Accessing Tricyclic Imines Comprising a 2-Azabicyclo[2.2.2]octane Scaffold by Intramolecular Hetero-Diels–Alder Reaction of 4-Alkenyl-Substituted N-Silyl-1,4-dihydropyridines

Synthesis ◽  
2019 ◽  
Vol 51 (22) ◽  
pp. 4296-4310 ◽  
Author(s):  
Heinrich-Karl A. Rudy ◽  
Klaus T. Wanner
Keyword(s):  
Chain Length ◽  
Trifluoroacetic Acid ◽  
Acid Catalysis ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Substituted Pyridines

Tricyclic imines inheriting a 2-azabicyclo[2.2.2]octane (isoquinuclidine) scaffold were provided with high regioselectivity in moderate to very good yields by a smooth, broadly applicable intramolecular hetero-Diels–Alder reaction of various 4-ω-alkenyl-substituted 1,4-dihydropyridines (DHPs) under trifluoroacetic acid catalysis. The required­ 4,4-disubstituted 1,4-DHPs were obtained by introduction of ω-alkenyl moieties of varying chain length via diorganomagnesium reagents into the 4-position of diversely 4-substituted pyridines after prior N-activation with triisopropylsilyltriflate.

Diels-Alder Reaction Curing of Chlorobutyl Rubber by bis-Maleimides

1989 ◽  
Vol 62 (1) ◽  
pp. 42-54 ◽  
Author(s):  
K. Ho ◽  
R. Steevensz
Keyword(s):  
Zinc Oxide ◽  
Double Bond ◽  
Chain Length ◽  
Crosslinking Agent ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Electronic Distribution ◽  
Curing Agents ◽  
Chlorobutyl Rubber

Abstract Different bis-maleimides are found to have different efficiencies and reactivities in the crosslinking of CIIR in the presence of zinc oxide. Although the degrees of crosslinking of CIIR by bis-maleimides cannot be defined absolutely, some trends concerning the efficiencies of the crosslinking are evident. In general, the aromatic bis-maleimides gave higher degrees of crosslinking than the aliphatic analogs. The reactivity and crosslinking efficiency of an individual bis-maleimide is very much affected by its end-to-end chain length and its electronic distribution, resulting from the interaction between the maleimide groups, and from the interaction between the maleimide groups and other functional groups present in the same molecule. The longer the bis-maleimide molecule and the more electron deficient the maleimido double bond, the greater its effectiveness as a crosslinking agent. Other curing mechanisms, possibly including polymerization of the maleimido groups, appear to be operative when using aromatic bis-maleimides as curing agents for CIIR.

scholarly journals Lewis Acid Catalysis of a Diels−Alder Reaction in Water

1996 ◽  
Vol 118 (33) ◽  
pp. 7702-7707 ◽  
Author(s):  
Sijbren Otto ◽  
Federica Bertoncin ◽  
Jan B. F. N. Engberts
Keyword(s):  
Lewis Acid ◽  
Acid Catalysis ◽  
Alder Reaction ◽  
Diels Alder ◽  
Lewis Acid Catalysis ◽  
Diels Alder Reaction ◽  
Reaction In Water

Face-selective Diels–Alder reactions of (1R,5R)-3-formyl-6,6-dimethylbicyclo[3.1.1]hept-3-en-2-one

1994 ◽  
Vol 72 (9) ◽  
pp. 1883-1893 ◽  
Author(s):  
Hsing-Jang Liu ◽  
Yanhong Li ◽  
Eric N.C. Browne
Keyword(s):  
Low Temperatures ◽  
Boron Trifluoride ◽  
General Type ◽  
Acid Catalysis ◽  
High Selectivity ◽  
Boron Trifluoride Etherate ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Very High

The stereofacially differentiated enone aldehyde 11 was chosen to study the effects of steric and electronic influence on the Diels–Alder reaction. Under Lewis acid catalysis, 11 adds to dienes at low temperatures at a reasonable rate. Yields of desired chiral adducts are good to high with zinc chloride and boron trifluoride etherate catalysis. In all cases only products of addition to the Re face of general type 27 were observed. The regiochemistry of the adducts is exclusively that predicted by the ortho and para rules. The stereochemistry shows a very high selectivity in favour of aldehyde-endo transition state products. Unusual byproducts were also obtained in some examples and mechanisms of these unexpected reactions are discussed.

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