Reaction of cholesterol with acetylated alkyl orthoacetates of D-glucopyranose

Summary The condensation of acetylated alkyl orthoacetates of D-glucose with cholesterol has been studied. It has been shown that either transesterification or glycosylation may take place, according to the reaction conditions. Conditions have been found under which the sole direction of the reaction is glycosylation, leading to the 1, 2-trans-glycoside. A standard method for glycosylating complex alcohols with sugar orthoesters has been proposed.Khimiya Prirodnykh Soedinenii, Vol. 2, No. 1, pp. 6–12, 1966     

Metal derivatives of amidoximes V. Dialkyl- or diphenyl-silyl derivatives of amidoximes

New monomeric dialkyl- or diphenyl-silylbisamidoximes and dialkyl(ethoxy)silylamidoximes have been characterised. Their infrared spectra have been interpreted and diamagnetic susceptibility of some of them has been determined.     

Rhamnose orthoacetates of aconitine and imperialine

The preparation and spectral properties of rhamnose orthoacetates of aconitine and imperialine are described.     

Rhamnose orthoacetates of aconitine and imperialine

The preparation and spectral properties of rhamnose orthoacetates of aconitine and imperialine are described.Tashkent Pharmaceutical Institute. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 743–746, September–October, 1993.     

Metal derivatives of amidoximes I. Mono-, bis- and tris-(trimethylsilyl)amidoximes

The preparation and properties of mono-, bis- and tris-(trimethylsilyl)amidoximes are described.     

Microwave-assisted preparations of amidrazones and amidoximes

In an operationally straightforward and efficient method, amidrazones and amidoximes are prepared in yields of 65-87% from imidoylbenzotriazoles by microwave heating for 5-20 min with the appropriate hydrazine or hydroxylamine.     

Identification of amidoximes by precipitation of their ferric complexes with thiocyanate

Summary A new qualitative reaction for the identification of amidoximes consists in the precipitation of the complex ions between iron(III) and the amidoxime with KSCN or NH₄SCN as a dark-brown compound sparingly soluble in water. The sensitivities for benzamidoxime, -hydroxy-phenacetamidoxime and phenacetamidoxime are 0.5, 0.7 and 1.4 mg/ml, respectively.

---

Zusammenfassung Eine neue qualitative Reaktion zur Identifizierung von Amidoximen beruht auf der Fällung der Komplexionen zur Eisen(III) und dem Amidoxim mit NH₄SCN oder KSCN als dunkelbrauner Niederschlag. Die gebildeten Verbindungen sind in Wasser schwer löslich. Die Empfindlichkeiten der Reaktionen mit Benzamidoxim, -Hydroxy-phenacetamidoxim und Phenacetamidoxim sind 0,5, 0,7 bzw. 1,4 mg/ml.

     

The electron impact mass spectra of some cevine orthoacetates

The most important fragmentation in the electron impact mass spectra of dihydrocevine orthoacetate and some analogues involves loss of an acetoxyl radical from the molecular ion, and is associated with strain in the orthoacetate group bridging a six-membered ring. The process is much less important in the less-strained dihydrocevine isoorthoacetate, which gives the ion m/z 112, characteristic of cevine alkaloids, as the most abundant. A further important difference concerns an ion involving the loss of C(20) and its substituents together with a hydrogen atom from M⁺˙, also relatively unimportant in the isoorthoacetate.     

Studies on the synthesis of amidoximes from nitroalkanes

The reaction of primary nitroalkanes with magnesium or lithium amides provides a convenient, one-step synthesis of substituted amidoximes.     

The reaction of amidoximes with carboxylic acids or their esters under high-pressure conditions

Russian Chemical Bulletin - 3,5-Disubstituted 1,2,4-oxadiazoles were synthesized by the reaction of amidoximes with carboxylic acids or their esters under high-pressure conditions (10 kbar). The...     

Solid-phase synthesis of amidines by the reduction of amidoximes

Amidines can be prepared on a solid support by reducing polymer-bound amidoximes with SnCl₂·2H₂O. The method has proved to be straightforward and highly efficient. Amidoximes attached to the solid support are readily available by treating resin-bound nitriles with hydroxylamine.     

O-nucleophilic features of amidoximes in acyl group transfer reactions

Analysis of kinetic behavior of isomeric Z-amidoximes and their Z-ions in reactions with 4-nitrophenyl-4-toluenesulfonate, diethylphosphate, and diethylphosphonate was performed in the framework of Bronsted relationship. The reactivity of amidoximate anions with respect to the mentioned substrates is comparable to that of typical -nucleophiles, oximate ions. The -effect decreased with the growing basicity of amidoximate ions, and for compounds with pK _a>12.0 it was totally lacking. The high nucleophilic activity of neutral amidoximes and their anionic forms was ascribed to the cyclic structure of the transition state involving two kinds of assistance: general acidic, and basic catalysis. A unique feature of amidoximes as -nucleophiles consists in their ability to perform efficient cleavage of ecotoxic substrates in a wide pH range, from basic to acid media.Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 11, 2004, pp. 1665–1677.Original Russian Text Copyright © 2004 by Prokopeva, Simanenko, Karpichev, Savelova, Popov.     

Coordination chemistry of polyoxomolybdates: The versatile behavior of amidoximes

The reactions of 2-thienylamidoxime and 2-thienylmethylamidoxime with [MoO₂(acae)₂] or x-(NBu₄ [Mo₈O₂₆]. in alcohols or acetonitrile, yield a number of compounds with different nuclearities and various molybdenum cores, such as the compact {Mo₄O₁₀(OMe)₂}²⁺ the cyclic {Mo₄O₁₂}, and the open {Mo₁₁On_211-1}²⁺ (n= 2 or 4) cores. Addition of NH₂OH to the reaction mixtures results in the formation of nitrosyl complexes containing either the Mo(NO)³ or the Mo(NO) ₂ ² units. The amidoxime component may be present either as RC(NH₂)NHO. RC(NHi2), RC(NH)NHO or RC(NH)NO²: ligands, or as hydrogen-bonded RC(NH₂)NOH molecules. The crystal structures of [MoO(acac)RIC'(NH₂)NO] {R^JC(NH)NO}](1), [Mo(NO)(acae)₂ {R^IC(NH₂)NO}] (4), (NBu₄)₂[Mo₄O₁₀(OMe)₂{R^IC(NH) NO}₂] (12a),(NBu₄)₂(H₃O)[Mo₅O₁₃(OMe)₄(NO)].2R¹C(NH₂)NOH(13b) and [R¹C(NH₂)₂)]₃[Mo₅O₁₃(OEt)₄(NO)] (14) (R¹=2-thienyl) are reported. The cryslallographic data for these compounds are as follows:1, mono-clinic. P2₁ a.a=24.547(4)A. b=8.188(4)A. c=9.607(3)A, ß=96.18(3)^c, R=0.046. R₁₀=0.050: 4. monoclinic, P2₁c.a=8.265(2)A, b=9.381(2)A,_c=24.770(4)A, c = 24.7701(4) A, ß=93.99(2). R=0.039. R=0.042;12a, monoclinic, C2/c, a= 19.570(5)A. b=16.883(4)A, c = 19.82(l)A. ß= 114.36(5)°, R=0.064,R.=0.074;13b monoclinic;. P2₁ c.a=18.197(5)A, b=15.857(14) A, c = 23.075(17) A, =93.20(3). R=O.050. R_w=0.057;14, trictinic PI, a = 9.871(3),b= 14.138(3).c= 14.781(8)A. =92.67(2)^c =99.36(1)° =90.52(2)°. R = 0.044. R_w = 0.049. Particular attention is focused on the various coordination modes that the different ligand forms adopt: µ- O, ²N,O, ₂N',O, µ-N: ²O. and ₃- N:N:₂O.     

Condensation of orthoacetates with aldehydes: a new strategy for the preparation of α,β-unsaturated esters

α,β-Unsaturated esters are formed in good yields when aldehydes are heated with orthoacetates in the presence of a catalytic amount of phenol.