Stereoselectivity of C(3)-methylation of camphor and derivatives

1984 ◽  
Vol 62 (10) ◽  
pp. 1899-1902 ◽  
Author(s):  
John H. Hutchinson ◽  
Thomas Money
Keyword(s):  
Major Product ◽  
Methyl Derivative

Contrary to general expectations, kinetic methylation of camphor, 9-bromocamphor, or 9,10-dibromocamphor produces the 3-exo-methyl derivative as the major product.

Synthesis of some partially methylated sucrose derivatives

1972 ◽  
Vol 25 (2) ◽  
pp. 407 ◽  
Author(s):  
GW O'Donnell ◽  
GN Richards
Keyword(s):  
Boron Trifluoride ◽  
Liquid Ammonia ◽  
Major Product ◽  
Methyl Derivative ◽  
Hydrolysis Products ◽  
Subsequent Deacetylation ◽  
Partially Methylated

1',6,6'-Tri-O-methylsucrose, a new compound, has been synthesized by methylation of 2,3,3',4,4'-penta-O-acetylsucrose with diazomethane and boron trifluoride with subsequent deacetylation. 2,3,3',4,4'-Penta-O-methylsucrose has been obtained in improved yield from the tri-O-trityl derivative by reduction with lithium in liquid ammonia. A major product of the incomplete methylation of 11,6,6'-tri-O-tritylsucrose was the 2,3,3',4'-tetra-O-methyl derivative, and after reductive detritylation 2,3,3',4'-tetra-O-methylsucrose, a new compound, was isolated and identified by examination of its hydrolysis products.

Novel Rearrangements of the 2-Chloroacrylonitrile Cycloadducts of Steroidal 14,16-Dien-17-yl Acetates

2001 ◽  
Vol 66 (12) ◽  
pp. 1777-1796 ◽  
Author(s):  
James R. Bull ◽  
Richard S. Gordon ◽  
Claudia Grundler
Keyword(s):  
Functional Group ◽  
Major Product ◽  
Similar Reaction ◽  
Rearrangement Product ◽  
Methyl Derivative ◽  
Bond Scission ◽  
Grob Fragmentation

Cycloaddition of 3-methoxyestra-1,3,5(10),14,16-pentaen-17-yl acetate (1) with 2-chloroacrylonitrile furnishes 17β-acetoxy-16α-chloro-3-methoxy-14,17α-ethenoestra-1,3,5(10)-triene-16β-carbonitrile (2) as the major product, which undergoes alkali-mediated rearrangement to (161R)-3-methoxy-17-oxo-16β,15β,14-(ethane[1,1,2]triyl)-14β-estra-1,3,5(10)-triene-161-carbonitrile (7). A similar reaction course is followed by the related 16-methyl derivative 4, and it is shown that minor 15-chloro-15-cyano cycloadducts 3 and 6 undergo Grob fragmentation. Functional group manipulations and regioselective bond-scission processes are described, for conversion of rearrangement product 7 into 16β,15β,14-(ethane[1,1,2]triyl) and cyclobuta[14β,15β] analogues of estradiol.

METABOLISM OF 17α-HYDROXYPROGESTERONE-4-14C-17α-CAPROATE BY HOMOGENATES OF RAT LIVER AND HUMAN PLACENTA

1961 ◽  
Vol 36 (4) ◽  
pp. 511-519 ◽  
Author(s):  
Margaret Wiener ◽  
Charles I. Lupa ◽  
E. Jürgen Plotz
Keyword(s):  
Rat Liver ◽  
Human Placenta ◽  
Steric Hindrance ◽  
Placental Tissue ◽  
Caproic Acid ◽  
Major Product ◽  
Side Chain ◽  
Anaerobic Conditions ◽  
Prolonged Action ◽  
Long Acting

ABSTRACT 17α-hydroxyprogesterone-4-14C-17α-caproate (HPC), a long-acting progestational agent, was incubated with homogenates of rat liver and human placenta. The rat liver was found to reduce Ring A of HPC under anaerobic conditions to form allopregnane-3β,17α-diol-20-one-17α-caproate and pregnane-3β,17α-diol-20-one-17α-caproate, the allopregnane isomer being the major product. The caproic acid ester was neither removed nor altered during the incubation. Placental tissue did not attack HPC under conditions where the 20-ketone of progesterone was reduced. It is postulated that this absence of attack on the side chain is due to steric hindrance from the caproate ester, and that this may account for the prolonged action of HPC.

Flavor Profile Analysis and GC/MS Detection of Phenolic Iodinated Disenfection Byproducts in Drinking Water for the USA Space Program

1999 ◽  
Vol 40 (6) ◽  
pp. 45-51 ◽  
Author(s):  
Andrea M. Dietrich ◽  
Susan Mirlohi ◽  
Willian F. DaCosta ◽  
Jennifer Peters Dodd ◽  
Richard Sauer ◽  
...  
Keyword(s):  
Drinking Water ◽  
Potable Water ◽  
Profile Analysis ◽  
Major Product ◽  
Space Program ◽  
Odor Threshold ◽  
Odor Evaluation ◽  
The Usa ◽  
Flavor Profile Analysis ◽  
Flavor Profile

Reactions of iodine and phenol were investigated to determine which iodophenols were produced and their odor properties. The research was performed in support of the USA space program that applies iodine to disinfect potable water for spacecraft use. Higher concentrations (50 mg/l) and higher iodine:phenol (e.g. 10:1) ratios resulted in the formation of greater iodophenol concentrations and higher substituted iodophenols. The reactions were fast and nearly complete within 1 hour. For pH 5.5 and 8 and all iodine:phenol ratios, formation of monosubstituted compounds indicated that 2-iodophenol was favored over 4-iodophenol. At the intermediate iodine:phenol ratios of 1:1 and 2:1, substantial amounts of the diiophenols formed and persisted for up to 32 days. The diiodophenols were not detected at iodine:phenol ratios of 0.2:1 and 10:1. The compound 2,4,6-triiodophenol was the major product formed at a 10:1 iodine:phenol ratio and the formation of this trisubstituted phenol appeared nearly complete. Odor evaluation indicated that the iodophenols have much lower odor threshold concentrations (OTC) than phenol. The 2- and 4- iodophenol had OTC values of ≅ 1 and 500 μg/l, respectively, with odors described as “medicinal, phenol, chemical”.

Evaluation of the Radioprotective Effects of Melatonin Against Ionizing Radiation-Induced Muscle Tissue Injury

2019 ◽  
Vol 12 (3) ◽  
pp. 247-255 ◽  
Author(s):  
Dheyauldeen Shabeeb ◽  
Mansoor Keshavarz ◽  
Alireza Shirazi ◽  
Gholamreza Hassanzadeh ◽  
Mohammed Reza Hadian ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Gastrocnemius Muscle ◽  
Tissue Injury ◽  
Histopathological Examination ◽  
Compound Action Potential ◽  
Optimal Dose ◽  
Treatment Method ◽  
Major Product ◽  
Muscle Tissues ◽  
Radiation Induced

Background: Radiotherapy (RT) is a treatment method for cancer using ionizing radiation (IR). The interaction between IR with tissues produces free radicals that cause biological damages.As the largest organ in the human body, the skeletal muscles may be affected by detrimental effects of ionizing radiation. To eliminate these side effects, we used melatonin, a major product secreted by the pineal gland in mammals, as a radioprotective agent. Materials and Methods: For this study, a total of sixty male Wistar rats were used. They were allotted to 4 groups: control (C), melatonin (M), radiation (R) and melatonin + radiation (MR). Rats’ right hind legs were irradiated with 30 Gy single dose of gamma radiation, while 100 mg/kg of melatonin was given to them 30 minutes before irradiation and 5 mg/ kg once daily afternoon for 30 days. Five rats in each group were sacrificed 4, 12 and 20 weeks after irradiation for histological and biochemical examinations. Results: Our results showed radiation-induced biochemical, histological and electrophysiological changes in normal rats’ gastrocnemius muscle tissues. Biochemical analysis showed that malondialdehyde (MDA) levels significantly elevated in R group (P<0.001) and reduced significantly in M and MR groups after 4, 12, and 20 weeks (P<0.001), However, the activity of catalase (CAT) and superoxide dismutase(SOD)decreased in the R group and increased in M and MR groups for the same periods of time compared with the C group (P<0.001), while melatonin administration inverted these effects( P<0.001).Histopathological examination showed significant differences between R group for different parameters compared with other groups (P<0.001). However, the administration of melatonin prevented these effects(P<0.001). Electromyography (EMG) examination showed that the compound action potential (CMAP) value in the R group was significantly reduced compared to the effects in the C and M groups after 12 and 20 weeks (P<0.001). The administration of melatonin also reversed these effects (P<0.001). Conclusion: Melatonin can improve biochemical, electrophysiological and morphological features of irradiated gastrocnemius muscle tissues.Our recommendation is that melatonin should be administered in optimal dose. For effective protection of muscle tissues, and increased therapeutic ratio of radiation therapy, this should be done within a long period of time.

6,11-Dihydrodibenzo[b,e]thiepin-11-yl 3-quinuclidinyl ethers: New potential intidepressants and antihistamine agents

1988 ◽  
Vol 53 (8) ◽  
pp. 1806-1811 ◽  
Author(s):  
Zdeněk Polívka ◽  
Jan Metyš ◽  
Miroslav Protiva
Keyword(s):  
Methyl Derivative ◽  
Antihistamine Activity ◽  
Antidepressant Agent ◽  
Anticataleptic Activity

Reactions of 11-chloro-6,11-dihydrodibenzo[b,e]thiepin and its 2-methyl derivative, and further of the methanesulfonates of 2-chloro- and 2-bromo-6,11-dihydrodibenzo[b,e]thiepin-11-ol with 3-quinuclidinol afforded the title ethers I-IV. The 2-methyl compound II (VÚFB-17 088) showed significant antihistamine activity and the 2-chloro compound III (VÚFB-17 089), having antireserpine and anticataleptic activity, proved a potential antidepressant agent.

Proteolysis of caseins and the proteose-peptone fraction of bovine milk

1983 ◽  
Vol 50 (3) ◽  
pp. 275-290 ◽  
Author(s):  
Anthony T. Andrews ◽  
Efstathios Alichanidis
Keyword(s):  
Gel Electrophoresis ◽  
Whey Proteins ◽  
Bovine Milk ◽  
Major Product ◽  
Natural Course ◽  
Pasteurized Milk ◽  
Proteose Peptone ◽  
History Of

SummaryThe proteolysis of highly purified samples of αs1-, αs2-, β-and κ-caseins by porcine plasmin and by bovine plasminogen with urokinase has been examined principally by gel electrophoresis. The resulting peptide band patterns were compared with those of total proteose-peptone (TPP) samples prepared from fresh and stored raw and pasteurized milk, and also with those obtained during the natural course of proteolysis by indigenous enzymes in milk during storage. TPP was found to contain at least 38 components detectable by a single electrophoresis run. Apart from residual traces of whey proteins and intact caseins nearly all of these components were fragments of caseins produced by indigenous plasmin, with products from the breakdown of αs1- and β-casein predominating. Over 90 % of TPP has been accounted for in this way. A fragment consisting of residues 29–105 of β-casein was isolated and characterized from both stored milk and from plasmin digests of β-casein. This fragment was a relatively major product of the natural proteolysis occurring during storage of milk, but contrary to a report in the literature it was not the same as proteose-peptone component 8-slow. Since many of the components of TPP resulted from proteolysis, the composition of TPP was found to vary according to the time and temperature of storage of the milk from which it was prepared. Thus, while the proteose-peptone fraction of milk can easily be defined operationally it cannot be rigorously defined in terms of its composition unless the history of the milk is also defined.

scholarly journals Zinc-mediated Reductive Dimerization Cyclization of Ethyl Arylmethylidenecyanoacetates in Aqueous Media

1999 ◽  
Vol 23 (7) ◽  
pp. 448-449
Author(s):  
Lei Wang ◽  
Yongmin Zhang
Keyword(s):  
Aqueous Media ◽  
Major Product ◽  
Trans Form ◽  
Reductive Dimerization

Zinc-mediated reductive dimerization–cyclization of ethyl arylmethylidenecyanoacetates occurs to give diethyl 2-amino-3-cyano-4,5-diaryl-1,3-cyclopentenedicarboxylates in moderate to good yields the trans, trans-form isomer being the major product.

scholarly journals Theoretical Insight into the Reversal of Chemoselectivity in Diels-Alder Reactions of α,β-Unsaturated Aldehydes and Ketones Catalyzed by Brønsted and Lewis Acids

Organics ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 38-49
Author(s):  
Lakhdar Benhamed ◽  
Sidi Mohamed Mekelleche ◽  
Wafaa Benchouk
Keyword(s):  
Lewis Acids ◽  
Major Product ◽  
Diels Alder ◽  
Unsaturated Ketone ◽  
Unsaturated Aldehydes ◽  
Aldehydes And Ketones ◽  
Theoretical Insight ◽  
Insight Into ◽  
Good Agreement

Experimentally, a reversal of chemoselectivity has been observed in catalyzed Diels–Alder reactions of α,β-unsaturated aldehydes (e.g., (2E)-but-2-enal) and ketones (e.g., 2-hexen-4-one) with cyclopentadiene. Indeed, using the triflimidic Brønsted acid Tf2NH as catalyst, the reaction gave a Diels–Alder adduct derived from α,β-unsaturated ketone as a major product. On the other hand, the use of tris(pentafluorophenyl)borane B(C6F5)3 bulky Lewis acid as catalyst gave mainly the cycloadduct of α,β-unsaturated aldehyde as a major product. Our aim in the present work is to put in evidence the role of the catalyst in the reversal of the chemoselectivity of the catalyzed Diels–Alder reactions of (2E)-but-2-enal and 2-Hexen-4-one with cyclopentadiene. The calculations were performed at the ωB97XD/6-311G(d,p) level of theory and the solvent effects of dichloromethane were taken into account using the PCM solvation model. The obtained results are in good agreement with experimental outcomes.

scholarly journals Prothrombin fragment 1 X 2 X 3, a major product of prothrombin activation in human plasma.

1986 ◽  
Vol 261 (28) ◽  
pp. 13210-13215 ◽  
Author(s):  
M J Rabiet ◽  
A Blashill ◽  
B Furie ◽  
B C Furie
Keyword(s):  
Human Plasma ◽  
Major Product ◽  
Prothrombin Fragment ◽  
Prothrombin Activation
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