Principles of Thesis Writing

Model Studies toward the Total Synthesis of Thebaine by an Intramolecular Cycloaddition Strategy

“…First, and as a basic proof of concept, we decided to study [4 + 2] cycloaddition of a simplified substrate 6 (Scheme 2). [12] Thus, 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 a-lithio pyridazine was converted to pyridazinylethanamine 5 by condensation with acetaldehyde followed by mesylation and displacement of the mesylate with N-methylamine. Acylation of the resulting amine 5 with but-3-enoic acid anhydride provided the amide 6 in 71 % yield.…”

“…[5] Normal or inverse electron demand intramolecular [4 + 2] cycloadditions [6] enable the construction of polycyclic scaffolds and have therefore been often used in alkaloid synthesis, namely by Padwa (benzofurane as the dienophile / furan as the diene), [7] Bodwell (indole / pyridazine), [8] Snyder (indole / tetrazine), [9] Stork (benzofuran / methoxybutadienyl), [10] Ciganek (benzofurane / pyranone) [11] and Hudlický. [5,12] Based on these reports, the implementation of pyridazines [13] in an approach to thebaine via the model compounds 1 using intramolecular Diels-Alder reaction of amide or amine [14] 2 was envisaged. Although compound 1 contains all of the thebaine carbon atoms and functionalities, it lacks the C10-C11 bond.…”