2‐Cyano‐4‐iodoacetanilide: a hydrogen‐bonded chain of R22(12) and R22(14) rings

The molecules of 2‐cyano‐4‐iodoacetanilide, C₉H₇IN₂O, are linked by N—H...N and C—H...O hydrogen bonds into chains of alternating R₂²(12) and R₂²(14) rings.     

Ga(22)

A metal-rich intermediate was captured prior to metal formation by means of a substitution reaction during the disproportionation of a metastable Ga(I) bromide solution. In the thus obtained Ga(22) cluster (see structure), the central gallium atom displays the unusual coordination number of 13.     

Synthese von (22R,25S)-16β-Amino-22,26-epiminocholestanen

By reacting the known 16-bromo-N-cyano-22,26-epimino-cholestanes (e.g.2) with NaN₃ inDMF 16-azido-N-cyano-22,26-epimino-cholestanes (e.g.4) were obtained. Reduction of4 with LiAlH₄ gives 16-amino-22,26-epimino-cholestane (9). Some acylated derivatives of9 are described, e.g. the known derivatives11 and13, which prove the stereochemistry at C-16.

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Herrn Prof. Dr.K. Kratzl mit den besten Wünschen zum 60. Geburtstag von der Abteilung für Pharmazeutisch-chemische Forschung der Chemie Linz AG gewidmet.     

Synthesis of (22R, 25R)-3β,26-Dihydroxy-5α-furostan-6-one #

The synthesis of a plant growth promoter furostanol which bears the characteristic functionality of teasterone on rings A and B is described.

     

Synthesis of (22E,24R)-5a-ergosta-2,7,22-trien-6-one

The synthesis of the 5a-hydroxy-2,7,22-trien-6-one (3) has been achieved by the mesylation of ergosterol (1a) and oxidation of the resulting mesylate (1b) with chronic acid to 3,5a-dihydroxy-7,22-dien-6-one 3-mesylate, followed by elimination.Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, 220141, Minsk, ul. Akad. Kuprevicha. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 100–102, January–February, 1999.     

Preparation of (R)-11-hydroxyaporphine directly from (R)-10,11-dihydroxyaporphine ((R)-apomorphine)

A Regioselective synthesis of (R)-11-hydroxyaporphine 2 directly from (R)-10,11-dihydroxyaporphine ((R)-apomorphine, 1 ) is described for the first time. The isopropylidene ketal ring of 10,11-(isopropyl-idenyldioxy)aporphine 5 obtained by the isopropylidenation of apomorphine was regioselectively opened by ten equivalents of trimethylaluminum to give (R)-10-hydroxy-11-tert-butyloxyaporphine 6 . The free 10-hydioxyl position of 6 was triflated with N-pbenyltrifluoromethanesulfonimide and potassium carbonate under reflux to give (R)-10-[(trifluoromethyl)sulfonyloxy]-11-tert-butyloxyaporphine 7 . The reduced product, 11-tert-butyloxyaporphine 8 was prepared from 7 by a palladium-catalyzed hydrogenolysis. The ether cleavage of (R)-11-tert-butyloxyaporphine with 48% hydrobromic acid afforded the desired (R)-11-hydroxyaporphine 2 in good yield.     

Asymmetric synthesis of (S,R)- and (R,R)-methiin stereoisomers

Abstract

An asymmetric synthesis of (+)- and (–)-methiine (S-methyl-(R)-cysteine sulfoxide) diastereomers has been developed. These natural sulfur compounds were isolated from a variety of Brassica vegetables. As the starting compound, (R)-cysteine was used, which was methylated to form (R)-S-methylcysteine. Then the oxidation of S-methylcysteine with tert-butyl hydroperoxide catalyzed by the chiral tetra(isopropylate)titanium/(S)- or (R)-Binol complex led to the formation of (1?R,2S)-(+)- or (1?R,2R)-(–)-methiin stereomers.     

Synthesis and Crystal Structure of 5（R）-（1R,2S,5R）-Menthoxy-4（R）- N-cyclohexylaminobutyrolactone

1INTRODUCTION Substitutedγ-butyrolactones are a group of impor-tant compounds containing unique carbon skeleton of butyrolactone which is widely present in many natural products and have received considerable interest because of their biological and medicinal properties[1～4].Therefore,much attention has been paid to the new asymmetric methods for synthesi-zing these interesting compounds[5～11].The prece-ding results led us to explore the possibility of using cyclohexylamine to convert5(…