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Приказ резултата 31-40 од 43
Structure-reactivity relationship in the solvolysis of 5,10-secosteroidal 5-p-nitrobenzoates
(Pergamon Press, 1979)
The solvolysis of (Z)- and (E)-3β-acyloxy-5,10-seco-1(10)-cholesten-5β-ol p-nitrobenzoates 4 and 5 has been investigated and compared with the solvolytic reactivity of the epimeric (Z)- and (E)-5α-p-nitrobenzoates 1 and ...
Non-sensitized photooxygenation of some steroidal isoxazolidines
(Pergamon press, 1991)
UV irradiation of the steroidal isoxazolidines 2a, 2b, and 2c in various solvents in the presence of molecular oxygen, results in oxidative cleavage of the epoxyimino bridge to give several products; the N-unsubstituted ...
Circular dichroism of some cyclopropane ring containing 1,3-cyclo-5,10-seco-steroidal ketones
(Elsevier, 1982)
Circular dichroism of the rearranged keto steroids 3 and 4, containing a condensed three and nine-membered ring system, shows that the conformation of the nine-membered ring is the same in solution as in the crystal; ...
Steroid template associated peptides: design, synthesis and 2D NMR characterization of a novel protected 18-Phe,19-Gly-containing steroidal compound
(Oxford : Pergamon-Elsevier Science Ltd, 2007)
We report herein the synthesis of a novel modified steroid with two rigidly positioned amino acids in C- and N-protected forms (Gly-OtBu and N-Fmoc-l-Phe) at the angular positions (C-18 methylamino group and C-19 carboxylic ...
Reaction of silyl ketene acetals with epoxides: a new method for the synthesis of gamma-butanolides
(Oxford : Pergamon-Elsevier Science Ltd, 2004)
Titanium tetrachloride promoted reaction of silyl ketene acetals with epoxides, followed by acidic work-up, affords butanolides in moderate/good yields. With epihalohydrins the reaction is regioselective and occurs at the ...
Oxidative 10-membered ring expansion and contraction of stereoisomeric 1(10)-unsaturated and 1,10-epoxy-5-oxo-5,10-secosteroids induced by peracids
(Oxford : Pergamon-Elsevier Science Ltd, 2012)
The present study is concerned with the oxidative behaviour of unsaturated and epoxy 5-oxo-5,10-secosteroids in the presence of m-CPBA or TFAA-UHP as oxidants in order to investigate potential parameters controlling the ...
5,10:13,14-Disecosteroids: novel modified steroids containing 10- and 9-membered rings
(Oxford : Pergamon-Elsevier Science Ltd, 2009)
In this paper a synthetic pathway to the modified 5,10:13,14-bisfragmentation cholestane derivatives 8-14 is described. The synthesis involves introduction of the 5α- and 14α-hydroxyl groups in the cholestane molecule and ...
Design, synthesis, and characterization of fullerene-peptide-steroid covalent hybrids
(Oxford : Pergamon-Elsevier Science Ltd, 2014)
The present study reports the synthesis, spectral characterization, self-assembly properties, and preliminary in vitro study of antioxidant capacity of two triple covalent hybrids consisting of fullerene C-60, peptide, and ...
Catalytic oxidations of enolizable ketones using 2-alkylidene-4- oxothiazolidine vinyl bromide
(Oxford : Pergamon-Elsevier Science Ltd, 2011)
Direct oxidation of enolizable ketones to α-hydroxy derivatives, vicinal dicarbonyls or tricarbonyl compounds has been achieved by a catalytic amount of 2-alkylidene-4-oxothiazolidine vinyl bromide in DMSO as a solvent. ...
Unusual mode of reactivity of 2-alkylidene-4-oxothiazolidine S-oxides under the Pummerer reaction conditions
(Oxford : Pergamon-Elsevier Science Ltd, 2013)
The reactivity of 2-alkylidene-4-oxothiazolidine S-oxides under the Pummerer reaction conditions, using Ac2O, TFAA, SOCl2 and SOBr2 as initiators, has been examined. Almost all reactions proceeded with absolute regioselectivity ...