Reactions of thermally generated tert-butyl and di(tert-alkyl) ketyl radicals in toluene: cage effects and hydrogen transfer

1991 ◽  
Vol 56 (1) ◽  
pp. 166-175 ◽  
Author(s):  
John S. Lomas ◽  
Sylvette Briand ◽  
Dominique Fain
Keyword(s):  
Hydrogen Transfer ◽  
Tert Butyl ◽  
Cage Effects

The long and winding road to new porphycenes

2012 ◽  
Vol 16 (05n06) ◽  
pp. 589-602 ◽  
Author(s):  
Igor Czerski ◽  
Arkadiusz Listkowski ◽  
Jan Nawrocki ◽  
Natalia Urbańska ◽  
Hubert Piwoński ◽  
...  
Keyword(s):  
Fluorescence Polarization ◽  
Hydrogen Transfer ◽  
Single Molecules ◽  
Tert Butyl ◽  
Tautomeric Forms ◽  
By Products ◽  
Double Hydrogen

We describe attempts — not always successful — made over the years to improve the efficiency of porphycene synthesis and to produce novel compounds, custom-designed for specific purposes. New porphycenes are reported, some of them obtained rather unexpectedly as by-products of the planned reactions. Structure and energy computations of possible tautomeric forms in porphycenes substituted by one, two, three, and four tert-butyl groups lead to predictions regarding the kinetics and mechanisms of intramolecular double hydrogen transfer. The occurrence of tautomerization in single molecules of tert-butylsubstituted porphycenes is demonstrated by using fluorescence polarization techniques.

Asymmetric calixarene derivatives as potential hosts in chiral recognition processes

2015 ◽  
Vol 87 (4) ◽  
pp. 415-439 ◽  
Author(s):  
Catalin V. Maftei ◽  
Elena Fodor ◽  
Peter G. Jones ◽  
M. Heiko Franz ◽  
Corneliu M. Davidescu ◽  
...  
Keyword(s):  
Chiral Recognition ◽  
Hydrogen Transfer ◽  
Amide Bond ◽  
Transfer Reactions ◽  
Ester Bond ◽  
X Ray ◽  
Tert Butyl ◽  
Asymmetric Catalytic ◽  
Catalytic Hydrogen ◽  
Derivatives Of

AbstractNew chiral derivatives of 15,35,55,75-tetra-tert-butyl-1,3,5,7(1,3)-tetrabenzenacyclooctaphane-12,32,52,72-tetraol [(1); tert-butyl-calix[4]-arene] were synthesized by coupling modified chiral quinuclidines derived from the natural-product-based alkaloids quincorine and quincoridine with the calix[4]arene 1 via either an ester bond or an amide bond. X-ray analyses of two products were performed. Applications of the products in asymmetric catalytic hydrogen transfer reactions are described. A protocol is presented to multi-substitute calix[4]arene at the methylene bridges, resulting in, e.g., 2,6-carboxyl-all-tert-butyl all-methoxy-calix[4]arene.

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