89525-44-0Relevant academic research and scientific papers
Protecting-group-free total synthesis of isoquinoline alkaloids by nickel-catalyzed annulation of o-halobenzaldimine with an alkyne as the key step
Korivi, Rajendra Prasad,Cheng, Chien-Hong
, p. 282 - 287 (2010)
An efficient short total synthesis of benzo[c]phenanthridine alkaloids including oxyavicine, oxynitidine, and oxysanguinarine is described. Thus, N-methyl-o-bromobenzaldimines 1 b-d undergo regioselective cyclization with 4-(benzo[d][1,3]dioxol-5-yl)but-3-yn-1-ol (2b) in the presence of [Ni(cod) 2] (cod = 1,5-cyclooctadiene). In situ oxidation of the resultant isoquinolinium salts gives isoquinolinone derivatives 5b-d with benzo[d][1,3]dioxol-5-yl substitution at the C3 atom and a (CH 2)2OH group at the C4 atom. Later, oxidation of the alcohol group in 5b-d to the aldehyde moiety followed by acid-catalyzed cyclization and dehydration completes the total syntheses to give oxyavicine, oxynitidine, and oxysanguinarine in 67, 65, and 60% yields, respectively. The synthesis requires four steps from o-bromobenzaldehyde derivatives. Transformations of these alkaloids to the other alkaloids in this family are also discussed herein.
Development of an intramolecular aryne ene reaction and application to the formal synthesis of (±)-crinine
Candito, David A.,Dobrovolsky, Dennis,Lautens, Mark
supporting information, p. 15572 - 15580 (2012/11/07)
A general and high yielding annulation strategy for the synthesis of various carbo- and heterocycles, based on an intramolecular aryne ene reaction is described. It was found that the geometry of the olefin is crucial to the success of the reaction, with exclusive migration of the trans-allylic-H taking place. Furthermore, the electronic nature of the aryne was found to be important to the success of the reaction. Deuterium labeling studies and DFT calculations provided insight into the reaction mechanism. The data suggests a concerted asynchronous transition state, resembling a nucleophilic attack on the aryne. This strategy was successfully applied to the formal synthesis of the ethanophenanthridine alkaloid (±)-crinine.
