DTBB-CATALYZED LITHIATION OF 3-FUNCTIONALIZED 1-CHLOROPROPENES

reaction of different 3-chlorinated allyl amines la,b or phenylether I c with an excess of lithium powder, a catalytic amount of DTBB (5 mol %) and an electrophile [(PrCHO)-C-i, (BuCHO)-C-t, Et2CO, (CH2)(5)CO] i n THF at -78 degrees C gives, after hydrolysis with water, the expecte d Z/E mixture of the corresponding products 2. The corresponding two-s tep process at temperatures ranging between -30 and -40 degrees C [ele ctrophiles: (PrCHO)-C-i, (BuCHO)-C-t, (CH2)(5)CO] yields propargylic d erivatives 3. A mechanistic explanation for this behaviour is given. ( C) 1998 Elsevier Science Ltd. All rights reserved.