Synthesis Based on Cyclohexadienes. 5. A New Approach to the Synthesis of a-Ring Aromatic Steroids - a Formal Total Synthesis of (+/-)-Estrone

1992 ◽  
Vol 45 (1) ◽  
pp. 187 ◽  
Author(s):  
GSRS Rao ◽  
DK Banerjee ◽  
LU Devi ◽  
U Sheriff
Keyword(s):  
Methyl Ester ◽  
Total Synthesis ◽  
Methyl Ether ◽  
Michael Addition ◽  
Palladium Chloride ◽  
Magnesium Bromide ◽  
New Approach ◽  
New Strategy

A new strategy for the construction of A-ring aromatic steroids which resulted in the formal total synthesis of estrone is described. Thus reaction of the adduct (9), obtained from 1-methoxy-4-methylcyclohexa-1,4-diene and acrolein , with 3-(m-methoxypheny1) propyl -magnesium bromide followed by oxidation afforded the bicyclo [2.2.2] octene derivative (14). Acid-catalysed rearrangement of (14) followed by an intramolecular Michael addition resulted in the cis tetraenone (18) which was dehydrogenated with palladium chloride to the pentaenone (22). Li/NH3 reduction of (22) gave 3-methoxy-D-homoestra-1,3,5(10)-trien-16-one (31) which has been converted into the methyl ether (37) of marrianolic acid, and its methyl ester (38).

On-Surface Radical Oligomerisation: A New Approach to STM Tip-Induced Reactions

2018 ◽  
Author(s):  
Gaolei Zhan ◽  
Younes Makoudi ◽  
Judicael Jeannoutot ◽  
Simon Lamare ◽  
Michel Féron ◽  
...  
Keyword(s):  
Sample Surface ◽  
Scanning Tunnelling Microscope ◽  
Transfer Event ◽  
New Approach ◽  
The Past ◽  
Organic Nanostructures ◽  
Scanning Tunnelling ◽  
New Strategy ◽  
Surface Fabrication ◽  
And Control

Over the past decade, on-surface fabrication of organic nanostructures has been widely investigated for the development of molecular electronic devices, nanomachines, and new materials. Here, we introduce a new strategy to obtain alkyl oligomers in a controlled manner using on-surface radical oligomerisations that are triggered by the electrons/holes between the sample surface and the tip of a scanning tunnelling microscope. The resulting radical-mediated mechanism is substantiated by a detailed theoretical study. This electron transfer event only occurs when <i>V</i><sub>s</sub> < -3 V or <i>V</i><sub>s</sub> > + 3 V and allows access to reactive radical species under exceptionally mild conditions. This transfer can effectively ‘switch on’ a sequence leading to formation of oligomers of defined size distribution due to the on-surface confinement of reactive species. Our approach enables new ways to initiate and control radical oligomerisations with tunnelling electrons, leading to molecularly precise nanofabrication.

Stereoselective total synthesis of preclavulone-A methyl ester and its diastereomer

2004 ◽  
Vol 45 (9) ◽  
pp. 1941-1944 ◽  
Author(s):  
Hisanaka Ito ◽  
Masami Konishi ◽  
Kazuo Iguchi
Keyword(s):  
Methyl Ester ◽  
Total Synthesis

A new approach to the total synthesis of B-norsteroids

1969 ◽  
Vol 10 (15) ◽  
pp. 1207-1208 ◽  
Author(s):  
U.K. Pandit ◽  
K. de Jongen Mrs ◽  
K. Erhart ◽  
H.O. Huisman
Keyword(s):  
Total Synthesis ◽  
New Approach

A Total Synthesis of Spirastrellolide A Methyl Ester

2013 ◽  
Vol 19 (11) ◽  
pp. 3596-3608 ◽  
Author(s):  
Alexander Arlt ◽  
Stefan Benson ◽  
Saskia Schulthoff ◽  
Barbara Gabor ◽  
Alois Fürstner
Keyword(s):  
Methyl Ester ◽  
Total Synthesis ◽  
Spirastrellolide A

ChemInform Abstract: Stereocontrolled Total Synthesis of (.+-.)-Pentalenolactone P Methyl Ester.

ChemInform ◽  
2010 ◽  
Vol 23 (12) ◽  
pp. no-no
Author(s):  
H.-J. KANG ◽  
C. S. RA ◽  
L. A. PAQUETTE
Keyword(s):  
Methyl Ester ◽  
Total Synthesis
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