408330-92-7Relevant academic research and scientific papers
Bioinspired Radical Stetter Reaction: Radical Umpolung Enabled by Ion-Pair Photocatalysis
Morack, Tobias,Mück-Lichtenfeld, Christian,Gilmour, Ryan
, p. 1208 - 1212 (2019)
A bioinspired, intermolecular radical Stetter reaction of α-keto acids and aldehydes is disclosed that is contingent on a formal “radical umpolung” concept. Enabled by secondary amine activation, electrostatic recognition ensures that the α-ketocarboxylic acids, which function as latent acyl radicals, are proximal to the in situ generated iminium salts. This photoactive contact ion pair is an electron donor–acceptor (EDA) complex, and undergoes facile single electron transfer (SET) and rapid decarboxylation prior to radical–radical recombination. Importantly, decarbonylation is mitigated by this strategy. The initial computational validation on which the process is predicated matches closely with experiment. Synergising organo- and photocatalysis activation principles finally expands the mechanistic and synthetic scope of the classic Stetter reaction to include α,β-unsaturated aldehydes as acceptors.
Reductive lithiation of cyclic benzofused ethers: A source of oxygen-functionalised organolithium compounds
Yus, Miguel,Foubelo, Francisco,Ferrández, José V,Bachki, Abderrazak
, p. 4907 - 4915 (2007/10/03)
The reaction of 2,3-dihydrobenzofuran (1) with lithium and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB, 5%) in THF at 0°C for 1.5h, followed by addition of an electrophile [E+=H2O, tBuCHO, PhCH2CHO, Ph(CH2)2CHO, PhCHO, furfural, Me2CO, Et2CO, cyclopentanone, cyclohexanone, cyclooctanone, (-)-menthone] in THF at -78°C gives, after hydrolysis, compounds 3. Some diols 3 are easily transformed into 2-substituted chromans 6 under acidic reaction conditions. The reductive lithiation of chroman (7) at 20°C for 3h leads exclusively to the intermediate 8, which is formed through a dearylation process, and isomerises to the apparently more stable benzylic intermediate 9. The reaction of these intermediates with different electrophiles {E+=tBuCHO, PhCHO, furfural, Me2CO, [CH3(CH2)4]2CO, cyclopentanone, cyclohexanone, (-)-menthone, Ph2CO}, at -78°C in THF leads, after hydrolysis, to a mixture of regioisomers 10 and 11. The reaction of 2,3-benzofuran (12) with an excess of lithium and a catalytic amount of DTBB (5%) in THF at 0°C for 45min leads to dianionic intermediate 13 through a dealkylation process, which after hydrolysis gives 2-vinylphenol 14. In the case of 4H-chromene (15), reductive opening is performed at 20°C for 45min, a mixture of dearylation and dealkylation intermediates 16 and 17, respectively, is obtained (2:1 ratio) giving, after hydrolysis, 3-phenylpropanal (18) and 2-allylphenol (19).
BASE INDUCED REACTION OF SILACYCLOBUTANE WITH ALDEHYDE OR EPOXIDE
Takeyama, Yoshihiro,Oshima, Koichiro,Utimoto, Kiitiro
, p. 6059 - 6062 (2007/10/02)
The reaction of silacyclobutane with benzaldehyde in the presence of a catalytic amount of potassium t-butoxide gave six-membered cyclic silyl ether.Meanwhile, treatment of a mixture of silacyclobutane and epoxide with lithium diisopropylamide provided si
