Bile acids XLII. Preparation of 5-alpha-cholestan-26-oic acids from kryptogenin

3β, 7α, 26-Triacetoxy-5α-cholestane was prepared from 25R-3β, 26-diacetoxy-5α-cholestan-7α-ol, and partially hydrolyzed with potassium carbonate in methanol-benzene. The three acetylated products thus obtained were characterized by thin layer and gas liquid chromatography, and mass spectrometry. By oxidation and alkaline hydrolysis, 3β, 7α-diacetoxy-5α-cholestan-26-ol was converted to 3β, 7α-dihydroxy-5α-cholestanoic acid. 7α, 26-Diacetoxy-5α-cholestan-3β-ol was characterized as indicated. The third product, 7α-acetoxy-5α-cholestane-3β, 26-diol was oxidized to 3-oxo-7α-acetoxy-5α-cholestanoic acid which was reduced catalytically and hydrolyzed to provide 3α, 7α-dihydroxy-5α-cholestanoic acids and its 3β-isomer. By comparison of the specific rotation of this sample of 3α, 7α-dihydroxy-5α-cholestanoic acid derived from 25R-kryptogenin with a similar product derived from arihydro-5α-cyprinol obtained from carp bile, the latter derivative appears to be primarily the 25S material.     

Improved synthesis of 5 beta-cholestan-26-oic acids.

An improved method for the synthesis of 3 alpha, 7 alpha-dihydroxy-5 beta-cholestan-26-oic acid and 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestan-26-oic acid is described. The method involves an Arndt-Eistert rearrangement of the corresponding diazoketone obtained by the action of diazoethane on 3 alpha, 7 alpha-diformyloxy-5 beta-cholane-24-carboxylic or 3 alpha, 7 alpha, 12 alpha-triformyloxy-5 beta-cholane-24-carboxylic acid chloride. The products are obtained in good yield and no isomeric 27-nor- 24-methyl acid contaminants are formed as encountered in the commonly employed Kolbe synthesis.     

Incorporation of 5-substituted uracil derivatives into nucleic acids. Part IV.The synthesis of 5-ethynyluracil.

5-Acetyluracil (I) has been treated with POCI3 to give 5-(1-chlorovinyl)-2,4-dichloropyrimidine (II). Treatment of II with KOEt gave a mixture of 2-ethoxy-5-ethynyl-4 (3H)-pyrimidinone (IIIA) and 4-ethoxy-5-ethynyl-2 (1H)-pyrimidinone (IIIB). IIIA and IIIB were isolated and characterised. The mixture of IIIA and IIIB upon treatment with HCI gave 5(1-chlorovinyl)uracil (IV). Reaction of IV with KOEt gave 5-ethynyluracil (V). 5-Ethynyluracil was more easily obtained by the treatment of II with KOH in aqueous dioxan.     

Bile acids. LXXVII. Large-scale preparation of 5 alpha-anhydrocyprinol from carp bile

An improved method of preparation of 5 alpha-anhydrocyprinol from large quantities of carp bile is reported. The following materials were obtained by this method: 5 alpha-anhydrocyprinol, 5 alpha-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol, 5 alpha-cholestane 3 alpha,7 alpha,12 alpha,26-tetrol, an unidentified sterol from the neutral lipid fraction, allocholic acid and allochenodeoxycholic acid from the bile acid fraction. Yields of 5 alpha-anhydrocyprinol and bile acids vary in different batches. The identity and purity of these materials were verified by thin-layer chromatography, gas liquid chromatography and gas chromatography-mass spectrometry.     

Thermal denaturation of mesophilic and thermophilic 5S ribonucleic acids.

The Tm of Bacillus stearothermophilus 5S ribonucleic acid (RNA) is 1.5 +/- 0.5 C higher than that of 5S RNAs from B. subtilis and Escherichia coli. Melting in 50% methanol and in formaldehyde indicate that both base stacking and helical regions are involved in the slightly increased thermal stability of B. stearothermophilus 5S RNA. It is probable that the 5S RNA makes only a minor contribution to the thermostability of B. stearothermophilus 50S ribosomal subunits.     

Bile acids. 38. Conversion of 5 -cholestane-3 ,7 -diol to allo bile acids by the rat

5alpha-[4-(14)C, 3alpha-(3)H]Cholestane-3beta,7alpha-diol was prepared from individual samples of 5alpha-[3alpha-(3)H]cholestane-3beta,7alpha-diol and 5alpha-[4-(14)C]cholestane-3beta,7alpha-diol, each derived from 3beta-acetoxycholest-5-en-7-one. Bile was collected for 11 days from adult male rats, with cannulated bile ducts, that had received intraperitoneally 0.90-0.92 mg of the doubly labeled diol. Bile from the first 10 hr, containing 63% of the administered (14)C and 6% of the (3)H, was hydrolyzed, and the bile acids were separated by acetic acid partition chromatography. Allochenodeoxycholic and allocholic acids contained at least 20.6% and 48.6%, respectively, of the (14)C retained in the biliary acids. Small amounts of (14)C (2.5% and 1.9%, respectively) were present in the 3beta isomers of these acids, but the tritium content totaled more than half of that found in the bile acid fraction. No evidence was obtained for presence of the extensive quantities of the allomuricholates.     

Preparation and mass spectral behaviour of some 5 beta-cholenoic acids.

Monounsaturated 5 beta-cholanoic acids with double bonds in rings A, B, and C were prepared by POCl3 and ZnCl2 dehydration from natural bile acids with selectively blocked hydroxyl functions. The yields ranged from 15 to 100%. The products were purified by thin-layer and AgNO3 thin-layer chromatography and the structures were confirmed by nuclear magnetic resonance spectroscopy and mass spectrometry. The methyl ester acetates of the unsaturated 5 beta-cholanoic acids possessed chromatographic properties closely similar to those of the corresponding saturated bile acids. Several characteristic fragments were seen in the mass spectra which, in conjunction with the chromatographic properties, permitted an unambiguous distinction between different monounsaturated acids, and between saturated and unsaturated bile acids of the same number and configuration of functional groups. The 20 5 beta-cholenoic acids examined represent all of the simple chemical and enzymatic dehydration products of natural bile acids and can be completely identified by their combined chromatographic and mass spectral properties.     

Potential bile acid metabolites. XVIII. Synthesis of stereoisomeric 3,6,12 alpha-trihydroxy-5 beta-cholanoic acids.

Two new 6-hydroxylated bile acids, 3 beta, 6 alpha, 12 alpha- and 3 beta, 6 beta, 12 alpha-trihydroxy-5 beta-cholanoic acids, were synthesized from deoxycholic acid. In addition, their C-3 epimers, 3 alpha, 6 alpha, 12 alpha- and 3 alpha, 6 beta, 12 alpha-trihydroxy acids, were prepared by a new route. The principal reactions used were 1) 6 beta-hydroxylation of 3-methoxy-3,5-dienes with m-chloroperbenzoic acid in aqueous dioxane; 2) catalytic hydrogenation of the resulting 6 beta-hydroxy-3-oxo-4-enes to the 6 beta-hydroxy-3-oxo-5 beta compounds with palladium on calcium carbonate catalyst in ethanol; and 3) stereoselective reduction of appropriate 3-oxo derivatives with potassium tri-sec-butylborohydride and tert-butylamine-borane complex. The thin-layer chromatographic, gas-liquid chromatographic, and high performance liquid chromatographic mobilities, and 1H- and 13C-nuclear magnetic resonance spectroscopic data of the four stereoisomers are presented. With this work all the 6-hydroxylated derivatives of lithocholic, deoxycholic, chenodeoxycholic, ursodeoxycholic, and cholic acids in the 5 beta series are now known and have been synthesized.