Electroorganic chemistry. 140. Electroreductively promoted intra- and intermolecular couplings of ketones with nitriles.
摘要:
Electroreduction of gamma and delta-cyano ketones in i-PrOH with Sn cathode gave alpha-hydroxy ketones and their dehydroxylated ketones as the intramolecularly coupled products. Guaiazulene, (-)-valeranone, polyquinanes, dihydrojasmone, methyl dihydrojasmonate, and rosaprostol have been synthesized by utilizing this electroreductive intramolecular coupling of gamma and delta-cyano ketones in one of the key steps. Similarly, electroreduction of a mixture of ketone and nitrile gave the corresponding intermolecularly coupled product. The product obtained by the electroreductive intermolecular coupling of (+)-dihydrocarvone with acetonitrile has been found to be the precursor of an effective chiral ligand for the enantioselective addition of diethylzinc to aldehydes.
Electroreduction of gamma and delta-cyano ketones in i-PrOH with Sn cathode gave alpha-hydroxy ketones and their dehydroxylated ketones as the intramolecularly coupled products. Guaiazulene, (-)-valeranone, polyquinanes, dihydrojasmone, methyl dihydrojasmonate, and rosaprostol have been synthesized by utilizing this electroreductive intramolecular coupling of gamma and delta-cyano ketones in one of the key steps. Similarly, electroreduction of a mixture of ketone and nitrile gave the corresponding intermolecularly coupled product. The product obtained by the electroreductive intermolecular coupling of (+)-dihydrocarvone with acetonitrile has been found to be the precursor of an effective chiral ligand for the enantioselective addition of diethylzinc to aldehydes.
Reductive radical cyclization of cyclic γ-cyanoketones promoted by samarium(II) iodide without photoirradiation
Reaction of cyclic γ-cyanoketones with 3 equiv. of SmI2 in the presence of t-BuOH as a proton source in HMPA–THF without photoirradiation gave the desired α-hydroxycycloalkanones along with overreduced ketones after hydrolysis. In the absence of t-BuOH, the formation of the overreduced ketones was depressed and the yields of the α-hydroxyketones increased, while the reaction proceeded slowly.