New Macrocyclic Ligands. VII. The Synthesis of Mixed-Donor Spiro-Linked Macrocycles

1995 ◽  
Vol 48 (12) ◽  
pp. 1917 ◽  
Author(s):  
J Kim ◽  
LF Lindoy ◽  
OA Matthews ◽  
GV Meehan ◽  
J Nachbaur ◽  
...  
Keyword(s):  
Comparative Studies ◽  
Macrocyclic Ligands ◽  
In Situ Reduction ◽  
Reduction Step ◽  
Double Ring ◽  
Single Ring ◽  
Ether Oxygen ◽  
Methylene Groups ◽  
Second Procedure

The syntheses of five new spiro -linked bis-macrocyles, incorporating four ether oxygen and four or six secondary nitrogen heteroatoms , are reported. Two strategies were employed-the first involved the condensation of a spiro tetraaldehyde with 2 equiv. of ethane-1,2-diamine or propane-1,3-diamine or 2,2′-diaminodiethylamine followed by in situ reduction of the resulting intermediate tetraimines . The second procedure began with pentaerythrityl tetraamine [C(CH2NH2)4] which was then condensed with 2 equiv. of a dialdehyde moiety in which two ether oxygen atoms, bridged by either two or three methylene groups, were incorporated in its backbone. A related in situ reduction step to that employed in the first procedure then yielded the required double-ring macrocycles. For use in comparative studies, the corresponding single-ring macrocycles were also synthesized where they had not been reported previously.

Can microwave assisted in situ reduction of supported Pt nanoparticles challenge the chemical method in controlling the dispersion profile-catalytic performance relationship?

RSC Advances ◽  
2015 ◽  
Vol 5 (67) ◽  
pp. 54460-54470 ◽  
Author(s):  
Salah A. Hassan ◽  
Heba M. Gobara ◽  
Mohamed M. Gomaa ◽  
Rasha S. Mohamed ◽  
Fikry H. Khalil
Keyword(s):  
Chemical Method ◽  
Solution Method ◽  
Silica Surface ◽  
Pt Nanoparticles ◽  
Catalytic Performance ◽  
In Situ Reduction ◽  
Reduction Step ◽  
Dispersion Profile ◽  
Microwave Assisted

In this comparative study of dispersion profile-catalytic performance relationships, Pt (of 0.3, 0.6 and 0.9 wt%) was supported on mesoporous silica surface via microwave assisted solution method or rotary chemical evaporation method in the in situ reduction step.

New Macrocyclic Ligands. XVI. Synthesis of a Series of N-Benzylated Macrocycles Incorporating N4O2-Donor Set

2003 ◽  
Vol 56 (11) ◽  
pp. 1141 ◽  
Author(s):  
Ronald R. Fenton ◽  
Leonard F. Lindoy ◽  
Jason R. Price ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Schiff Base ◽  
Single Crystal ◽  
Metal Ion ◽  
Benzyl Chloride ◽  
Macrocyclic Ligands ◽  
Ring Closure ◽  
In Situ Reduction ◽  
Macrocyclic Ring ◽  
X Ray

The synthesis of five 20-membered, N-benzylated macrocyclic ligands incorporating N4O2-donor sets and from one to three benzyl substituents for use in metal-ion recognition studies is described. The new derivatives were obtained by both benzylation of the pre-formed parent macrocycle using benzyl chloride in acetonitrile in the presence of base or, in one case, by performing macrocyclic ring closure using the appropriate N-benzylated triamine precursor by means of a bis-Schiff base condensation with the corresponding dialdehyde, followed by in situ reduction of the diamine linkages so formed. The single crystal X-ray structure of the symmetrically substituted, di-N-benzylated derivative is reported.

STUDIES ON THE AROMATISATION OF NEUTRAL STEROIDS IN PREGNANT WOMEN

1964 ◽  
Vol 45 (4) ◽  
pp. 535-559 ◽  
Author(s):  
E. Bolté ◽  
S. Mancuso ◽  
G. Eriksson ◽  
N. Wiqvist ◽  
E. Diczfalusy
Keyword(s):  
Pregnant Women ◽  
Comparative Studies ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Radioactive Material ◽  
Placental Barrier ◽  
Therapeutic Abortion ◽  
Limited Ability ◽  
Better Than

ABSTRACT In 15 cases of therapeutic abortion by laparotomy the placenta was disconnected from the foetus and perfused in situ with tracer amounts of radioactive dehydroepiandrosterone (DHA), dehydroepiandrosterone sulphate (DHAS), androst-4-ene-3,17-dione (A), testosterone (T) and 17β-oestradiol (OE2). Analysis of the placentas, perfusates and urine samples revealed an extensive aromatisation of DHA, A and T; more than 70% of the radioactive material recovered was phenolic, and at least 80 % of this phenolic material was identified as oestrone (OE1), 17β-oestradiol (OE2) and oestriol (OE3), the latter being detected only in the urine. Comparative studies indicated that A and T were aromatised somewhat better than DHA and that all three unconjugated steroids were aromatised to a much greater extent than DHAS. Radioactive OE1 and OE2 were isolated and identified in the placentas and perfusates, but no OE3, epimeric oestriols, or ring D ketols could be detected in these sources, not even when human chorionic gonadotrophin (HCG) was added to the blood prior to perfusion. Lack of placental 16-hydroxylation was also apparent when OE2 was perfused. Regardless of the precursor perfused, there was three times more OE2 than OE1 in the placenta and three times more OE1 than OE2 in the perfusate. This was also the case following perfusion with OE2. The results are interpreted as suggesting the existence in the pregnant human of a placental »barrier« limiting the passage of circulating androgen. The barrier consists of a) limited ability to transfer directly DHAS and b) an enzymic mechanism resulting in the rapid and extensive aromatisation of the important androgens DHA, A and T.

Catalytic dehydrogenation of amines to imines and the in-situ reduction of sulfoxides into sulfides

2021 ◽  
Author(s):  
Xixi Liu ◽  
Yanxin Wang ◽  
Bo Li ◽  
Bing Liu ◽  
Wei Wang ◽  
...  
Keyword(s):  
Catalytic Dehydrogenation ◽  
In Situ Reduction

Physicochemical properties of geopolymer composites with DFT calculations of in-situ reduction of graphene oxide

2021 ◽  
Author(s):  
Amun Amri ◽  
Ahmad Ainun Najib ◽  
Monita Olivia ◽  
Mohammednoor Altarawneh ◽  
Aman Syam ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Dft Calculations ◽  
Physicochemical Properties ◽  
In Situ Reduction ◽  
Geopolymer Composites
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