Tertiary α-cyanoamines served as the precusors of iminiumions in the presence of titanium tetrachloride. Various intramolecular nucleophiles, olefinic and acetylenic, were found to produce cyclized products. The influences of ring sizes and substitutions on the double bonds were also investigated.
A tandem Diels–Alder/Mannich approach to the synthesis of AE and ABE ring analogues of Delphinium alkaloids
作者:Kirsten J. Goodall、Margaret A. Brimble、David Barker
DOI:10.1016/j.tet.2012.05.037
日期:2012.7
The one-pot TiCl4 catalysed Diels–Alder/Mannich reaction of α-cyanoaminoacrylates with 2-silyloxy-1,4-butadienes gives 6-keto-3-azabicyclo[3.3.1]nonane-1-carboxylates. Reduction of the ketone and alkylation of the resultant alcohol gives 6-alkoxy-3-azabicyclo[3.3.1]nonanes mimicking the AE rings of a number of Delphinium and Aconitum alkaloids, with the same stereochemistry as the natural products