The Synthesis and Properties of Some α,β-Unsaturated Valerolactams¹

Asymmetric Total Synthesis of (+)-Apovincamine and a Formal Synthesis of (+)-Vincamine. Demonstration of a Practical “Asymmetric Linkage” between Aromatic Carboxylic Acids and Chiral Acyclic Substrates

“…Completion of the Synthesis of (+)-Apovincamine (1a) and a Formal Total Synthesis of (+)-Vincamine (2). Reduction of the diene lactam 14 by the method of Shamma and Rosenstock gave the piperidine 18 (Scheme ). Electrophilic bromination of the enamine-like double bond in 18 with 2 equiv of N -bromoacetamide provided the dibromide 19 in 67% overall yield from 14 .…”

Intramolecular Pyridone/Enyne Photocycloaddition: Partitioning of the [4 + 4] and [2 + 2] Pathways

“…The literature, however, does not support this analysis. For 3,4-dihydropyridone structures such as 19 , the UV absorption is found at λ max = 260 nm (ε ≈ 5000), and a 5,6-dihydropyridone structure as in 20 has a λ max = 250 nm (ε ≈ 1500) . These data suggest that the differences in the yield for photocycloaddition of 11 relative to 12 may lie in the 2-pyridone excited state and not the photoinstability of the [2 + 2] products.…”

“…For 3,4-dihydropyridone structures such as 19, the UV absorption is found at λ max = 260 nm (ε ≈ 5000), 8 and a 5,6-dihydropyridone structure as in 20 has a λ max = 250 nm (ε ≈ 1500). 9 These data suggest that the differences in the yield for photocycloaddition of 11 relative to 12 may lie in the 2-pyridone excited state and not the photoinstability of the [2 þ 2] products. Kaneko observed that for some pyridones, electron-deficient alkenes would undergo [2 þ 2] photocycloaddition at the 5,6-position, whereas electron-rich alkenes preferentially added to the pyridone 2,3-bond.…”

A new route for the synthesis of 5,6-dihydropyridin-2(1H)-ones, 2-pyridones and (4-hydroxy-2-oxopiperid-3-yl)pyridinium chlorides by intramolecular cyclization of N-3-oxoalkylchloroacetamide derivatives

“…[15][16][17][18] However, there are some restrictions on their synthesis such as inaccessibility of the starting reagents, low applicability of the preparation methods and difficult reaction conditions. 1,16,19,20 Therefore, it may be interesting to develop new, flexible methods which allow 5,6-dihydropyridin-2(1H)-ones to be obtained under mild conditions. We have studied the possibility of synthesising 5,6-dihydropyridin-2(1H)-ones by means of an intramolecular Wittig reaction based on N-3-oxoalkylchloroacetamides.…”