4,4'-Di-tert-butylbiphenyl-Catalysed Reductive Opening of Azetidines with Lithium: A Direct Preparation of 3,N-Dilithioalkylamines

Article abstract of DOI:10.1016/S0040-4020(01)85645-3

The reaction of N-phenylazetidine 1a with an excess of lithium powder and a catalytic amount of 4,4'-di-tert-butylbiphenyl (5 molpercent) in THF at -15 deg C leads to the corresponding dianion 2a, which by treatment with different electrophiles (H2O, D2O, Bu^tCHO, PhCHO, <*>(CH2)5C<*>O, PhCH=NPh, CO2) yields, after hydrolysis with water, the expected functionalysed amines 3aa-ah.The same method applied to N-isopropyl-2-phenylazetidine 1c affords compounds 3ca-ce (electrophiles: H2O, D2O, PhCHO, Me2CO, CH2=CHCH2Br) resulting from the more stable benzylic intermediate 2c.Finally, the regiochemistry in the reductive opening of 2-methyl-N-phenylazetidine 1d followed by deuterolysis was studied: a mixture of both regioisomers 3da+3da' was obtained, the ratio being the oposite as expected according to the stability of both intermediates 2d and 2d'.