Efficient “Dehomologation” of Di-O-isopropylidenehexofuranose Derivatives To GiveO-Isopropylidenepentofuranoses by Sequential Treatment with Periodic Acid in Ethyl Acetate and Sodium Borohydride

1996 ◽  
Vol 61 (15) ◽  
pp. 5178-5179 ◽  
Author(s):  
Meiqiang Xie ◽  
David A. Berges ◽  
Morris J. Robins
Keyword(s):  
Ethyl Acetate ◽  
Sodium Borohydride ◽  
Periodic Acid ◽  
Sequential Treatment

Flavan derivatives. XXXIII. 2-Methoxyflavan-3,4-dione and 2-Methoxyflavan-3,4-diol derivatives

1972 ◽  
Vol 25 (4) ◽  
pp. 857 ◽  
Author(s):  
JW Clark-Lewis ◽  
I Dainis ◽  
EJ McGarry ◽  
MI Baig
Keyword(s):  
Sodium Borohydride ◽  
Catalytic Hydrogenation ◽  
Room Temperature ◽  
Periodic Acid ◽  
Metal Hydrides ◽  
Borohydride Reduction ◽  
Complex Metal ◽  
Sodium Borohydride Reduction ◽  
A Minor ◽  
Minor Quantity

Sodium borohydride reduction of 3-hydroxy-7-benzyloxy-2,3,4'-trimethoxy-flavanone and of 3-hydroxy-2,3,7,4'-tetramethoxyflavanone is shown to yield mainly trans-trans-2-methoxyflavan-3,4-dials, a novel class of flavan derivatives. The 7-benzyloxy hemiacetal also gave a minor quantity of the cis-cis-2-methoxyflavan-3,4-dial and less of the corresponding 2,3-cis-flavan-3,4-trans-dial. Catalytic hydrogenation over palladium, or reduction with complex metal hydrides at room temperature or above, converted the hemiacetals into the flavonols from which they were originally prepared by oxidation with periodic acid in methanol.

STEROIDS AND RELATED PRODUCTS: XIX. THE SYNTHESIS OF 3,9,12,20-TETRAOXYGENATED 9,12-seco STEROIDS. PART III. 11-AZA STEROIDS. PART I

1962 ◽  
Vol 40 (11) ◽  
pp. 2153-2162 ◽  
Author(s):  
Ch. R. Engel ◽  
S. Rakhit
Keyword(s):  
Methyl Ester ◽  
Ethylene Glycol ◽  
Ethyl Acetate ◽  
Good Yield ◽  
Boron Trifluoride ◽  
Osmium Tetroxide ◽  
Periodic Acid ◽  
Boron Trifluoride Etherate ◽  
The Other ◽  
Other Hand

The smooth conversion of 3β-acetoxy-5α-pregnane-12,20-dione (IV), readily available from hecogenin (I), to Δ9(11)-3β,20β-diacetoxy-5α-pregnan-12-one (VIII) is reported. Ozonolysis of this product in ethyl acetate gave, in almost 90% yield, 3β-hydroxy-20β-acetoxy-9-oxo-9,12-seco-11-nor-5α-pregnan-12-oic acid (XI), further characterized by its ester derivatives XIa and XIb. The conversion of the seco acid XI to Δ8(9)-3β-hydroxy-20β-acetoxy-9-amino-9,12-seco-11-nor-5α-pregnen-12-oic acid lactam (12 → 9) (XII) and thence to Δ8(9)-N-acetyl-3β,20β-diacetoxy-11-aza-5α-pregnene (XIVa), the first 11-aza steroids to be known, is described. On the other hand, Δ9(11)-3β,20β-diacetoxy-5α-pregnen-12-one (VIII) is readily transformed to the 9α,11α-glycol VII with osmium tetroxide and thence, with periodic acid, to 3β,9α-dihydroxy-20β-acetoxy-11-oxo-11,12-seco-5α-pregnan-12-oic acid (X), characterized as the methyl ester Xa and diacetoxy methyl ester Xb, and easily converted to the acetoxy hydroxy keto dicarboxylic seco acid XIII. In the course of this work it is shown that, whereas ketalization of the saturated 12,20-diketone IV with ethylene glycol and boron trifluoride etherate gives a good yield of the 12-monoketal (in accordance with the reports of the literature), treatment of the analogous 16-unsaturated 12,20-diketone with the same reagents under the same conditions leads not to ketal formation but to addition of ethylene glycol in position 16.

Simultaneous Gas Chromatographic Determination of Dibutyltin and IHbutyltin Compounds in Biological and Sediment Samples

1986 ◽  
Vol 69 (6) ◽  
pp. 981-984
Author(s):  
Taizo Tsuda ◽  
Hiroshi Nakanishi ◽  
Takashi Morita ◽  
Junko Takebayashi
Keyword(s):  
Gas Chromatography ◽  
Ethyl Acetate ◽  
Simultaneous Determination ◽  
Electron Capture ◽  
Silica Gel ◽  
Sodium Borohydride ◽  
Biological Samples ◽  
Chromatographic Determination ◽  
Sediment Samples

Abstract A method is described for the simultaneous determination of nanogram amounts of dibutyltin and tributyltin compounds in biological and sediment samples. These compounds are converted to the corresponding chlorides with HC1, extracted with ethyl acetate-hexane (3 + 2) for biological samples and with hexane for sediment samples, and hydrogenated with sodium borohydride. The corresponding hydrides, Bu2SnH2 and Bu3SnH, are detected by electron-capture gas chromatography after cleanup by silica gel column chromatography. Detection limits are 1.0-2.0 and 0.5-1.0 ng/g, respectively, for biological and sediment samples.

scholarly journals Investigation of Hopanoid Biomarkers in Lake Sediments by GC-MS and RP-HPLC-APCI-MS

2009 ◽  
Vol 6 (1) ◽  
pp. 77-88 ◽  
Author(s):  
Gamze Kavran Belin
Keyword(s):  
Lake Sediments ◽  
Silica Gel ◽  
Sodium Borohydride ◽  
Periodic Acid ◽  
Swiss Alps ◽  
Anoxic Sediment ◽  
Sediment Samples ◽  
Geological Materials ◽  
Rp Hplc ◽  
Bacterial Lipid

Hopanoids are mainly derived from bacteriohopanpolyols that occur especially in bacteria, show the importance of bacterial lipid contributions in geological materials. In this work, GC-MS and RP-HPLC-APCI-MS analyses of hopanoid biomarkers in oxic and anoxic sediment samples from Lake Cadagno (Swiss Alps) and Lake Voua de la Motte (Haute Savoie, France) are presented and discussed. Samples were ultrasonically extracted, fractionated by flush chromatography on silica gel and derivatised before the analyses. Periodic acid/ sodium borohydride cleavage was used to identify highly functionalised hopanoids

PREPARATION OF SOME NEW BRANCHED-CHAIN CARBOHYDRATES FROM D-α-FRUCTOHEPTONIC LACTONE

1954 ◽  
Vol 32 (4) ◽  
pp. 404-414 ◽  
Author(s):  
R. J. Woods ◽  
A. C. Neish
Keyword(s):  
Nitric Acid ◽  
Hydrochloric Acid ◽  
Hydrogen Chloride ◽  
Sodium Borohydride ◽  
Periodic Acid ◽  
Equimolar Amount ◽  
Glassy Material ◽  
Sodium Amalgam ◽  
Aldonic Acid ◽  
Branched Chain

D-α-Fructoheptonic lactone (I) was oxidized with an equimolar amount of periodic acid to give formaldehyde and a hexuronic lactone (II) which was hydrolyzed to crystalline 4-C-hydroxymethyl-L-xyluronic acid (III), (68% yield). Hydrogenation of III gave an aldonic acid which was isolated as crystalline 2-C-hydroxymethyl-L-xylonic lactone (V). Reduction of V by sodium amalgam gave 2-C-hydroxymethyl-D-xylose (VI), which crystallized after purification as the 2,5-dichlorophenylhydrazone. Hydrogenation of VI gave 1,1-di(C-hydroxymethyl)-D-threitol (VII) which was purified as the crystalline hexaacetate. Treatment of III with methanolic hydrogen chloride gave a glassy material which was reduced by sodium borohydride and hydrolyzed by hydrochloric acid to give 4,4-di(C-hydroxymethyl)-D-threose (IX), which was isolated and characterized as the crystalline 2,5-dichlorophenylhydrazone. Oxidation of III by either bromine or nitric acid gave 2-C-hydroxymethyl-D-xylaric acid (IV), which was characterized as the crystalline ammonium salt.

Ultrastructure of the Parotid Gland of the Nine-Banded Armadillo

1977 ◽  
Vol 35 ◽  
pp. 640-641
Author(s):  
J. R. Ruby
Keyword(s):  
Endoplasmic Reticulum ◽  
Parotid Gland ◽  
Periodic Acid ◽  
Acinar Cells ◽  
Duct System ◽  
Parotid Glands ◽  
Dasypus Novemcinctus ◽  
Anterior Portion ◽  
Periodic Acid Schiff ◽  
Thin Sections

Parotid glands were obtained from five adult (four male and one female) armadillos (Dasypus novemcinctus) which were perfusion-fixed. The glands were located in a position similar to that of most mammals. They extended interiorly to the anterior portion of the submandibular gland.In the light microscope, it was noted that the acini were relatively small and stained strongly positive with the periodic acid-Schiff (PAS) and alcian blue techniques, confirming the earlier results of Shackleford (1). Based on these qualities and other structural criteria, these cells have been classified as seromucous (2). The duct system was well developed. There were numerous intercalated ducts and intralobular striated ducts. The striated duct cells contained large amounts of PAS-positive substance.Thin sections revealed that the acinar cells were pyramidal in shape and contained a basally placed, slightly flattened nucleus (Fig. 1). The rough endoplasmic reticulum was also at the base of the cell.

Demonstration of Retinal Glycogen with Silver Methenamine

1971 ◽  
Vol 29 ◽  
pp. 564-565
Author(s):  
A. W. Sedar ◽  
G. H. Bresnick
Keyword(s):  
Lactic Acid ◽  
Chromic Acid ◽  
Periodic Acid ◽  
Müller Cell ◽  
External Limiting Membrane ◽  
Electron Microscope Level ◽  
Reactive Process ◽  
Inner Limiting Membrane ◽  
Muller Cell ◽  
And Migration

After experimetnal damage to the retina with a variety of procedures Müller cell hypertrophy and migration occurs. According to Kuwabara and others the reactive process in these injuries is evidenced by a marked increase in amount of glycogen in the Müller cells. These cells were considered originally supporting elements with fiber processes extending throughout the retina from inner limiting membrane to external limiting membrane, but are known now to have high lactic acid dehydrogenase activity and the ability to synthesize glycogen. Since the periodic acid-chromic acid-silver methenamine technique was shown to demonstrate glycogen at the electron microscope level, it was selected to react with glycogen in the fine processes of the Müller cell that ramify among the neural elements in various layers of the retina and demarcate these cells cytologically. The Rhesus monkey was chosen as an example of a well vascularized retina and the rabbit as an example of a avascular retina to explore the possibilities of the technique.

Cytochemical Localization of Polysaccharides in Diplodia Maydis With Thiosemicarbazide : Evaluation of Three Fixatives For Pa:Tsc:Os Reaction

1976 ◽  
Vol 34 ◽  
pp. 48-49 ◽  
Author(s):  
Judith A. Murphy ◽  
Mary R. Thompson ◽  
A.J. Pappelis
Keyword(s):  
Reaction Center ◽  
Osmium Tetroxide ◽  
Periodic Acid ◽  
Cytochemical Localization ◽  
Thin Sections ◽  
Selective Reaction ◽  
Amorphous Character

In an attempt to identify polysaccharide components in thin sections of D. maydis, procedures were employed such that a PAS localization could be carried out. Three different fixatives were evaluated ie. glutaraldehyde, formaldehyde and paraformaldehyde. These were used in conjunction with periodic acid (PA), thiosemicarbazide(TSC), and osmium tetroxide(Os) to localize polysaccharides in V. maydis using a pre-embedded reaction procedure. Polysaccharide localization is based on the oxidation of vic-glycol groups by PA, and the binding of TSC as a selective reaction center for the formation of osmium black. The reaction product is sufficiently electron opaque, insoluble in lipids, not altered when tissue is embedded, and has a fine amorphous character.

Biodegradable polyester neuroprostheses promote the reconnection of separated peripheral nerve stubs

1992 ◽  
Vol 50 (2) ◽  
pp. 1094-1095
Author(s):  
Beverly L. Giammara ◽  
Jennifer S. Stevenson ◽  
Peggy E. Yates ◽  
Robert H. Gunderson ◽  
Jacob S. Hanker
Keyword(s):  
Image Analysis ◽  
Basement Membrane ◽  
Periodic Acid ◽  
Light And Electron Microscopy ◽  
Computer Assisted ◽  
Type Iii Collagen ◽  
Image Analysis System ◽  
Biodegradable Polyester ◽  
Adult Rats ◽  
Type Iv

An 11mm length of sciatic nerve was removed from 10 anesthetized adult rats and replaced by a biodegradable polyester Vicryl™ mesh sleeve which was then injected with the basement membrane gel, Matrigel™. It was noted that leg sensation and movement were much improved after 30 to 45 days and upon sacrifice nerve reconnection was noted in all animals. Epoxy sections of the repaired nerves were compared with those of the excised segments by the use of a variation of the PAS reaction, the PATS reaction, developed in our laboratories for light and electron microscopy. This microwave-accelerated technique employs periodic acid, thiocarbohydrazide and silver methenamine. It stains basement membrane or Type IV collagen brown and type III collagen (reticulin), axons, Schwann cells, endoneurium and perineurium black. Epoxy sections of repaired and excised nerves were also compared by toluidine blue (tb) staining. Comparison of the sections of control and repaired nerves was done by computer-assisted microscopic image analysis using an Olympus CUE-2 Image Analysis System.

Sign in / Sign up

Export Citation Format

Share Document