Heterocycle stabilized carbanions. Two series of anomalous products from 1-alkyl-4,6-diphenyl-2-pyridones

Abstract

Methyl-, 1 -ethyl, and 1 -n-butyl-4,6-diphenyI-2-pyridones with lithium di-isopropylamide yield normal products with ketone and aldehydes as electrophiles, but dimeric derivatives with acid chlorides, esters, and alkyl halides. The alkylpyridones react with ethyl-and n-butyl-lithium and an electrophile to give products resulting from alkylation at the 3-and reaction with electrophile a t the 4-position. Structures are supported by spectra and reaction mechanisms disc ussed . l-REww.-4,6 J ) I P H I . S ~L -~-P Y R ~C O N E (la) with lithium compound (lc) reacted in sitzt with benzophenoce to di-isopropylaniide (1,L)A) gives a stable a-anion (Za), give the alcohol (3c) (480/6) , with P-toluoaldehyde to which undergoes clean a-alkylation on addition of give the alcohol (3d) (44%), and with methyl benzoate to e1ectrophiles.l We now show that l-alkyl-4,6-diphenyl-2-pyridonrs ( l b -4 ) when treated likewise frequently undergo anomaloiis dirnerisations in place of the expected ' I. E.

Ring lithiation of pyridones

“…(EtOH) 263 nm (log E 4.30); vmax. (Nujol) 1 640 and 1 550 cm-'; m/z 140 (M+',14), 109 (22), 83 (lo), 82 (12), and 45 (100).…”

“…6 k 7 . 2 0 ( 5 H, m, ArH), and 3.45 (3 H, s, NMe); mjz 215 ( M + ' , loo), 170 (23), 110 (22), and 77 (22).…”

“…(EtOH) 257 nm (log E 3.80); v,,,. (Nujol) 1 770, 1 645, and 1 600 cm-'; G(CDCI,) 8.10 (2 H, d, J 8 Hz, 2-H and 6-H), 7.20 ( 5 H, m, ArH), and 6.25 (2 H, d, J 8 Hz, 3-H and 5-H); m/z 215 (M", 9) 214 (63), 171 (3, 170 (39), 169 (24), 143 (3), 142 (28), 141 (52), 115 (6), 94 (22), 77 (loo), and 65 (38) (Found: M + , 215.0578. C,,H,NO, requires M , 21 5.0582).…”