Synthetic Applications of Ketene Cycloadditions Lactams and Coumarins

• Main Author: Shieh, Chia Hui
• Other Authors: Brady, William Thomas
• Format: Others
• Language: English
• Published: North Texas State University 1984
• Subjects: ketene cycioaddition reactions; ketenes; ring formation; synthesizing products; Ketenes.; Ring formation (Chemistry); Coumarins.; Lactams.; Organic compounds > Synthesis.
• Online Access: https://digital.library.unt.edu/ark:/67531/metadc330680/

The objective of this study was to develop new synthetical routes to natural and industrial products utilizing ketene cycioaddition reactions. The cycioaddition of diphenylketene with α,β-unsaturated imines yields (2+2) cycioaddition products, g-lactams. However, electron donating groups, such as dimethylamine, in the 4-position of the α,β-unsaturated imines result in (4+2) cycloaddition products, ∂-lactams. Dichloroketene reacted with α,β-unsaturated imines to yield (4+2) cycloaddition products, g-lactams. Large substituents in the 4-position of a, ^-unsaturated imines resulted in a (2+2) cycioaddition product, β-lactam. The ∂-lactams derived from dichloroketene are easily dehydrochlorinated to the corresponding 2-pyridornes.