Diastereoselective Tandem Addition−Cyclization Reactions of Unsaturated Tertiary Amines Initiated by Photochemical Electron Transfer (PET)

2000 ◽  
Vol 65 (25) ◽  
pp. 8690-8703 ◽  
Author(s):  
Samuel Bertrand ◽  
Norbert Hoffmann ◽  
Stéphane Humbel ◽  
Jean Pierre Pete
Keyword(s):  
Electron Transfer ◽  
Tertiary Amines ◽  
Cyclization Reactions

Efficient radical addition of tertiary amines to alkenes using photochemical electron transfer

2006 ◽  
Vol 78 (12) ◽  
pp. 2227-2246 ◽  
Author(s):  
Norbert Hoffmann ◽  
Samuel Bertrand ◽  
Siniša Marinković ◽  
Jens Pesch
Keyword(s):  
Electron Transfer ◽  
Tertiary Amine ◽  
Pyrrolizidine Alkaloids ◽  
Isotopic Labeling ◽  
Heterogeneous Photocatalysis ◽  
Radical Addition ◽  
Mechanistic Study ◽  
Tertiary Amines ◽  
Cyclization Reactions ◽  
Inorganic Semiconductors

An efficient photoinduced radical addition of tertiary amine, mainly cyclic derivatives, to electron-deficient alkenes was developed. The reaction was applied to the asymmetric synthesis of the pyrrolizidine alkaloids laburnine and isoretronecanol. The method was then optimized for the addition of a larger variety of tertiary amines, in particular acyclic ones. Radical tandem addition cyclization reactions with unsaturated tertiary amines have also been investigated. A detailed mechanistic study using isotopic labeling enabled the optimization of a corresponding reaction with N,N-dialkylaniline derivatives. The origin of the high reaction stereoselectivity achieved with menthyloxyfuranone was elucidated. The radical addition of tertiary amines was also performed with heterogeneous photocatalysis using inorganic semiconductors as sensitizers.

ChemInform Abstract: Electron-Transfer Activation. Photocyanation of Tertiary Amines.

ChemInform ◽  
2010 ◽  
Vol 22 (47) ◽  
pp. no-no
Author(s):  
J. SANTAMARIA ◽  
M. T. KADDACHI ◽  
J. RIGAUDY
Keyword(s):  
Electron Transfer ◽  
Tertiary Amines

scholarly journals Semiconductors as sensitisers for the radical addition of tertiary amines to electron deficient alkenes

2003 ◽  
Vol 5 (3) ◽  
pp. 175-182 ◽  
Author(s):  
Siniša Marinković ◽  
Norbert Hoffmann
Keyword(s):  
Electron Transfer ◽  
Organic Synthesis ◽  
Radical Reaction ◽  
Heterogeneous Photocatalysis ◽  
Radical Addition ◽  
Point Of View ◽  
Tertiary Amines ◽  
Radical Intermediate ◽  
Radical Chain ◽  
High Yields

Using heterogeneous photocatalysis, the radical addition of tertiary amines with electron deficient alkenes can be performed in high yields (up to 98%) and high facial diastereoselectivity. The photochemical induced electron transfer process initiates the radical chain reaction and inorganic semiconductors likeTiO2and ZnS were used. According to the proposed mechanism, the reaction takes place at the surface of the semiconductor and the termination step results from an interfacial electron transfer from the conduction band to the oxoallyl radical intermediate. Frequently, semiconductors are used for the mineralisation of organic compounds in wastewater. However, in this case, they are used in organic synthesis. The process can be performed in a convenient way and is particularly interesting from the ecological and economical point of view. No previous functionalization of the tertiary amines is necessary for C − C bond formation. Further on, the amines are used both as reactant and as solvent. The excess is recycled by distillation and the inexpensive sensitiser can be easily removed by filtration. In this way, products of high interest for organic synthesis are obtained by a diastereoselective radical reaction.

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