The Rates and Products of Addition of 4-Chlorobenzenesulfenyl Chloride to a Series of Side Chain Methyl Substituted Styrenes

1974 ◽  
Vol 52 (9) ◽  
pp. 1807-1812 ◽  
Author(s):  
George H. Schmid ◽  
Dennis G. Garratt
Keyword(s):  
Steric Hindrance ◽  
Side Chain ◽  
Methyl Groups ◽  
Methyl Group

The rates of addition and the product compositions have been determined for the addition of 4-chlorobenzenesulfenyl chloride to a series of seven side chain methyl substituted styrenes in 1,1,2,2-tetrachloroethane at 25°. Unlike the addition to the corresponding series of methylated ethylenes, the effect of the methyl groups is not cumulative. The effect of the methyl groups depends upon whether or not the β-methyl group is cis to the phenyl. When it is cis, the rate of addition is decreased compared to styrene and substitution of additional methyl groups has only a small effect on the rate of addition. In compounds lacking a cis-β-methyl group the rate of addition more closely resembles that for addition to the methylated ethylenes. Steric hindrance between the cis-methyl and phenyl groups is believed to be the cause of this difference in behavior between the ethylene and styrene series.

scholarly journals Stereochemistry of the incorporation of valine methyl groups into methylene groups in cephalosporin C.

1984 ◽  
Vol 222 (3) ◽  
pp. 777-788 ◽  
Author(s):  
C P Pang ◽  
R L White ◽  
E P Abraham ◽  
D H G Crout ◽  
M Lutstorf ◽  
...  
Keyword(s):  
Side Chain ◽  
Methyl Groups ◽  
Cephalosporin C ◽  
Cephalosporium Acremonium ◽  
Methyl Group ◽  
Methylene Groups ◽  
Methylene Group

‘Chiral methyl valines’, i.e. samples of valine labelled stereospecifically in the methyl groups with 2H and 3H, were incorporated into cephalosporin C by a suspension of washed cells of Cephalosporium acremonium. Analysis by 3H n.m.r. of the cephalosporin C produced showed that the conversion of the 3-pro-S-methyl group of valine into the acetoxymethyl side-chain was a highly stereospecific process. By contrast, conversion of the 3-pro-R-methyl group into the endocyclic methylene group of the dihydrothiazine ring was shown to proceed by a non-stereospecific process.

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.

scholarly journals Effect of side-chain length in lignin model compound on MnO2 oxidation: comparison of oxidations between C6-C2- and C6-C1-type compounds

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Shirong Sun ◽  
Tomoya Yokoyama
Keyword(s):  
Isotope Effects ◽  
Aromatic Nucleus ◽  
Side Chain ◽  
Direct Oxidation ◽  
Initial Oxidation ◽  
Methyl Group ◽  
Lignin Model Compound ◽  
Oxidation Rates ◽  
Kinetic Isotope ◽  
Lignin Model

AbstractMonomeric C6-C2-type lignin model compounds with a p-hydroxyphenyl (H), guaiacyl (G), syringyl (S), or p-ethylphenyl (E) nucleus (1-phenylethanol derivatives) were individually oxidized by MnO2 at a pH of 1.5 and room temperature. The results were compared with those of the corresponding C6-C1-type benzyl alcohol derivatives obtained in our recent report to examine the effect of the presence of the β-methyl group on the oxidation. The presence decelerated the oxidation regardless of the type of aromatic nucleus, although it did not change the order of the oxidation rates: G > S >> H > E. This deceleration results from the steric factor of the β-methyl group in the C6-C2-type compounds. The MnO2 oxidations of the corresponding C6-C2-type compounds deuterated at their α-(benzyl)positions showed that the magnitudes of the kinetic isotope effects are smaller than those observed in the oxidations of the corresponding C6-C1-type compounds, regardless of the type of aromatic nucleus. These smaller magnitudes suggest that the presence of the β-methyl group shifts the initial oxidation mode of MnO2 from direct oxidation of the benzyl position to one-electron oxidation of the aromatic nucleus. Only the S-type compounds afforded products via degradation of the aromatic nuclei.

Net charges and valence AO's in the methylamines; the hydrogen basis set and the properties of nitrogen

1985 ◽  
Vol 63 (7) ◽  
pp. 1487-1491 ◽  
Author(s):  
Giuseppe Del Re ◽  
Sándor Fliszár ◽  
Michel Comeau ◽  
Claude Mijoule
Keyword(s):  
Basis Set ◽  
Basis Sets ◽  
Methyl Groups ◽  
Extended Form ◽  
Amine Nitrogen ◽  
Methyl Group ◽  
Net Charges ◽  
Extended Basis

Net charges and valence AO's for ammonia, methylamine, dimethylamine, and trimethylamine were calculated using extended basis sets. Superposition effects, evaluated by replacing Pople's standard 6-31G* basis by an extended form in which the basis of the ammonia H atoms and of the methyl groups of trimethylamine are retained in the treatment of each molecule, indicate that the quality of the treatment of amine nitrogen atoms is strongly dependent on the number of methyl groups. A new, augmented basis is proposed for the hydrogens, which appears to be reasonably well balanced: comparison with familiar (e.g., 6-31G*) calculations illustrates in what manner the treatment of nitrogen is worsened when even just one methyl group is replaced by hydrogen unless the impoverishment of the basis is suitably taken care of.

The Preparation and Properties of Some Cyclic β-Diketone Diimines

1973 ◽  
Vol 51 (4) ◽  
pp. 505-513 ◽  
Author(s):  
Kenneth Charles Moss ◽  
Frank Price Robinson
Keyword(s):  
Spectral Data ◽  
Schiff Bases ◽  
Steric Hindrance ◽  
Condensation Reaction ◽  
Side Chain ◽  
Mass Spectral Data ◽  
Mass Spectral ◽  
Aliphatic Diamines

The condensation reaction between a series of aliphatic diamines and a series of five- and six-membered cyclic β-diketones to form Schiff bases was investigated. Mass spectral data show that reaction occurred on the side-chain carbonyl except where steric hindrance forced condensation to occur on the ring carbonyl. N.m.r. studies show that these Schiff bases exist primarily in the ketamine form in solution, irrespective of the solvent. I.r. data confirm this. The preparation of a number of Cu(II) and Ni(II) complexes from some of the ligands is also described.

Synthesis of Side-Chain Locked Analogs of 1α,25-Dihydroxyvitamin D3 Bearing a C17 Methyl Group

2018 ◽  
Vol 20 (9) ◽  
pp. 2641-2644 ◽  
Author(s):  
Rita Sigüeiro ◽  
Miguel A. Maestro ◽  
Antonio Mouriño
Keyword(s):  
Side Chain ◽  
Dihydroxyvitamin D3 ◽  
Methyl Group

Transition metal-free C(sp3)–H bond coupling among three methyl groups

2017 ◽  
Vol 53 (38) ◽  
pp. 5346-5349 ◽  
Author(s):  
Yufeng Liu ◽  
Xi Zhan ◽  
Pengyi Ji ◽  
Jingwen Xu ◽  
Qiang Liu ◽  
...  
Keyword(s):  
Transition Metal ◽  
Methyl Groups ◽  
Methyl Ketones ◽  
Reaction Conditions ◽  
Methyl Group ◽  
Metal Free

A coupling of multiple C(sp3)–H bonds of the methyl group in methyl ketones with dimethyl sulfoxides was developed under transition metal-free reaction conditions.

scholarly journals Modulation of Methyl Group Metabolism by Streptozotocin-induced Diabetes and All-trans-retinoic Acid

2004 ◽  
Vol 279 (44) ◽  
pp. 45708-45712 ◽  
Author(s):  
Kristin M. Nieman ◽  
Matthew J. Rowling ◽  
Timothy A. Garrow ◽  
Kevin L. Schalinske
Keyword(s):  
Retinoic Acid ◽  
Diabetic Rats ◽  
Significant Decline ◽  
Methionine Synthase ◽  
Methyl Groups ◽  
Culture Studies ◽  
Methyl Group ◽  
Trans Retinoic Acid ◽  
All Trans Retinoic Acid ◽  
Streptozotocin Induced Diabetes

The hepatic enzyme glycineN-methyltransferase (GNMT) plays a major role in the control of methyl group and homocysteine metabolism. Because disruption of these vital pathways is associated with numerous pathologies, understanding GNMT control is important for evaluating methyl group regulation. Recently, gluconeogenic conditions have been shown to modulate homocysteine metabolism and treatment with glucocorticoids and/or all-trans-retinoic acid (RA)-induced active GNMT protein, thereby leading to methyl group loss. This study was conducted to determine the effect of diabetes, alone and in combination with RA, on GNMT regulation. Diabetes and RA increased GNMT activity 87 and 148%, respectively. Moreover, the induction of GNMT activity by diabetes and RA was reflected in its abundance. Cell culture studies demonstrated that pretreatment with insulin prevented GNMT induction by both RA and dexamethasone. There was a significant decline in homocysteine concentrations in diabetic rats, owing in part to a 38% increase in the abundance of the transsulfuration enzyme cystathionine β-synthase; treatment of diabetic rats with RA prevented cystathionine β-synthase induction. A diabetic state also increased the activity of the folate-independent homocysteine remethylation enzyme betaine-homocysteineS-methyltransferase, whereas the activity of the folate-dependent enzyme methionine synthase was diminished 52%. In contrast, RA treatment attenuated the streptozotocin-mediated increase in betaine-homocysteineS-methyltransferase, whereas methionine synthase activity remained diminished. These results indicate that both a diabetic condition and RA treatment have marked effects on the metabolism of methyl groups and homocysteine, a finding that may have significant implications for diabetics and their potential sensitivity to retinoids.

Extractives of Australian timbers. X. Autoxidation and other reactions of the conjugated side-chain of eberlin lactone. Isolation of a new isomer of ebelin lactone

1970 ◽  
Vol 23 (10) ◽  
pp. 2085 ◽  
Author(s):  
RA Eade ◽  
J Ellis ◽  
JS Shannon ◽  
HV Simes ◽  
JJH Simes
Keyword(s):  
Double Bond ◽  
Solid State ◽  
Osmium Tetroxide ◽  
Side Chain ◽  
Methyl Groups ◽  
Stepwise Manner ◽  
Terminal Double Bond ◽  
Conjugated Triene

The conjugated triene side-chain of ebelin lactone has been degraded in a stepwise manner using osmium tetroxide. A new isomer of ebelin lactone has been isolated from the sapogenin mixture and has been assigned the structure (9) in which the 25(26) double bond has the cis configuration. Autoxidation of ebelin lactone in the solid state yields a mixture from which three compounds have been isolated and identified; all three arise from oxidation of the side-chain at the terminal double bond and methyl groups.

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