Chromium Trioxide-pyridine Complex Research Articles

Synthesis of phosphonomethylated acid chlorides, alcohols, and aldehydes of the furan series

Diethoxyphosphorylmethyl derivatives of furancarboxylic acids react with thionyl chloride in the presence of DMF to form the corresponding acid chlorides. Compounds synthesized were reduced with sodium borohydride in the DMF-dioxane medium to give hydroxymethyl compounds. Obtained phosphorylated alcohols were oxidized to aldehydes by chromium trioxide-pyridine complex in methylene chloride. The diethoxyphosphorylmethyl group remains untouched in all these transformations. A series of phosphorylated acid chlorides, alcohols, and aldehydes including all six versions of mutual location of phosphorus-containing substituent and another functional group in the furan ring was synthesized. It is established that 2,3- and 3,2-(diethoxyphosphorylmethyl)(chlorocarbonyl)furans in the course of vacuum distillation undergo cyclization to 4,5(2,3-furo)- and 4,5(3,2-furo)-1,2-oxaphosphorines.

Cyclization and rearrangement of diterpenoids. IV. Synthesis of Δ12- and Δ13(14)-iso-20-deoxyluteones

Δ12- and Δ13(14)-Iso-20-deoxyluteones have been synthesized from 13E- and 13Z-bicyclogeranylgeranylacetones. The latter were reduced to the corresponding alcohols, which were acetylated, and the acetates obtained were cyclized with fluorosulfonic acid in nitropropane. The reaction product was saponified to a mixture of tricyclic alcohols which were oxidized with the chromium trioxidepyridine complex to a mixture of Δ12- and Δ13(14)-iso-20-deoxyluteones and this was separated chromatographically.

The Total Synthesis of (+)-Taxoquinone, (−)-7α-Acetoxyroyleanone, (−)-Dehydroroyleanone, (−)-Horminone, (−)-7-Oxoroyleanone, and (+)-Inuroyleanol

Abstract Methylation of 12-benzoyloxyabieta-8,11,13-trien-11-ol with methyl iodide afforded 11-benzoyloxy-12-methoxyabieta- and 12-benzoyloxy-11-methoxyabieta-8,11,13-triene (9). Oxidation of the latter product with chromium trioxide, followed by sodium borohydride reduction and acetylation, gave 7β-acetoxy-12-benzoyloxy-11-methoxyabieta-8,11,13-triene (17) and its 7α-acetoxy isomer (18) in a ratio of ca. 5 : 1. On the other hand, treatment of 9 with lead tetraacetate produced 17 and 18 in a ratio oi ca. 1 : 2. The 7β-acetate (17) was then oxidized with chromium trioxide and the resulting p-quinone derivative was hydrolyzed with aqueous sodium hydroxide to give taxoquinone (1), which on dehydration gave dehydroroyleanone. Similarly, the 7α-acetate (18) was converted into horminone (4) via the p-quinone derivative, which was treated with aqueous sodium hydrogencarbonate to give 7α-acetoxyroyleanone. Oxidation of 4 with manganese dioxide afforded 7-oxoroyleanone. Methylation of 1 with diazomethane, followed by oxidation with a chromium trioxide-pyridine complex, afforded 12-methoxyabieta-8,12-diene-7,11,14-trione, which on reduction with sodium dithionite gave inuroyleanol.

Synthesis of epimeric 2-d1-5.BETA.-pregnane-3,11,20-triones.

In order to clarify the stereochemistry of hydrogen loss from the C-2 position during microbial transformation of 5β-pregnane-3, 11, 20-trione into the Δ1-unsaturated compound, the stereospecific synthesis of epimeric C-2 deuterated substrates has been carried out. A key intermediate, 5β-pregn-2-ene-11α, 20β-diol diacetate, was obtained from the readily available 11α-hydroxyprogesterone through two synthetic routes. The trans-diaxial opening of the 2β, 3β-epoxide with lithium aluminum deuteride provided the 2α-d1-3β-ol. Deuterioboration of the Δ2-olefin and subsequent oxidation of the organoborane afforded the 2α-d1-3β-ol. On oxidation with chromium trioxide-pyridine complex, the epimeric 2-d1-5β-pregnane-3β, 11α, 20β-triols were converted to the desired 2-d1-5β-pregnane-3, 11, 20-triones.

ChemInform Abstract: PREPARATION OF D‐B‐FRIEDOOLEAN‐5(10)‐EN‐1‐ONE AND RELATED COMPOUNDS. A COMMENT ON THE STRUCTURE OF ′GLUT‐5(10)‐EN‐1‐ONE′ FROM EUPHORBIA NERIFOLIA

AbstractOxidation des Oleanens (I) mit dem CrO3‐Pyridin‐Komplex liefert die Titelverbindung (IIa) "sowie die Verbindungen (IIb) und (IIc) (Ausb.‐Angaben in mg).

Oxidation of primary and secondary alcohols in partially protected sugars with the chromium trioxide-pyridine complex in the presence of acetic anhydride

Oxidation of primary and secondary alcohols in partially protected sugars with the chromium trioxide-pyridine complex in the presence of acetic anhydride

Preparation of D:B-Friedoolean-5(10)-en-1-one and Related Compounds. A Comment on the Structure of “Glut-5(10)-en-1-one” from Euphorbia Nerifolia

Abstract In order to examine the structure, “glut-5(10)-en-1-one”, proposed for a new triterpene from Euphorbia nerifolia, this ketone (≡ D : B-friedoolean-5(10)en-1-one) was prepared. Oxidation of D : B-friedoolean-5(10)-ene with chromium trioxide-pyridine complex gave the allylic oxidation products, D : B-friedoolean-5(10)-en-1-one, D : B-friedoolean-5(10)-en-6-one, and D : B-friedoolean-5(10)-ene-1,6-dione. The spectral data and physical constants of the synthetic ketone (D : B-friedoolean-5(10)-en-1-one) were not identical with those of the new triterpene; this requires revision of the structure of this natural triterpene. Oxidation of D : B-friedoolean-5(10)-en-3-one enol acetate under the same conditions to give D : B-friedooleane-1,5(10)-dien-3-one is also described.

Synthesis of 4-d1-testosterone and 4-d1-androstenedione.

In order to clarify the stereochemistry at C-4 in enzymatic saturation of Δ4-3-ketoste-roids synthesis of 4-deuterated testosterone and androst-4-ene-3, 17-dione (XVIII, XIX) has been undertaken. The key intermediate leading to the required substrate, 4α-d1-5α-androstane-3β, 4β, 17β-triol 3, 17-bis (dimethyl-tert-butylsilyl) ether (XVI), was prepared by stereospecific reduction with lithium aluminum deuteride from 3β, 17β-dihydroxy-5α-androstan-4-one disilyl ether (XIII), which was readily obtainable from androst-4-ene-3β, 17β-diol disilyl ether (XI) by hydroboration, followed by oxidation with chromium trioxide-pyridine complex. Dehydration of XVI with phosphorus oxychloride in pyridine provided the Δ4 olefine (XVIIb) which on chromium trioxide oxidation was led to the desired compounds. Reductive dehalogenation of 4-bromotestosterone silyl ether (II) with lithium aluminum deuteride and subsequent oxidation with chromium trioxide-pyridine complex afforded 4-d1-testosterone silyl ether (VII) in which the deuterium incorporation, however, proved to be unsatisfactory.

InSituAllylic Oxidations With Collins Reagent

Abstract Chromium trioxide-pyridine complex (Collins Reagent) oxidizes alcohols to aldehydes and ketones in high yield, and has been particularly effective in oxidizing acid-sensitive alcohols. A great improvement in the utility of the reagent was reported by Ratcliffe and Rodehorst who made the complex in situ in methylene chloride – thus avoiding the problems involved in isolating crystalline complex. The primary problems include keeping the crystalline complex dry; avoiding fires during addition of CrO3 to pyridine; and having to make the complex in a separate step in the first place. Dauben, Lorber, and Fullerton found that the isolated complex is extremely effective in allylic oxidations, i.e. in oxidizing olefins to enones. Shaw and Sherry also were able to oxidize alkynes to acetylenic ketones in low yields with the isolated complex. In unpublished experiments, the in situ Ratcliffe procedure was tried for allylic oxidations – but with poor yields. Shaw and Sherry reported similar problems with the...

The preparation of tritiated betulaprenols and dolichols

A rapid and simple procedure is described for the preparation of tritium-labeled polyprenols. The isoprenoid alcohols are oxidized by chromium trioxide-pyridine complex in dichloromethane and the resulting aldehydes are isolated and reduced with 3H-labeled sodium borohydride. Radioactive betulaprenols and dolichols have been obtained in high yield and purity by using this procedure.

Oxidative deoximation

A number of ketoximes have been deoximated by treatment with Jones reagent, chromium trioxide–pyridine complex, and periodic acid, reagents which have not previously been employed for this purpose. The oximes of camphor and of 1-tetralone also gave 2-nitroiminobornane and 1,1-dinitrotetralin, respectively.

Studies on asterosaponins—V : A novel steroid conjugate, 5α-pregn-9(11)-ene-3β,6α-diol-20-one-3-sulfate, from a starfish saponin, asterosaponin A

A new crystalline steroid conjugate was obtained by partial acid hydrolysis of asterosaponin A, a steroidal saponin from the starfish, Asterias amurensis. The structure of the conjugate was established as 5α-pregn-9(11)-ene-3β,6α-diol-20-one-3-sulfate ( 2) on the basis of elemental analysis, IR and PMR spectra measurement and chemical reaction. Solvolysis of compound 2 yielded 5α-pregn-9(11)-ene-3β,6α-diol-20-one. Oxidation with chromium trioxide-pyridine complex followed by solvolysis afforded a new steroid, 5α-pregn-9(11)-ene-3β-ol-6,20-dione, whose structure was deduced by the measurement of ORD curve and PMR spectra. Thus, the location of carbohydrate moiety in asterosaponin A has been assigned to 6α-hydroxy group of the steroid conjugate.

Total Synthesis of 13β-Allylgonanes. I. Synthesis of dl-17α-Ethynyl-17β-hydroxy-13β-allylgon-4-en-3-one

dl-17α-Ethynyl-17β-hydroxy-13β-allylgon-4-en-3-one (XXIV) was synthesized via 17β, 2'-epoxy pentaene (X). The double bonds at C-14 and -8 of X was hydrogenated sequentially by conventional methods. 17β, 2'-Epoxy triene (XIII) was treated with p-toluenesulfonic acid in acetic anhydride to give 13β-allylgonane (XIV) as a major product. Birch reduction of the tetrahydropyranyl ether (XIX) followed by acid treatment yielded the 4-en-3-one compound (XXI), which was oxidized with chromium trioxidepyridine complex to the 17-ketone (XXII). The enol ether (XXIII) was treated with lithium acetylide in ethylenediamine, and then with acid to yield XXIV. The progestational activity of XXIV is as potent as norgestrel.

Synthesis of Epimeric 2- and 4-Deuterio-5β-androstane-3, 17-diones

In order to clarify the stereochemistry of hydrogen loss from C-2 and C-4 during the microbial l1- and l4-dehydrogenation the titled compounds have been synthesized as the suitable substrates. The key intermediates leading to the desired compounds, l2- and l3-olefins (V, VI), were prepared from 5β-androstane-3α, 17β-diol 3-tosylate 17-acetate (IV). Epoxidation with per-acid followed by trans-diaxial opening of the resulting β-epoxides (VII, VIII) with lithium aluminum deuteride gave 2α- and 4α-deuterio-5β-androstane-3β, 17β-diols (X, XIV). On the other hand V and VI were transformed into the 2β- and 4β-deuterio-3β, 17β-diols (XII, XVI) by treatment with deuterated diborane and then with hydrogen peroxide. Upon oxidation with chromium trioxide-pyridine complex these labeled diols were led to the 2- and 4-deuterated 3, 17-diketones (XI, XIII, XV, XVII), respectively.

Preparation of conjugated acetylenic ketones by oxidation of alkynes with chromium trioxide-pyridine complex or sodium chromate

Preparation of conjugated acetylenic ketones by oxidation of alkynes with chromium trioxide-pyridine complex or sodium chromate

Improved procedure for oxidations with the chromium trioxide-pyridine complex

Improved procedure for oxidations with the chromium trioxide-pyridine complex

Studies on Abscisic Acid

Methyl α-cyclocitrylideneacetate was successively oxidized with selenium dioxide and chromium trioxide-pyridine complex to give methyl 1'-hydroxy-α-cyclocitrylideneacetate and a mixture of methyl 3'-keto-β-cyclocitrylideneacetate and methyl 4'-keto-α-cyclocitrylideneacetate. Further, oxidation of methyl α-cyclocitrylideneacetate with tert-butyl chromate afforded methyl 4'-keto-α-cyclocitrylideneacetate and methyl 1'-hydroxy-4'-keto-α-cyclocitrylineacetate. Similarly, methyl α-cyclogeranate was oxidized to methyl 3-keto-β-cyclogeranate and methyl 4-keto-α-cyclogeranate. Methyl 1'-hydroxy-4'-keto-α-cyclocitrylideneacetate, methyl 1-hydroxy-4-keto-α-cyclogeranate and their related compounds did not show growth inhibitory activities on rice seedlings.

Total Synthesis of Nepseudin

Abstract The Hoesch reaction of 6-hydroxy-2,3-dihydrobenzo[b]furan with 2,3,4-trimethoxyphenylacetonitrile yielded 6-hydroxy-5-(2,3,4-trimethoxyphenylacetyl)-2,3-dihydrobenzo[b]furan. The cyclization of the dihydrobenzofuran with ethyl orthoformate-pyridine-piperidine gave dihydrodehydronepseudin, an isoflavone. The dehydrogenation of the above isoflavone with N.B.S. or Pd-G yielded dehydronepseudin. Nepseudin was derived by the reduction of dehydronepseudin with sodium borohydride and by subsequent oxidation with the chromium trioxidepyridine complex.

Isolation of Helminthosporol as a Natural Plant Growth-regulator and its Chemical Structure

Helminthosporol was isolated as a natural plant growth-regulator produced by Helminthosporium sativum and its structure was assigned as I. Oxidation of I with chromium trioxide-pyridine complex gave helminthosporal (II). The glycol (III), obtained by the reduction of I or II, yielded I by the oxidation with activated manganese dioxide. I spontaneously changed into helminthosporic acid (IV), when the former in organic solvent was let to stand in the air.

THE STRUCTURE OF TUBEROSTEMONINE. I. THE DEHYDROGENATION OF TUBEROSTEMONINE. (1)

The alkaloid tuberostemonine, obtained from Stemona tuberosa L., was dehydrogenated over 40% palladium-asbestos to give, along with small amounts of three crystalline compounds, tuberostemonane, C20H29N, as an oil, the yield of which was raised to 70% by the use of 20% palladium-charcoal as a catalyst under selected conditions. Oxidation of tuberostemonane with chromium trioxide-pyridine complex or with potassium permanganate afforded an orange-red substance, C16H19O2N, whose ultraviolet and infrared spectra indicated that it is an isatin, suggesting that tuberostemonane possesses an indole skeleton.