Oxido

A substantial fraction of the named enzymes are oxido-reductases, responsible for shuttling electrons along metabolic pathways that reduce carbon dioxide to sugar (in the case of plants), or reduce oxygen to water (in the case of mammals). The oxido-reductases that drive these processes involve a small set of redox active cofactors , that is, small chemical groups that gain or lose electrons. These cofactors include iron porjDhyrins, iron-sulfur clusters and copper complexes as well as organic species that are ET active. 

Epoxide opening with nucleophiles occurs at the less substituted carbon atom of the oxlrane ting. Cataiytic hydrogenolysis yields the more substituted alcohol. The scheme below contains also an example for trons-dibromination of a C—C double bond followed by dehy-drobromination with strong base for overall conversion into a conjugated diene. The bicycKc tetraene then isomerizes spontaneously to the aromatic l,6-oxido[l0]annulene (E. Vogel, 1964). 

Benzotriazinium salts, 2-aryl-4-oxido-1-oxides, betaines... 

S-N rearrangement, 3, 36 ionization constants, 3, 4 oxidation, 3, 37 quatemization, 3, 17 Pyridazine-3 (2 H) - thiones analysis, 3, 2 tautomerism, 3, 5 Pyridazinium betaine, 3-oxido-photolysis, 3, 11 Pyridazinium betaine, 5-oxido-photolysis, 3, 11 Pyridazinium dicyanomethylide photolysis, 3, 12... 

OXIDO-REDUCTASES FROM GENETICALLY ENGINEERED YEAST STRAINS AND THEIR BIO ANALYTICAL APPLICATION... 

Synthesis of the 11,12-Oxido and 14,15-Oxido Analogs of Leukotriene A4 and the Corresponding Analogs of Leukotrienes C4 and D4... 

The 11,12-oxido and 14,15-oxido analogs of leukotriene A4 were synthesized to help answer the question of whether these compounds might be biosynthesized from arachidonate by the 12- and 15-lipoxygenation pathways and serve as physiologic regulators. Hydrolysis products of the 14,15-oxide were later found to be formed in biological systems. 

Oxido analog of LTA4 and the corresponding analogs of LTC4 and LTD4 (Ref. 1) ... 

This remarkably selective internal epoxidation of peroxyarachidonic acid to form 14,15-oxido-arachidonic acid occurs as shown because of unusually favorable stereoelectronics. The corresponding reaction sequence with eicosa-(E)-8,ll,14-trienoic acid affords the Ai4,i5 epoxide in 94% isolated yield and >95% purity. 

A solution of 6a,7 x-oxido-5a-cholestan-3j8-ol acetate (232, 3.07 g) in anhydrous ether (100 ml) is treated with lithium aluminum deuteride (0.88 g) and... 

Deuteration at the 6/3-position by reduction of a 6a, 7a-oxido steroid with lithium aluminum deuteride, 205... 

Keto steroids can be obtained in excellent yields via the Beckmann degradation of 17a-hydroxy-or 16a,17a-epoxy-20-ketopregnanes. In the case of the 17-hydroxy compounds, substituents at C-16 readily survive e.g., 16 -Br, 16jS-Cl, Iba-OAc). The 16,17-oxido-20-oximinopregnanes produce 16a-acetoxy-17-ketones. 

The enol lactone (12.7 g) is added to 157 ml of 0.5 M perbenzoic acid in benzene and allowed to stand at 25° for 140 hr. The solution is cooled to 15° and 15% sodium bisulfite solution is added to neutralize the excess peracid. The organic layer is separated and washed with saturated sodium bicarbonate solution and water. The benzene solution is dried over anhydrous sodium sulfate, filtered and concentrated to 30 ml. The product is crystallized by adding 80 ml of petroleum ether, filtered and washed with petroleum ether to yield 12.8 g (98%) of 3a,20,23-trihydroxy-16a-methyl-17(20)-oxido-ll-oxo-21-norchol-22-enoic acid-24(20)-lactone 3,23-diacetate mp 225-227°. 

Hydrolysis of 6p,l9-Oxido-3a,5a-cyclo steroids.A solution of 0.1 g of 3a,5a-cyclo-6)5,19-oxidocholestane in 20 ml of acetone is treated with 1.0 ml of water and 0.5 ml of 1 N sulfuric acid. After standing for 2 hr at room temperature, the solution is neutralized with saturated sodium bicarbonate solution and extracted with ether. The combined ether extracts are washed with water and concentrated to dryness under reduced pressure. Recrystallization of the crude product from methanol yields 85 mg choIest-5-ene-3, 19-diol mp 147-149° [aj —30°. 

The 10l -acetoxy group can be red actively removed with zinc and acetic acid or chromous chloride to give I9-norsteroids in high yield. Thermal elimination (boiling tetralin) of acetic acid from the crude 10)5-acetoxy-A -3-ketone or treatment with methanolic alkali leads to aromatization of ring A. Estrone alkyl ethers are formed from 10)5-acetoxy-19-nor-A -androstene-3,17-dione by treatment with alcohols and perchloric acid. Similar aromatizations are observed with 5,10-oxido, 5,10-dihydroxy, 5,10-halohydrins or 5,10-dihalo-3-ketones. ... 

K. Heusler, unpublished results. 62a. This statement does not apply to the reaction of 6/S-hydroxy steroids, as both the hypoiodite as well as the lead tetraacetate reactions furnish the same 6/S, 19-oxido compounds in high yields. 

Similar observations led Bernstein and co-workers" to assign structure (108a) to the rearrangement product of 5a,6a-oxido-3)5,17a-dihydroxy-6j5-methylpregnan-20-one 17-acetate (106) with anhydrous hydrogen fluoride or... 

Similarly, treatment of 5a,6a-oxido-3,20-bisethylenedioxy-6j9-methyl-pregnan-17a-ol (107) with 72% perchloric acid in acetone gives 17a-hydroxy-6l5-methyl-10(5 6)fl >e<3-pregnane-3,5,20-trione (108b). 

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