Preparation of <i>Z</i>-α,β-Unsaturated Diazoketones from Aldehydes. Application in the Construction of Substituted Dihydropyridin-3-ones
作者:Isac G. Rosset、Antonio C. B. Burtoloso
DOI:10.1021/jo401191s
日期:2013.9.20
The stereoselective preparation of α,β-unsaturateddiazoketones with Z geometry is described from aldehydes and a new olefination reagent. When prepared from amino aldehydes, these diazoketones could be converted to substituted dihydropyridin-3-ones in just one step, after an intramolecular N–H insertion reaction. The straightforward synthesis of a natural trihydroxylated piperidine demonstrates the
1,6-Dihydro-3(2H)-pyridinones. VI. Introduction of an amidocarbonylmethyl chain at C-4 of the 1,6-dihydro-3(2H)-pyridinone nucleus via photochemical (2+2) cycloaddition reaction.
Photochemical reaction of N-substituted 1, 6-dihydro-3 (2H)-pyridinones (1) with vinyl acetate resulted in predominant formation of head-to-tail adducts with small amounts of head-to-head adducts. The head-to-tail adduct derivatives (22 and 30) were transformed into lactones (24 and 34), which were further derived to the 4-N, N-dimethyl-carbamoylmethyl-1, 6-dihydro-3 (2H)-pyridinones (2a and 2b, respectively).
The allyl alcohol (11) derived from the dihydropyridinone (8) by a few steps was transformed into the ester (15) via the Claisen rearrangement, oxidation, esterification, and then hydrogenation. N-Chlorination of 15 followed by a basic hydrolysis afforded the lactone (3) exclusively which was converted into (±)-eburnamonine (1) by the known sequence.