102729-88-4Relevant articles and documents
APPLICATIONS of ORGANOLITHIUM and RELATED REAGENTS in SYNTHESIS. Part V. Directed Metallation of Secondary Picolin- and Isonicotinamides. A Useful Method for the Synthesis of 2,3- and 3,4-Disubstituted Pyridines, Including Furopyridin-3(1H)-one and Furopyridine-1(3H)-one
Epsztajn, Jan,Bieniek, Adam,Plotka, Mieczyslaw W.
, p. 442 - 474 (2007/10/02)
The metallation reaction of N-methyl-, N-benzyl- and N-phenyl-amides (1a-c) and (2a-c) derived from picolinic and isonicotinic acids by BunLi in THF leading to the corresponding bis(N- and 3-)lithiated amides (3a-c) and (4a-c), are described.The N-phenylamides (anilides) (1c) and (2c), in comparison with the other aliphatic derivatives, demonstrate greater abilities to direct ortho lithiation at the 3-position of the pyridine ring, and give with very good yields bis(N- and 3-)lithiated anilides (3c) and (4c), respectively.The N-benzylamides (1b) and (2b) are ortho metallated under kinetic control at -78 deg C to form the bis(N- and 3-)lithiated benzylamides (3b) and (4b), but the organometallic intermediates rearrange at room temperature to give the thermodynamically more stable bis(N- and α-)lithiated amides (3g) and (4g) (benzyl-type anions).The generated carbanions (3c), (4c), (3g) and (4g) were trapped by a variety of electrophiles (e.g. alkyl halides and aldehydes).The synthesis of furopyridin-3(1H)-one (18) and furopyridin-(3H)-one (19) is included.
