Models for incomplete nucleophilic attack on a protonated carbonyl group and electron-deficient alkenes: salts and zwitterions from 1-dimethylamino-naphthalene-8-carbaldehyde.
The X-ray crystal structures of salts and zwitterionic Knoevenagel products from 1-dimethylamino-naphthalene-8-carbaldehyde show long N-C bonds between peri-groups which provide models for incomplete nucleophilic attack on a protonated carbonyl group and electron-deficient alkenes respectively. For the salts the N-C bonds lie in the range 1.625-1.638 Å with C-OH bonds intermediate in length between single and double bonds, while for the zwitterions the N-C bonds lie in the range 1.612-1.660 Å. The structural assignment of the former is supported by solid state (13)C and (15)N NMR studies on doubly isotopically-labelled material. Several zwitterions were converted to naphtha[1,8-bc]azepines by a mechanism involving the tertiary amino effect.
School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS, UK.
Alberth
A
Lari
Matuesz B
MB
Pitak
Simon J
SJ
Coles
Gregory J
GJ
Rees
Stephen P
SP
Day
Mark E
ME
Smith
John V
JV
Hanna
John D
JD
Wallis
D000447:Aldehydes / Q000737:chemistry*; D000475:Alkenes / Q000737:chemistry*; D001381:Azepines / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D004583:Electrons; D008872:Microwaves; D008958:Models, Molecular; D015394:Molecular Structure; D009281:Naphthalenes / Q000737:chemistry*; D011522:Protons; D012492:Salts / Q000737:chemistry
C580780:1-dimethylamino-naphthalene-8-carbaldehyde; D000447:Aldehydes; D000475:Alkenes; D001381:Azepines; D009281:Naphthalenes; D011522:Protons; D012492:Salts