An examination of substituent effects on the stabilization of a silicon-selenium double bond

2002 ◽  
Vol 90 (2) ◽  
pp. 663-668 ◽  
Author(s):  
Hsin-Yi Liao ◽  
Ming-Der Su ◽  
San-Yan Chu
Keyword(s):  
Double Bond ◽  
Substituent Effects

The influence of structural modification on progesterone and androgen receptor binding of norethisterone. Correlation with nuclear magnetic resonance signals

1987 ◽  
Vol 115 (3) ◽  
pp. 406-412 ◽  
Author(s):  
H.-O. Hoppen ◽  
P. Hammann
Keyword(s):  
Androgen Receptor ◽  
Double Bond ◽  
Progesterone Receptor ◽  
Substituent Effects ◽  
Binding Affinities ◽  
Rough Approximation ◽  
Methylene Group ◽  
Nmr Signals ◽  
C Nmr

Abstract. The relative binding affinities (RBA) of eight progestogens structurally derived from 17α-ethinyl-19-nortestosterone (norethisterone) have been estimated a) for the progesterone receptor from human premenopausal endometrium and b) for the androgen receptor in human mammary carcinoma in vitro. Introduction of a methylene group at C-11, a methyl group at C-18, or a double bond between C-15 and C-16 of the norethisterone molecule increases the RBA to the progesterone receptor. As a rough approximation, the substituent effects seem to be additive. RBA to the androgen receptor follows a more complex pattern when norethisterone is structurally modified. An additional methyl at C-18 enhances affinity to the androgen receptor. The double bond between C-15 and C-16 has no effect except when introduced into desogestrel, where it reduces RBA to the lowest value in the study. The methylene group at C-11 increases androgen RBA when present as the only substituent, but reduces androgen RBA when together with any other substituent. The complete assignment of 13C-NMR signals has been achieved for all 8 steroids investigated. The 13C-resonance signal of C-17 shows a correlation with the RBA to the progesterone receptor, and with the progestogen/androgen RBA ratios.

The SN Mechanism in aromatic compounds. 25. Substituent effects of multiple-bond nitrogen.

1958 ◽  
Vol 11 (3) ◽  
pp. 302 ◽  
Author(s):  
J Miller ◽  
AJ Parker
Keyword(s):  
Double Bond ◽  
Nitrogen Atom ◽  
Nucleophilic Substitution ◽  
Benzene Ring ◽  
Aromatic Compounds ◽  
Halogen Atom ◽  
Multiple Bond ◽  
Substituent Effects ◽  
Aromatic Nucleophilic Substitution ◽  
Substituent Constants

The substituent effects in aromatic nucleophilic substitution of groups attached to the benzene ring by a multiple-bond nitrogen atom are considered. Attachment is para to a replaceable halogen atom, and generally as a 4-substituent to l-chloro-2-nitrobenzene. Comparisons with some other groups are shown. Reasons are given for the greater T effect of a triple than of a double bond. Hammett substituent constants (σ*) are computed. Those for the nitroso and diazonium groups .are the largest so far obtained for electrically neutral and cationic groups respectively. The activating power of four of the nitrogen groups in electrophilic as well as nucleophilic substitution is discussed briefly.

1,1′,3,3′-Tetraalkyl-2,2′-biperimidinylidenes: Unexpected Substituent Effects on the Reactivity of Carbon—Carbon Double Bond.

ChemInform ◽  
2003 ◽  
Vol 34 (20) ◽  
Author(s):  
Buelent Alici ◽  
Tuncer Hoekelek ◽  
Engin Cetinkaya ◽  
Bekir Cetinkaya
Keyword(s):  
Double Bond ◽  
Substituent Effects ◽  
Carbon Double Bond

scholarly journals Sequential Diels–Alder/[3,3]-sigmatropic rearrangement reactions of β-nitrostyrene with 3-methyl-1,3-pentadiene

2013 ◽  
Vol 9 ◽  
pp. 2137-2146 ◽  
Author(s):  
Peter A Wade ◽  
Alma Pipic ◽  
Matthias Zeller ◽  
Panagiota Tsetsakos
Keyword(s):  
Double Bond ◽  
Substituent Effects ◽  
Product Formation ◽  
Sigmatropic Rearrangement ◽  
Diels Alder ◽  
Initial Assessment ◽  
Concerted Mechanism ◽  
Rearrangement Process ◽  
Zwitterionic Intermediate ◽  
Nitronic Ester

The tin(IV)-catalyzed reaction of β-nitrostyrene with (E)-3-methyl-1,3-pentadiene in toluene afforded two major nitronic ester cycloadducts in 27% and 29% yield that arise from the reaction at the less substituted diene double bond. Also present were four cycloadducts from the reaction at the higher substituted diene double bond, two of which were the formal cycloadducts of (Z)-3-methyl-1,3-pentadiene. A Friedel–Crafts alkylation product from the reaction of the diene, β-nitrostyrene, and toluene was also obtained in 10% yield. The tin(IV)-catalyzed reaction of β-nitrostyrene with (Z)-3-methyl-1,3-pentadiene in dichloromethane afforded four nitronic ester cycloadducts all derived from the reaction at the higher substituted double bond. One cycloadduct was isolated in 45% yield and two others are formal adducts of the E-isomer of the diene. The product formation in these reactions is consistent with a stepwise mechanism involving a zwitterionic intermediate. The initially isolated nitronic ester cycloadducts underwent tin(IV)-catalyzed interconversion, presumably via zwitterion intermediates. Cycloadducts derived from the reaction at the less substituted double bond of (E)-3-methyl-1,3-pentadiene underwent a [3,3]-sigmatropic rearrangement on heating to afford 4-nitrocyclohexenes. Cycloadducts derived from the reaction at the higher substituted diene double bond of either diene failed to undergo a thermal rearrangement. Rates and success of the rearrangement are consistent with a concerted mechanism possessing a dipolar transition state. An initial assessment of substituent effects on the rearrangement process is presented.

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