Zdzisław Paryzek

Reaction of some trisubstituted steroid epoxides with triphenylphosphine - iodine complex. Deoxygenation of epoxides

Abstract Triphenylphosphine - iodine complex was found to be an effective reagent for deoxygenation of trisubstituted steroidal epoxides. The mechanism of the reaction is proposed.

SYNTHESIS AND CLEAVAGE OF LACTONES AND THIOLACTONES. APPLICATIONS IN ORGANIC SYNTHESIS. A REVIEW

1 . Introduction ....................................................................................................................... 210 2 . Cyclizations ........................................................................................................................ 211 a ) Cyclization of Hydroxyacids and Hydroxyacid Derivatives ......................................... 211 b) The Sharpless Asymmetric Dihydroxylation of Unsaturated Carboxylic Aci a3 ........... 213 c) Cyclization of Aldehydes and Ketocarboxylic Acids .................................................... 214 d ) Cyclization of Hydroxynitriles ....................................................................................... 215 e) Cyclization of Haloacids ................................................................................................ 215 fl Cyclization of Unsaturated Carboxylic Acids, Esters and Amides ................................ 215 g) Halolactonization of Unsaturated Carboxylic Acids, Esters and Amides .................... 216 h) Selenolactonization of Unsaturated Carboxylic Acid, Esters and Amides ................... 218 3 . Reductions .......................................................................................................................... 219 a) Reduction of Cyclic Anhydrides .................................................................................... 219 b) Reductive Alkylation of Anhydrides ............................................................................... 220 c) Barbier Alkylation of Anhydrides .................................................................................. 220 4 . Oxidations .......................................................................................................................... 221 a ) Oxidation of Diols .......................................................................................................... 221 b) Oxidation of Cyclic Ketones to Lactones (BaeyerVilliger Reaction) .......................... 222 c) Oxidative Cyclization of y-Hydroxyolefins .................................................................... 223 d} Oxidation of Cyclic Ethers ............................................................................................. 224 e) Oxidation of Olefins ....................................................................................................... 224 . ................................................. I . SYNTHESIS OF LACTONFS GENERAL METHODS 210

The reaction of cholesterol with ozone and alcohols: a revised mechanism and structure of the principal product

The structure of the product formed in the course of the reaction of cholesterol acetate with ozone in alcohol-containing solvents has been revised. In methanol–chloroform, it is shown to be the hydroperoxide, 3β-acetoxy-5α-hydroperoxy-7β-methoxy-5α-B-homo-6-oxacholestane (8a), and not the previously claimed cyclic hemiperacetal, 3β-acetoxy-5-hydroxy-7a-methoxy-B-dihomo-6,7-dioxacholestane (1; R1= AC, R2= Me).

THE PREPARATION OF 1-ALLYLURACIL. N(1)-ALKYLATION OF N(3)-PROTECTED URACIL DERIVATIVES

(2001). THE PREPARATION OF 1-ALLYLURACIL. N(1)-ALKYLATION OF N(3)-PROTECTED URACIL DERIVATIVES. Organic Preparations and Procedures International: Vol. 33, No. 4, pp. 400-405.

Reaction of ozone with steroidal allylic alcohols: evidence for intramolecular interception of the ‘Criegee carbonyl/carbonyl oxide intermediate’

The reaction of 3β-acetoxycholest-5-en-7β-ol with ozone at –70 °C gives 3β-acetoxy-7β-hydroxy-5,7aβ-epoxy-5β-B-homo-6-oxacholestane (3) and 3β-acetoxy-7β-hydroperoxy-5,7aβ-epoxy-5β-B-homo-6-oxacholestane (11) resulting from the interception of a classical carbonyl/carbonyl oxide intermediate by intramolecular nucleophilic attack of the allylic hydroxy group on the carbonyl carbon atom. It is shown also that the two possible modes of cleavage of the primary ozonide are realized.

Epoxidation of lanost-9(11)-enes. The effect of a β-carbonyl group upon the stereochemistry of epoxidation

m-Chloroperbenzoic acid epoxidation of 3β-acetoxylanost-9(11)-en-7-one afforded two isomeric epoxides, the β-isomer being the major product. This result is in contrast with the epoxidation of other 9(11)-olefins having no carbonyl group. It is interpreted in terms of the ‘directive effect’ of the β-carbonyl group which generally influences the steric course of the epoxidation of β-oxo-olefins and is of polar character.

Stereospecific Reduction of 7-OXO Group in 3β-Acetoxycholest-5-en-7-one

Abstract The stereospecific synthesis of 3β-acetoxycholest-5-en-7β-ol from cholesterol is described.

New steroid dimer derived from cholic acid as receptor for lanthanum(III) and calcium(II) nitrates

Abstract New steroid dimer, ethylene bridged bis-carbamate ( 3) was synthesized from cholic acid in few steps. Complexes of 3 with lanthanum(III) and calcium(II) nitrates were prepared in reaction of 3 and appropriate metal salts. They were characterized by spectral data (Infrared (IR), ultraviolet-visible (UV/Vis), nuclear magnetic resonance (NMR) spectroscopy and fast-atom bombardment (FAB), electrospray (ESI) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS)) and elemental analysis. The similarity in complexing behavior of steroidal dimer toward calcium and lanthanum ions was observed.

A new approach to the synthesis of the 17β-butenolide fragment of cardenolides

Abstract A new, efficient synthesis of the 17β-butenolide fragment characteristic of cardenolides is effected by [2 + 2]-cycloaddition of dichloroketene to 3β-acetoxypregna-5,20-diene, as a key step.

Steroidal cyclobutanones. Part 2. Diastereofacial selection in the cycloaddition of dichloroketene and 3β-acetoxy-20a-homopregna-5,20-diene. Crystal structure of the cycloadduct, (20S)-3β-acetoxy-20,24-cyclo-22,22-dichlorochol-5-en-23-one

The reaction of dichloroketene and 3β-acetoxy-20a-homopregna-5,20-diene 1 is shown to give one diastereoisomeric cycloadduct 2 arising from attack at the rear side of the preferred rotamer 1b of the steroid skeleton. The structure of dichlorocyclobutanone 2 was determined by X-ray crystallography. Reduction of 2 gives chlorocyclobutanone 3 and cyclobutanone 4. Examination of the cyclobutanones by CD, 1H and 13C NMR spectroscopy demonstrates that these techniques can be used for the determination of the configuration of 2 and 3.