4,4'-DI-TERT-BUTYLBIPHENYL-CATALYZED REDUCTIVE OPENING OF AZETIDINES WITH LITHIUM - A DIRECT PREPARATION OF 3,N-DILITHIOALKYLAMINES

The reaction of N-phenylazetidine 1a with an excess of lithium powder and a catalytic amount of 4,4'-ditert-butylbiphenyl (5 mol %) in THF at -15 degrees C leads to the corresponding dianion 2a, which by treatment with different electrophiles (H2O, D2O, Bu(CHO, PhCHO, (CH2)(5)CO, PhCH=NPh, CO2) yields, after hydrolysis with mater, the expected functionalysed amines 3aa-ah. The same method applied to N-isopropyl-2-phenylazetidine Ic affords compounds 3ca-ce (electrophiles: H2O, D2O, PhCHO, Me(2)CO, CH2=CHCH2Br) resulting from the more stable benzylic intermediate 2c. Finally, the regiochemistry in the reductive opening of 2-methyl-N-phenylazetidine Id 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'.