Amines, photochemistry

Three techniques have been utilized to promote generation of an azomethine ylid from bis(trimethylsilmethyl)amines photochemistry, chemistry with silver fluoride and electrochemistry. 

Steroidal Alkaloids and Amines Synthesis, Reactions, and Transformations of Steroidal Amines Photochemistry... 

The photochemistry of linearly conjugated 2,4-cyclohexadiene-l-ones (e.g. 4) has been studied extensively7. These linearly conjugated systems generally photorearrange to a (Z)-dienylketene 5 (equation 1) this process is usually reversible, so that in the absence of a nucleophile little change is observed. In the presence of amines or alcohols, however, amides and esters are typically isolated. In the presence of weaker nucleophiles a slow formation of phenol derived products is usually observed. 

The SET between amine and acceptor may be enhanced by photoexcitation and may lead to the formation of exciplexes2 or molecular complex with charge transfer character3. The photochemistry between aromatic acceptors and amines via the exciplexes has been discussed earlier (Scheme l)4. 

The importance of tertiary amines in the photochemically induced electron transfer reactions has also been addressed5. Direct irradiation of aromatic or aliphatic amines often leads to the scission of C—N, N—H or C—H bonds that lead to the subsequent chemical reactions by radical pathways6. In this section, photochemical reactions of amines reported since 1978 will be considered with emphasis on photoinduced electron transfer. Photochemical reactions of inorganic and organometallic compounds will not be included unless photochemistry of amine moieties is the primary interest. 

Photochemistry of amines and amino compounds folded conformations of the singlet exciplex intermediates in non-polar solvents31. 

Earlier reviews on the photochemistry of unsatured ketones and amines are available39,40. The photoreactions of a,/i-unsaturated carbonyl compounds in the presence of amines have been reported to yield 1 1 amine adducts32,33 as well as photoreduction... 

The effect of an a-silyl group attached to tertiary amine on 2-cyclohexenone photochemistry has been clarified by Mariano s group42,43, who illustrates the importance of... 

Substituent effects on benzene photochemistry in the presence of amines are described53 in equations 19-21. The a-C—H of an amine is shown to add photolytically to the 2,5-positions of toluene (equation 19). In contrast, trifluoro-substituted benzene was excited to react with trimethylamine to give 50 and 52 by a side-chain substitution. This chemistry arose from facile defluorination of the anion radicals of 49 and 51. 

Intramolecular secondary aminostyrenes 95-97 were also studied100. iV-2,2-Trimethyl-3-phenyl-3-buten-l-amine 95 was irradiated to obtain the elimination product 98 (equation 29). Irradiation of Af-methyl-4-phenyM-penten-l-amine 96 results in a single product 99 in 80% yield by GC analysis (equation 30). Similarily, irradiation of iV-methyl-5-phenyl-5-hexen-l -amine 97 results in the formation of a single product 100 in 70% yield (equation 31). The photochemistry of the (aminopropyl) indene 101 is also similar (equation 32). 

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