) wurde mit Methylmagnesiumjodid (±)-Thiacarnegin (3) dargestellt. Diese Reaktion bietet ein neues Verfahren für die Synthese von 4-substituierten Dihydro-2H-1,3-benzothiazinen.3 wurde auch durch Reduktion von 6,7-Dimethoxy-3,4-dimethyl-2H-1,3-benzothiaziniumjodid (5) erhalten. Die Reduktion der quartären Ammoniumsalze9 a–c ergab ebenfalls die Cryptostillin I-, II-, III-(±)-4-thiaanalogen Verbindungen (10 a–c). Reduktion der 4H-1,3-Benzothiazinium-Salze11 a–c lieferte die entsprechenden Isomeren12 a–c der obengenannten Verbindungen.相似文献
118.
S. G. Mikhalenok N. M. Kuz'menok A. M. Zvonok 《Chemistry of Heterocyclic Compounds》2005,41(8):977-986
It was established that, in addition to ethyl 4-aryl-3-(2,3-epoxyalkanoyl)-4,5-dihydro-1H-pyrazole-5-carboxylates, the reaction
of diazoacetic ester with β-arylacryloyloxiranes also gives ethyl 4-aryl-3(5)-(3-hydroxy-2-methylalkanoyl)-1H-pyrazole-5(3)-carboxylates.
The latter are formed from the tautomeric ethyl 4-aryl-5-(2,3-epoxyalkanoyl)-4,5-dihydro-1H-pyrazole-3-carboxylates as a result
of intramolecular oxidative-reductive disproportionation.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, 1150–1160, August, 2005. 相似文献
119.
L. I. Belen’kii A. V. Kolotaev V. Z. Shirinyan M. M. Krayushkin Yu. P. Strokach T. M. Valova Z. O. Golotyuk V. A. Barachevskii 《Chemistry of Heterocyclic Compounds》2005,41(1):86-92
The polar [4+2] cycloaddition reaction of 1,2-bis(2,5-dimethyl-3-thienyl)acetylene with thiobenzamide and certain aldehydes of the thiophene and furan series catalyzed by boron trifluoride etherate gives the corresponding 4-hetaryl-5,6-di(2,5-dimethyl-3-thienyl)-2-phenyl-4H-1,3-thiazines. The photochromic properties of the products have been studied.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 100–106, January, 2005. 相似文献
120.
Ji-Chang Xiao 《Journal of fluorine chemistry》2005,126(4):473-476
A microwave-assisted fluorination method for 1,3-dicarbonyl compounds using Selectfluor® has been developed. 2-Monofluorinated products can be obtained in high yield in neutral reaction conditions with addition of 1 eq. of Selectfluor®. Treatment of 1,3-dicarbonyls with 3 eq. of Selectfluor® in the presence of tetrabutylammonium hydroxide (TBAH) as the base results in the formation of 2,2-difluorinated derivatives only. 相似文献